Method and device for stabilizing a vehicle

Abstract

A method of stabilizing a vehicle involving the following steps is described: recording characteristic actual values that describe the driving condition of a vehicle; determining setpoint values that are at least partially assigned to the actual values; comparing actual values and setpoint values and influencing actual values based on comparison results, one of the recorded actual values being characteristic of the roll state of the vehicle, and one of the setpoint values being assigned to the recorded actual value that is characteristic of the roll state of the vehicle. A device for stabilizing a vehicle is also described.

Description

[0001] The present invention relates to a method of stabilizing a vehicle including the steps: recording characteristic actual values that describe the driving condition of a vehicle, determining setpoint values that are at least partially assigned to the actual values, comparing actual values and setpoint values and influencing actual values based on comparison results. The present invention also relates to a device for stabilizing a vehicle having means for recording characteristic values that describe the driving condition of a vehicle, means for determining setpoint values that are at least partially assigned to the actual values, means for comparing actual values and setpoint values and means for influencing actual values based on comparison results.

BACKGROUND INFORMATION

[0002] Methods and devices according to the definition of the species are used in systems intended to increase driving safety based on vehicle dynamics. For example, the electronic stability program (ESP) gives the driver of a vehicle both improved basic functions with respect to the anti-lock brake system (ABS) and the anti-slip control (ASC), both systems acting primarily in situations critical to longitudinal dynamics. Examples of this include full braking and severe accelerations. The electronic stability program (ESP) also supports the driver in situations critical to transverse dynamics. The system improves driving stability in all operating states, i.e., in full braking, partial braking, free rolling, traction, thrust and load reversal as soon as an extreme driving situation occurs. Even in extreme steering maneuvers, the electronic stability program (ESP) drastically reduces the danger of swerving and largely makes it possible to keep the automobile under safe control even in critical traffic situations.

[0003] To regulate vehicle dynamics, it is known to use the float angle of the vehicle and the yaw rate of the vehicle as controlled variables. The consideration of these controlled variables makes it possible to largely eliminate the danger of swerving.

[0004] However, in addition to the danger of swerving, there also exists the danger that a vehicle will roll over due to extreme driving maneuvers. This applies all the more considering that more and more passenger cars are being offered that have a comparatively short wheelbase and a high center of gravity. The problem of the danger of rollover exists in commercial vehicles in any case.

ADVANTAGES OF THE INVENTION

[0005] The invention builds on the method of the definition of the species in that one of the recorded actual values is characteristic of the roll state of the vehicle and one of the setpoint values is assigned to the recorded actual value that is characteristic of the roll state of the vehicle. In this manner, the roll state of the vehicle is also taken into consideration as part of a known vehicle dynamics control, thus making it possible to prevent a rollover of a vehicle even having a high center of gravity and a short wheelbase and under extreme driving maneuvers.

[0006] Preferably, one of the recorded actual values is the yaw rate and one of the setpoint values is assigned to the yaw rate. It is thus advantageously possible to combine the regulation of the roll state according to the present invention with the regulation of the yaw rate already known as part of the electronic stability program (ESP)

[0007] It is also advantageous if one of the recorded actual values is the float angle and if one of the setpoint values is assigned to the float angle. It is thus possible to combine the regulation of the roll state according to the present invention with the regulation of the float angle, the latter being known from the electronic stability program (ESP). It is advantageous in particular if the yaw rate regulation, float angle regulation and the regulation of the roll state are integrated in one system.

[0008] It is advantageous that the roll angle is the actual value that is characteristic of the roll state of the vehicle. It is thus possible to measure the roll angle directly and to record the roll state of the vehicle in this manner.

[0009] However, it may also be useful if a pressure change in an air spring of the vehicle is the value that is characteristic of the roll state of the vehicle. Commercial vehicles in particular are frequently equipped with air springs so that it is advantageously possible to use the pressure change for recording the roll state.

[0010] Preferably, setpoint values are determined from the input values of vehicle speed and steering angle. The input values of vehicle speed and steering angle are also already used in the known electronic stability program (ESP) so that it is also of particular advantage to use these values as input values in the context of the present invention to determine the setpoint value that is characteristic of the roll state of the vehicle.

[0011] Preferably, actual values are influenced by braking interventions and/or engine interventions. This is also already known in the electronic stability program (ESP), for example, for the yaw rate. It is also possible to influence the actual value that is characteristic of the roll state of the vehicle in an advantageous manner by braking interventions and/or engine interventions.

[0012] Preferably the roll angle is influenced by an actuator. This influencing may occur in addition to or as an alternative to the influencing of the braking system and/or the engine so that numerous measures based on the present invention are available with respect to a rollover prevention.

