Device for controlling suspension shock absorbers of vehicles based upon phantom substitute therefor

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the art of vehicle suspension, and more particularly, to a device for controlling the damping coefficients of shock absorbers provided between a body of a four wheeled vehicle and the wheels thereof by constructing a phantom damping system substantially equivalent to the damping system provided by the actual shock absorbers.

2. Description of the Prior Art

In the art of the vehicle suspension, it is already known to variably control the damping coefficients of the shock absorbers incorporated therein so that a more desirable suspension performance is available.

For example, when the damping coefficient of a shock absorber disposed in parallel with a suspension spring supporting the vehicle body at a corresponding portion thereof on a wheel is variably controlled to be proportional to a ratio of the vertically stroking velocity of the corresponding body portion to the difference between the vertically stroking velocity of the corresponding body portion and the vertically stroking velocity of the wheel, the shock absorber can be imagined as acting between the vehicle body and a phantom stationary overhead construction, as generally called “sky hook damper”.

If the shock absorber for the vehicle body could act against a stationary overhead construction, the stability performance of the vehicle body would of course be much improved, because the end of the shock absorber opposite to the vehicle body would no longer fluctuate as it actually does together with the wheel along the road surface in the actual construction.

SUMMARY OF THE INVENTION

On the other hand, when the four wheeled vehicles turn, the vehicles would become more stable against the turn and a rolling due to the turn if the mass center or the center of gravity of the vehicle body could be lowered.

In view of the above, it is a primary object of the present invention to provide a device for controlling the damping coefficients of those shock absorbers mounted in the suspension of a four wheeled vehicle in such an ordinary arrangement that each acts between each wheel and a corresponding portion of the vehicle body in parallel with a corresponding suspension spring, so that the center of gravity of the vehicle body is lowered during a turn running according to the art of constructing a phantom damping system by the actual shock absorbers.

According to the present invention, such a primary object is accomplished by a device for controlling damping coefficients of shock absorbers of a four wheeled vehicle having a vehicle body, front left, front right, rear left and rear right wheels each supporting the vehicle body at a corresponding portion thereof, and the shock absorbers each acting between each of the wheels and the corresponding portion of the vehicle body, comprising:

means for constructing a phantom damping system composed of a phantom side shock absorber disposed vertically at a lateral inside of a turn running of the vehicle to have a lower end movable along a ground surface together with the vehicle and an upper end vertically movable relative to the lower end with a first phantom damping coefficient therebetween, and a phantom angular shock absorber arranged to act between the upper end of the phantom side shock absorber and the vehicle body with a second phantom damping coefficient therebetween, such that the phantom damping system provides the vehicle body with a substantially same phantom vertical damping force against a vertical movement of the vehicle body and a substantially same phantom angular damping moment against a rolling angular movement of the vehicle body as the shock absorbers acting between the wheels and the corresponding portions of the vehicle body during a rolling of the vehicle body due to the turn running of the vehicle;

means for calculating values of at least the first and second phantom damping coefficients for obtaining an optimum rolling performance of the vehicle body by the phantom damping system during the turn running of the vehicle; and

means for controlling the damping coefficients of the shock absorbers acting between the wheels and the corresponding portions of the vehicle body based upon the calculated values of the first and second phantom damping coefficients.

When the phantom damping system is so constructed as described above, the vehicle body will be provided with a substantially same damping effect by the phantom side and angular shock absorbers as that provided by the shock absorbers acting between the wheels and the corresponding portions of the vehicle body against a vertical movement as well as against a rolling movement due to a turn running of the vehicle.

Further, in the rolling of the vehicle body damped by the shock absorbers acting between the wheels and the corresponding portions of the vehicle body, the vehicle body will roll around a roll center generally vertically aligned with the mass center of the vehicle body and substantially maintained at a constant height, because the vertical forces generated in the left side and the right side of the suspension system by a rolling of the vehicle body will generally balance in the vertical direction.

However, the vehicle body damped by the above-mentioned phantom damping system rolls around the pivot point of the phantom angular shock absorber connected with the upper end of the phantom side shock absorber positioned at the lateral inside of the turn running of the vehicle. As will be appreciated from the detailed descriptions made hereinbelow, the condition that the vertically disposed phantom side shock absorber, and therefore the upper end thereof, is positioned at the lateral inside of the turn running of the vehicle means that a vertically disposed central axis of the phantom side shock absorber is positioned at a concave side of a phantom curved trace drawn by the center of gravity or the mass center of the vehicle body of the turn running vehicle. Therefore, the mass center of the vehicle body damped by the above-mentioned phantom damping system lowers according to a rolling thereof due to a turn running of the vehicle.

The basic principle of the damping coefficient control according to the present invention will be described with reference to

FIGS. 1 and 2

.

Referring to

FIG. 1

showing a standard skeleton model of the suspension system of a four wheeled vehicle from a back thereof, a vehicle body

110

is supported by left and right wheels

112

L and

112

R via a pair of parallel combinations of left and right suspension springs

114

L and

114

R and left and right shock absorbers

116

L and

116

R, respectively. The shock absorbers

116

L and

116

R correspond to a pair of shock absorbers

22

FL and

22

FR or a pair of shock absorbers

22

RL and

22

RR described hereinbelow with reference to

FIG. 4

, and are each of a variable type in which its damping coefficient is variably controllable by a control signal supplied from a controller such as electric control means

24

of

FIG. 4. 118

is the center of gravity or mass center of the vehicle body

110

. It is herein assumed that the vehicle is making a left turn, so that the left side of the vehicle is an inside of the turn, while the right side of the vehicle is an outside of the turn.

The roll motion of the vehicle body supported by such a suspension system is expressed with regard to a movement in the vertical direction and a rotation around the mass center

118

as follows:

\begin{matrix} M (\frac{\ddot{X} in + \ddot{X} out}{2}) = KXin + KXout + Cin \dot{X} in + Cout \dot{Xout} & (1) \\ I \ddot{Ψ} = \frac{W}{2} KXin - \frac{W}{2} KXout + \frac{W}{2} Cin \dot{X} in - \frac{W}{2} Cout \dot{X} out & (2) \end{matrix}

wherein M and I are the mass and the inertial moment of the vehicle body

110

around the mass center

118

thereof, respectively, Xin and Xout are vertical shiftings of inside (left side) and outside (right side) portions of the vehicle body vertically above the inside and outside wheels

112

L and

112

R relative thereto, respectively, to be positive toward downward, Ψ is a roll angle of the vehicle body around the mass center

118

to be positive in the counter-clockwise direction as viewed in

FIG. 1

, K is a spring constant common to the inside and outside springs

114

L and

114

R, Cin and Cout are damping coefficients of the inside and outside shock absorbers

116

L and

116

R, respectively, and W is the wheel tread.

FIG. 2

is a skeleton model similar to

FIG. 1

, showing a vehicle suspension system incorporating a phantom side shock absorber

122

and a phantom angular shock absorber

124

instead of the left side and right side shock absorbers

116

L and

116

R shown in FIG.

1

. The lower end of the phantom side shock absorber

122

is assumed to move along the ground surface in parallel with the wheels

112

L and

112

R by a phantom side wheel

120

. In

FIG. 2

, the other portions corresponding to those shown in

FIG. 1

are designated by the same reference numerals as in FIG.

1

and are assumed to operate in the same manner as in FIG.

1

.

The motions of such a suspension system with regard to a vertical movement and a rotation around the mass center

118

are expressed as follows:

\begin{matrix} M (\frac{\ddot{X} in + \ddot{X} out}{2}) = KXin + KXout + (\frac{LCg}{W} + \frac{Cg}{2}) \dot{X} in + (- \frac{LCg}{W} + \frac{Cg}{2}) \dot{X} out & (3) \\ I \ddot{Ψ} = \frac{W}{2} KXin - \frac{W}{2} KXout + (\frac{LCg}{W} + \frac{Cg}{2}) \dot{X} inL + (- \frac{LCg}{W} + \frac{Cg}{2}) \dot{X} outL + \frac{W}{2} Ca \dot{X} in - \frac{W}{2} Ca \dot{X} out & (4) \end{matrix}

wherein, in addition to those defined for equations 1 and 2, Cg and Ca are damping coefficients of the phantom side and angular shock absorbers

122

and

124

, respectively, and L is a lateral distance of the phantom side shock absorber

122

from the mass center

118

.

By denoting WCa/2 as Cn, equation 4 is rewritten as follows:

\begin{matrix} I \ddot{Ψ} = \frac{W}{2} KXin - \frac{W}{2} KXout + (\frac{LCg}{W} + \frac{Cg}{2}) \dot{X} inL + (- \frac{LCg}{W} + \frac{Cg}{2}) \dot{X} outL + Cn (\dot{X} in - \dot{X} out) & (5) \end{matrix}

Therefore, if such conditions as set out below in equations 6 and 7 are ensured, the suspension system of

FIG. 1

will operate to be substantially equivalent to that of

FIG. 2

with respect to vertical and rolling movements of the vehicle body:

\begin{matrix} (\frac{LCg}{W} + \frac{Cg}{2}) \dot{X} in + (- \frac{LCg}{W} + \frac{Cg}{2}) \dot{X} out = Cin \dot{X} in + Cout \dot{X} out & (6) \\ (\frac{LCg}{W} + \frac{Cg}{2}) \dot{X} inL + (- \frac{LCg}{W} + \frac{Cg}{2}) \dot{X} outL + Cn (\dot{X} in - \dot{X} out) = \frac{W}{2} Cin \dot{X} in - \frac{W}{2} Cout \dot{X} out & (7) \end{matrix}

By denoting Cn/L as Cm, equation 7 is further rewritten as follows:

\begin{matrix} (\frac{LCg}{W} + \frac{Cg}{2}) \dot{X} in + (- \frac{LCg}{W} + \frac{Cg}{2}) \dot{X} out + Cm (\dot{X} in - \dot{X} out) = \frac{W}{2 L} Cin \dot{X} in - \frac{W}{2 L} Cout \dot{X} out & (8) \end{matrix}

By denoting T as follows,

\begin{matrix} (\frac{LCg}{W} + \frac{Cg}{2}) \dot{X} in + (- \frac{LCg}{W} + \frac{Cg}{2}) \dot{X} out = T & (9) \end{matrix}

equations 6 and 8 are rewritten as follow:

\begin{matrix} T = Cin \dot{X} in + Cout \dot{X} out & (10) \\ T + Cm (\dot{X} in - \dot{X} out) = \frac{W}{2 L} Cin \dot{X} in - \frac{W}{2 L} Cout \dot{X} out & (11) \end{matrix}

Equation 11 is further rewritten as follows:

\begin{matrix} \frac{2 TL}{W} + \frac{2 L}{W} Cm (\dot{X} in - \dot{X} out) = Cin \dot{X} in + Cout \dot{X} & (12) \end{matrix}

By adding equations 10 and 12 with one another, the following equation is obtained:

\begin{matrix} T + \frac{2 TL}{W} + \frac{2 L}{W} Cm (\dot{X} in - \dot{X} out) = 2 Cin \dot{X} in & (13) \end{matrix}

Since Cm=Cn/L and Cn=WCa/2, equation 13 is rewritten as follows:

\begin{matrix} T + \frac{2 TL}{W} + Ca (\dot{X} in - \dot{X} out) = 2 Cin \dot{X} in & (14) \end{matrix}

Therefore, the damping coefficient Cin of the inside shock absorber

116

L to let the suspension system of

FIG. 1

operate to be equivalent to that of

FIG. 2

is obtained as follows:

\begin{matrix} \begin{matrix} Cin = {T + \frac{2 TL}{W} + Ca (\dot{X} in - \dot{X} out)} / 2 \dot{X} in \\ = (\frac{T}{2} + \frac{TL}{W}) / \dot{X} in + \frac{Ca}{2} (1 - \frac{\dot{X} out}{\dot{X} in}) \\ = \frac{T}{2 W} (W + 2 L) / \dot{X} in + \frac{Ca}{2} (1 - \frac{\dot{X} out}{\dot{X} in}) \end{matrix} & (15) \end{matrix}

