Patent Application
20200369316
The present invention relates to a high-performance steering apparatus for vehicles that obtains a desired steering torque by performing control so that a torsional angle of a torsion bar or the like follows a value corresponding to vehicle driving information, and maintains the desired steering torque without being affected by a road surface state and aging-changes of mechanism system characteristics.
An electric power steering apparatus (EPS) being one of steering apparatuses for vehicles provides a steering system of a vehicle with an assist torque (a steering assist torque) by means of a rotational torque of a motor, and applies a driving force of the motor which is controlled by using an electric power supplied from an inverter as the assist torque to a steering shaft or a rack shaft by means of a transmission mechanism including a reduction mechanism. In order to accurately generate the assist torque, such a conventional electric power steering apparatus performs feedback control of a motor current. The feedback control adjusts a voltage supplied to the motor so that a difference between a steering assist command value (a current command value) and a detected motor current value becomes small, and the adjustment of the voltage supplied to the motor is generally performed by an adjustment of a duty ratio of pulse width modulation (PWM) control.
A general configuration of the conventional electric power steering apparatus will be described with reference to
A controller area network (CAN) 40 exchanging various information of a vehicle is connected to the control unit 30, and it is possible to receive the vehicle speed Vs from the CAN 40. Further, it is also possible to connect a non-CAN 41 exchanging a communication, analog/digital signals, a radio wave or the like except for the CAN 40 to the control unit 30.
The control unit 30 mainly comprises a central processing unit (CPU) (including a micro controller unit (MCU), a micro processor unit (MPU) and so on), and general functions performed by programs within the CPU are shown in
Functions and operations of the control unit 30 will be described with reference to
A compensation signal CM from a compensation signal generating section 34 is added to the adding section 32A, and a characteristic compensation of the steering system is performed by the addition of the compensation signal CM so as to improve a convergence, an inertia characteristic and so on. The compensation signal generating section 34 adds a self-aligning torque (SAT) 343 and an inertia 342 at an adding section 344, further adds a convergence 341 to the added result at an adding section 345, and then outputs the added result at the adding section 345 as the compensation signal CM.
Thus, in assist control by a conventional electric power steering apparatus, a steering torque applied by a manual input of a driver is detected as a torsional torque of a torsion bar by a torque sensor, and a motor current is mainly controlled as an assist current depending on the detected steering torque. However, in the case of performing control by this method, different steering torques can be generated depending on a steering angle due to a difference of a road surface state (for example, a cant of the road surface). Variations of a motor output characteristic due to long-term use can also affect the steering torque.
In order to solve the above problems, for example, an electric power steering apparatus shown in the publication of Japanese Patent No. 5208894 B2 (Patent Document 1) has beenproposed. The electric power steering apparatus of Patent Document 1 sets a target value of the steering torque based on a relation (a steering reaction characteristic map) between the steering angle, which is determined based on a relation between the steering angle or the steering torque and an amount of response, and the steering torque in order to apply an appropriate steering torque based on a tactile characteristic of a driver.
However, in the electric power steering apparatus of Patent Document 1, it is necessary to obtain the steering reaction characteristic map preliminarily. Further, since the apparatus performs control based on a deviation between a target value of the steering torque and a detected steering torque, an influence to the steering torque may remain.
The present invention has been developed in view of the above-described circumstances, and an object of the present invention is to provide a steering apparatus for vehicles that easily obtains equivalent steering torques to vehicle driving information such as a steering angle without being affected by a road surface state and aging-changes of mechanism characteristics of a steering system.
The present invention relates to a steering apparatus for vehicles that comprises at least a torsion bar having an arbitrary spring constant and a sensor detecting a torsional angle, drives and controls a motor, and assists and controls a steering system, the above-described object of the present invention is achieved by that comprising: a torsional angle control section that calculates a motor current command value based on a target torsional angle corresponding to vehicle driving information and the torsional angle; wherein the torsional angle control section comprises a torsional angle feedback compensating section that calculates a target torsional angular velocity by a deviation between the target torsional angle and the torsional angle, a torsional angular velocity calculating section that calculates a torsional angular velocity by the torsional angle, a velocity control section that calculates a pre-limitation motor current command value by performing proportional compensation based on the target torsional angular velocity and the torsional angular velocity, and an output limiting section that limits upper and lower limit values of the pre-limitation motor current command value, and outputs the motor current command value; and wherein the steering apparatus for vehicles drives and controls the motor based on the motor current command value.
