JP7437603B2 - Vehicle steering device - Google Patents

Description

The present invention relates to a high-performance vehicle steering device that achieves a desired steering torque based on the torsion angle of a torsion bar, etc., and is unaffected by road surface conditions and unaffected by changes in mechanical system characteristics over time.

An electric power steering system (EPS), which is one type of vehicle steering system, uses the rotational force of a motor to provide assist force (steering assist force) to the vehicle's steering system using electric power supplied from an inverter. The driving force of the controlled motor is applied as assist force to the steering shaft or rack shaft by a transmission mechanism including a speed reduction mechanism. Such conventional electric power steering devices perform feedback control of motor current in order to accurately generate assist force. Feedback control adjusts the motor applied voltage so that the difference between the steering assist command value (current command value) and the motor current detection value becomes small, and the motor applied voltage is generally adjusted using PWM (pulse width modulation). This is done by adjusting the duty of modulation) control.

The general configuration of an electric power steering device is shown in FIG. 1 and explained. A column shaft (steering shaft, handle shaft) 2 of a steering wheel 1 includes a reduction mechanism 3, universal joints 4a and 4b, a pinion rack mechanism 5, a tie rod 6a, 6b, and further connected to steering wheels 8L, 8R via hub units 7a, 7b. Further, the column shaft 2 having a torsion bar is provided with a torque sensor 10 for detecting the steering torque Ts of the handle 1 and a steering angle sensor 14 for detecting the steering angle θh. 20 is connected to the column shaft 2 via the speed reduction mechanism 3. A control unit (ECU) 30 that controls the electric power steering device is supplied with electric power from the battery 13 and also receives an ignition key signal via the ignition key 11 . The control unit 30 calculates a current command value of an assist (steering assist) command based on the steering torque Ts detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12, and compensates the current command value. The current supplied to the EPS motor 20 is controlled by the voltage control command value Vref.

A CAN (Controller Area Network) 40 that exchanges various vehicle information is connected to the control unit 30, and the vehicle speed Vs can also be received from the CAN 40. Furthermore, a non-CAN 41 for transmitting and receiving communications other than the CAN 40, analog/digital signals, radio waves, etc. can also be connected to the control unit 30.

The control unit 30 is mainly composed of a CPU (including an MCU, MPU, etc.), and the general functions executed by a program inside the CPU are shown in FIG.

The function and operation of the control unit 30 will be explained with reference to FIG. 2. The steering torque Ts detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12 (or from the CAN 40) 31. The current command value calculation unit 31 calculates a current command value Iref1, which is a control target value of the current supplied to the motor 20, based on the input steering torque Ts and vehicle speed Vs, using an assist map or the like. The current command value Iref1 is input to the current limiting unit 33 via the adding unit 32A, and the current command value Irefm with the maximum current limited is input to the subtracting unit 32B, and the deviation I (= Irefm-Im) is calculated, and its deviation I is input to a PI (proportional-integral) control unit 35 for improving characteristics of steering operation. The voltage control command value Vref whose characteristics have been improved by the PI control unit 35 is input to the PWM control unit 36, and the motor 20 is further driven by PWM via an inverter 37 serving as a drive unit. The current value Im of the motor 20 is detected by the motor current detector 38 and fed back to the subtraction section 32B.

The compensation signal CM from the compensation signal generation unit 34 is added to the addition unit 32A, and the addition of the compensation signal CM compensates for the characteristics of the steering system and improves convergence, inertial characteristics, etc. . The compensation signal generation unit 34 adds the self-aligning torque (SAT) 343 and the inertia 342 in the addition unit 344, further adds convergence 341 to the addition result in the addition unit 345, and compensates the addition result of the addition unit 345. It is a signal commercial.

In this way, in assist control in conventional electric power steering devices, the steering torque manually applied by the driver is detected by a torque sensor as the torsional torque of the torsion bar, and the assist current is mainly adjusted according to the torque. The motor current is controlled as follows. However, when controlling with this method, the steering torque may vary depending on the steering angle due to differences in road surface conditions (for example, slope). Variations in motor output characteristics due to aging may also affect the steering torque.

In order to solve this problem, an electric power steering device as shown in, for example, Japanese Patent No. 5208894 (Patent Document 1) has been proposed. In the electric power steering device of Patent Document 1, in order to provide an appropriate steering torque based on the driver's tactile characteristics, the steering angle and steering torque are determined based on the relationship between the steering angle or the steering torque and the amount of response. The target value of the steering torque is set based on the relationship (steering reaction force characteristic map).

Patent No. 5208894

However, in the electric power steering device of Patent Document 1, a steering reaction force characteristic map must be obtained in advance, and control is performed based on the deviation between the target value of the steering torque and the detected steering torque. Therefore, there is a possibility that the influence on the steering torque remains.

Furthermore, in assist control using an electric power steering device, steady errors caused by friction in the steering system may have an adverse effect on the control, so it is desired to reduce such steady errors.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a system that is not affected by road surface conditions, is not affected by changes in the mechanical characteristics of the steering system over time, and is capable of controlling the steering angle, etc. An object of the present invention is to provide a vehicle steering device that can easily achieve the same steering torque. Another objective is to reduce steady-state errors caused by the effects of friction.

The present invention provides a vehicle that is equipped with at least a torsion bar having an arbitrary spring constant and a sensor that detects the torsion angle of the torsion bar, and that assists and controls a steering system by driving and controlling a motor based on a motor current command value. Regarding the steering device, the above-mentioned object of the present invention is to cause the torsion angle to follow a target torsion angle obtained by converting a target steering torque calculated based on at least a steering angle and a steering state using the spring constant . a torsion angle control section that calculates a motor current command value; the torsion angle control section performs proportional compensation and pseudo-integral compensation based on the target torsion angle and a deviation of the torsion angle; This is achieved by calculating the motor current command value by performing differential compensation, and driving and controlling the motor based on the motor current command value .