[0013] It is useful to implement the method of the present invention in a vehicle combination for the roll regulation of the tractor vehicle and trailer or semitrailer. It is thus possible, for example, to prevent a rollover for the individual parts of a vehicle combination independently, which is useful in particular with respect to the rocking motion of truck trailers or mobile homes towed by passenger cars.

[0014] The invention builds on the device of the definition of the species in that one of the recorded actual values is characteristic of the roll state of the vehicle and one of the setpoint values is assigned to the recorded actual value that is characteristic of the roll state of the vehicle. In this manner, the roll state of the vehicle is also taken into consideration as part of a known vehicle dynamics control, thus making it possible to prevent a rollover of a vehicle even having a high center of gravity and a short wheelbase and under extreme driving maneuvers.

[0015] Preferably, one of the recorded actual values is the yaw rate and one of the setpoint values is assigned to the yaw rate. It is thus advantageously possible to combine the regulation of the roll state according to the present invention with the regulation of the yaw rate already known as part of the electronic stability program (ESP).

[0016] It is also useful if one of the actual values of the present invention is the float angle and if one of the setpoint values is assigned to the float angle. It is thus possible to combine the regulation of the roll state according to the present invention with the regulation of the float angle, the latter being known from the electronic stability program (ESP). It is advantageous in particular if the yaw rate regulation, float angle regulation and the regulation of the roll state are integrated in one system.

[0017] It is useful that means are provided for measuring the roll angle and that the roll angle is the actual value that is characteristic of the roll state of the vehicle. It is thus possible to measure the roll angle directly and to record the roll state of the vehicle in this manner.

[0018] It may also be advantageous that means are provided for measuring the pressure in an air spring of the vehicle and that a pressure change is the actual value that is characteristic of the roll state of the vehicle. Commercial vehicles in particular are frequently equipped with air springs so that it is advantageously possible to use the pressure change for recording the roll state.

[0019] It is advantageous in particular that means are provided for measuring the vehicle speed, that means are provided for measuring the steering angle and that setpoint values are determined from the input values of vehicle speed and steering angle. The input values of vehicle speed and steering angle are also already used in the known electronic stability program (ESP) so that it is also of particular advantage to use these values as input values in the context of the present invention to determine the setpoint value that is characteristic of the roll state of the vehicle.

[0020] Advantageously, means are provided for influencing the braking system and/or the engine, and actual values are influenced by braking interventions and/or engine interventions. This is also already known in the electronic stability program (ESP), for example, for the yaw rate. It is also possible to influence the actual value that is characteristic of the roll state of the vehicle in an advantageous manner by braking interventions and/or engine interventions.

[0021] It may also be useful that an actuator is provided and that the roll angle is influenced by an actuator. This influencing may occur in addition to or as an alternative to the influencing of the braking system and/or the engine so that numerous measures based on the present invention are available with respect to a rollover prevention.

[0022] It is of particular advantage that multiple roll regulation devices are provided for the tractor vehicle and for a trailer or a semitrailer in a vehicle combination. It is thus possible, for example, to prevent a rollover for the individual parts of a vehicle combination independently, which is useful in particular with respect to the rocking motion of truck trailers or mobile homes towed by passenger cars.

[0023] The invention is based on the knowledge that the additional regulation of the roll state of a vehicle within an already known electronic stability program makes it possible to achieve particularly high driving safety.

DRAWINGS

[0024] The invention will now be explained using preferred embodiments as examples with reference to the appended drawing in which:

[0025] FIG. 1 shows a block diagram to explain a first embodiment of the invention and

[0026] FIG. 2 shows a block diagram to explain a second embodiment of the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0027] A block diagram is shown in FIG. 1 to explain a first embodiment of the invention. The input values of vehicle speed v and steering angle δ are fed to means 10 for determining a setpoint value. These means 10 for determining a setpoint value are based on a reference model which, among other things, takes the roll angle of the vehicle into consideration. Details of the reference model are discussed further below. As its output value, the reference model has a setpoint roll angle φsetpoint. This setpoint roll angle φsetpoint is one of the input values of a closed-loop control circuit. The other input value is φactual. As a result of the comparison or subtraction of the values φsetpoint and φactual in means 12, the comparison result is supplied to roll regulator 14. This roll regulator 14 delivers an output value to means 16 to influence the actual value. These means may, for example, exert an influence on the braking system, the engine or on a roll angle control. The output value of the closed-loop control circuit, which directly regulates roll angle φ in the present example, is then fed back to means 12 as φactual to compare actual values and setpoint values. This roll angle regulation described in simplified form using the present exemplary embodiment may accordingly be expanded to include the regulation of other values, for example, the yaw rate or the float angle. In order to take transient events into consideration, an expansion of the system may involve a 1st or 2nd order lowpass.