Further, by substituting Cin of equation 15 for that of equation 10, the damping coefficient Cout of the outside shock absorber

116

L to let the suspension system of

FIG. 1

operate to be equivalent to that of

FIG. 2

is obtained as follows:

\begin{matrix} T = \frac{T}{2 W} (W + 2 L) + \frac{Ca}{2} (\dot{X} in - \dot{X} out) + C out \dot{X} out & (16) \\ \begin{matrix} C out \dot{X} out = T - \frac{T}{2 W} (W + 2 L) - \frac{Ca}{2} (\dot{X} in - \dot{X} out) \\ = \frac{T}{2 W} (2 W - W - 2 L) - \frac{Ca}{2} (\dot{X} in - \dot{X} out) \end{matrix} & (17) \\ C out = \frac{T}{2 W} (W - 2 L) / \dot{X} out - \frac{Ca}{2} (\frac{\dot{X} in}{\dot{X} out} - 1) & (18) \end{matrix}

The formulae of Cin and Cout by equations 15 and 18 are further rewritten as follows:

\begin{matrix} C in = \frac{T}{2 W \dot{X} in} (W + 2 L) + \frac{Ca}{2} (1 - \frac{\dot{X} out}{\dot{X} in}) & (19) \\ C out = \frac{T}{2 W \dot{X} out} (W - 2 L) + \frac{Ca}{2} (1 - \frac{\dot{X} in}{\dot{X} out}) & (20) \end{matrix}

Therefore, by controlling the damping coefficients of the inside and outside shock absorbers

116

L and

116

R as modified from the phantom damping coefficients Cg and Ca as expressed by equations 19 and 20 according to the change rates of Xin and Xout, the suspension system of

FIG. 1

will operate as if it were the suspension system of

FIG. 2

, so that, when the vehicle body rolls due to a turn running of the vehicle, the vehicle body rolls around the pivot point P in the connection between the upper end of the phantom side shock absorber

122

and the phantom angular shock absorber

124

, thereby more lowering the height of the mass center

118

according to a more rolling. Of course, the phantom damping coefficients Cg and Ca may be controlled in any appropriate manner according to any control concept separate from the inventive concept of the present invention.

The above-mentioned phantom damping system may be applied separately to a pair of front wheels and a pair of rear wheels as shown in

FIGS. 3A and 3B

. In such a case, by discriminating the parameters particular to the front and rear suspensions by suffixes “f” and “r”, respectively, the following equations 24 and 25 are obtained, corresponding to equation 9:

\begin{matrix} (\frac{LCg}{W} + \frac{Cg}{2}) \dot{X} f in + (- \frac{LCg}{W} + \frac{Cg}{2}) \dot{X} f out = Tf & (21) \\ (\frac{LCg}{W} + \frac{Cg}{2}) \dot{X} r in + (- \frac{LCg}{W} + \frac{Cg}{2}) \dot{X} r out = Tr & (22) \end{matrix}

Then, the damping coefficients for a set of front and rear and inside and outside of a turn during a rolling out are obtained as follows:

\begin{matrix} Cf in = \frac{Tf}{2 Wf \dot{X} f in} (Wf + 2 Lf) + \frac{Caf}{2} (1 - \frac{\dot{X} f out}{\dot{X} f in}) & (23) \\ Cf out = \frac{Tf}{2 Wf \dot{X} f out} (Wf - 2 Lf) + \frac{Caf}{2} (1 - \frac{\dot{X} f in}{\dot{X} f out}) & (24) \\ Cr in = \frac{Tr}{2 Wr \dot{X} r in} (Wr + 2 Lr) + \frac{Car}{2} (1 - \frac{\dot{X} r out}{\dot{X} r in}) & (25) \\ Cr out = \frac{Tr}{2 Wr \dot{X} r out} (Wr - 2 Lr) + \frac{Car}{2} (1 - \frac{\dot{X} r in}{\dot{X} r out}) & (26) \end{matrix}

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings,

FIG. 1

is a standard skeleton model of the suspension system of a four wheeled vehicle viewed from a back thereof;

FIG. 2

is a skeleton model similar to

FIG. 1

, showing a vehicle suspension system incorporating a phantom side shock absorber and a phantom angular shock absorber instead of the left side and right side shock absorbers shown in

FIG. 1

;

FIGS. 3A and 3B

are skeleton models similar to that of

FIG. 2

, separately showing front and rear halves of the similar phantom damping system;

FIG. 4

is a diagrammatical view showing a four wheeled vehicle in which the damping coefficient control device according to the present invention is incorporated in the form of several embodiments;

FIG. 5

is a flowchart showing the outline of the operation of the damping coefficient control device according to the present invention;

FIGS. 6A and 6B

are maps for obtaining basic values of Cgf, Cgr and Caf, Car for Cgf, Cgr and Caf, Car and based upon the absolute values of vertical accelerations Ghf and Ghr of the front and rear mass centers;

FIGS. 7A and 7B

are maps for obtaining modification amounts ΔCgtf, ΔCgtr and ΔCatf, ΔCatr for Cgf, Cgr and Caf, Car based upon throttle opening rate {dot over (φ)};

FIGS. 8A and 8B

are maps for obtaining modification amounts ΔCgbf, ΔCgbr and ΔCabf, ΔCabr for Cgf, Cgr and Caf, Car based upon brake stroke Sb;

FIGS. 9A and 9B

are maps for obtaining modification amounts ΔCgsf, ΔCgsr and ΔCasf, ΔCasr for Cgf, Cgr and Caf, Car based upon swaying indexes Dsf and Dsr;

FIGS. 10A and 10B

are maps for obtaining modification amounts ΔCgrf, ΔCgrr and ΔCarf, ΔCarr for Cgf, Cgr and Caf, Car based upon rattling indexes Drf and Drr;

FIGS. 11A and 11B

are maps for obtaining modification amounts ΔCgff, ΔCgfr and ΔCaff, ΔCafr for Cgf, Cgr and Caf, Car based upon flapping indexes Dff and Dfr;

FIGS. 12A and 12B

are maps for obtaining modification amounts ΔCgmf, ΔCgmr and ΔCamf, ΔCamr for Cgf, Cgr and Caf, Car based upon masses Mf and Mr;

FIGS. 13A and 13B

are maps for obtaining modification factors ΔKghf, ΔKghr and ΔKahf, ΔKahr for Cgf, Cgr and Caf, Car based upon vertical stroking velocities Uhf and Uhrm;

FIG. 14

is a map for obtaining standard yaw rate γt based upon steering angle θ and vehicle speed V;

FIG. 15

is a map for obtaining modification amounts ΔCgyf, ΔCgyr, ΔCayf, ΔCayr, ΔLyf and ΔLyr based upon yaw rate deviation Δγ with a discrimination of the sign of γ;

FIGS. 16A

,

16

B and

16

C are maps for obtaining sharing ratios Kgtf, Katf and Kltf based upon throttle opening rate {dot over (φ)} for front drive vehicles;

FIGS. 17A

,

17

B and

17

C are maps for obtaining sharing ratios Kgtf, Katf and Kltf based upon throttle opening rate {dot over (φ)} for rear drive vehicles;

FIGS. 18A

,

18

B and

18

C are maps for obtaining sharing ratios Kgbf, Kabf and Klbf based upon brake stroke Sb for ordinary type vehicles;

FIGS. 19A

,

19

B and

19

C are maps for obtaining sharing ratios Kgbf, Kabf and Klbf based upon brake stroke Sb for sports type vehicles;

FIG. 20

is a map for obtaining lateral distances Lf and Lr based upon G

1

·θV

2

+G

2

·{dot over (θ)}·V

2

;

FIG. 21

is a map for obtaining mean pressure values ΔPf and ΔPr based upon vertical accelerations {umlaut over (X)}i;

FIG. 22

is a map for obtaining lateral distances Lqf and Lqr based upon ΔPf and ΔPr;

FIG. 23

is a map for discriminating slip states area A, B, C and D;

FIGS. 24A

,

24

B and

24

C are maps for obtaining Klst and Klsr based upon slip angle β and slip state area;

FIG. 25

is a flowchart for obtaining modification amounts ΔCgcl and ΔCac

1

for suppressing a consonant rolling of the vehicle body to a slalom driving based upon steering angle θ;

FIG. 26

is a flowchart for obtaining modification amounts ΔCgc

2

and ΔCac

2

for suppressing a consonant rolling of the vehicle body to a slalom driving based upon lateral acceleration of the vehicle body; and

FIGS. 27A and 27B

are flowcharts to be combined for obtaining modification amounts ΔCgc

3

f, ΔCac

3

f and ΔCgc

3

r, ΔCac

3

r for suppressing a consonant rolling of the vehicle body to a slalom driving based upon rolling accelerations of the vehicle body.

DESCRIPTION OF THE EMBODIMENTS

In the following, the present invention will be described in more detail in the form of some preferred embodiments with reference to the accompanying drawings.

Referring to

FIG. 4

, the vehicle herein shown has front left, front right, rear left and rear right wheels

10

FL,

10

FR,

10

RL and

10

RR suspended from a vehicle body

12

. The front left and front right wheels

10

FL and

10

Fr are steered by a steering system including a steering wheel

14

, a rack-and-pinion assembly

16

, and left and right connecting rods

18

L and

18

R. The rear wheels

10

RL and

10

RR are driven by a drive system not shown in the figure, while the wheels

10

FL,

10

FR,

10

RL and

10

RR are separately braked by their wheel cylinders not shown in the figure being supplied with a hydraulic pressure from a hydraulic circuit according to a depression of a brake pedal by a driver, though not shown in

FIG. 4

, or under a control of electric control means

24

. The vehicle body

12

is supported on the wheels

10

FL,

10

FR,

10

RL and

10

RR at portions thereof corresponding to these wheels via respective corresponding parallel combinations of suspension springs not shown in the figure and shock absorbers

22

FL,

22

FR,

22

RL and

22

RR, as diagrammatically shown in FIG.

1

.

The electric control means

24

includes a microcomputer for conducting control calculations described in detail hereinbelow based upon signals supplied thereto from wheel stroke sensors

26

FL,

26

FR,

26

RL and

26

RR indicating up and down strokes Xfl, Xfr, Xrl and Xrr of the front left, front right, rear left and rear right wheels, respectively, relative to the vehicle body, signals from vertical acceleration sensors

28

FL,

28

FR,

28

RL and

28

RR indicating vertical accelerations {umlaut over (X)}fl, {umlaut over (X)}fr, {umlaut over (X)}rl and {umlaut over (X)}rr of body portions vertically above the front left, front right, rear left and rear right wheels, respectively, a signal from a lateral acceleration sensor

30

indicating lateral acceleration Gy of the vehicle body, a signal from a vehicle speed sensor

32

indicating vehicle speed V, a signal from a throttle opening sensor

33

indicating opening φ of a throttle valve (not shown), a signal from a steering angle sensor

34

indicating steering angle θ, a signal from a brake stroke sensor

35

indicating brake stroke Sb of a brake pedal (not shown), a signal from a yaw rate sensor

36

indicating yaw rate γ of the vehicle, etc.

The damping control device according to the present invention is essentially incorporated in the electric control means

24

, so as to receive such motion parameters of the vehicle as described above, to conduct certain control calculations as described hereinbelow, and to vary the damping coefficients of the shock absorbers

22

FL-

22

RR so that the suspension system of the vehicle having a construction such as shown in

FIG. 1

operates like a suspension system such as shown in

FIGS. 3A and 3B

.

In the following, the basic construction of the damping control device according to the present invention will be described in the form of its operation with reference to FIG.

5

.

Referring to

FIG. 5

, when the damping control device according to the present invention is started for operation, in step

10

, signals are read in from those sensors described above.

In step

20

, it is judged if the lateral acceleration Gy is zero or positive, i.e. if the lateral acceleration is zero or acting leftward of the vehicle. When the answer is yes, the control proceeds to step

30

, while when the answer is no, the control proceeds to step

40

.