Further, the above object of the present invention is that the torsion angle control section adjusts the motor current command value by performing differential advance type PID control based on the target torsion angle, a deviation of the torsion angle, and the torsion angle. The method further includes a compensation change flag setting unit that sets a desired value to a compensation change flag that makes the pseudo-integral compensation variable by calculation or by multiplying the compensation change flag, and makes the pseudo-integral compensation variable by multiplying the compensation change flag. or by further comprising an input limiter that limits upper and lower limits of the target torsion angle; or by further comprising a rate limiter that limits the amount of change in the target torsion angle; This can be achieved more effectively by further including an output limiting section that limits the upper and lower limits of the motor current command value .

According to the vehicle steering device of the present invention, the target torsion angle can be adjusted by controlling the target torsion angular velocity calculated based on the target torsion angle or by controlling the target torsion angle. The steering wheel operates so that the torsion angle follows the steering angle, thereby achieving a desired steering torque and providing an appropriate steering torque based on the driver's steering sensation.

Further, by performing pseudo-integral compensation in the control, steady-state errors caused by the influence of friction can be reduced. Furthermore, by making the pseudo-integral compensation variable, it is possible to adjust the degree of SAT transmitted from the road surface with respect to the driver's hand feeling.

FIG. 1 is a configuration diagram showing an outline of an electric power steering device. FIG. 2 is a block diagram showing an example of the configuration inside a control unit (ECU) of the electric power steering device. It is a structural diagram showing an example of installation of an EPS steering system and various sensors. FIG. 1 is a block diagram showing a configuration example (first embodiment) of the present invention. FIG. 2 is a block diagram showing a configuration example of a target steering torque generation section. FIG. 3 is a diagram showing an example of characteristics of a basic map. FIG. 3 is a diagram showing an example of characteristics of a damper gain map. FIG. 3 is a diagram showing an example of characteristics of a hysteresis correction section. FIG. 2 is a block diagram showing a configuration example (first embodiment) of a twist angle control section. FIG. 7 is a diagram illustrating an example of setting upper and lower limit values in an input restriction section. 1 is a flowchart showing an operation example (first embodiment) of the present invention. 3 is a flowchart illustrating an example of the operation of a target steering torque generation section. It is a flowchart which shows the example of operation (1st Embodiment) of a twist angle control part. It is a graph which shows the time series example of the steering angle used in the simulation which confirms the followability effect to a target steering torque. It is a graph which shows the result of the simulation which confirms the followability effect to a target steering torque. FIG. 3 is a block diagram showing a configuration example (second embodiment) of a twist angle control section. It is a block diagram showing an example of composition (3rd embodiment) of a twist angle control part. It is a flow chart which shows an example of operation of a twist angle control part (3rd embodiment). It is a block diagram showing an example of composition (4th embodiment) of a twist angle control part. FIG. 7 is an image diagram showing an example of level setting in a compensation change flag setting section. It is a flow chart which shows an example of operation (4th embodiment) of a twist angle control part. 7 is a graph showing data and results used in a simulation to confirm the effect of pseudo-integral compensation. FIG. 3 is a block diagram showing a configuration example (fifth embodiment) of the present invention. FIG. 3 is a block diagram showing an example of insertion of a phase compensation section. FIG. 1 is a configuration diagram showing an overview of an SBW system. It is a block diagram showing the example of composition (6th embodiment) of the present invention. It is a block diagram showing an example of composition of a target steering angle generation part. It is a block diagram showing an example of composition of a steering angle control part. It is a flowchart which shows the operation example (6th Embodiment) of this invention.

The present invention is a vehicle steering device that is unaffected by road surface conditions and achieves a steering torque equivalent to a steering angle, etc., and the torsion angle of a torsion bar, etc. is adjusted to a value corresponding to a steering angle, etc. The desired steering torque is achieved by controlling the steering torque to follow the steering torque.

Embodiments of the present invention will be described below with reference to the drawings.

First, installation examples of various sensors for detecting information related to an electric power steering device, which is one of the vehicle steering devices according to the present invention, will be described. FIG. 3 is a diagram showing an installation example of an EPS steering system and various sensors, and the column shaft 2 is equipped with a torsion bar 2A. Road surface reaction force Fr and road surface information μ act on the steering wheels 8L and 8R. An upper angle sensor is provided on the handle side of the column shaft 2 across the torsion bar 2A, and a lower angle sensor is provided on the steering wheel side of the column shaft 2 across the torsion bar 2A. detects the steering wheel angle θ ₁ , and the lower angle sensor detects the column angle θ ₂ . The steering angle θh is detected by a steering angle sensor installed at the top of the column shaft 2, and from the deviation of the steering wheel angle θ ₁ and column angle θ ₂ , the torsion angle Δθ of the torsion bar and the torsion bar torque are determined by the following equations 1 and 2. Tt can be determined. Note that Kt is a spring constant of the torsion bar 2A.

トーションバートルクＴｔは、例えば特開２００８－２１６１７２号公報で示されるトルクセンサを用いて検出することも可能である。なお、本実施形態では、トーションバートルクＴｔを操舵トルクＴｓとしても扱うこととする。

The torsion bar torque Tt can also be detected using, for example, a torque sensor disclosed in Japanese Patent Laid-Open No. 2008-216172. Note that in this embodiment, the torsion bar torque Tt is also treated as the steering torque Ts.

Next, a configuration example of the present invention will be explained.

FIG. 4 is a block diagram showing a configuration example (first embodiment) of the present invention, and the driver's steering is assisted and controlled by a motor in the EPS steering system/vehicle system 100. In addition to the steering angle θh, the vehicle speed Vs and the right-turn or left-turn steering state STs output from the right-turn/left-turn determination unit 110 are input to the target steering torque generation unit 120 that outputs the target steering torque Tref. Ru. The target steering torque Tref is converted into a target torsion angle Δθref by the conversion unit 130, and the target torsion angle Δθref is input to the torsion angle control unit 140 together with the torsion angle Δθ of the torsion bar 2A. The torsion angle control unit 140 calculates a motor current command value Imc such that the torsion angle Δθ becomes the target torsion angle Δθref, and the motor of the EPS is driven by the motor current command value Imc.