Alternatively, the above-described object of the present invention is achieved by that comprising: a torsional angle control section that calculates a motor current command value based on a target torsional angle corresponding to vehicle driving information, the torsional angle, a first rotation angle and a second rotation angle; wherein the torsional angle control section comprises a torsional angle feedback compensating section that calculates a target torsional angular velocity by a deviation between the target torsional angle and the torsional angle, a first angular velocity calculating section that calculates a first angular velocity by the first rotation angle, a second angular velocity calculating section that calculates a second angular velocity by the second rotation angle, a velocity control section that calculates a pre-limitation motor current command value by performing proportional compensation based on a target angular velocity that is obtained by the target torsional angular velocity and the first angular velocity, and the second angular velocity, and an output limiting section that limits upper and lower limit values of the pre-limitation motor current command value, and outputs the motor current command value; and wherein the steering apparatus for vehicles drives and controls the motor based on the motor current command value.
Alternatively, the above-described object of the present invention is achieved by that comprising: a torsional angle control section that calculates a motor current command value based on a target torsional angle corresponding to vehicle driving information, a first rotation angle and a second rotation angle; wherein the torsional angle control section comprises a torsional angle feedback compensating section that calculates a target torsional angular velocity by a deviation between a target rotation angle that is obtained by the target torsional angle and the first rotation angle and the second rotation angle, a first angular velocity calculating section that calculates a first angular velocity by the first rotation angle, a second angular velocity calculating section that calculates a second angular velocity by the second rotation angle, a velocity control section that calculates a pre-limitation motor current command value by performing proportional compensation based on a target angular velocity that is obtained by the target torsional angular velocity and the first angular velocity, and the second angular velocity, and an output limiting section that limits upper and lower limit values of the pre-limitation motor current command value, and outputs the motor current command value; and wherein the steering apparatus for vehicles drives and controls the motor based on the motor current command value.
Further, the above-described object of the present invention is efficiently achieved by that wherein the torsional angle control section further comprises an input limiting section that limits upper and lower limit values of the target torsional angle; or wherein the torsional angle control section further comprises a rate limiting section that limits a change amount of the target torsional angle; or further comprising: a target steering torque generating section that generates a target steering torque based on the vehicle driving information, and a converting section that converts the target steering torque into the target torsional angle used at the torsional angle control section; or wherein the target steering torque generating section comprises a basic map section that obtains a first torque signal in accordance with the vehicle driving information by using a basic map being vehicle speed sensitive, a damper calculating section that obtains a second torque signal based on angular velocity information by using a damper gain map being vehicle speed sensitive, and a hysteresis correcting section that obtains a third torque signal by performing hysteresis correction to the vehicle driving information depending on a steering state, and calculates the target steering torque by the first torque signal, the second torque signal and the third torque signal; or wherein the steering apparatus for vehicles drives and controls the motor based on a current command value that is obtained by adding an assist current command value calculated based on a steering torque to the motor current command value.
By performing velocity control using proportional compensation to the target torsional angular velocity or the target angular velocity which is calculated based on the target torsional angle corresponding to the vehicle driving information, the steering apparatus for vehicles of the present invention operates so that the torsional angle follows the target torsional angle, obtains a desired steering torque to the vehicle driving information, and can supply an appropriate steering torque based on steering feeling of a driver. The torsional angle control section comprises the velocity control section that controls the torsional angular velocity or the angular velocity, thereby, followability to the target torsional angle can be improved, an influence to the torsional angle due to a change of a steering angle inputted from a driver can be suppressed, and followability of the torsional angle to the target torsional angle against abrupt steering can be improved.
In the accompanying drawings:
The present invention is a steering apparatus for vehicles to obtain an equivalent steering torque corresponding to vehicle driving information such as a steering angle, a vehicle speed and a steering state without being affecting a road surface state, and obtains a desired steering torque by performing control so that a torsional angle of a torsion bar or the like follows a value depending on the vehicle driving information.