In step

30

, by setting a flag F to 1, Xfl, Xfr, Xrl and Xrr detected by the wheel stroke sensors

26

FL,

26

FR,

26

RL and

26

RR are substituted for Xfin, Xfout, Xrin and Xrout, respectively, and {umlaut over (X)}fl, {umlaut over (X)}fr, {umlaut over (X)}rl and {umlaut over (X)}rr detected by the vertical acceleration sensors

28

FL,

28

FR,

28

RL and

28

RR are substituted for {umlaut over (X)}fin, {umlaut over (X)}fout, {umlaut over (X)}rin and {umlaut over (X)}rout, respectively.

In step

40

, by setting the flag F to 0, Xfr, Xfl, Xrr and Xrl are substituted for Xfin, Xfout, Xrin and Xrout, respectively, and {umlaut over (X)}fr, {umlaut over (X)}fl, {umlaut over (X)}rr and {umlaut over (X)}rl are substituted for {umlaut over (X)}fin, {umlaut over (X)}fout, {umlaut over (X)}rin and {umlaut over (X)}rout, respectively.

Thus, the parameters Xfr, Xfl, Xrr and Xrl and {umlaut over (X)}fr, {umlaut over (X)}fl, {umlaut over (X)}rr and {umlaut over (X)}rl are alternatively set up for a left turn (with a straight running being included in this side only for convenience) and a right turn for the phantom shock absorber control.

In step

50

, the damping coefficients Cgf and Cgr of the front the rear phantom side shock absorbers

122

F and

122

R, the damping coefficients Caf and Car of the front and rear phantom angular shock absorbers

124

F and

124

R, and the lateral distances Lf and Lr of the front and rear phantom side shock absorbers

122

F and

122

R are calculated as described in detail hereinbelow.

In step

60

, the damping coefficients Cfin, Cfout, Crin and Crout for the shock absorbers of the front and rear wheels serving at the inside and outside of the turn, respectively, are calculated based upon the Cgf, Cgr, Caf, Car, Lf and Lr calculated in step

50

.

In step

70

, it is judged if the flag F is 1. When the answer is yes, the control proceeds to step

80

, while when the answer is no, the control proceeds to step

90

.

In step

80

, Cfin, Cfout, Crin and Crout are put in for the damping coefficients Cfl, Cfr, Crl and Crr of the front left, front right, rear left and rear right shock absorbers

22

FL,

22

FR,

22

RL and

22

RR, while in step

90

, Cfin, Cfout, Crin and Crout are put in for the damping coefficients Cfr, Cfl, Crr and Crl of the front right, front left, rear right and rear left shock absorbers

22

FR,

22

FL,

22

RR and

22

RL.

In step

100

, the damping coefficients of the shock absorbers are controlled according to the values of the Cfl-Crr.

In the following, the calculations of Cgf, Cgr, Caf, Car, Lf and Lr conducted in step

50

will be described in more detail with respect to several embodiments.

Basically, the damping coefficients Cgf and Cgr of the phantom side shock absorbers

112

F and

112

R are substantially dependent upon the vertical stroking acceleration of the vehicle body relative to the ground surface, provided that the wheels are kept in contact with the ground surface. On the other hand, the damping coefficients Caf and Car of the phantom angular shock absorbers

124

F and

124

R are substantially dependent upon the rolling acceleration of the vehicle body around the front and rear mass centers

118

F and

118

R, respectively.

Therefore, vertical accelerations Ghf and Ghr of the front and rear mass centers

118

F and

118

R and rotational accelerations Grf and Grr of the vehicle body around the front and rear mass centers

118

F and

118

R are calculated as follows:

Ghf=({umlaut over (X)}fin+{umlaut over (X)}fout)/2

Ghr=({umlaut over (X)}rin+{umlaut over (X)}rrout)/2

Grf=({umlaut over (X)}fin−{umlaut over (X)}fout)/Wf

Grr=({umlaut over (X)}rin−{umlaut over (X)}rout)/Wr

Then, looking at maps such as shown in

FIGS. 6A and 6B

based upon the absolute values of Ghf, Ghr, Grf and Grr, basic values of Cgf, Cgr, Caf and Car are obtained. Basic values of the lateral distances Lin and Lout of the front and rear phantom side shock absorbers

122

F and

122

R may be appropriately determined in comparison with the magnitudes of the wheel tread Wf and Wr, respectively.

Although in the maps of

FIGS. 6A and 6B

, the performances of Cgf and Cgr against the absolute values of Ghf and Ghr are respectively shown by a common curve, separate performance curves may be set up for Cgf and Cgr against the same absolute values of Ghf and Ghr, respectively. Similarly, although the performances of Caf and Car against the absolute values of Grf and Grr are shown by a common curve, the performances of Caf and Car may be separately set up against the same absolute values of Grf and Grr, respectively. The general performances of Cgf, Cgr, Caf and Car relative to Ghf and Ghr will be apparent from the maps. In any event, it will be appreciated that the maps of

FIGS. 6A and 6B

are designed as an embodiment of providing a phantom damping system such as shown in

FIGS. 3A and 3B

with a certain desirable operation performance. The present invention is not limited to such a particular performance.

The damping coefficients Cgf and Cgr of the front and rear phantom side shock absorbers

122

F and

122

R and the damping coefficients Caf and Car of the front and rear phantom angular shock absorbers

124

F and

124

R may be modified according to a rate (i.e. speed) of opening or closing the throttle valve (not shown) of the vehicle according to such performances as shown in

FIGS. 7A and 7B

, respectively. The rate of opening or closing of the throttle valve will be available by differentiating the throttle opening φ detected by the throttle opening sensor

33

.

As an embodiment, modification amounts ΔCgtf and ΔCgtr for additively modifying Cgf and Cgr according to the throttle opening change rate {dot over (φ)} are so determined as to respectively follow such performances as shown by the maps of

FIG. 7A

, wherein ΔCgtf for the front phantom side shock absorber

116

L is made larger than ΔCgtr for the rear phantom side shock absorber

122

R, so as thereby to suppress a nose diving of the vehicle body by an abrupt acceleration of a rear drive vehicle.

Similarly, in the maps of

FIG. 7B

showing modification amounts ΔCatf and ΔCatr for additively modifying Caf and Car according to the throttle opening change rate {dot over (φ)}, ΔCatf for the front phantom angular shock absorber

124

F is made larger than ΔCatr for the rear phantom angular shock absorber

124

R, for the same reason as described above with respect to ΔCgtf and ΔCgtr. The general performances of ΔCgtf, ΔCgtr, ΔCatf and ΔCatr relative to {dot over (φ)} will be apparent from the maps.

The modifications by ΔCgtf, ΔCgtr, ΔCatf and ΔCatr are such that Cgf, Cgr, Caf and Car basically obtained from the maps of

FIGS. 6A and 6B

are respectively increased by ΔCgtf, ΔCgtr, ΔCatf and ΔCatr.

The damping coefficients Cgf, Cgr, Caf and Car may further be modified according to a braking in a manner such as shown by maps of

FIGS. 8A and 8B

, respectively.

As an embodiment, modification amounts ΔCgbf and ΔCgbr for additively modifying Cgf and Cgr are changed against a brake stroke Sb detected by the brake stroke sensor

35

as shown by the curves of FIG.

8

A. Similarly, as an embodiment, modification amounts ΔCabf and ΔCabr for additively modifying Caf and Car are changed against the braking Sb as shown by the curves of FIG.

8

B.

As will be noted in

FIGS. 8A and 8B

, the modification amounts ΔCgbf and ΔCabf for the front phantom side and angular shock absorbers are made appropriately larger than the modification amounts ΔCgbr and Δcabr for the rear phantom side and angular shock absorbers, respectively, so that thereby a nose diving of the vehicle body by an abrupt braking is suppressed. The general performances of ΔCgbf, ΔCgbr, ΔCabf and ΔCabr relative to Sb will be apparent from the maps.

The modifications by ΔCgbf, ΔCgbr, ΔCabf and ΔCabr may also be made such that these modification amounts are added to the corresponding Cgf, Cgr, Caf and Car basically obtained from the maps of

FIGS. 6A and 6B

.

The damping coefficients Cgf, Cgr, Caf and Car may further be modified against a swaying of the vehicle body. For such a modification, first the vertical accelerations {umlaut over (X)}j (j=fin, fout, rin and rout) detected by the vertical acceleration sensors

28

FL-

28

RR are each processed by a band pass filter for passing those of consonant frequencies of the vertical stroking vibrations of front and rear portions of the vehicle body above the front and rear suspension springs, so as to obtain swaying indexes Dsf and Dsr for the front and rear portions of the vehicle. Then, modification amounts ΔCgsf and ΔCgsr for additively modifying Cgf and Cgr are obtained against the magnitudes of Dsf and Dsr, respectively, according to such maps as shown in FIG.

9

A. Similarly, modification amounts ΔCasf and ΔCasr for additively modifying Caf and Car are obtained against Dsf and Dsr, respectively, according to such maps as shown in FIG.

9

B. By the damping coefficients Cgf, Cgr, Caf and Car being increased by the modification amounts ΔCgsf, ΔCgsr, ΔCasf and ΔCasr, respectively, according to the magnitudes of Dsf and Dsr, a consonant swaying of the vehicle body is effectively suppressed.

The general performances of ΔCgsf, ΔCgsr, ΔCasf and ΔCasr relative to Dsf or Dsr will be apparent from the maps. However, it will be desirable that the modifications by ΔCgsf, ΔCgsr, ΔCasf and ΔCasr are not directly made but are made in a harmony with a rattling of the vehicle body and a flapping of the wheels described hereinbelow.

The damping coefficients Cgf, Cgr, Caf and Car may further be modified against a rattling of the vehicle body. For such a modification, the vertical accelerations {umlaut over (X)}j (j=fin, fout, rin and rout) detected by the vertical acceleration sensors

28

FL-

28

RR are processed by a band pass filter for passing those of rattling frequencies of front and rear portions of the vehicle body to obtain rattling indexes Drf and Drr for the front and rear portions of the vehicle. Then, negative modification amounts ΔCgrf and ΔCgrr for Cgf and Cgr are obtained against the magnitudes of Drf and Drr according to maps such as shown in

FIG. 10A

, so that the front and rear phantom side shock absorbers

122

F and

122

R are softened according to an increase of the rattling indexes Drf and Drr. Similarly, negative modification amounts ΔCarf and ΔCarr for Caf and Car are obtained against the magnitudes of Drf and Drr according to maps such as shown in

FIG. 10B

, so that the front and rear phantom angular shock absorbers

124

F and

124

R are also softened according to an increase of the rattling indexes Drs and Drr. The general performances of ΔCgrf, ΔCgrr, ΔCarf and ΔCarr relative to Drf or Drr will be apparent from the maps.

The damping coefficients Cgf, Cgr, Caf and Car may further be modified against a flapping of the wheels. For this purpose, vertical velocities {dot over (X)}j (j=fin, fout, rin and rout) of the wheels are obtained by differentiating the vertical strokes Xj (j=fin, fout, rin and rout) detected by the vertical stroke sensors

26

FL-

26

RR or integrating the vertical accelerations {umlaut over (X)}j (j=fin, fout, rin and rout) detected by the vertical acceleration sensors

28

FL-

28

RR on a time basis, and then by processing the vertical stroking velocities {dot over (X)}j by a band pass filter for passing those of the flapping frequencies of the wheels to obtain flapping indexes Dff and Dfr. Then, modification amounts ΔCgff and ΔCgfr for additively modifying Cgf and Cgr are obtained against the magnitudes of Dff and Dfr according to maps such as shown in

FIG. 11A

, so that the front and rear phantom side shock absorbers

122

F and

122

R are hardened according to an increase of the flapping indexes Dff and Dfr. Similarly, modification amount ΔCaff and ΔCafr for additively modifying Caf and Car are obtained against Dff and Dfr according to maps such as shown in

FIG. 11B

, so that the front and rear phantom angular shock absorbers

124

F and

124

R are also hardened according to an increase of the flapping indexes Dff and Dfr. The general performances of ΔCgff, ΔCgfr, ΔCaff and ΔCafr relative to Dff or Dfr will be apparent from the maps.