The right-turn/left-turn determination unit 110 determines whether the steering is right or left based on the motor angular velocity ωm, and outputs the determination result as a steering state STs. That is, when the motor angular velocity ωm is a positive value, it is determined that the motor is turning to the right, and when the motor angular velocity ωm is a negative value, it is determined that the motor is turning to the left. Note that instead of the motor angular velocity ωm, an angular velocity calculated by performing velocity calculation on the steering angle θh, the steering wheel angle θ ₁ or the column angle θ ₂ may be used.

FIG. 5 shows a configuration example of the target steering torque generation section 120, which includes a basic map section 121, a differentiation section 122, a damper gain section 123, a hysteresis correction section 124, a multiplication section 125, and an addition section 126. and 127, the steering angle θh is input to the basic map section 121, the differentiation section 122, and the hysteresis correction section 124, and the steering state STs output from the right/left turn determination section 110 is input to the hysteresis correction section 124. .

The basic map unit 121 has a basic map, and uses the basic map to output a torque signal (first torque signal) Tref_a using the vehicle speed Vs as a parameter. The basic map is adjusted by tuning. For example, as shown in FIG. 6(A), the torque signal Tref_a increases as the magnitude (absolute value) |θh| of the steering angle θh increases, and It also increases as the number increases. Note that in FIG. 6A, the sign section 121A outputs the sign (+1, -1) of the steering angle θh to the multiplication section 121B, and the magnitude of the torque signal Tref_a is calculated from the magnitude of the steering angle θh using a map. The torque signal Tref_a is obtained by multiplying the signal by the sign of the steering angle θh, but as shown in FIG. In this case, the manner of change, such as the inclination, may be changed depending on whether the steering angle θh is positive or negative. Further, although the basic map shown in FIG. 6 is vehicle speed sensitive, it does not have to be vehicle speed sensitive.

The differentiator 122 calculates the steering angular velocity ωh, which is angular velocity information, by differentiating the steering angle θh, and the steering angular velocity ωh is input to the multiplier 125.

The damper gain section 123 outputs a damper gain _DG that is multiplied by the steering angular velocity ωh. The steering angular velocity ωh is multiplied by the damper gain _DG in the multiplier 125, and the multiplication result is input to the adder 127 as a torque signal (second torque signal) Tref_b. The damper gain _DG is determined according to the vehicle speed Vs using a vehicle speed sensitive damper gain map included in the damper gain section 123. For example, as shown in FIG. 7, the damper gain map has a characteristic of gradually increasing as the vehicle speed Vs increases. The damper gain map may be variable depending on the steering angle θh. Note that the damper gain section 123 and the multiplication section 125 constitute a damper calculation section.

The hysteresis correction unit 124 calculates a torque signal (third torque signal) Tref_c based on the steering angle θh and the steering state STs according to Equation 3 below. Note that in Equation 3 below, x=θh, y=Tref_c, a>1, c>0, and _Ahys is the hysteresis width.

右切り操舵から左切り操舵、左切り操舵から右切り操舵へ切り替える際に、最終座標（ｘ１，ｙ１）の値に基づき、切り替え後の数３の“ｂ”に以下の数４を代入する。これにより、切り替え前後の連続性が保たれる。

When switching from right-turn steering to left-turn steering and from left-turn steering to right-turn steering, the following equation 4 is substituted for "b" in equation 3 after switching based on the value of the final coordinates (x1, y1). This maintains continuity before and after switching.

上記数４は、上記数３中のｘにｘ１を、ｙ_Ｒ及びｙ_Ｌにｙ１を代入することにより導出することができる。

The above equation 4 can be derived by substituting x1 for x and y1 for y _R and y _L in the above equation 3.

Any positive number greater than 1 can be used as "a". For example, when Napier's number "e" is used, Equation 3 and Equation 4 become Equation 5 and Equation 6 below.

数５及び数６においてＡ_ｈｙｓ＝１［Ｎｍ］、ｃ＝０．３と設定し、０［ｄｅｇ］から開始し、＋５０［ｄｅｇ］、－５０［ｄｅｇ］の操舵をした場合の、ヒステリシス補正されたトルク信号Ｔｒｅｆ＿ｃの線図例を図８に示す。即ち、ヒステリシス補正部１２４からのトルク信号Ｔｒｅｆ＿ｃは、０の原点→Ｌ１（細線）→Ｌ２（破線）→Ｌ３（太線）のようなヒステリシス特性である。

Hysteresis correction when setting A _hys = 1 [Nm] and c = 0.3 in Equation 5 and Equation 6, and steering from 0 [deg] to +50 [deg] and -50 [deg] FIG. 8 shows an example of a diagram of the torque signal Tref_c. That is, the torque signal Tref_c from the hysteresis correction unit 124 has a hysteresis characteristic such as the origin of 0 → L1 (thin line) → L2 (broken line) → L3 (thick line).

Note that A _hys , which is a coefficient representing the output width of the hysteresis characteristic, and c, which is a coefficient representing roundness, may be made variable depending on the vehicle speed Vs and/or the steering angle θh.

Torque signals Tref_c, Tref_b, and Tref_a are sequentially added by adding units 127 and 126, and output as target steering torque Tref.

Note that the steering angular velocity ωh is obtained by differential calculation with respect to the steering angle θh, and low-pass filter (LPF) processing is appropriately performed to reduce the influence of high-frequency noise. Further, differential calculation and LPF processing may be performed using a high pass filter (HPF) and gain. Furthermore, the steering angular velocity ωh is calculated by performing differential calculation and LPF processing on the steering wheel angle _θ1 detected by the upper angle sensor or the column angle _θ2 detected by the lower angle sensor, instead of the steering angle θh. Also good. The motor angular velocity ωm may be used as the angular velocity information instead of the steering angular velocity ωh, and in this case, the differentiator 122 is not required.