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
First, an installation example of various sensors that detect information related to an electric power steering apparatus being one of steering apparatuses for vehicle of the present invention, will be described. FIG.3 is a diagram showing an installation example of an EPS steering system and various sensors. A torsion bar 2A is provided in a column shaft 2. Road surface reaction force Fr and road surface information p operate on steered wheels 8L and 8R. An upper side angle sensor is disposed on a steering wheel side of the column shaft 2 above the torsion bar 2A, and a lower side angle sensor is disposed on a steered wheel side of the column shaft 2 below the torsion bar 2A. The upper side angle sensor detects a steering wheel angle θ1, and the lower side angle sensor detects a column angle θ2. A steering angle θh is detected by a steering angle sensor disposed on an upper portion of the column shaft 2. A torsional angle Δθ of the torsion bar and a torsion bar torque Tt can be calculated by the following expressions 1 and 2 from a deviation between the steering wheel angle θ1 and the column angle θ2. In the expression 2, Kt is a spring constant of the torsion bar 2A.
θ2−Θ1=Δθ [Expression 1]
Kt·Δθ=Kt·(θ2−θ1)=Tt [Expression 2]
The torsion bar torque Tt can be also detected by using, for example, a torque sensor disclosed in Japanese Unexamined Patent Publication No. 2008-216172 A.
Next, a configuration example of the present invention will be described.
The right-turning/left-turning judging section 110 judges whether steering is right-turning or left-turning based on a motor angular velocity ωm, and outputs the judgment result as the steering state STs . That is, when the motor angular velocity ωm is a positive value, the right-turning/left-turning judging section 110 judges the steering “right-turning”, and when the motor angular velocity ωm is a negative value, the right-turning/left-turning judging section 110 judges the steering “left-turning”. Instead of the motor angular velocity ωm, an angular velocity calculated by velocity calculation with respect to the steering angle θh, the steering wheel angle θ1 or the column angle θ2, may be used.
The basic map section 121 has a basic map, and outputs a torque signal (a first torque signal) Tref_a having the vehicle speed Vs as a parameter by using the basic map. The basic map has been adjusted by tuning. For example, as shown in
The differential section 122 calculates a steering angular velocity ωh by differentiating the steering angle θh, and the steering angular velocity ωh is inputted into the multiplying section 125.
The damper gain section 123 outputs a damper gain DG by which the steering angular velocity ωh is multiplied. The steering angular velocity ωh that is multiplied by the damper gain DG at the multiplying section 125, is inputted into the adding section 127 as a torque signal (a second torque signal) Tref_b. The damper gain DG is obtained depending on the vehicle speed Vs by using a vehicle speed sensitive damper gain map that the damper gain section 123 has. The damper gain map, for example, as shown in
The hysteresis correcting section 124 calculates a torque signal (a third torque signal) Tref_c based on the steering angle θh and the steering state STs in accordance with the following expression 3. In the following expression 3, x and y are set to θh and Tref_c respectively (x=θh and y=Tref_c), and Ahys is a hysteresis width.
when right-turning y=Ahys[1−exp{−a(x−b)}]
when left-turning y=−Ahys[1−exp{a(x−b)}] [Expression 3]
When switching from the right-turning steering to the left-turning steering and when switching from the left-turning steering to the right-turning steering, based on the final coordinates (x1, y1), a value “b” of the following expression 4 is substituted into the value “b” in the expression 3 after switching. Thereby, continuity when switching the steering is maintained.
Setting Ahys=1 [Nm] and a=0.3 in the expressions 3 and 4, in the case that an initial angle of the steering wheel is 0 [deg] and the steering wheel is steered between +50 [deg] and −50 [deg], a changing example of the torque signal Tref_c which hysteresis correction is applied to is shown in
Ahys which is a coefficient expressing an output width of the hysteresis characteristic, and “a” which is a coefficient expressing roundness, may be variable depending on the vehicle speed Vs and/or the steering angle θh.
The torque signals Tref_a, Tref_b and Tref_c are added at the adding sections 126 and 127, and the added result is outputted as the target steering torque Tref.
The steering angular velocity ωh is obtained by differential calculation to the steering angle θh, and low pass filter (LPF) processing is appropriately performed in order to reduce an affection of a noise in a high frequency band. The differential calculation and the LPF processing may be performed by using a high pass filter (HPF) and a gain. The steering angular velocity ωh may be calculated by the differential calculation and the LPF processing to the steering wheel angle θ1 detected by the upper side angle sensor or the column angle θ2 detected by the lower side angle sensor, instead of the steering angle θh. The motor angular velocity ωm may be used instead of the steering angular velocity ωh, and in this case, the differential section 122 becomes unnecessary.