The modifications by ΔCgsf, ΔCgsr, ΔCasf and ΔCasr against the swaying of the vehicle body, ΔCgrf, ΔCgrr, ΔCarf and ΔCarr against the rattling of the vehicle body, and ΔCgff, ΔCgfr, ΔCaff and ΔCafr against the flapping of the wheels may be made, as a matter of individual principle, such that each of these modification amounts is added to each corresponding one of Cgf, Cgr, Caf and Car basically obtained from the maps of

FIGS. 6A and 6B

. However, when the modification amounts against the swaying of the vehicle body, the rattling of the vehicle body, and the flapping of the wheels are applied at the same time, there might occur an interference there among, canceling the effects of the respective modification amounts. Therefore, it might be better that these modification amounts are processed in relation to one another before being respectively added to Cgf, Cgr, Caf and Car, such that the larger as a whole of a set of ΔCgsf, ΔCgsr, ΔCasf and ΔCasr and a set of ΔCgff, ΔCgfr, ΔCaff and ΔCafr are selected, while the larger as a whole of a set of thus selected set and a set of ΔCgrf, ΔCgrr, ΔCarf and ΔCarr in the absolute values thereof are selected for an execution of the modification. The comparison of such two sets of modification amounts as a whole may be made, for example, by comparing the absolute value of the largest one of each set so that the set including the winner is selected. The first selection is to put a priority on either the modification against the swaying of the vehicle body or the flapping of the wheels, without sacrificing much of the other, because the performances of the two modification amounts are rather similar. On the other hands, the second selection is to put a priority on one of the modification against either the swaying of the vehicle body or the flapping of the wheels and the modification against the rattling of the vehicle body, substantially sacrificing the other, because the performances of the two modification amounts are rather opposite.

The damping coefficients Cgf, Cgr, Caf and Car may further be modified according to a change of the load on the vehicle. For such a purpose, maps such as shown in

FIGS. 12A and 12B

may be prepared. According to the map of

FIG. 12A

, modification amounts ΔCgmf and ΔCgmr for additively modifying Cgf and Cgr are varied against a front part Mf and a rear part Mr of the total mass including the vehicle body and the load on the vehicle, so as to be substantially proportionally increased relative to increases of front and rear masses Mf and Mr from standard front and rear masses Mof and Mor determined for a standard load. The magnitudes of Mf and Mr will be available from Xj (j=fin, fout, rin and rout) output by the wheel stroke sensors

26

FL,

26

FR,

26

RL and

26

RR. Similarly, modification amounts ΔCamf and ΔCamr for additively modifying Caf and Car are varied against increases of Mf and Mr relative to Mof and Mor as shown in the map of FIG.

12

B. The general performances of ΔCgmf, ΔCgmr, ΔCamf and ΔCamr relative to Mf or Mr will be apparent from the maps.

The modifications by ΔCgmf, ΔCgmr, ΔCamf and ΔCamr may also be made such that these modification amounts are added to the corresponding Cgf, Cgr, Caf and Car basically obtained from the maps of

FIGS. 6A and 6B

.

The damping coefficients Cgf, Cgr, Caf and Car may further be modified according to a change of vertical stroking velocity of the vehicle body. For this purpose, vertically stroking velocities {dot over (X)}j (j=fin, fout, rin and rout) of the wheels are obtained by differentiating the vertical strokes Xj (j=fin, fout, rin and rout) or integrating the vertical accelerations {umlaut over (X)}j (=fin, fout, rin and rout) on a time basis, such that vertical stroking velocities Uhf and Uhr of front and rear portions of the vehicle body are obtained as a mean value of {dot over (X)}fin and {dot over (X)}fout and a mean value of {dot over (X)}rin and {dot over (X)}rout, respectively. Then, by referring to maps such as shown in

FIGS. 13A and 13B

, modification factors Kghf, Kghr, Kahf and Kahr are obtained as factors to be multiplied to Cgf, Cgr, Caf and Car, respectively, for reflecting a variation of the damping performances of the front and rear phantom side and angular shock absorbers

122

F,

122

R,

124

F and

124

R according to the velocity of damping movement, as shown by the curves of

FIGS. 13A and 13B

. The general performances of Kghf, Kghr, Kahf and Kahr relative to Uhf or Uhr will be apparent from the maps.

In each of the above-mentioned maps of

FIGS. 9A

,

9

B to

13

A,

13

B, the relative difference between the modification amounts for the front and rear phantom side or angular shock absorbers is only an example. The relative magnitudes of the modification amounts for the front and the rear may be the same as one another or may be reversed against one another according to the designs of vehicles.

The damping coefficients Cgf, Cgr, Caf and Car and the lateral distances Lf and Lr may further be modified against a side slipping condition of the vehicle reflecting thereon a tendency for oversteering or understeering. For this purpose, a standard (or theoretical) yaw rate γt is calculated based upon the steering angle θ detected by the steering angle sensor

34

and vehicle speed V detected by the vehicle speed sensor

32

as follows:

γt=Vθ/(1+αV

2

)H

γt←γ/(1+Ts)

wherein, H is a wheel base of the vehicle, α is an appropriate stability factor, and T and s are a time constant and the composite variable in the Laplace transformation, respectively. The steering angle θ and the yaw rate γt or γ are made positive when the vehicle is making a left turn, while they are made negative when the vehicle is making a right turn.

Then, a deviation Δγ of an actual yaw rate γ detected by the yaw rate sensor

36

against the standard yaw rate γt is calculated as Δγ=γ−γt. Or alternatively, the standard yaw rate γt may be obtained from a map such as shown in

FIG. 14

according to the values of steering angle θ and vehicle speed V.

Then, by looking at a map such as shown in

FIG. 15

according to the magnitude and the sign of Δγ, modification amounts ΔCgyf, ΔCgyr, ΔCayf, ΔCayr, ΔLyf and ΔLyr for additively modifying Cgf, Cgr, Caf, Car, Lf and Lr are obtained, such that when Δγ is positive, ΔCgyf, etc. are read out in the first and fourth quadrants, while when Δγ is negative, ΔCgyf, etc. are read out in the second and third quadrants.

The general performances of ΔCgyf, ΔCgyr, ΔCayf, ΔCayr, ΔLyf and ΔLyr relative to Δγ will be apparent from the map. The modification amounts ΔCgyf, etc. thus read out may further be processed so as not to exceed limit values in the absolute values thereof respectively imposed thereon.

The damping coefficients Cgf and Cgr designed have the same performance relative to |Ghf| and |Ghr| in

FIG. 6A

may be modified to be shared by such a proportioning factor Kgtf as shown in

FIG. 16A

according to the throttle opening rate {dot over (φ)} and the vehicle speed. According to the proportioning factor Kgtf, the damping coefficients for the front and rear phantom side shock absorbers

122

F and

122

R may be modified such as Cgf ←(Cgf+Cgr)·Kgtf and Cgr←(Cgf+Cgr)·(1−Kgtf), respectively, provided that Cgf and Cgr are first read out from a map such as shown in FIG.

6

A.

Similarly, Caf and Car may also be modified from the values read out from a map such as shown in

FIG. 6B

by a proportioning factor Katf such as shown in

FIG. 16B

according to the throttle opening rate {dot over (φ)} and the vehicle speed. In this case, the damping coefficients for the front and rear phantom angular shock absorbers

124

F and

124

R may be modified such as Caf←(Caf+Car)·Katf and Car←(Caf+Car)·(1−Katf) based upon Caf and Car first read out from a map such as shown in FIG.

6

B.

Similarly, the lateral distances Lf and Lr may also be modified from the values initially determined to start from certain predetermined values or read out from those maps therefor described hereinbelow by a proportioning factor Katf such as shown in

FIG. 16C

according to the throttle opening rate {dot over (φ)} and the vehicle speed. In this case, the distances for the front and rear phantom side shock absorbers

122

F and

122

R may be modified such as Lf←(Lf+Lr)·Kltf and Lr←(Lf+Lr)·(1−Kltf) based upon Lf and Lr initially set up or first read out from a map described hereinbelow.

Cgf, Cgr, Caf, Car, Lf and Lr of a rear drive vehicle may be modified in the same manner as above by Kgtf, Katf and Kltf read out respectively from maps such as shown in

FIGS. 17A

,

17

B and

17

C. The general performances of Kgtf, Katf and Kltf relative to Rt and the vehicle speed will be apparent from the maps. They are generally opposite to those of the front drive vehicle.

A similar modification of sharing of the damping actions by the front and rear phantom side or angular shock absorbers

122

F and

122

R or

124

F and

124

R between the front and the rear may be made against a brake stroke denoted as Sb with reference to

FIGS. 8A and 8B

. For this purpose, maps such as shown in

FIGS. 18A

,

18

B and

18

C are prepared for an ordinary type four wheeled vehicle, while maps such as shown in

FIGS. 19A

,

19

B and

19

C are prepared for a sports type four wheeled vehicle in which it is desirable that the cornering power of the rear wheels saturates earlier than in the ordinary type vehicle for an easier cornering.

In

FIGS. 18A

,

18

B and

18

C, Kgbf, Kabf and Klbf are sharing ratios of the damping actions by the front and rear phantom side and angular shock absorbers

122

F,

122

R and

124

F,

124

R between the front and rear shock absorbers against the brake stroke Sb according to various vehicle speeds in an ordinary type four wheeled vehicle, and are applied to Cgf, Cgr, Caf, Car, Lf and Lr in a similar manner as above such that these are modified as Cgf←(Cgf+Cgr)·Kgbf, Cgr←(Cgf+Cgr)·(1−Kgbf), Caf←(Caf+Car)·Kabf, Car←(Caf+Car)·(1−Kabf), Lf←(Lf+Lr)·Klbf and Lr←(Lf+Lr)·(1−Klbf), respectively. The general performances of Kgbf, Kabf and Klbf relative to Sb will be apparent from the maps.

Similarly, Kgbf, Kabf and Klbf in

FIGS. 19A

,

19

B and

19

C are sharing ratios of the damping actions by the front and rear phantom side and angular shock absorbers

122

F,

122

R and

124

F,

124

R between the front and the rear shock absorbers against the brake stroke Sb according to various vehicle speeds in a sports type four wheeled vehicle, and are applied to Cgf, Cgr, Caf, Car, Lf and Lr in a similar manner as above such that these are modified as Cgf←(Cgf+Cgr)·Kgbf, Cgr←(Cgf+Cgr)·(1−Kgbf), Caf←(Caf+Car)·Kabf, Car←(Caf+Car)·(1−Kabf), Lf←(Lf+Lr)·Klbf and Lr←(Lf+Lr)·(1−Klbf), respectively. The general performances of Kgbf, Kabf and Klbf relative to Sb will be apparent from the maps. They are generally opposite to those of the ordinary type vehicle. In the sports type vehicles, it is desirable that the cornering power of the rear wheels saturates earlier than in the ordinary type vehicle for an easier turn.

The lateral distances Lf and Lr may be determined based upon an amount such as G

1

·θ·V

2

+G

2

·{dot over (θ)}·V

2

, wherein θ and V are the steering angle and the vehicle speed, respectively, while G

1

and G

2

are gains for such values as θ·V

2

and {dot over (θ)}·V

2

, such as to be Lqf and Kqr showing such performances as shown in FIG.

20

. The general performances of Lqf and Lqr relative to such a parameter as G

1

·θ·V

2

+G

2

·{dot over (θ)}·V

2

will be apparent from the map.