The converter 130 has a characteristic of −1/Kt, which is the inverse sign of the reciprocal of the spring constant Kt of the torsion bar 2A, and converts the target steering torque Tref into a target torsion angle Δθref.

The torsion angle control unit 140 calculates the motor current command value Imc based on the torsion angle Δθ of the torsion bar 2A and the target torsion angle Δθref by performing follow-up control on the torsion angle of the torsion bar that is fed back. FIG. 9 is a block diagram showing a configuration example of the torsion angle control section 140, which includes an input limiter 141, a rate limiter 142, a torsion angle feedback (FB) compensator 143, and a torsion angular velocity calculator 144. , a speed control unit 160, an output limiting unit 145, and a subtracting unit 146, the target torsion angle Δθref output from the converting unit 130 is input to the input limiting unit 141, and the torsion angle Δθ is subtracted and input to the subtracting unit 146. At the same time, it is input to the torsion angular velocity calculation section 144.

The input restriction unit 141 controls the target torsion so that the torsion angle control unit 140 does not output an abnormal motor current command value Imc when the target torsion angle Δθref becomes an abnormal value during communication, calculation of the microcomputer, ECU, etc. Limit the upper and lower limits of the angle Δθref. As shown in FIG. 10, an upper limit value and a lower limit value for the target torsion angle Δθref are set in advance, and when the input target torsion angle Δθref is greater than or equal to the upper limit value, the upper limit value is set as the target torsion angle Δθref', and the lower limit value is set. In the following cases, the lower limit value is set as the target torsion angle Δθref', and in other cases, the target torsion angle Δθref is output as is as the target torsion angle Δθref'. The upper and lower limit values to be set may be the maximum and minimum values of the torsion angle used for control, or the maximum and minimum values of the range of detectable torsion angles. This ensures safety.

The rate limiting unit 142 controls the amount of change in the target torsion angle Δθref' in order to prevent the value from changing discontinuously instead of changing continuously when the target torsion angle Δθref becomes an abnormal value. A limit is applied to the target torsion angle and a target torsion angle Δθref is output. Normally, the target torsion angle changes continuously and is not limited by the rate limiting unit 142, but due to some abnormality, the target torsion angle temporarily changes to an abnormal value. If this occurs, the rate limiting unit 142 applies a limit to prevent discontinuous changes.For example, the difference between the target torsion angle Δθref' of the previous sample and the target torsion angle Δθref' of the current sample is changed. If the absolute value of the amount of change is larger than a predetermined value, the target torsion angle Δθref' is added or subtracted so that the absolute value of the amount of change becomes the predetermined value, and the result is output as the target torsion angle Δθref', and the If the target torsion angle Δθref' is less than the value of , the target torsion angle Δθref' is output as is as the target torsion angle Δθref''. A restriction may be applied, for example, by setting the amount of change to be the ratio of the difference with respect to the target torsion angle Δθref'' one sample before.

Note that the arrangement of the input limiting section 141 and the rate limiting section 142 may be reversed, but the arrangement as shown in FIG. 9 is preferable. Furthermore, in cases where handling of abnormal values or discontinuous values is handled by other means, the input limiting section 141 and/or the rate limiting section 142 can be deleted.

The torsion angle FB compensation unit 143 multiplies the deviation Δθ ₀ between the target torsion angle Δθref and the torsion angle Δθ calculated by the subtraction unit 146 by a compensation value C _FB (transfer function), and calculates the torsion angle by the target torsion angle Δθref. A target torsional angular velocity ωref that Δθ follows is output.The compensation value C _FB may be a simple gain Kpp or a commonly used compensation value such as a compensation value for PI control.The target torsional angular velocity ωref is a speed control The torsion angle FB compensation part 143 and the speed control part 160 make it possible to make the torsion angle Δθ follow the target torsion angle Δθref and realize a desired steering torque.

The torsion angular velocity calculation unit 144 calculates the torsion angular velocity ωt by differential calculation with respect to the torsion angle Δθ, and the torsion angular velocity ωt is input to the speed control unit 160. As the differential calculation, pseudo-differentiation using HPF and gain may be performed. Further, the torsion angular velocity ωt may be calculated by another means or from a method other than the torsion angle Δθ and input to the speed control unit 160.

The speed control unit 160 calculates a motor current command value Imca such that the torsional angular velocity ωt follows the target torsional angular velocity ωref. The speed control section 160 includes a proportional section 161, a gain section 162, a pseudo integration section 163, a subtraction section 164, and an addition section 165. The proportional section 161 performs proportional compensation, and the gain section 162 and pseudo integration section 163 perform Perform integral compensation. The subtraction unit 164 calculates the difference Δω (=ωref−ωt) between the target torsional angular velocity ωref and the torsional angular velocity ωt, and the difference Δω is input to the proportional unit 161 and the gain unit 162. The proportional section 161 performs proportional compensation by multiplying the difference Δω by the gain Kvp. The gain unit 162 multiplies the difference Δω by the gain Kvi, and the pseudo-integration unit 163 performs pseudo-integration on the multiplication result. As the pseudo-integral, for example, a function expressed in a first-order lag format as shown in Equation 7 below is used.

ここで、Ｔは時定数、ωｃは遮断周波数、ｓはラプラス演算子である。ゲイン部１６２及び擬似積分部１６３による擬似積分補償により、摩擦の影響による定常誤差を低減することができる。比例部１６１からの出力及び擬似積分部１６３からの出力が加算部１６５で加算され、モータ電流指令値Ｉｍｃａとして出力される。なお、擬似積分部１６３での擬似積分での１次遅れの遮断周波数は、経験的に０．１～５Ｈｚの範囲で設定するのが良い。また、擬似積分を上記数７以外の関数で行っても良い。

Here, T is a time constant, ωc is a cutoff frequency, and s is a Laplace operator. The pseudo-integral compensation performed by the gain section 162 and the pseudo-integral section 163 can reduce steady-state errors due to the influence of friction. The output from the proportional section 161 and the output from the pseudo-integral section 163 are added by an adding section 165 and output as a motor current command value Imca. Note that the cutoff frequency of the first-order lag in the pseudo integration in the pseudo integration section 163 is preferably set in the range of 0.1 to 5 Hz empirically. Further, the pseudo-integration may be performed using a function other than the above-mentioned equation 7.