[0028] As mentioned above, the means for determining setpoint values make use of a reference model, which now advantageously takes the roll angle into consideration in addition to the float angle and the yaw rate. This reference model is based on the differential equation system shown below in Equation 1 1$\begin{array}{cc}\left[\begin{array}{ccc}m·v,& 0,& m_s·h\\ 0,& I_z,& -I_{\mathrm{xy}}\\ m_s·h·v,& -I_{\mathrm{xy}},& I_x\end{array}\right]·\&AutoLeftMatch;\left[\begin{array}{c}\stackrel{.}{\beta }\\ \ddot{\psi }\\ \ddot{\phi }\end{array}\right]=\left[\begin{array}{cccc}{Y}_{\beta },& Y_{\psi }-m·v,& 0,& Y_{\phi }\\ N_{\beta },& N_{\psi },& 0,& N_{\phi }\\ 0,& m_s·h·v,& L_p,& L_{\phi }\end{array}\right]·\left[\begin{array}{c}\beta \\ \psi \\ \stackrel{.}{\phi }\\ \phi \end{array}\right]+\&AutoLeftMatch;\left[\begin{array}{c}{Y}_{\delta }\\ N_{\delta }\\ 0\end{array}\right]·\delta & \left(1\right)\end{array}$

[0029] The following relations apply: 2$Y_{\beta }=-C_f-C_r$$Y_{\psi }=\frac{-a·C_f+b·C_r}{v}$$Y_{\delta }=C_f$$N_{\beta }=-a·C_f+b·C_r$$N_{\psi }=\frac{-a^2·C_f+b^2·C_r}{v}$$N_{\delta }=a·C_f$

[0030] The symbols used in the equations have the following meaning:

[0031] Nφ: roll-steer influence,

[0032] Lφ: roll stiffness,

[0033] Lφ: roll damping,

[0034] β: float angle,

[0035] ψ: yaw angle,

[0036] φ: roll angle,

[0037] δ: wheel steering angle,

[0038] a, b: distance from vehicle center of gravity to front axle or rear axle,

[0039] h: height of center of gravity,

[0040] m: vehicle mass (s: movable body mass relative to chassis)

[0041] I: mass moment of inertia (z: vertical axis, x: roll axis, xy: deviation torque),

[0042] v: vehicle speed,

[0043] c: lateral tire stiffness (f: front, r: rear).

[0044] The stationary solution of these equations delivers a reference model for the vehicle yaw rate and the degree of roll freedom: 3$\begin{array}{cc}\frac{\stackrel{.}{\psi }}{\delta }=\frac{L_{\phi }·\left(N_{\beta }·Y_{\delta }-N_{\delta }·Y_{\beta }\right)}{\begin{array}{c}{L}_{\phi }·\left(m·v·N_{\beta }-N_{\beta }·Y_{\psi }+N_{\psi }·Y_{\beta }\right)+\\ m_s·h·v·\left(N_{\phi }·Y_{\beta }-N_{\beta }·Y_{\phi }\right)\end{array}}\frac{\phi }{\delta }=\frac{m_s·h·v·\left(N_{\beta }·Y_{\delta }-N_{\delta }·Y_{\beta }\right)}{\begin{array}{c}{L}_{\phi }·\left(m·v·N_{\beta }-N_{\beta }·Y_{\psi }+N_{\psi }·Y_{\beta }\right)+\\ m_s·h·v·\left(N_{\phi }·Y_{\beta }-N_{\beta }·Y_{\phi }\right)\end{array}}& \left(2\right)\end{array}$

[0045] The setpoint yaw rate

{dot over (ψ)}=ƒ(δ,vf)

[0046] is thus obtained as a function of the steering angle and the vehicle speed, vf being a speed value which describes the speed in longitudinal direction. In a comparable manner, a setpoint roll angle

φ=ƒ(δ,vf),

[0047] is obtained which is also a function of the steering angle and speed value vf.

[0048] If no explicit measurement of the roll angle is available, it is nonetheless possible to implement an indirect roll angle regulation through the measurement of other values that characterize a roll movement of the vehicle. However, this requires a corresponding adaptation of the reference model to the particular measured value used.

[0049] FIG. 2 shows an example of indirect roll regulation. In means 10 for determining setpoint values, a modified reference model is used, which is explained in detail further below. In this case, a pressure change Δp is used as a controlled variable, pressure values measured in air springs of commercial vehicles, for example, being used. A modified reference model, which takes the pressure change dynamics into consideration, is used as a reference model. This is described in detail further below. The output signal of a subtraction 12 is supplied to roll regulator 14, the difference between a value Δpsetpoint, which is an output value of means 10, and a measured value Δpactual, which is the output value of the closed-loop control circuit, being formed. The roll regulator outputs an output signal to means 16 to influence the actual values. In turn, these means may include the braking system, the engine control or special actuator technology to influence the roll angle.