The lateral distances Lf and Lr may be determined based upon the forces acting in the front shock absorbers

22

FL and

22

FR and the rear shock absorbers

22

RL and

22

RR, respectively. For this purpose, the forces acting at the respective shock absorbers

22

FL-

22

RR are estimated based upon the vertical stroke velocities {dot over (X)}i (i=fin, fout, rin and rout) obtained by differentiating the vertical strokes Xj (i=fin, fout, rin and rout) detected by the vertical stroke sensors

26

FL-

26

RR or integrating the vertical accelerations {umlaut over (X)}i (i=fin, fout, rin and rout) detected by the vertical acceleration sensors

28

FL-

28

RR. Then, by looking at a map such as shown in

FIG. 21

, pressure differences ΔPf and ΔPr are read out as mean values of the pressures generated across the pistons (not shown) of the front shock absorbers

22

FL and

22

FR and the rear shock absorbers

22

RL and

22

RR, representing the forces acting thereon based upon a particular design of shock absorbers concerned. Then, the lateral distances Lf and Lr may be obtained as Lpf and Lpr by looking at a map such as shown in FIG.

22

. The performances of Lpf and Lpr relative to ΔPf and ΔPr will be apparent from the map.

The lateral distances Lf and Lr may further be modified according to a side sliding condition of the vehicle. For this purpose, first a side slide acceleration is calculated as a difference between the lateral acceleration Gy detected by the lateral acceleration sensor

30

and a product of the vehicle speed V detected by the vehicle speed sensor

32

and the yaw rate γ detected by the yaw rate sensor

36

, such as Gy−Vγ. Then, by integrating Gy−Vγ on a time basis, a side slide velocity is obtained. Then, by dividing such a side slide velocity by a longitudinal velocity, i.e. the vehicle speed, a value β of the so-called slip angle is obtained.

Then, based upon the slip angle β and its change rate {dot over (β)}, the running state of the vehicle is discriminated among a stable state, an oversteering state, an understeering state and a dissipating state, as shown by areas A, B, C and D, respectively, in FIG.

23

. Modification factors Klsf and Klsr to be multiplied to the standard or otherwise modified lateral distances Lf and Lr are determined according to the absolute value of the slip angle β and the discriminated running state as follows:

When the vehicle is running in the stable area A, Klsf and Klsr are made

1

, respectively. When the vehicle is running in the oversteering area B, Klsr for Lr is kept at

1

, while Klsf for Lf is increased starting from

1

according to an increase of β as shown in FIG.

24

A. When the vehicle is running in the understeering area C, Klsf for Lf is kept at 1, while Klsr for Lr is increased starting from 1 according to an increase of β as shown in FIG.

24

B. When the vehicle is running in the dissipating area D, Klsf and Kisr for Lf and Lr are both increased starting from a value substantially larger than 1 according to an increase of β as shown in FIG.

24

C. The performances of Klsf and Klsr relative to the absolute value of β will be apparent from the maps.

The first and second phantom damping coefficients Cg and Ca may further be modified against a rolling of the body of a vehicle consonant to a slalom driving of the vehicle.

In an embodiment for such a modification, ΔCgc

1

and ΔCac

1

for additively modifying Cg and Ca are calculated as shown by a flowchart of FIG.

25

.

Referring to

FIG. 25

, when the damping control is started, in step

200

, it is judged if a flag F

1

described hereinbelow is 1. As well known in the art, flags like this are normally reset to zero at each start of the control. When the answer is no, the control proceeds to step

202

, while when the answer is yes, the control proceeds to step

212

described hereinbelow.

In step

202

, it is judged if a flag F

2

described hereinbelow is 1. When the answer is yes, the control proceeds to step

226

described hereinbelow, while when the answer is no, the control proceeds to step

204

, and it is judged if the steering angle θ detected by the steering sensor

34

is positive. The steering angle θ is made positive when the vehicle is steered for a left turn, while θ is made negative when the vehicle is steered for a right turn. When the answer is yes, the control proceeds to step

206

, while when the answer is no, the control proceeds to step

208

described hereinbelow

In step

206

, the flag F

1

is set to 1, and the control proceeds to step

210

, wherein values of θ max and θo described hereinbelow are reset to zero.

Instep

212

, a count number n initially reset to zero at each start of the control is incremented by 1. What is counted by n will be described hereinbelow.

In step

214

, it is judged if θn·θn−1 is positive. θn is the value of the steering angle θ detected by the steering sensor

34

at the instant of the current scanning cycle passing through step

214

with the count number n processed in the preceding step

212

. Therefore, θn−1 means the steering angle θ detected by the steering sensor

34

at the moment of the control proceeding through step

214

in the one preceding cycle of scanning through the flowchart. When θn·θn−1 is positive, it may be assumed that the steering of the vehicle remains in a left turn, while when θn·θn−1 is negative, it may be assumed that the steering was changed from a left turn to a right turn across a neutral position. When the answer is yes, the control proceeds to step

216

, while when the answer is no, the control proceeds to step

236

described hereinbelow.

In step

216

, it is judged if θn is larger than θn−1. When the answer is yes, the control proceeds to step

218

, and θ max is made to be θn, while when the answer is no, the control proceeds to step

220

, and θ max is made to be θn−1. Therefore, it will be noted that by steps

216

,

218

and

220

, the largest of a series of θn, θn−1, θn−2, . . . is selected for θ max.

In step

222

, it is judged if the count number n is larger than a threshold value nc predetermined therefor. The threshold count number nc is determined in relation with the cycle time of the scanning control through this flowchart so as to count a time duration corresponding to a half of a cycle period of a consonant rolling of the vehicle body.

Returning to step

208

, when the control comes to this step, the flag F

2

is set to 1. This branch path is prepared for a right turn of the vehicle.

In step

224

, values of θmin and θo described hereinbelow are reset to zero, respectively. Then, in step

226

, the count number n is incremented by 1.

In step

228

, it is judged if θn·θn−1 is positive. When θn·θn−1 is positive, it may be assumed that the steering of the vehicle remains in a right turn, while when θn·θn−1 is negative, it may be assumed that the steering was changed from a right turn to a left turn across a neutral position. When the answer is yes, the control proceeds to step

230

, while when the answer is no, the control proceeds to step

236

.

In step

230

, it is judged if θn is smaller than θn−1. When the answer is yes, the control proceeds to step

232

, and θmin is made θn, while when the answer is no, the control proceeds to step

234

, and θ min is made to be θn−1. Therefore, it will be noted that by steps

230

,

232

and

234

, the smallest of a series of θn, θn−1, θn−2, . . . is selected for θ min.

Coming again to step

222

, when the answer is yes, the control proceeds to step

236

, wherein the count number n is reset to zero, and the flags F

1

and F

2

are also reset to zero. When the answer of step

222

is no, the control bypasses step

236

to come to step

238

. On the other hands, as described above, step

236

is also reached from step

214

or

228

when θn·θn−1 is negative, i.e. when the steering was changed from a left turn to a right turn or from a right turn to a left turn across the neutral. Therefore, it will be note that when a slalom driving is synchronized with the consonant rolling frequency of the vehicle body, the threshold count number nc is counted up with a detection of the largest value of the steering angle θ in a left turn or the smallest value of the steering angle θ (largest in the absolute value) in a right turn during the slalom driving.

In step

238

, it is judged if the absolute value of the lateral acceleration Gy detected by the lateral acceleration sensor

30

is larger than a threshold value Gyt predetermined therefor in order to determined whether or not to carry out the modification of Cg and Ca against a rolling of the body of the vehicle consonant to a slalom driving. When the answer is yes, the control proceeds to step

240

, while when the answer is no, the control proceeds to step

252

described hereinbelow.

In step

240

, a sum of the absolute values of θmax and θmin is calculated as Uc

1

, such as Uc

1

=θmax−θmin. Then, in step

242

, it is judged if Uc

1

is larger than a threshold value Uc

1

t predetermined therefor in order to still determine whether or not to carry out the modification of Cg and Ca against a rolling of the vehicle body consonant to a slalom driving. When the answer is yes, the control proceeds to step

244

, while when the answer is no, the control proceeds to step

252

.

In step

244

, modification amounts ΔCgc

1

and ΔCac

1

for Cg and Ca against a rolling of the body of the vehicle consonant to a slalom driving are respectively made Egc

1

and Eac

1

appropriately determined therefor.

In step

246

, it is judged if a flag F

3

is 1. The flag F

3

is initially reset to zero at each start of the control. When the answer is no, the control proceeds to step

248

, and a timer is set. Then, in step

250

, the flag F

3

is set to 1. Then the control returns to step

200

. When the answer of step

246

is yes, i.e. after the timer was once set up, the control bypasses steps

248

and

250

.

In step

252

, it is judged if the timer started in step

248

has counted up a time preset therein. When the answer is no, the control returns to step

200

. When the answer is yes, the control proceeds to step

254

, and the modification amounts ΔCgc

1

and ΔCac

1

are set to zero. Then, in step

256

, the timer is reset, and then, in step

258

, the flag F

3

is reset to zero. Then the control returns to step

200

.

Thus, it will be appreciated that according to this embodiment, the modification amounts ΔCgc

1

and ΔCac

1

for Cg and Ca against a rolling of the vehicle body consonant to a slalom driving are made substantial amounts such as Egc

1

and Eac

1

, respectively, when the absolute value of the lateral acceleration is larger than a threshold value predetermined therefor, and further the steering wheel is turned alternately leftward and rightward so much across the neutral point in a slaloming manner at a frequency around a consonant rolling frequency of the vehicle body that a sum of the absolute angles of a largest leftward steering and a largest rightward steering exceeds a threshold value predetermined therefor, wherein ΔCgc

1

and ΔCac

1

are respectively set at such values as Egc

1

and Eac

1

until such a consonant slalom steering is stopped or at least a predetermined time lapses when once so set.

The values of Egc

1

and Eac

1

may be varied according to the magnitude of the sum of the absolute angles of the largest leftward steering and the largest rightward steering by looking at an appropriate map not shown. Further, the values of ΔCgc

1

and ΔCac

1

thus obtained may be appropriately shared between the front and rear halves of the phantom damping system according to such arts as described with reference to

FIGS. 13A and 13B

,

16

A-

16

C,

17

A-

17

C,

18

A-

18

C or

19

A-

19

C, or any other arts.

Additive modification amounts for Cg and Ca against a rolling of the vehicle body consonant to a slalom driving of the vehicle may be obtained based upon the lateral acceleration of the vehicle body.

FIG. 26

is a flowchart similar to

FIG. 25

, showing such an embodiment for obtaining modification amounts denoted ΔCgc

2

and ΔCac

2

based upon the lateral acceleration of the vehicle body. The modification amounts ΔCgc

2

and ΔCac

2

of this embodiment are obtained according to the same technical concept as in the embodiment shown in

FIG. 25

, except that the slalom is processed based upon the lateral acceleration Gy detected by the lateral acceleration sensor

30

, instead of the steering angle θ in the former embodiment. Therefore, for the sake of convenience of review, steps in

FIG. 26

corresponding to those in

FIG. 25

are numbered to be larger by 100 than those in FIG.

25

.

When the control is started, in step

300

, it is judged if a flag F

4

is set to 1. When the answer is no, the control proceeds to step

302

, while when the answer is yes, the control proceeds to step

312

.

In step

302

, it is judged if a flag F

5

is 1. When the answer is yes, control proceeds to step

326

, while when the answer is no, the control proceeds to step

304

, and it is judged if the lateral acceleration Gy detected by the lateral acceleration sensor

30

is positive. As already described with reference to step

20

of

FIG. 5

, the lateral acceleration Gy is made positive when it is directed leftward of the vehicle as in a left turn of the vehicle, while Gy is made negative when it is directed rightward of the vehicle as in a right turn of the vehicle. When the answer is yes, the control proceeds to step

306

, while when the answer is no, the control proceeds to step

308

.

In step

306

, the flag F

4

is set to 1, and the control proceeds to step

310

, wherein values of Gymax and Gyo described hereinbelow are reset to zero.

Instep

312

, a count number n initially reset to zero at each start of the control is incremented by 1. What is counted by n is the same as in the flowchart of FIG.

25

.