Output limiting section 145 limits the upper and lower limits of motor current command value Imca output from speed control section 160, and outputs motor current command value Imc. Similar to the input limiter 141, limits are applied by setting upper and lower limits in advance to the motor current command value Imca. Note that, in the case where handling of abnormal values is performed by other means, the output limiting section 145 can also be deleted, as in the case of the input limiting section 141.

In such a configuration, an example of the operation of this embodiment will be described with reference to flowcharts in FIGS. 11 to 13.

When the operation starts, the right-turn/left-turn determination unit 110 inputs the motor angular velocity ωm, determines whether the steering is right or left based on the sign of the motor angular velocity ωm, and sets the determination result as the steering state STs. The target steering torque is output to the target steering torque generation section 120 (step S10).

The target steering torque generation unit 120 receives the steering state STs, the steering angle θh, and the vehicle speed Vs, and generates the target steering torque Tref (step S20). An example of the operation of the target steering torque generation section 120 will be described with reference to the flowchart of FIG. 12.

The steering angle θh input to the target steering torque generation section 120 is sent to the basic map section 121, the differentiation section 122, and the hysteresis correction section 124, the steering state STs is sent to the hysteresis correction section 124, and the vehicle speed Vs is sent to the basic map section 121 and the damper gain section 123. (step S21).

The basic map unit 121 uses the basic map shown in FIG. 6(A) or (B) to generate a torque signal Tref_a according to the steering angle θh and the vehicle speed Vs, and outputs it to the adding unit 126 (step S22 ).

The differentiator 122 differentiates the steering angle θh and outputs the steering angular velocity ωh (step S23), and the damper gain unit 123 outputs the damper gain _DG according to the vehicle speed Vs using the damper gain map shown in FIG. 7 (step S23). S24), the multiplier 125 multiplies the steering angular velocity ωh and the damper gain _DG to calculate the torque signal Tref_b, and outputs it to the adder 127 (step S25).

The hysteresis correction unit 124 performs hysteresis correction on the steering angle θh by switching between calculations according to Equation 5 and Equation 6 according to the steering state STs (step S26), generates a torque signal Tref_c, and sends it to the addition unit 127. Output (step S27). Note that although the hysteresis width A _hys , c, x1, and y1 in Equation 5 and Equation 6 are set and held in advance, b and b' are calculated in advance from Equation 6, and b and b' are used instead of x1 and y1. You can also keep it.

Then, the adding unit 127 adds the torque signals Tref_b and Tref_c, and the adding unit 126 adds the torque signal Tref_a to the addition result to calculate the target steering torque Tref (step S28).

The target steering torque Tref generated by the target steering torque generation section 120 is input to the conversion section 130, where it is converted into a target torsion angle Δθref (step S30). The target twist angle Δθref is input to the twist angle control section 140.

The torsion angle control unit 140 inputs the torsion angle Δθ together with the target torsion angle Δθref, and calculates a motor current command value Imc (step S40). An example of the operation of the twist angle control section 140 will be described with reference to the flowchart of FIG. 13.

The target torsion angle Δθref input to the torsion angle control unit 140 is input to the input limiting unit 141, and the torsion angle Δθ is input to the torsion angular velocity calculation unit 144 and subtraction unit 146 (step S41).

The input limiter 141 limits the upper and lower limits of the target torsion angle Δθref using preset upper and lower limit values, and outputs the result as a target torsion angle Δθref' to the rate limiter 142 (step S42). limits the amount of change in the target torsion angle Δθref' and outputs it to the subtraction unit 146 as the target torsion angle Δθref' (step S43).

The subtraction unit 146 calculates the deviation Δθ ₀ by subtracting the torsion angle Δθ from the target torsion angle Δθref (step S44). The deviation Δθ ₀ is input to the torsion angle FB compensator 143, and the torsion angle FB compensation unit 143 calculates the deviation Δθ 0. The unit 143 compensates for the deviation Δθ ₀ by multiplying the deviation Δθ ₀ by the compensation value C _FB (step S45), and outputs the result to the speed control unit 160 as the target torsional angular velocity ωref.

The torsion angular velocity calculation unit 144 that has input the torsion angle Δθ calculates the torsion angular velocity ωt by differential calculation with respect to the torsion angle Δθ (step S46), and outputs it to the speed control unit 160.

In the speed control unit 160, the subtraction unit 164 calculates the difference Δω between the target torsion angular velocity ωref and the torsion angular velocity ωt, and the difference Δω is input to the proportional unit 161 and the gain unit 162 (step S47). The proportional unit 161 performs proportional compensation on the difference Δω by multiplying by the gain Kvp, and outputs it to the adding unit 165 (step S48). The difference Δω input to the gain unit 162 is multiplied by the gain Kvi in the gain unit 162 and pseudo-integral compensation using equation 7 is performed in the pseudo-integration unit 163, and is output to the addition unit 165 ( Step S49). In the adding section 165, the output from the proportional section 161 and the output from the pseudo-integrating section 163 are added together and outputted to the output limiting section 145 as a motor current command value Imca (step S50).

The output limiter 145 limits the upper and lower limits of the motor current command value Imca using preset upper and lower limits (step S51), and outputs it as the motor current command value Imc (step S52).

The motor is driven based on the motor current command value Imc output from the twist angle control unit 140, and current control is performed (step S60).

Note that the order of data input, calculation, etc. in FIGS. 11 to 13 can be changed as appropriate.