[0050] The reference model is based on the following differential equation system: 4$\begin{array}{cc}\left[\begin{array}{cccc}m·v,& 0,& m_s·h,& 0\\ 0,& I_z,& -I_{\mathrm{xy}},& 0\\ m_s·h·v,& -I_{\mathrm{xy}},& I_x,& 0\\ 0,& 0,& 0,& 1\end{array}\right]·\left[\begin{array}{c}\stackrel{.}{\beta }\\ \ddot{\psi }\\ \ddot{\phi }\\ \Delta \stackrel{.}{p}\end{array}\right]=\&AutoLeftMatch;\left[\begin{array}{ccccc}{Y}_{\beta },& Y_{\psi }-m·v,& 0,& Y_{\phi },& 0\\ N_{\beta },& N_{\psi },& 0,& N_{\phi },& 0\\ 0,& m_s·h·v,& L_p,& L_{\phi },& {\tilde{A}}_k\\ 0,& 0,& Q_{\stackrel{.}{\phi }},& Q_{\phi },& Q_{\Delta p}\end{array}\right]·\left[\begin{array}{c}\beta \\ \stackrel{.}{\psi }\\ \stackrel{.}{\phi }\\ \phi \\ \Delta p\end{array}\right]·\left[\begin{array}{c}{Y}_{\delta }\\ N_{\delta }\\ 0\\ 0\end{array}\right]·\delta & \left(3\right)\end{array}$

[0051] This differential equation system has the stationary solution: 5$\begin{array}{cc}\frac{\stackrel{.}{\psi }}{\delta }=\frac{L_{\phi }·\left(N_{\beta }·Y_{\delta }-N_{\delta }·Y_{\beta }\right)}{\begin{array}{c}{L}_{\phi }·\left(m·v·N_{\beta }-N_{\beta }{Y}_{\psi }+N_{\psi }·Y_{\beta }\right)+\\ m_s·h·v·\left(N_{\phi }·Y_{\beta }-N_{\beta }·Y_{\phi }\right)\end{array}}\frac{\phi }{\delta }=\frac{m_s·h·v·\left(N_{\beta }·Y_{\delta }-N_{\delta }·Y_{\beta }\right)}{\begin{array}{c}{L}_{\phi }·\left(m·v·N_{\beta }-N_{\beta }·Y_{\psi }+N_{\psi }·Y_{\beta }\right)+\\ m_s·h·v·\left(N_{\phi }·Y_{\beta }-N_{\beta }·Y_{\phi }\right)\end{array}}\frac{\Delta p}{\delta }=\frac{-{\tilde{A}}_k·m_s·h·v·\left(N_{\beta }·Y_{\delta }-N_{\delta }·Y_{\beta }\right)}{\begin{array}{c}{\tilde{Q}}_p·(L_{\phi }·\left(m·v·N_{\beta }-N_{\beta }·Y_{\psi }+N_{\psi }·Y_{\beta }\right)+\\ m_s·h·v·\left(N_{\phi }·Y_{\beta }-N_{\beta }·Y_{\phi }\right))\end{array}}& \left(4\right)\end{array}$

[0052] The values Q, {tilde over (Q)}, Ã are linearization coefficients, which relate to pneumatic values such as flow coefficients and piston cross section. These linearization coefficients are used for a linearized approximation in solving the largely non-linear differential equations relating to the pressure change dynamics in an air spring.

[0053] Thus a setpoint pressure change Δp=f(δ, vf) is specified as a function of the steering angle and of the value vf, which characterizes the speed in the longitudinal direction. Accordingly, it is possible to set up a pressure regulation, which acts indirectly on the degree of roll freedom.

[0054] The above description of the exemplary embodiments according to the present invention is only intended to illustrate and not to limit the invention. Various changes and modifications are possible within the context of the invention without departing from the scope of the invention and its equivalents.

FIELD OF THE INVENTION

[0055] The present invention relates to a method of stabilizing a vehicle including the steps: recording characteristic actual values that describe the driving condition of a vehicle, determining setpoint values that are at least partially assigned to the actual values, comparing actual values and setpoint values and influencing actual values based on comparison results. The present invention also relates to a device for stabilizing a vehicle including an arrangement for recording characteristic values that describe the driving condition of a vehicle, an arrangement for determining setpoint values that are at least partially assigned to the actual values, an arrangement for comparing actual values and setpoint values and an arrangement for influencing actual values based on comparison results.

BACKGROUND INFORMATION

[0056] Methods and devices are used in other systems intend to increase driving safety based on vehicle dynamics. For example, the electronic stability program (ESP) gives the driver of a vehicle both improved basic functions with respect to the anti-lock brake system (ABS) and the anti-slip control (ASC), both systems acting primarily in situations critical to longitudinal dynamics. Examples of this include full braking and severe accelerations. The electronic stability program (ESP) also supports the driver in situations critical to transverse dynamics. The system improves driving stability in all operating states, i.e., in full braking, partial braking, free rolling, traction, thrust and load reversal as soon as an extreme driving situation occurs. Even in extreme steering maneuvers, the electronic stability program (ESP) may drastically reduce the danger of swerving and may keep the automobile under safe control even in critical traffic situations.