The converting section 130 has a characteristic of −1/Kt obtained by inverting the sign of the reciprocal of the spring constant Kt of the torsion bar 2A, and converts the target steering torque Tref into a target torsional angle Δθref.
The torsional angle control section 140 calculates the motor current command value Imc based on the target torsional angle 66 θref and the torsional angle Δθ.
The input limiting section 141 limits upper and lower limit values of the target torsional angle Δθref so that the torsional angle control section 140 does not output the abnormal motor current command value Imc when the target torsional angle Δθref becomes an abnormal value in a communication, a calculation of a microcomputer or an ECU, and so on. The input limiting section 141 presets the upper limit value and the lower limit value with respect to the target torsional angle Δθref. In the case that the target torsional angle Δθref is larger than or equal to the upper limit value, the input limiting section 141 outputs the upper limit value as a target torsional angle Δθref′. In the case that the target torsional angle Δθref is smaller than or equal to the lower limit value, the input limiting section 141 outputs the lower limit value as the target torsional angle Δθref′. Otherwise, the input limiting section 141 outputs the target torsional angle Δθref, as it is, as the target torsional angle Δθref′. The set upper limit value and lower limit value may be the maximum value and the minimum value of a torsional angle used in the control respectively, and may be also the maximum value and the minimum value of a detectable torsional angle respectively. This enables security of safety.
The rate limiting section 142 limits a change amount of the target torsional angle Δθref′ so that the value of the target torsional angle Δθref′ does not change continuously and the target torsional angle Δθref′ fluctuates discontinuously when the target torsional angle Δθref becomes an abnormal value. The target torsional angle normally changes continuously, and the rate limiting section 142 does not limit it. When the target torsional angle temporarily becomes an abnormal value by any abnormality, the discontinuous change is prevented by the limitation of the rate limiting section 142. For example, a difference between the present and the previous target torsional angles Δθref′ is used as the change amount, when an absolute value of the change amount is larger than a predetermined value, addition or subtraction to the target torsional angle Δθref′ is performed so that the absolute value of the change amount becomes the predetermined value, and the result is outputted as a target torsional angle Δθref″. When the absolute value of the change amount is smaller than or equal to the predetermined value, the target torsional angle Δθref′ is outputted, as it is, as the target torsional angle Δθref″. The limitation may be performed such as by using a rate of the difference to the previous target torsional angle Δθref′ as the change amount.
Although the input limiting section 141 and the rate limiting section 142 may be arranged reversely, the arrangement as shown in
The torsional angle FB compensating section 143 multiplies a deviation Δθ0, which is calculated at the subtracting section 146, between the target torsional angle Δθref″ and the torsional angle Δθ by a compensation value CFB (a transfer function), and outputs a target torsional angular velocity ωref that enables followability of the torsional angle Δθ to the target torsional angle Δθref. The compensation value CFB may be simply a gain Kpp, or may be a compensation value generally used, such as a compensation value of PI-control. The target torsional angular velocity ωref is inputted into the velocity control section 150. By using the torsional angle FB compensating section 143 and the velocity control section 150, the torsional angle A follows the target torsional angle Δθref, and it is possible to obtain the desired steering torque.
The torsional angular velocity calculating section 144 calculates a torsional angular velocity ωt by differential calculation to the torsional angle Δθ, and the torsional angular velocity ωt is inputted into the velocity control section 150. Pseudo-differential by an HPF and a gain may be performed as the differential calculation.
The velocity control section 150 calculates a motor current command value (a pre-limitation motor current command value) Imcb that enables followability of the torsional angular velocity ωt to the target torsional angular velocity ωref. The velocity control section 150 calculates a difference (ωref−ωt) between the target torsional angular velocity ωref and the torsional angular velocity ωt at a subtracting section 151, multiplies the difference by a compensation value Kv ata compensating section 152, and outputs the multiplied result as the motor current command value Imcb. Although a compensation value of proportional (P) compensation is used as the compensation value Kv, a compensation value of proportional integral (PI) compensation or the like may be used.
The output limiting section 145 limits upper and lower limit values of the motor current command value Imcb outputted from the velocity control section 150, and outputs the motor current command value Imc. As with the input limiting section 141, the output limiting section 145 performs the limitation by presetting the upper limit value and the lower limit value with respect to the motor current command value Imcb.