The effect of followability to the target steering torque according to this embodiment will be explained based on simulation results in comparison with a case where only proportional compensation is performed in the speed control section.

In the simulation, assuming a situation where the steering wheel is being steered, the steering angle θh is changed sinusoidally with an amplitude of about 30 degrees and a frequency of about 1.0 Hz, as shown in FIG. 14, and the target in that case is The changes in the steering torque Tref and the steering torque Ts were investigated. In addition, in FIG. 14, the horizontal axis is time [sec], and the vertical axis is steering angle [deg].

The simulation results are shown in FIG. In FIG. 15, the horizontal axis is time [sec] and the vertical axis is steering torque [Nm]. The thick line represents the target steering torque, and the thin line represents the steering torque when only proportional compensation is performed in the speed control section. The dashed line indicates the steering torque in this embodiment in which proportional compensation and pseudo-integral compensation are performed in this embodiment. From FIG. 15, it can be seen that even when only proportional compensation is performed in the speed control section, the steering torque follows the target steering torque relatively well over the entire range, but errors remain. On the other hand, in the case of the present embodiment, it can be seen that the steady-state error is reduced and the target steering torque is tracked better.

Another configuration example of the present invention will be explained.

In the speed control section 160 in the torsion angle control section 140 in the first embodiment shown in FIG. 9, a proportional section 161 that performs proportional compensation, and a gain section 162 and a pseudo-integral section 163 that perform pseudo-integral compensation are arranged in parallel. However, by summing these two compensations, the two compensations can be equivalently represented by a gain and a phase delay filter. An example of the configuration of the twist angle control section in this case (second embodiment) is shown in FIG. 16. With this configuration as well, control performance similar to that of the first embodiment can be achieved.

The torsion angle control section according to the second embodiment shown in FIG. 16 differs from the first embodiment only in the configuration of a speed control section 260, and the other configurations are the same. The speed control section 260 includes a gain section 261, a phase lag filter section 262, and a subtraction section 164, and similarly to the speed control section 160, it inputs the target torsion angular velocity ωref and the torsion angular velocity ωt, and calculates the torsion angular velocity ωt from the target torsion angular velocity ωref. A motor current command value Imca that follows is calculated. The gain unit 261 multiplies the difference Δω between the target torsion angular velocity ωref and the torsion angular velocity ωt calculated by the subtraction unit 164 by a gain Kv. The phase lag filter section has a phase lag filter, and performs filter processing using the phase lag filter on the output from the gain section 261 to calculate a motor current command value Imca.

The operation example of the second embodiment differs from the operation example of the first embodiment only in the operation of the speed control section as described above, and the other operations are the same.

The torsion angle control section may be configured to perform three types of compensation: proportional compensation, pseudo-integral compensation, and differential compensation, without providing the speed control section. For example, as in the configuration example (third embodiment) shown in FIG. 17, a configuration of differential-first type PID (proportional-integral-derivative) control (PI-D control) is adopted, and with this configuration, the configuration is different from that of the first embodiment. Substantially equivalent target value followability can be achieved. Note that the configuration of the torsion angle control section is not limited to the configuration of PI-D control, but may be a configuration such as proportional differential prior type PID control as long as it performs proportional compensation, pseudo-integral compensation, and differential compensation.

The torsion angle control unit in the third embodiment shown in FIG. 17 calculates a motor current command value by PI-D control based on the target torsion angle and the torsion angle. Therefore, compared to the configuration example of the torsion angle control section in the first embodiment shown in FIG. In place of the section 162, pseudo-integration section 163, subtraction section 164, and addition section 165, a proportional section 351, gain sections 352 and 355, pseudo-integration section 353, differentiation section 354, addition section 356, and subtraction section 357 are provided. A proportional section 351 performs proportional compensation, a gain section 352 and a pseudo-integral section 353 perform pseudo-integral compensation, and a differential section 354 and a gain section 355 perform differential compensation.

The deviation Δθ ₀ between the target torsion angle Δθref and the torsion angle Δθ calculated by the subtraction unit 146 is input to the proportional unit 351 and the gain unit 352, and the torsion angle Δθ is input to the differentiation unit 354 instead of the torsion angular velocity calculation unit 144. The proportional unit 351 performs proportional compensation by multiplying the deviation Δθ ₀ by the gain Kp.The gain unit 352 multiplies the deviation Δθ ₀ by the gain Ki, and applies the pseudo-integrator to the multiplication result. 353 performs pseudo-integration. In the pseudo-integration, a function expressed in a first-order lag format similar to that of the pseudo-integration section 163 may be used, or a function in another format may be used. 354 differentiates the torsion angle Δθ, and multiplies the differential result by a gain Kd in a gain unit 355.The output of the proportional unit 351 and the output of the pseudo-integrator 353 are added in an adder 356. A subtraction unit 357 subtracts the output of the gain unit 355 from the addition result, and the subtraction result is output as a motor current command value Imca.

The operation example of the third embodiment is different from the operation example of the first embodiment except for the operation of the torsion angle control section, and is otherwise the same. FIG. 18 shows an example of the operation of the twist angle control section in the third embodiment.

The target torsion angle Δθref is input to the input restriction section 141, and the torsion angle Δθ is input to the differentiating section 354 and the subtracting section 146 (step S41A).

The input limiting unit 141 and the rate limiting unit 142 perform a limiting process on the target torsional angle by the same operation as in the first embodiment, and the target torsional angle Δθref” is added and input to the subtracting unit 146. The deviation Δθ ₀ is calculated (steps S42 to S44).The deviation Δθ ₀ is input to the proportional section 351 and the gain section 352.

The proportional unit 351 performs proportional compensation for the deviation Δθ ₀ by multiplying by the gain Kp, and outputs the result to the adding unit 356 (step S48A). For the deviation Δθ ₀ input to the gain section 352, pseudo-integral compensation is performed by multiplication by the gain Ki in the gain section 352 and pseudo-integration in the pseudo-integration section 353, and the result is output to the addition section 356 (step S49A). In the addition section 356, the output from the proportional section 351 and the output from the pseudo integration section 353 are added (step S50A).