[0057] To regulate vehicle dynamics, other systems use the float angle of the vehicle and the yaw rate of the vehicle as controlled variables. The consideration of these controlled variables may allow elimination of the danger of swerving.

[0058] However, in addition to the danger of swerving, there also exists the danger that a vehicle will roll over due to extreme driving maneuvers. This applies all the more considering that more and more passenger cars are being offered that have a comparatively short wheelbase and a high center of gravity. The problem of the danger of rollover exists in commercial vehicles in any case.

SUMMARY OF THE INVENTION

[0059] The present invention may provide that one of the recorded actual values is characteristic of the roll state of the vehicle and one of the setpoint values is assigned to the recorded actual value that is characteristic of the roll state of the vehicle. In this manner, the roll state of the vehicle is also taken into consideration as part of a vehicle dynamics control, thus a rollover of a vehicle may be prevented even when the vehicle has a high center of gravity and a short wheelbase and undergoes extreme driving maneuvers.

[0060] One of the recorded actual values may be the yaw rate and one of the setpoint values may be assigned to the yaw rate. The regulation of the roll state according to the present invention may be combined with the regulation of the yaw rate already known as part of the electronic stability program (ESP).

[0061] One of the recorded actual values may be the float angle and one of the setpoint values may be assigned to the float angle. The regulation of the roll state according to the present invention may be combined with the regulation of the float angle, the latter being known from the electronic stability program (ESP). The yaw rate regulation, float angle regulation and the regulation of the roll state may be integrated in one system.

[0062] The roll angle may be the actual value that is characteristic of the roll state of the vehicle. The roll angle may be measured directly and the roll state of the vehicle may be recorded in this manner.

[0063] However, a pressure change in an air spring of the vehicle may be the value that is characteristic of the roll state of the vehicle. Commercial vehicles may be equipped with air springs to allow use of the pressure change for recording the roll state.

[0064] Setpoint values may be determined from the input values of vehicle speed and steering angle. The input values of vehicle speed and steering angle are also already used in the electronic stability program (ESP) so that these values may be used as input values in the context of the present invention to determine the setpoint value that is characteristic of the roll state of the vehicle.

[0065] Actual values may be influenced by braking interventions and/or engine interventions. This is also already known in the electronic stability program (ESP), for example, for the yaw rate. The actual value that is characteristic of the roll state of the vehicle may be influenced by braking interventions and/or engine interventions.

[0066] The roll angle may be influenced by an actuator. This influencing may occur in addition to or as an alternative to the influencing of the braking system and/or the engine so that numerous measures based on the present invention are available with respect to a rollover prevention.

[0067] The method of the present invention may be implemented in a vehicle combination for the roll regulation of the tractor vehicle and trailer or semitrailer. Thus, for example, a rollover may be prevented for the individual parts of a vehicle combination independently, which may be utilized with respect to the rocking motion of truck trailers or mobile homes towed by passenger cars.

[0068] The present invention may provide that one of the recorded actual values is characteristic of the roll state of the vehicle and one of the setpoint values is assigned to the recorded actual value that is characteristic of the roll state of the vehicle. In this manner, the roll state of the vehicle is also taken into consideration as part of a vehicle dynamics control, thus a rollover of a vehicle maybe prevented even when the vehicle has a high center of gravity and a short wheelbase and undergoes extreme driving maneuvers.

[0069] One of the recorded actual values may be the yaw rate and one of the setpoint values may be assigned to the yaw rate. The regulation of the roll state according to the present invention may be combined with the regulation of the yaw rate already known as part of the electronic stability program (ESP).

[0070] One of the actual values of the present invention may be the float angle and one of the setpoint values may be assigned to the float angle. The regulation of the roll state according to the present invention may be combined with the regulation of the float angle, the latter being known from the electronic stability program (ESP). The yaw rate regulation, float angle regulation and the regulation of the roll state may be integrated in one system.

[0071] An arrangement may be provided for measuring the roll angle and that the roll angle is the actual value that is characteristic of the roll state of the vehicle. Thus, the roll angle may be measured directly and the roll state of the vehicle may be recorded in this manner.

[0072] An arrangement may be provided for measuring the pressure in an air spring of the vehicle and that a pressure change is the actual value that is characteristic of the roll state of the vehicle. Commercial vehicles may be equipped with air springs to use the pressure change for recording the roll state.

[0073] An arrangement may be provided for measuring the vehicle speed, an arrangement may be provided for measuring the steering angle and setpoint values may be determined from the input values of vehicle speed and steering angle. The input values of vehicle speed and steering angle are also already used in the electronic stability program (ESP) so that these values may be used as input values in the context of the present invention to determine the setpoint value that is characteristic of the roll state of the vehicle.