In such a configuration, an operating example of the present embodiment will be described with reference to flowcharts of
As the operation starts, the right-turning/left-turning judging section 110 inputs the motor angular velocity ωm, judges whether steering is right-turning or left-turning based on a sign of the motor angular velocity ωm, and outputs the judgment result as the steering state STs to the target steering torque generating section 120 (Step S10).
The target steering torque generating section 120 inputs the steering angle θh and the vehicle speed Vs with the steering state STs, and generates the target steering torque Tref (Step S20). An operating example of the target steering torque generating section 120 will be described with reference to a flowchart of
The steering angle θh inputted into the target steering torque generating section 120 is inputted into the basic map section 121, the differential section 122 and the hysteresis correcting section 124, the steering state STs is inputted into the hysteresis correcting section 124, and the vehicle speed Vs is inputted into the basic map section 121 and the damper gain section 123 (Step S21).
The basic map section 121 generates the torque signal Tref_a corresponding to the steering angle θh and the vehicle speed Vs by using the basic map shown in
The differential section 122 differentiates the steering angle θh, and outputs the steering angular velocity ωh (Step S23). The damper gain map 123 outputs the damper gain DG corresponding to the vehicle speed Vs by using the damper gain map shown in
The hysteresis correcting section 124 performs the hysteresis correction to the steering angle θh by switching the calculations of the expressions 3 and 4 depending on the steering state STs (Step S26), generates the torque signal Tref_c, and outputs it to the adding section 127 (Step S27). Although the hysteresis width Ahys, “a”, x1 and y1 are preset and retained, it is possible to calculate “b” depending on steering directions (right-turning and left-turning) in advance, and retain “b” instead of x1 and y1.
The torque signals Tref_b and Tref_c are added at the adding section 127, the torque signal Tref_a is added to the added result at the adding section 126, and the target steering torque Tref is calculated (Step S28).
The target steering torque Tref generated at the target steering torque generating section 120 is inputted into the converting section 130, and is converted into the target torsional angle Δθref at the converting section 130 (Step S30). The target torsional angle Δθref is inputted into the torsional angle control section 140.
The torsional angle control section 140 inputs the torsional angle Δθ with the target torsional angle Δθref, and calculates the motor current command value Imc (Step S40). An operating example of the torsional angle control section 140 will be described with reference to a flowchart of
The target torsional angle Δθref inputted into the torsional angle control section 140 is inputted into the input limiting section 141, and the torsional angle Δθ is inputted into the torsional angular velocity calculating section 144 and the subtracting section 146 (Step S41).
The input limiting section 141 limits the upper and lower limit values of the target torsional angle Δθref by the preset upper limit value and lower limit value, and outputs the limited result as the target torsional angle Δθref′ to the rate limiting section 142 (Step S42). The rate limiting section 142 limits the change amount of the target torsional angle Δθref ′, and outputs the limited result as the target torsional angle Δθref″ to the subtracting section 146 (Step S43).
The deviation Δθ0 is calculated at the subtracting section 146 by subtracting the torsional angle Δθ from the target torsional angle Δθref″ (Step S44). The deviation Δθ0 is inputted into the torsional angle FB compensating section 143. The torsional angle FB compensating section 143 compensates the deviation Δθ0 by multiplying the deviation Δθ0 by the compensation value CFB (Step S45), and outputs the target torsional angular velocity ωref to the velocity control section 150.
The torsional angular velocity calculating section 144 inputting the torsional angle Δθ calculates the torsional angular velocity cot by the differential calculation to the torsional angle Δθ (Step S46), and outputs it to the velocity control section 150.
In the velocity control section 150, the difference between the target torsional angular velocity ωref and the torsional angular velocity ωt is calculated at the subtracting section 151, the proportional processing by the compensation value Kv is performed to the difference at the compensating section 152, and the result of the proportional processing is outputted as the motor current command value Imcb to the output limiting section 145 (Step S47).
The output limiting section 145 limits the upper and lower limit values of the motor current command value Imcb by the preset upper limit value and lower limit value (Step S48), and outputs the limited result as the motor current command value Imc (Step S49).
Current control is performed by driving the motor based on the motor current command value Imc outputted from the torsional angle control section 140 (Step S50).
Each Order of the data inputs, the calculations, or the like in
An effect of the followability to the target steering torque by the present embodiment will be described based on a simulation result.