In step

314

, it is judged if Gyn·Gyn−1 is positive. Gyn is the value of the lateral acceleration Gy detected by the lateral acceleration sensor

30

at the instant of the current scanning cycle passing through step

314

with the count number n processed in the preceding step

312

. Therefore, Gyn−1 means the lateral acceleration Gy detected by the lateral acceleration sensor

30

at the moment of the control proceeding through step

314

in the one preceding cycle of scanning through the flowchart. When Gyn·Gyn−1 is positive, it may be assumed that the turning of the vehicle remains in a left turn, while when Gyn·Gyn−1 is negative, it may be assumed that the direction of the turn was changed from a left turn to a right turn across a neutral position. When the answer is yes, the control proceeds to step

316

, while when the answer is no, the control proceeds to step

336

described hereinbelow.

In step

316

, it is judged if Gyn is larger than Gyn−1. When the answer is yes, the control proceeds to step

318

, and Gymax is made to be Gyn, while when the answer is no, the control proceeds to step

320

, and Gymax is made to be Gyn−1. Therefore, it will be noted that by steps

316

,

318

and

320

, the largest of a series of Gyn, Gyn−1, Gyn−2, . . . is selected for Gymax.

In step

322

, it is judged if the count number n is larger than a threshold value nc predetermined therefor. As is the same as nc in step

220

of the flowchart of

FIG. 25

, the threshold count number nc is determined in relation with the cycle time of the scanning control through this flowchart so as to count a time duration corresponding to a half of a cycle period of a consonant rolling of the vehicle body.

Returning to step

308

, when the control comes to this step, the flag F

5

is set to 1. This branch path is prepared for a right turn of the vehicle.

In step

324

, values of Gymin and Gyo described hereinbelow are reset to zero, respectively. Then, in step

326

, the count number n is incremented by 1.

In step

328

, it is judged if Gyn·Gyn−1 is positive. When Gyn·Gyn−1 is positive, it may be assumed that the turning of the vehicle remains in a right turn, while when Gyn·Gyn−1 is negative, it may be assumed that the direction of the turning was changed from a right turn to a left turn across a neutral position. When the answer is yes, the control proceeds to step

330

, while when the answer is no, the control proceeds to step

336

.

In step

330

, it is judged if Gyn is smaller than Gyn−1. When the answer is yes, the control proceeds to step

332

, and Gymin is made to be Gyn, while when the answer is no, the control proceeds to step

334

, and Gymin is made to be Gyn−1. Therefore, it will be noted that by steps

330

,

332

and

334

, the smallest of a series of Gyn, Gyn−1, Gyn−2, . . . is selected for Gymin.

Coming again to step

322

, when the answer is yes, the control proceeds to step

336

, wherein the count number n is reset to zero, and the flags F

4

and F

5

are also reset to zero. When the answer of step

322

is no, the control bypasses step

336

to come to step

338

. On the other hands, as described above, step

336

is also reached from step

314

or

328

when Gyn·Gyn−1 is negative, i.e. when the turning direction was changed from a left turn to a right turn or from a right turn to a left turn across the neutral. Therefore, it will be note that when a slalom driving is synchronized with the consonant rolling frequency of the vehicle body, the threshold count number nc is counted up with a detection of the largest value of the lateral acceleration Gy in a left turn or the smallest value of the lateral acceleration Gy (largest in the absolute value) in a right turn during the slaloming driving.

In step

338

, it is judged if the absolute value of the lateral acceleration Gy is larger than a threshold value Gyt predetermined therefor in order to determined whether or not to carry out the modification of Cg and Ca against a rolling of the body of the vehicle consonant to a slalom driving. When the answer is yes, the control proceeds to step

340

, while when the answer is no, the control proceeds to step

352

described hereinbelow.

In step

340

, a sum of the absolute values of Gymax and Gymin is calculated as Uc

2

, such as Uc

2

=Gymax−Gymin. Then, in step

342

, it is judged if Us

2

is larger than a threshold value Uc

2

t predetermined therefor in order to still determine whether or not to carry out the modification of Cg and Ca against a rolling of the vehicle body consonant to a slalom driving. When the answer is yes, the control proceeds to step

344

, while when the answer is no, the control proceeds to step

352

.

In step

344

, modification amounts ΔCgc

2

and ΔCac

2

for Cg and Ca against a rolling of the vehicle body consonant to a slalom driving are respectively made Egc

2

and Eac

2

appropriately determined therefor.

In step

346

, it is judged if a flag F

6

is 1. The flag F

6

is initially reset to zero at each start of the control. When the answer is no, the control proceeds to step

348

, and a timer is set. Then, in step

350

, the flag F

6

is set to 1. Then the control returns to step

300

. When the answer of step

346

is yes, i.e. after the timer was once set, the control bypasses steps

348

and

350

.

In step

352

, it is judged if the timer started in step

348

has counted up a time preset therein. When the answer is no, the control returns to step

300

. When the answer is yes, the control proceeds to step

354

, and the modification amounts ΔCgc

2

and ΔCac

2

are reset to zero. Then, in step

356

, the timer is reset, and then, in step

358

, the flag F

6

is reset to zero. Then the control returns to step

300

.

Thus, it will also be appreciated that according to this embodiment, the modification amounts ΔCgc

2

and ΔCac

2

for Cg and Ca against a rolling of the vehicle body consonant to a slalom driving are made substantial amounts such as Egc

2

and Eac

2

, respectively, when the absolute value of the lateral acceleration is larger than a threshold value predetermined therefor, and further the lateral acceleration changes alternately leftward and rightward so much across the neutral in a slaloming manner at a frequency around a consonant rolling frequency of the vehicle body that a sum of the absolute values of a largest leftward lateral acceleration and a largest rightward lateral acceleration exceeds a threshold value predetermined therefor, wherein ΔCgc

2

and ΔCac

2

are respectively set at such values as Egc

2

and Eac

2

until such a consonant slalom steering is stopped or at least a predetermined time lapses when once so set.

The values of Egc

2

and Eac

2

may also be varied according to the magnitude of the sum of the absolute values of the largest leftward lateral acceleration and the largest rightward lateral acceleration by looking at an appropriate map not shown. Further, the values of ΔCgc

2

and ΔCac

2

thus obtained may also be appropriately shared between the front and rear halves of the phantom damping system according to such arts as described with reference to

FIGS. 13A and 13B

,

16

A-

16

C,

17

A-

17

C,

18

A-

18

C or

19

A-

19

C, or any other arts.

Additive modification amounts against a rolling of the vehicle body consonant to a slalom driving of the vehicle may be obtained based upon rolling acceleration of the vehicle body.

FIGS. 27A and 27B

present in combination a flowchart similar to

FIG. 25

or

26

, showing such an embodiment for obtaining modification amounts denoted as ΔCgc

3

f, ΔCgc

3

r, and ΔCac

3

f, ΔCac

3

r based upon the rolling acceleration of the vehicle body. The modification amounts of this embodiment are also obtained according to the same technical concept as in the embodiments shown in

FIGS. 25 and 26

, except that the slalom is separately processed based upon rolling accelerations of the front and rear portions of the vehicle body corresponding to the pair of front and rear wheels. The rolling accelerations of the front and rear portions of the vehicle are available from the output signals of the vertical acceleration sensors

28

FL,

28

FR,

28

RL and

28

RR indicating up and down accelerations {umlaut over (X)}fin, {umlaut over (X)}fout, {umlaut over (X)}rin and {umlaut over (X)}rout of body portions vertically above the corresponding wheels.

Also for the sake of convenience of review, steps in

FIG. 27A

for the front portion of the vehicle body corresponding to those in

FIG. 25

or

26

are numbered to be larger by 200 or 100 than those in

FIG. 25

or

26

, respectively, and steps in

FIG. 27B

for the rear portion of the vehicle body corresponding to those in

FIG. 25

or

26

are numbered to be larger by 300 or 200 than those in

FIG. 25

or

26

, respectively.

Referring to

FIG. 27A

for obtaining the modification amounts ΔCgc

3

f and ΔCac

3

f for Cgf and Caf, when the control is started, in step

400

, it is judged if a flag F

7

is set to 1. When the answer is no, the control proceeds to step

402

, while when the answer is yes, the control proceeds to step

412

.

In step

402

, it is judged if a flag F

8

is 1. When the answer is yes, control proceeds to step

426

, while when the answer is no, the control proceeds to step

403

, and a rolling acceleration of the front portion of the vehicle body, denoted as Grf, is calculated based upon the vertical accelerations {umlaut over (X)}fin and {umlaut over (X)}fout of the portions of the vehicle body vertically above the front wheels inside and outside of a turn detected by the vertical acceleration sensors

28

FL and

28

FR, respectively, as Grf=({umlaut over (X)}fin−{umlaut over (X)}fout)/Wf.

In step

404

, it is judged if the rolling acceleration Grf is positive. In analogy with the lateral acceleration, the rolling acceleration Grf is made positive when it is directed clockwise as viewed from the back of the vehicle as in a left turn of the vehicle, while Grf is made negative when it is directed counter-clockwise as viewed from the back of the vehicle as in a right turn of the vehicle. When the answer is yes, the control proceeds to step

406

, while when the answer is no, the control proceeds to step

408

.

In step

406

, the flag F

7

is set to 1, and the control proceeds to step

410

, wherein values of Grfmax and Grfo described hereinbelow are reset to zero.

Instep

412

, a count number nf initially reset to zero at each start of the control is incremented by 1. What is counted by nf is the same as in the flowchart of

FIG. 25

or

26

.

In step

414

, it is judged if Grfn−Grfn−1 is positive. Grfn is the value of the rolling acceleration Grf calculated in step

403

at the instant of the current scanning cycle passing through step

414

with the count number nf processed in the preceding step

412

. Therefore, Grfn−1 means the rolling acceleration Grf calculated in step

403

at the moment of the control proceeding through step

414

in the one preceding cycle of scanning through the flowchart. When Grfn·Grfn−1 is positive, it may be assumed that the turning of the vehicle remains in a left turn, while when Grfn·Grfn−1 is negative, it may be assumed that the direction of the turn was changed from a left turn to a right turn across a neutral position. When the answer is yes, the control proceeds to step

416

, while when the answer is no, the control proceeds to step

436

described hereinbelow.

In step

416

, it is judged if Grfn is larger than Grfn−1. When the answer is yes, the control proceeds to step

418

, and Grfmax is made to be Grfn, while when the answer is no, the control proceeds to step

420

, and Grfmax is made to be Grfn−1. Therefore, it will be noted that by steps

416

,

418

and

420

, the largest of a series of Grfn, Grfn−1, Grfn−2, . . . is selected for Grfmax.

In step

422

, it is judged if the count number nf is larger than a threshold value nc predetermined therefor. As is the same as nc in step

220

of the flowchart of

FIG. 25

, or nc in step

320

of the flowchart of

FIG. 26

, the threshold count number nc is determined in relation with the cycle time of the scanning control through this flowchart so as to count a time duration corresponding to a half of a cycle period of a consonant rolling of the vehicle body.

Returning to step

408

, when the control comes to this step, the flag F

8

is set to 1. This branch path is prepared for a right turn of the vehicle.

In step

424

, values of Grfmin and Grfo described hereinbelow are also reset to zero, respectively. Then, in step

426

, the count number nf is incremented by 1.

In step

428

, it is judged if Grfn·Grfn−1 is positive. When Grfn·Grfn−1 is positive, it may be assumed that the turning of the vehicle remains in a right turn, while when Grfn·Grfn−1 is negative, it may be assumed that the direction of the turning was changed from a right turn to a left turn across a neutral position. When the answer is yes, the control proceeds to step

430

, while when the answer is no, the control proceeds to step

436

.

In step

430

, it is judged if Grfn is smaller than Grfn−1. When the answer is yes, the control proceeds to step

432

, and Grfmin is made to be Grfn, while when the answer is no, the control proceeds to step

434

, and Grfmin is made to be Grfn−1. Therefore, it will be noted that by steps

430

,

432

and

434

, the smallest of a series of Grfn, Grfn−1, Grfn−2, . . . is selected for Grfmin.