[0074] An arrangement may be provided for influencing the braking system and/or the engine, and actual values are influenced by braking interventions and/or engine interventions. This is also already known in the electronic stability program (ESP), for example, for the yaw rate. The actual value that is characteristic of the roll state of the vehicle may be influenced by braking interventions and/or engine interventions.

[0075] An actuator may be provided and the roll angle may be influenced by an actuator. This influencing may occur in addition to or as an alternative to the influencing of the braking system and/or the engine so that numerous measures based on the present invention are available with respect to a rollover prevention.

[0076] Multiple roll regulation devices may be provided for the tractor vehicle and for a trailer or a semitrailer in a vehicle combination. Thus, for example, a rollover may be prevented for the individual parts of a vehicle combination independently, which may be utilized with respect to the rocking motion of truck trailers or mobile homes towed by passenger cars.

[0077] The present invention is based on the knowledge that the additional regulation of the roll state of a vehicle within an electronic stability program of another system may allow high driving safety.

BRIEF DESCRIPTION OF THE DRAWINGS

[0078] FIG. 1 shows a block diagram to explain a first exemplary embodiment of the present invention.

[0079] FIG. 2 shows a block diagram to explain a second exemplary embodiment of the present invention.

DETAILED DESCRIPTION

[0080] A block diagram is shown in FIG. 1 to explain a first exemplary embodiment of the present invention. The input values of vehicle speed v and steering angle δ are fed to arrangement 10 for determining a setpoint value. This arrangement 10 for determining a setpoint value is based on a reference model which, among other things, takes the roll angle of the vehicle into consideration. Details of the reference model are described below. As its output value, the reference model has a setpoint roll angle φsetpoint. This setpoint roll angle φsetpoint is one of the input values of a closed-loop control circuit. The other input value is φactual. As a result of the comparison or subtraction of the values φsetpoint and φactual in arrangement 12, the comparison result is supplied to roll regulator 14. This roll regulator 14 delivers an output value to arrangement 16 to influence the actual value. This arrangement may, for example, exert an influence on the braking system, the engine or on a roll angle control.

[0081] The output value of the closed-loop control circuit, which directly regulates roll angle φ in the present example, is then fed back to arrangement 12 as φactual to compare actual values and setpoint values. This roll angle regulation described in simplified form using the present exemplary embodiment may accordingly be expanded to include the regulation of other values, for example, the yaw rate or the float angle. In order to take transient events into consideration, an expansion of the system may involve a 1st or 2nd order lowpass.

[0082] As mentioned above, an arrangement for determining setpoint values makes use of a reference model, which now takes the roll angle into consideration in addition to the float angle and the yaw rate. This reference model is based on the differential equation system shown below in Equation 1 6$\begin{array}{cc}\left[\begin{array}{ccc}m·v,& 0,& m_s·h\\ 0,& I_z,& -I_{\mathrm{xy}}\\ m_s·h·v,& -I_{\mathrm{xy}},& I_x\end{array}\right]·\&AutoLeftMatch;\left[\begin{array}{c}\stackrel{.}{\beta }\\ \ddot{\psi }\\ \ddot{\phi }\end{array}\right]=\left[\begin{array}{cccc}{Y}_{\beta },& Y_{\psi }-m·v,& 0,& Y_{\phi }\\ N_{\beta },& N_{\psi },& 0,& N_{\phi }\\ 0,& m_s·h·v,& L_p,& L_{\phi }\end{array}\right]·\left[\begin{array}{c}\beta \\ \psi \\ \stackrel{.}{\phi }\\ \phi \end{array}\right]+\&AutoLeftMatch;\left[\begin{array}{c}{Y}_{\delta }\\ N_{\delta }\\ 0\end{array}\right]·\delta & \left(1\right)\end{array}$

[0083] The following relations apply: 7$Y_{\beta }=-C_f-C_r$$Y_{\psi }=\frac{-a·C_f+b·C_r}{v}$$Y_{\delta }=C_f$$N_{\beta }=-a·C_f+b·C_r$$N_{\psi }=\frac{-a^2·C_f+b^2·C_r}{v}$$N_{\delta }=a·C_f$

[0084] The symbols used in the equations have the following meaning:

[0085] Nφ: roll-steer influence,

[0086] Lφ: roll stiffness,

[0087] Lφ: roll damping,

[0088] β: float angle,

[0089] ψ: yaw angle,

[0090] φ: roll angle,

[0091] δ: wheel steering angle,

[0092] a, b: distance from vehicle center of gravity to front axle or rear axle,

[0093] h: height of center of gravity,

[0094] m: vehicle mass (s: movable body mass relative to chassis)

[0095] I: mass moment of inertia (z: vertical axis, x: roll axis, xy: deviation torque),

[0096] v: vehicle speed,

[0097] c: lateral tire stiffness (f: front, r: rear).