First, a simulation result in the case of performing only a conventional assist control will be shown. Assuming ordinary steering, as shown in
A time sequence waveform of the simulation result is shown in
Next, a simulation result in the case of performing the torsional angle control will be shown. In the torsional angle control, the compensation values of the torsional angle FB compensating section 143 and the compensating section 152 in the velocity control section 150 are set to a proportional gain, and the torsional angular velocity calculating section 144 has a structure of an HPF where a cutoff frequency is 50 Hz and a transfer function is expressed by the following expression 5 (Thpf is a time constant of a filter).
As with the case of performing only the assist control, an inputted steering angle θh is data of the sine wave shape as shown in
Another configuration example of the present invention will be described.
Since the torsional angle Δθ of the torsion bar 2A can be replaced with the deviation between the steering wheel angle θ1 and the column angle θ2 as shown by expression 1, the torsional angle control section 140 of the first embodiment shown in
Compared with the torsional angle control section 140 of the first embodiment, in a torsional angle control section 240 of the second embodiment, the steering wheel angle (a first rotation angle) θ1 and the column angle (a second rotation angle) θ2 are inputted in addition to the target torsional angle Δθref and the torsional angle Δθ, angular velocity calculating sections 244 and 247 for the steering wheel angle θ1 and the column angle θ2 respectively are added instead of the torsional angular velocity calculating section 144 for the torsional angle Δθ, and an adding section 248 is further added. By setting what is obtained by adding a steering wheel angular velocity (a first angular velocity) ω1 calculated by differentiating the steering wheel angle θ1 to the target torsional angular velocity ωref to a target angular velocity ωrefc, it is possible to regard the velocity control section 150 as a configuration of velocity control with respect to a column angular velocity (a second angular velocity).
Compared with the first embodiment, an operating example of the second embodiment is different in only the operation of the torsional angle control section, and other operations are the same.
An operating example of the torsional angle control section in the second embodiment is shown by a flowchart of
By replacing the torsional angle Δθ with the deviation between the steering wheel angle θ1 and the column angle θ2, besides the second embodiment, the torsional angle control section 140 can be equivalently replaced with a configuration example (a third embodiment) shown in
Compared with the torsional angle control section of the second embodiment, in a torsional angle control section of the third embodiment, the torsional angle Δθ is not inputted, and an adding section 349 is added. By setting what is obtained by adding the steering wheel angle θ1 to the target torsional angle Δθref″ to a target rotation angle θrefc, multiplying the deviation Δθ0 between the target rotation angle θrefc and the column angle θ2 by the compensation value CFB, and setting what is obtained by adding the steering wheel angular velocity ω1 to the multiplied result to the target angular velocity ωrefc, as with the second embodiment, it is possible to regard the velocity control section 150 as a configuration of velocity control with respect to a column angular velocity.
Compared with the second embodiment, an operating example of the third embodiment is different in only the operation of the torsional angle control section, and other operations are the same.
An operating example of the torsional angle control section in the third embodiment is shown by a flowchart of
In the second and the third embodiments, by simply making a reduction mechanism perform reduction ratio transformation, data obtained by dividing a motor angular velocity by a reduction ratio may be used as the column angular velocity ω2. In this case, the angular velocity calculating section 247 becomes unnecessary. Further, the steering angle θh may be used instead of the steering wheel angle θ1.
Even when a current command value (an assist current command value) calculated based on a steering torque in a conventional EPS, for example, a current command value Iref1 outputted from a current command value calculating section 31 or a current command value Iref2 obtained by adding a compensation signal CM to the current command value Iref1 in
A configuration example (a fourth embodiment) of applying the above to the first embodiment is shown in
With respect to the target steering torque generating section 120 in the above embodiments (the first to the fourth embodiments), in such a case of focusing on a cost and a processing time, it is possible to omit the damper calculating section and/or the hysteresis correcting section 124. In the case of omitting the damper calculating section, the differential section 122 and the adding section 127 can be also omitted. In the case of omitting the hysteresis correcting section 124, the right-turning/left-turning judging section 110 and the adding section 127 can be also omitted. Further, it is possible to insert a phase compensating section 128 performing phase compensation into a front stage or a rear stage of the basic map section 121. That is, it is possible to change a configuration of an area “R” surrounded by a broken line in
Although the present invention is applied to a column-type EPS in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-204910 | Oct 2017 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/039148 | 10/22/2018 | WO | 00 |