Coming again to step

422

, when the answer is yes, the control proceeds to step

436

, wherein the count number nf is reset to zero, and the flags F

7

and F

8

are also reset to zero. When the answer of step

422

is no, the control bypasses step

436

to come to step

438

. On the other hands, as described above, step

436

is also reached from step

414

or

428

when Grfn·Grfn−1 is negative, i.e. when the turning direction was changed from a left turn to a right turn or from a right turn to a left turn across the neutral. Therefore, it will be note that when a slalom driving is synchronized with the consonant rolling frequency of the vehicle body, the threshold count number nc is counted up with a detection of the largest value of the rolling acceleration Grf in a left turn or the smallest value of the rolling acceleration Grf (largest in the absolute value) in a right turn during the slaloming driving.

In step

438

, it is judged if the absolute value of the rolling acceleration Grf is larger than a threshold value Grft predetermined therefor in order to determined whether or not to carry out the modification of Cgf and Caf against a rolling of the front portion of the vehicle body consonant to a slalom driving. When the answer is yes, the control proceeds to step

440

, while when the answer is no, the control proceeds to step

452

described hereinbelow.

In step

440

, a sum of the absolute values of Grfmax and Grfmin is calculated as Uc

3

, such as Uc

3

=Grfmax−Grfmin. Then, in step

442

, it is judged if Uc

3

is larger than a threshold value Uc

3

t predetermined therefor in order to still determine whether or not to carry out the modification of Cgf and Caf against a rolling of the front portion of the vehicle body consonant to a slalom driving. When the answer is yes, the control proceeds to step

444

, while when the answer is no, the control proceeds to step

452

.

In step

444

, modification amounts ΔCgc

3

f and ΔCac

3

f for Cgf and Caf against a rolling of the front portion of the vehicle body consonant to a slalom driving are made Egc

3

f and Eac

3

f appropriately determined therefor.

In step

446

, it is judged if a flag F

9

is 1. The flag F

9

is initially reset to zero at each start of the control. When the answer is no, the control proceeds to step

448

, and a timer is set. Then, in step

450

, the flag F

9

is set to 1. Then the control proceeds to step

500

. When the answer of step

446

is yes, i.e. after the timer was once set, the control bypasses steps

448

and

450

.

In step

452

, it is judged if the timer started in step

448

has counted up a time preset therein. When the answer is no, the control proceeds to step

500

. When the answer is yes, the control proceeds to step

454

, and the modification amounts ΔCgc

3

f and ΔCac

3

f are reset to zero. Then, in step

456

, the timer is reset, and then, in step

458

, the flag F

9

is reset to zero. Then the control proceeds to step

500

.

Continuing to the steps of

FIG. 27A

, referring to

FIG. 27B

for obtaining the modification amounts ΔCgc

3

r and ΔCac

3

r for Cgr and Car, in step

500

, it is judged if a flag F

10

is set to 1. When the answer is no, the control proceeds to step

502

, while when the answer is yes, the control proceeds to step

512

.

In step

502

, it is judged if a flag F

11

is 1. When the answer is yes, control proceeds to step

526

, while when the answer is no, the control proceeds to step

503

, and a rolling acceleration of the rear portion of the vehicle body, denoted as Grr, is calculated based upon the vertical accelerations {umlaut over (X)}rl and {umlaut over (X)}rr of the portions of the vehicle body vertically above the rear left and rear right wheels detected by the vertical acceleration sensors

28

RL and

28

RR, respectively, as Grr=({umlaut over (X)}rin−{umlaut over (X)}rout)/Wr.

In step

504

, it is judged if the rolling acceleration Grr is positive. The rolling acceleration Grr is also made positive when it is directed clockwise as viewed from the back of the vehicle as in a left turn of the vehicle, while Grr is made negative when it is directed counter-clockwise as viewed from the back of the vehicle as in a right turn of the vehicle. When the answer is yes, the control proceeds to step

506

, while when the answer is no, the control proceeds to step

508

.

In step

506

, the flag F

10

is set to 1, and the control proceeds to step

510

, wherein values of Grrmax and Grro described hereinbelow are reset to zero.

Instep

512

, a count number nr initially reset to zero at each start of the control is incremented by 1. What is counted by nr is the same as in the flowchart of

FIG. 25

or

26

.

In step

514

, it is judged if Grrn·Grrn−1 is positive. Grrn is the value of the rolling acceleration Grr calculated in step

503

at the instant of the current scanning cycle passing through step

514

with the count number nr processed in the preceding step

512

. Therefore, Grrn−1 means the rolling acceleration Grr calculated in step

503

at the moment of the control proceeding through step

514

in the one preceding cycle of scanning through the flowchart. When Grrn·Grrn−1 is positive, it may be assumed that the turning of the vehicle remains in a left turn, while when Grrn·Grrn−1 is negative, it may be assumed that the direction of the turn was changed from a left turn to a right turn across a neutral position. When the answer is yes, the control proceeds to step

516

, while when the answer is no, the control proceeds to step

536

described hereinbelow.

In step

516

, it is judged if Grrn is larger than Grrn−1. When the answer is yes, the control proceeds to step

518

, and Grrmax is made to be Grrn, while when the answer is no, the control proceeds to step

520

, and Grrmax is made to be Grrn−1. Therefore, it will be noted that by steps

516

,

518

and

520

, the largest of a series of Grrn, Grrn−1, Grrn−2, . . . is selected for Grrmax.

In step

522

, it is judged if the count number nr is larger than the threshold value nc which is the same count number as used in step

422

.

Returning to step

508

, when the control comes to this step, the flag F

11

is set to 1. This branch path is prepared for a right turn of the vehicle.

In step

524

, values of Grrmin and Grro described hereinbelow are also reset to zero, respectively. Then, in step

526

, the count number nr is incremented by 1.

In step

528

, it is judged if Grrn·Grrn−1 is positive. When Grrn·Grrn−1 is positive, it may be assumed that the turning of the vehicle remains in a right turn, while when Grrn·Grrn−1 is negative, it may be assumed that the direction of the turning was changed from a right turn to a left turn across a neutral position. When the answer is yes, the control proceeds to step

530

, while when the answer is no, the control proceeds to step

436

.

In step

530

, it is judged if Grrn is smaller than Grrn−1. When the answer is yes, the control proceeds to step

532

, and Grrmin is made to be Grrn, while when the answer is no, the control proceeds to step

534

, and Grrmin is made to be Grrn−1. Therefore, it will be noted that by steps

530

,

532

and

534

, the smallest of a series of Grrn, Grrn−1, Grrn−2, . . . is selected for Grrmin.

Coming again to step

522

, when the answer is yes, the control proceeds to step

536

, wherein the count number nr is reset to zero, and the flags F

10

and F

11

are also reset to zero. When the answer of step

522

is no, the control bypasses step

536

to come to step

538

. On the other hands, as described above, step

536

is also reached from step

514

or

528

when Grrn·Grrn−1 is negative, i.e. when the turning direction was changed from a left turn to a right turn or from a right turn to a left turn across the neutral. Therefore, it will be note that when a slalom driving is synchronized with the consonant rolling frequency of the vehicle body, the threshold count number nc is counted up with a detection of the largest value of the rolling acceleration Grf in a left turn or the smallest value of the rolling acceleration Grf (largest in the absolute value) in a right turn during the slaloming driving.

In step

538

, it is judged if the absolute value of the rolling acceleration Grr is larger than a threshold value Grrt predetermined therefor in order to determined whether or not to carry out the modification of Cgr and Car against a rolling of the rear portion of the vehicle body consonant to a slalom driving. When the answer is yes, the control proceeds to step

540

, while when the answer is no, the control proceeds to step

552

described hereinbelow.

In step

540

, a sum of the absolute values of Grrmax and Grrmin is calculated as Uc

4

, such as Uc

4

=Grrmax−Grrmin. Then, in step

542

, it is judged if Uc

4

is larger than a threshold value Uc

4

t predetermined therefor in order to still determine whether or not to carry out the modification of Cgr against a rolling of the rear portion of the vehicle body consonant to a slalom driving. When the answer is yes, the control proceeds to step

544

, while when the answer is no, the control proceeds to step

552

.

In step

544

, modification amounts ΔCgc

3

r and ΔCac

3

r for Cgr and Car against a rolling of the rear portion of the vehicle body consonant to a slalom driving are made Egc

3

r and Eac

3

r appropriately determined therefor.

In step

546

, it is judged if a flag F

12

is 1. The flag F

12

is initially reset to zero at each start of the control. When the answer is no, the control proceeds to step

548

, and a timer is set. Then, in step

550

, the flag F

12

is set to 1. Then the control returns to step

400

. When the answer of step

446

is yes, i.e. after the timer was once set, the control bypasses steps

548

and

450

.

In step

552

, it is judged if the timer started in step

548

has counted up a time preset therein. When the answer is no, the control returns to step

400

. When the answer is yes, the control proceeds to step

554

, and the modification amounts ΔCgc

3

r and ΔCac

3

r are reset to zero. Then, in step

556

, the timer is reset, and then, in step

558

, the flag F

12

is reset to zero. Then the control returns to step

400

.

Thus, it will be appreciated that according to this embodiment, the modification amounts ΔCgc

3

f and ΔCac

3

f for Cgf and Caf and ΔCgc

3

r and ΔCac

3

r for Cgr and Car against a rolling of the vehicle body consonant to a slalom driving are obtained separately for the front and rear portions of the vehicle body to be made substantial amounts such as Egc

3

f and Eac

3

f and Egc

3

r and Eac

3

r, respectively, when the absolute values of the rolling acceleration of the front and rear portions of the vehicle are larger than a threshold value predetermined therefor, and further the rolling acceleration changes alternately leftward and rightward so much across the neutral in a slaloming manner at a frequency around a consonant rolling frequencies of the front and rear portions of the vehicle body, respectively, that a sum of the absolute values of a largest clockwise rolling acceleration and a largest counter-clockwise rolling acceleration of the vehicle body as viewed from the back of the vehicle exceeds a threshold value predetermined therefor, wherein ΔCgc

3

f and ΔCac

3

f and ΔCgc

3

r and ΔCac

3

r are respectively set at such values as Egc

3

f and Eac

3

f and Egc

3

r and Eac

3

r until such a consonant slalom steering is stopped or at least a predetermined time lapses when once so set.

The values of Egc

3

f and Eac

3

f and Egc

3

r and Eac

3

r may also be varied according to the magnitude of the sum of the absolute values of the largest clockwise rolling acceleration and the largest counter-clockwise rolling acceleration by looking at an appropriate map not shown.

Although the present invention has been described in detail with respect to a basic preferred embodiment and various modifications thereof, it will be apparent for those skilled in the art that other various modifications are possible with respect to the shown embodiments within the scope of the present invention.