[0098] The stationary solution of these equations delivers a reference model for the vehicle yaw rate and the degree of roll freedom: 8$\begin{array}{cc}\frac{\stackrel{.}{\psi }}{\delta }=\frac{L_{\phi }·\left(N_{\beta }·Y_{\delta }-N_{\delta }·Y_{\beta }\right)}{\begin{array}{c}{L}_{\phi }·\left(m·v·N_{\beta }-N_{\beta }·Y_{\psi }+N_{\psi }·Y_{\beta }\right)+\\ m_s·h·v·\left(N_{\phi }·Y_{\beta }-N_{\beta }·Y_{\phi }\right)\end{array}}\frac{\phi }{\delta }=\frac{m_s·h·v·\left(N_{\beta }·Y_{\delta }-N_{\delta }·Y_{\beta }\right)}{\begin{array}{c}{L}_{\phi }·\left(m·v·N_{\beta }-N_{\beta }·Y_{\psi }+N_{\psi }·Y_{\beta }\right)+\\ m_s·h·v·\left(N_{\phi }·Y_{\beta }-N_{\beta }·Y_{\phi }\right)\end{array}}& \left(2\right)\end{array}$

[0099] The setpoint yaw rate

{dot over (ψ)}=ƒ(δ,vf)

[0100] is thus obtained as a function of the steering angle and the vehicle speed, vf being a speed value which describes the speed in longitudinal direction. In a comparable manner, a setpoint roll angle

φ=ƒ(δ,vf),

[0101] is obtained which is also a function of the steering angle and speed value vf.

[0102] If no explicit measurement of the roll angle is available, an indirect roll angle regulation may be implemented through the measurement of other values that characterize a roll movement of the vehicle. However, this requires a corresponding adaptation of the reference model to the measured value used.

[0103] FIG. 2 shows an example of indirect roll regulation. In arrangement 10 for determining setpoint values, a modified reference model is used, which is described below. In this case, a pressure change Δp is used as a controlled variable, pressure values measured in air springs of commercial vehicles, for example, being used. A modified reference model, which takes the pressure change dynamics into consideration, is used as a reference model. This is described below. The output signal of a subtraction 12 is supplied to roll regulator 14, the difference between a value Δpsetpoint, which is an output value of arrangement 10, and a measured value Δpactual, which is the output value of the closed-loop control circuit, being formed. The roll regulator outputs an output signal to arrangement 16 to influence the actual values. In turn, this arrangement may include the braking system, the engine control or special actuator technology to influence the roll angle.

[0104] The reference model is based on the following differential equation system: 9$\begin{array}{cc}\left[\begin{array}{cccc}m·v,& 0,& m_s·h,& 0\\ 0,& I_z,& -I_{\mathrm{xy}},& 0\\ m_s·h·v,& -I_{\mathrm{xy}},& I_x,& 0\\ 0,& 0,& 0,& 1\end{array}\right]·\left[\begin{array}{c}\stackrel{.}{\beta }\\ \ddot{\psi }\\ \ddot{\phi }\\ \Delta \stackrel{.}{p}\end{array}\right]=\&AutoLeftMatch;\left[\begin{array}{ccccc}{Y}_{\beta },& Y_{\psi }-m·v,& 0,& Y_{\phi },& 0\\ N_{\beta },& N_{\psi },& 0,& N_{\phi },& 0\\ 0,& m_s·h·v,& L_p,& L_{\phi },& {\tilde{A}}_k\\ 0,& 0,& Q_{\stackrel{.}{\phi }},& Q_{\phi },& Q_{\Delta p}\end{array}\right]·\left[\begin{array}{c}\beta \\ \stackrel{.}{\psi }\\ \stackrel{.}{\phi }\\ \phi \\ \Delta p\end{array}\right]·\left[\begin{array}{c}{Y}_{\delta }\\ N_{\delta }\\ 0\\ 0\end{array}\right]·\delta & \left(3\right)\end{array}$