Differential compensation is performed on the torsion angle Δθ inputted to the differentiator 354 by differential calculation in the differentiator 354 and multiplication by a gain Kp in the gain unit 355, and output to the subtractor 357 (step S50B). . Then, the subtraction unit 357 calculates the motor current command value Imca by subtracting the output of the gain unit 355 from the addition result output from the addition unit 356 (step S50C), and outputs it to the output restriction unit 145.

The output limiter 145 limits the upper and lower limits of the motor current command value Imca by the same operation as in the first embodiment (step S51), and outputs it as the motor current command value Imc (step S52).

Note that the order of data input, calculation, etc. in FIG. 18 can be changed as appropriate.

The ratio of pseudo-integral compensation in the torsion angle control section in the first and third embodiments may be changed depending on the driving situation. By changing the ratio of pseudo-integral compensation, the SAT feeling (road surface reaction force feeling) transmitted from the road surface can be changed as appropriate with respect to the driver's hand feeling. Regarding road surface information such as SAT feeling, the amount of steering feeling to be communicated to the driver depends on the driving situation and driving, such as actively communicating it to understand the road surface condition, or suppressing it to reduce the feeling of resistance. It depends on the person's preference. Therefore, the amount of information to be transmitted can be adjusted.

FIG. 19 shows a configuration example (fourth embodiment) in which the function of changing the ratio of pseudo-integral compensation described above (hereinafter referred to as "compensation change function") is added to the torsion angle control section in the third embodiment. show. In the torsion angle control section in the fourth embodiment, the deviation Δθ ₀ between the target torsion angle Δθref and the torsion angle Δθ is multiplied by the compensation change flag Cf before being multiplied by the gain Ki, which is an integral gain, so that the pseudo-integral Change the compensation ratio.Compared with the configuration example of the torsion angle control unit in the third embodiment shown in FIG. is added, the deviation Δθ ₀ output from the subtraction unit 146 is multiplied by the compensation change flag Cf output from the compensation change flag setting unit 471 in the multiplication unit 472, and the multiplication result is input to the gain unit 352. Ru.

The compensation change flag setting unit 471 sets the compensation change flag Cf to a desired value. For example, a level meter as shown in FIG. 20 is provided so that the driver can adjust the SAT feeling from the road surface by changing the level with the level meter. In FIG. 20, "HIGH" indicates that the SAT feeling becomes stronger, "LOW" indicates that the SAT feeling becomes weaker, and "HIGH" indicates that the compensation change flag Cf is set to a value close to 0 (minimum 0). , "LOW" sets a large value. If the driver wants to change the SAT feeling, he sets the level on the level meter to the desired level and presses the "SET" button. By pressing the "SET" button, a value is set in the compensation change flag Cf corresponding to the set level, and the SAT feeling changes. If you press the "CANCEL" button instead of the "SET" button, the set level is canceled and you return to the original level. Note that the SAT feeling may be changed by eliminating the "SET" button and the "CANCEL" button and changing the value of the compensation change flag Cf at the time the level is set.

The operation example of the fourth embodiment is different from the operation example of the third embodiment except for the operation of the torsion angle control section, and is otherwise the same. FIG. 21 shows an example of the operation of the twist angle control section in the fourth embodiment.

In the fourth embodiment, the same operation as in the third embodiment is performed up to proportional compensation (step S48A), and the deviation Δθ ₀ calculated by the subtraction unit 146 is input to the multiplication unit 472 instead of the gain unit 352. In the multiplier 472, the deviation Δθ ₀ is multiplied by the compensation change flag Cf set by the compensation change flag setting unit 471, and the multiplication result is input to the gain unit 352 (step S48B). The subsequent operations are the same as in the third embodiment (step S49A~). Note that, as in the case of FIG. 18, the order of data input, calculation, etc. in FIG. 21 can be changed as appropriate.

In the fourth embodiment, the value of the compensation change flag Cf is changed according to the driver's settings to change the SAT feeling, but the value of the compensation change flag Cf is changed in conjunction with variables indicating driving conditions such as steering torque. You may also do this. By predefining the characteristics of the compensation change flag Cf for variables, it becomes possible to automatically change the SAT feeling.

In the fourth embodiment, the multiplier 472 that multiplies the compensation change flag Cf is provided at the front stage of the gain unit 352, but since it is sufficient if the ratio of pseudo-integral compensation can be changed, It may be provided at the later stage.

Further, in the fourth embodiment, a compensation change function is added to the torsion angle control section in the third embodiment, but it is also possible to add a compensation change function to the torsion angle control section in the first embodiment. . When adding a compensation change function to the torsion angle control section in the first embodiment, a multiplication section that multiplies the compensation change flag Cf is provided before the gain section 162 in the speed control section 160, and The difference Δω from the angular velocity ωt is multiplied by the compensation change flag Cf, and the multiplication result is input to the gain section 162. The multiplication section may be provided after the gain section 162 or after the pseudo-integration section 163.

Here, the effect of pseudo-integral compensation when a reaction force from the road surface occurs and its influence on the steering feel will be explained based on simulation results.

In the simulation, in order to simply simulate the reaction force from the road surface, the intermediate shaft was gradually increased in frequency from 0.1 Hz to 2 Hz, with a single amplitude of 5 Nm, as shown in Fig. 22(A). We applied a varying sweep signal torque (hereinafter referred to as "intermediate shaft torque") to examine how the steering torque (torsion bar torque) changes with and without pseudo-integral compensation. Further, in order to keep the steering angle fixed at 0 degrees, the target steering torque was fixed at 0 Nm. Pseudo-integral compensation was performed using a first-order delay with a cutoff frequency of 1 Hz and a gain.