Claims

1. A device for controlling damping coefficients of shock absorbers of a four wheeled vehicle having a vehicle body, front left, front right, rear left and rear right wheels each supporting the vehicle body at a corresponding portion thereof, and the shock absorbers each acting between each of the wheels and the corresponding portion of the vehicle body, comprising:means for constructing a phantom damping system composed of a phantom side shock absorber disposed vertically at a lateral inside of a turn running of the vehicle to have a lower end movable along a ground surface together with the vehicle and an upper end vertically movable relative to the lower end with a first phantom damping coefficient therebetween, and a phantom angular shock absorber arranged to act between the upper end of the phantom side shock absorber and the vehicle body with a second phantom damping coefficient therebetween, such that the phantom damping system provides the vehicle body with a substantially same phantom vertical damping force against a vertical movement of the vehicle body and a substantially same phantom angular damping moment against a rolling angular movement of the vehicle body as the shock absorbers acting between the wheels and the corresponding portions of the vehicle during a rolling of the vehicle body due to the turn running of the vehicle; means for calculating values of at least the first and second phantom damping coefficients for obtaining an optimum rolling performance of the vehicle body by the phantom damping system during the turn running of the vehicle; and means for controlling the damping coefficients of the shock absorbers acting between the wheels and the corresponding portions of the vehicle body based upon the calculated values of the first and second phantom damping coefficients.
2. A device according to claim 1, wherein the phantom damping system constructing means construct the phantom damping system as front and rear halves thereof corresponding separately to the shock absorbers acting between the front left and front right wheels and the corresponding portions of the vehicle body and to the shock absorbers acting between the rear left and rear right wheels and the corresponding portions of the vehicle body.
3. A device according to claim 2, wherein the calculating means further calculate lateral distances of the phantom side and angular shock absorbers of the front and rear halves of the phantom damping system according to a sum of an appropriately gained first product of steering angle and a square of vehicle speed and an appropriately gained second product of change rate of the steering angle and a square of vehicle speed, such that the lateral distances are generally increased according to an increase of the sum when the sum is not larger than a threshold value and are generally decreased according to an increase of the sum when the sum is larger than the threshold value.
4. A device according to claim 2, wherein the calculating means further calculate lateral distances of the phantom side and angular shock absorbers of the front and rear halves of the phantom damping system according to forces acting across the front and rear shock absorbers, such that lateral distances are generally increased according to an increase of the forces up to respective saturation values.
5. A device according to claim 2, wherein the calculating means further calculate a slip angle and a change rate of the slip angle of the vehicle body, thereby discriminating a slipping state of the vehicle about at least an oversteering state, and further calculate modification factor for proportionally modifying a lateral distance of the phantom side and angular shock absorber of the front half of the phantom damping system according to the absolute value of the slip angle of the vehicle body and the slipping state, such that when the vehicle is in the oversteering state, the modification factor for the lateral distance of the front half of the phantom damping system is generally increased according to an increase of the absolute value of the slip angle.
6. A device according to claim 2, wherein the calculating means further calculate a slip angle and a change rate of the slip angle of the vehicle body, thereby discriminating a slipping state of the vehicle about at least an understeering state, and further calculate modification factor for proportionally modifying a lateral distance of the phantom side and angular shock absorbers of the rear half of the phantom damping system according to the absolute value of the slip angle of the vehicle body and the slipping state, such that, when the vehicle is in the understeering state, the modification factor for the lateral distance of the rear half of the phantom damping system is generally increased according to an increase of the absolute value of the slip angle.
7. A device according to claim 2, wherein the calculating means further calculate a slip angle and a change rate of the slip angle of the vehicle body, thereby discriminating a slipping state of the vehicle about at least a dissipating state, and further calculate modification factors for proportionally modifying lateral distances of the phantom side and angular shock absorbers of the front and rear halves of the phantom damping system according to the absolute value of the slip angle of the vehicle body and the slipping state, such that, when the vehicle is in the dissipating state, the modification factors for the lateral distances of the front and rear halves of the phantom damping system are magnified to be larger than 1 and are further generally increased according to an increase of the absolute value of the slip angle.
8. A device according to claim 2, wherein the calculating means calculate a basic value of the first phantom damping coefficient of the phantom side shock absorber of the front half of the phantom damping system based upon a mean value of vertical accelerations of the portions of the vehicle body corresponding to the front left and front right wheels by looking at a map prepared therefor, and a basic value of the first phantom damping coefficient of the phantom side shock absorber of the rear half of the phantom damping system based upon a mean value of vertical accelerations of the portions of the vehicle body corresponding to the rear left and rear right wheels by looking at a map prepared therefor, and a basic value of the second phantom damping coefficient of the phantom angular shock absorber of the front half of the phantom damping system based upon a rotational acceleration of a mass of a front portion of the vehicle body corresponding to the front left and front right wheels by looking at a map prepared therefor, and a basic value of the second phantom damping coefficient of the phantom angular shock absorber of the rear half of the phantom damping system based upon a rotational acceleration of a mass of a rear portion of the vehicle body corresponding to the rear left and rear right wheels by looking at a map prepared therefor.
9. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to a rate of throttle opening, such that the throttle opening rate dependent modification amounts for the front and rear halves are generally increased according to an increase of the throttle opening rate, the modification amount for the front half being more increased than the modification amount for the rear half.
10. A device according to claim 9, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the throttle opening rate, such that the throttle opening rate dependent modification amounts for the front and rear halves are generally increased according to an increase of the throttle opening rate, the modification amount for the front half being more increased than the modification amount for the rear half.
11. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first and second phantom damping coefficients and standard lateral distances of the front and rear halves of the phantom side and angular shock absorbers according to a deviation of a yaw rate of the vehicle from a standard yaw rate thereof theoretically calculatable from a steering angle and a vehicle speed, such that the yaw rate dependent modification amounts for the front and rear halves are generally increased in the absolute values thereof according to an increase in the absolute value of the yaw rate deviation, the sign of the yaw rate dependent modification amounts being dependent on the sign of the yaw rate deviation such that the signs of the yaw rate dependent modification amounts are reversed according to a reversal of the sign of the yaw rate deviation.
12. A device according to claim 8, wherein the calculating means further calculate modification factors for modifying shares of the first and second phantom damping coefficients and lateral distances of the front and rear halves of the phantom side and angular shock absorbers between the front and rear halves according to a rate of throttle opening, such that the throttle opening rate dependent modification factors for the front half are smaller as vehicle speed is higher and are generally decreased according to an increase of the throttle opening rate, the decrease being larger as the vehicle speed is higher, when the vehicle is a front drive vehicle.
13. A device according to claim 8, wherein the calculating means further calculate modification factors for modifying shares of the first and second phantom damping coefficients and lateral distances of the front and rear halves of the phantom side and angular shock absorbers between the front and rear halves according to a rate of throttle opening, such that the throttle opening rate dependent modification factors for the front half are larger as vehicle speed is higher and are generally increased according to an increase of the throttle opening rate, the increase being larger as the vehicle speed is higher, when the vehicle is a rear drive vehicle.
14. A device according to claim 8, wherein the calculating means further calculate modification factors for modifying shares of the first and second phantom damping coefficients and lateral distances of the front and rear halves of the phantom side and angular shock absorbers between the front and rear halves according to a brake stroke, such that the brake stroke dependent modification factors for the front half are generally increased according to an increase of the brake stroke, the increase being larger as the vehicle speed is higher, when the vehicle is an ordinary type vehicle.
15. A device according to claim 8, wherein the calculating means further calculate modification factors for modifying shares of the first and second phantom damping coefficients and lateral distances of the front and rear halves of the phantom side and angular shock absorbers between the front and rear halves according to a brake stroke, such that the brake stroke dependent modification factors for the front half are generally decreased according to an increase of the brake stroke, the decrease being larger as the vehicle speed is higher, when the vehicle is a sports type vehicle.
16. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear masses of the vehicle body corresponding to the front and rear wheels, such that the mass dependent modification amounts for the front and rear halves are generally increased according to an increase of the front and rear masses.
17. A device according to claim 16, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the front and rear masses, such that the mass dependent modification amounts for the front and rear halves are generally increased according to an increase of the front and rear masses.
18. A device according to claim 8, wherein the calculating means further calculate modification factors for proportionally modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to vertically stroking velocities of front and rear portions of the vehicle body corresponding to the front and rear wheels, such that the vertically stroking velocity dependent modification factors for the front and rear halves are generally increased according to an increase of the vertically stroking velocities.
19. A device according to claim 18, wherein the calculating means further calculate modification factors for proportionally modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the vertically stroking velocities, such that the vertically stroking velocity dependent modification factors for the front and rear halves are generally increased according to an increase of the vertically stroking velocities.
20. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear flapping indexes indicating liabilities of the front and rear wheels to flap, such that the flapping index dependent modification amounts for the front and rear halves are generally increased according to an increase of the flapping indexes.
21. A device according to claim 20, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the flapping indexes, such that the flapping index dependent modification amounts for the front and rear halves are generally increased according to an increase of the flapping indexes.
22. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to a brake stroke, such that the brake stroke dependent modification amounts for the front and rear halves are generally increased according to an increase of the brake stroke, the modification amount for the front half being more increased than the modification amount for the rear half.
23. A device according to claim 22, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the brake stroke, such that the brake stroke dependent modification amounts for the front and rear halves are generally increased according to an increase of the brake stroke, the modification amount for the front half being more increased than the modification amount for the rear half.
24. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear swaying indexes indicating liabilities of front and rear portions of the vehicle body corresponding to the front and rear wheels to sway, such that the swaying index dependent modification amounts for the front and rear halves are generally increased according to an increase of the swaying indexes.
25. A device according to claim 24, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the swaying indexes, such that the swaying index dependent modification amounts for the front and rear halves are generally increased according to an increase of the swaying indexes.
26. A device according to claim 25, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear flapping indexes indicating liabilities of the front and rear wheels to flap, such that the flapping index dependent modification amounts for the front and rear halves are generally increased according to an increase of the flapping indexes, and modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the flapping indexes, such that the flapping index dependent modification amounts for the front and rear halves are generally increased according to an increase of the flapping indexes, and then further select either the swaying index dependent modification amounts or the flapping index dependent modification amounts which are larger than the other as a whole for additively modifying the basic values of the first and second phantom damping coefficients.
27. A device according to claim 26, wherein the calculating means further calculate modification amounts for subtractively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear rattling indexes indicating liabilities of front and rear portions of the vehicle body corresponding to the front and rear wheels to rattle, such that the rattling index dependent modification amounts for the front and rear halves are generally increased in the absolute values thereof according to an increase of the rattling indexes, and modification amounts for subtractively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the rattling indexes, such that the rattling index dependent modification amounts for the front and rear halves are generally increased in the absolute values thereof according to an increase of the rattling indexes, and then further select either the selected swaying index dependent or flapping index dependent modification amounts or the rattling index dependent modification amounts which are larger than the other as a whole in the absolute values thereof for additively or subtractively modifying the basic values of the first and second phantom damping coefficients.
28. A device according to claim 8, wherein the calculating means further calculate modification amounts for subtractively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear rattling indexes indicating liabilities of front and rear portions of the vehicle body corresponding to the front and rear wheels to rattle, such that the rattling index dependent modification amounts for the front and rear halves are generally increased in the absolute values thereof according to an increase of the rattling indexes.
29. A device according to claim 28, wherein the calculating means further calculate modification amounts for subtractively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the rattling indexes, such that the rattling index dependent modification amounts for the front and rear halves are generally increased in the absolute values thereof according to an increase of the rattling indexes.
30. A device according to claim 1, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first and second phantom damping coefficients the phantom side and angular shock absorbers when a maximum difference between leftward and rightward steering angles during a half of a cycle period of a consonant rolling of the vehicle body exceeds a threshold value predetermined therefor.
31. A device according to claim 1, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first and second phantom damping coefficients of the phantom side and angular shock absorbers when a maximum difference between leftward and rightward lateral accelerations of the vehicle body during a half of a cycle period of a consonant rolling of the vehicle body exceeds a threshold value predetermined therefor.
32. A device according to claim 1, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first and second phantom damping coefficients of the phantom side and angular shock absorbers when a maximum difference between clockwise and counter-clockwise rolling accelerations of the vehicle body as viewed from the back of the vehicle during a half of a cycle period of a consonant rolling of the vehicle body exceeds a threshold value predetermined therefor.

Priority Claims (4)

Number	Date	Country
11-175401	Jun 1999	JP
11-175421	Jun 1999	JP
11-192225	Jul 1999	JP
11-201623	Jul 1999	JP

US Referenced Citations (5)

Number	Name	Date
5440488	Yamaoka et al.	Aug 1995
5802486	Uchiyama	Sep 1998
5810384	Iwasaki et al.	Sep 1998
5944153	Ichimaru	Aug 1999
5950776	Iwasaki et al.	Sep 1999

Foreign Referenced Citations (3)

Number	Date	Country
A-7-125518	May 1995	JP
A-9-309316	Dec 1997	JP
A-11-268512	Oct 1999	JP

Device for controlling suspension shock absorbers of vehicles based upon phantom substitute therefor

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

Priority Claims (4)

US Referenced Citations (5)

Foreign Referenced Citations (3)