[0105] This differential equation system has the stationary solution: 10$\begin{array}{cc}\frac{\stackrel{.}{\psi }}{\delta }=\frac{L_{\phi }·\left(N_{\beta }·Y_{\delta }-N_{\delta }·Y_{\beta }\right)}{\begin{array}{c}{L}_{\phi }·\left(m·v·N_{\beta }-N_{\beta }{Y}_{\psi }+N_{\psi }·Y_{\beta }\right)+\\ m_s·h·v·\left(N_{\phi }·Y_{\beta }-N_{\beta }·Y_{\phi }\right)\end{array}}\frac{\phi }{\delta }=\frac{m_s·h·v·\left(N_{\beta }·Y_{\delta }-N_{\delta }·Y_{\beta }\right)}{\begin{array}{c}{L}_{\phi }·\left(m·v·N_{\beta }-N_{\beta }·Y_{\psi }+N_{\psi }·Y_{\beta }\right)+\\ m_s·h·v·\left(N_{\phi }·Y_{\beta }-N_{\beta }·Y_{\phi }\right)\end{array}}\frac{\Delta p}{\delta }=\frac{-{\tilde{A}}_k·m_s·h·v·\left(N_{\beta }·Y_{\delta }-N_{\delta }·Y_{\beta }\right)}{\begin{array}{c}{\tilde{Q}}_p·(L_{\phi }·\left(m·v·N_{\beta }-N_{\beta }·Y_{\psi }+N_{\psi }·Y_{\beta }\right)+\\ m_s·h·v·\left(N_{\phi }·Y_{\beta }-N_{\beta }·Y_{\phi }\right))\end{array}}& \left(4\right)\end{array}$

[0106] The values Q, {tilde over (Q)}, Ã are linearization coefficients, which relate to pneumatic values such as flow coefficients and piston cross section. These linearization coefficients are used for a linearized approximation in solving the largely non-linear differential equations relating to the pressure change dynamics in an air spring.

[0107] Thus a setpoint pressure change Δp=f(δ, vf) is specified as a function of the steering angle and of the value vf, which characterizes the speed in the longitudinal direction. Accordingly, a pressure regulation may be set up, which acts indirectly on the degree of roll freedom.

[0108] The above description of the exemplary embodiments according to the present invention is only intended to illustrate and not to limit the present invention. Various changes and modifications may be allowed within the context of the present invention without departing from the scope of the present invention and its equivalents.

Claims

1. A method of stabilizing a vehicle including the steps: recording characteristic actual values that describe the driving condition of a vehicle, determining setpoint values that are at least partially assigned to the actual values, comparing actual values and setpoint values, and influencing actual values based on comparison results, wherein one of the recorded actual values is characteristic of the roll state of the vehicle and one of the setpoint values is assigned to the recorded actual value that is characteristic of the roll state of the vehicle.

2. The method as recited in claim 1, wherein one of the recorded actual values is the yaw rate and one of the setpoint values is assigned to the yaw rate.

3. The method as recited in claim 1 or 2, wherein one of the recorded actual values is the float angle and one of the setpoint values is assigned to the float angle.

4. The method as recited in one of claims 1 through 3, wherein the roll angle is the actual value that is characteristic of the roll state of the vehicle.

5. The method as recited in one of the preceding claims, wherein a pressure change in an air spring of the vehicle is the actual value that is characteristic of the roll state of the vehicle.

6. The method as recited in one of the preceding claims, wherein setpoint values are determined from the input values of vehicle speed and steering angle.

7. The method as recited in one of the preceding claims, wherein actual values are influenced by braking interventions and/or engine interventions.

8. The method as recited in one of the preceding claims, wherein the roll angle is influenced by an actuator.

9. The method as recited in one of the preceding claims, wherein it is implemented in a vehicle combination for the roll regulation of the tractor vehicle and trailer or semitrailer.

10. A device for stabilizing a vehicle including means for recording characteristic actual values that describe the driving condition of a vehicle, means (10) for determining setpoint values that are at least partially assigned to the actual values, means (12) for comparing actual values and setpoint values, and means (16) for influencing actual values based on comparison results, wherein one of the recorded actual values is characteristic of the roll state of the vehicle and one of the setpoint values is assigned to the recorded actual value that is characteristic of the roll state of the vehicle.

11. The device as recited in claim 10, wherein one of the recorded actual values is the yaw rate and one of the setpoint values is assigned to the yaw rate.

12. The device as recited in claim 10 or 11, wherein one of the recorded actual values is the float angle and one of the setpoint values is assigned to the float angle.

13. The device as recited in one of claims 10 through 12, wherein means are provided for measuring the roll angle and the roll angle is the actual value that is characteristic of the roll state of the vehicle.

14. The device as recited in one of claims 10 through 13, wherein means are provided for measuring the pressure in an air spring of the vehicle and a pressure change is the actual value that is characteristic of the roll state of the vehicle.

15. The device as recited in one of claims 10 through 14, wherein means are provided for measuring the vehicle speed and means are provided for measuring the steering angle and setpoint values are determined from the input values of vehicle speed and steering angle.

16. The device as recited in one of claims 10 through 15, wherein means are provided for influencing the braking system and/or the engine and actual values are influenced by braking interventions and/or engine interventions.

17. The device as recited in one of claims 10 through 16, wherein an actuator is provided and the roll angle is influenced by an actuator.

18. The device as recited in one of claims 10 through 17, wherein multiple roll regulation devices are provided for the tractor vehicle and trailer or semitrailer in a vehicle combination.