The simulation results are shown in FIG. 22(B). In FIG. 22(B), the horizontal axis is time [sec] and the vertical axis is steering torque [Nm]. The thick line indicates the steering torque with pseudo-integral compensation, and the broken line indicates the steering torque without pseudo-integral compensation. It is shown in The target steering torque is shown by a thin line, but in this simulation, the target steering torque was fixed at 0 Nm, so it overlaps with the horizontal axis. For comparison, the steering torque when pure integral compensation is performed instead of pseudo-integral compensation is shown by a dashed-dotted line. Looking at FIG. 22(B), the amplitude of the waveform indicated by the broken line is larger than the others, and if there is no pseudo-integral compensation, the influence of the intermediate shaft torque is likely to be reflected in the steering torque (easily reflected in the steering torque). I understand that. On the other hand, the amplitude of the waveform indicated by the thick line is smaller, indicating that the influence of intermittent shaft torque on steering torque is reduced when there is pseudo-integral compensation compared to when there is no pseudo-integral compensation. . Furthermore, the influence of the intermittent shaft torque is reduced as the frequency of the intermittent shaft torque becomes smaller, and it can be seen that information on the road reaction force is appropriately conveyed to the driver as a steering feeling. In the case of compensation using pure integrals, the smaller the frequency of the intermittent shaft torque, the closer the steering torque is to 0Nm, making it difficult for information on road reaction force to be transmitted to the driver as a steering feeling. There is a possibility that it may be felt as a sense of discomfort.

When using a level meter as shown in Figure 20, as the level approaches "HIGH", it approaches the setting of the broken line in this simulation (in the case of no pseudo-integral compensation), and road reaction force information becomes available to the driver. This becomes easier to convey as a steering feeling. When the level approaches "LOW", the setting becomes a thick line in this simulation (when there is pseudo-integral compensation), and it becomes difficult for information on road reaction force to be transmitted to the driver as a steering feeling.

The motor current command value Imc output from the torsion angle control unit in the first to fourth embodiments is combined with the current command value (hereinafter referred to as "assist current command value") calculated based on the steering torque in the conventional EPS. ) may be added, for example, to the current command value Iref1 output from the current command value calculation unit 31 shown in FIG. 2, or the current command value Iref2 obtained by adding the compensation signal CM to the current command value Iref1.

FIG. 23 shows a configuration example (fifth embodiment) in which the above content is applied to the first embodiment. The assist control section 500 includes a current command value calculation section 31 or a current command value calculation section 31, a compensation signal generation section 34, and an addition section 32A. The assist current command value Iac (corresponding to the current command value Iref1 or Iref2 in FIG. 2) output from the assist control section 500 and the motor current command value Imc output from the torsion angle control section 140 are added by an adding section 580. , the current command value Ic that is the addition result is input to the current limiting section 590, and current control is performed by driving the motor based on the current command value Icm with the maximum current limited.

In the target steering torque generation unit 120 in the first to fifth embodiments, if cost or processing time is important, at least one of the basic map unit 121, damper calculation unit, and hysteresis correction unit 124 may be left out. , others may be omitted. When the basic map section 121 is omitted, the addition section 126 can also be omitted; when the damper calculation section is omitted, the differentiation section 122 and the addition section 127 can also be omitted; when the hysteresis correction section 124 is omitted, the right cut/left cut The cut determination section 110 and addition section 127 can also be omitted. Further, a phase compensation section 128 that performs phase compensation may be inserted before or after the basic map section 121. That is, the configuration of the region R surrounded by the broken line in FIG. 5 may be configured as shown in FIG. 24(A) or (B). In the phase compensation unit 128, when phase lead compensation is set as phase compensation and the phase lead compensation is performed using a first-order filter with a numerator cutoff frequency of 1.0 Hz and a denominator cutoff frequency of 1.3 Hz, for example, A refreshing feel can be achieved. The target steering torque generation section is not limited to the above-mentioned configuration as long as it is configured based on the steering angle.

Although the present invention is applied to a column-type EPS in FIGS. 1 and 3, the present invention is not limited to upstream-type EPS such as column-type, but can also be applied to downstream-type EPS such as rack and pinion. Furthermore, by performing feedback control based on the target torsion angle, it is also applicable to a steer-by-wire (SBW) reaction force device, etc., which includes at least a torsion bar (with an arbitrary spring constant) and a sensor for detecting the torsion angle. An embodiment (sixth embodiment) in which the present invention is applied to an SBW reaction force device including a torsion bar will be described.

First, the entire SBW system including the SBW reaction device will be explained. FIG. 25 is a diagram showing an example of the configuration of the SBW system in correspondence with the general configuration of the electric power steering device shown in FIG. 1. In FIG. Note that the same configurations are denoted by the same reference numerals, and detailed explanations will be omitted.

The SBW system does not have an intermediate shaft that is mechanically connected to the column shaft 2 at the universal joint 4a, and is a system in which the operation of the handle 1 is transmitted to the steering mechanism consisting of the steering wheels 8L, 8R, etc. by electric signals. . As shown in FIG. 25, the SBW system includes a reaction force device 60 and a drive device 70, and a control unit (ECU) 50 controls both devices. The reaction force device 60 detects the steering angle θh using the steering angle sensor 14, and at the same time transmits the motion state of the vehicle transmitted from the steered wheels 8L and 8R to the driver as a reaction torque. The reaction torque is generated by the reaction motor 61. Note that some SBW systems do not have a torsion bar in the reaction device, but the SBW system to which the present invention is applied is a type that has a torsion bar, and the torque sensor 10 detects the steering torque Ts. do. Further, the angle sensor 74 detects the motor angle θm of the reaction force motor 61. The drive device 70 drives a drive motor 71 in accordance with the driver's steering of the steering wheel 1, and applies the driving force to the pinion rack mechanism 5 through a gear 72, and then through tie rods 6a and 6b. Turn the direction wheels 8L and 8R. An angle sensor 73 is arranged near the pinion rack mechanism 5, and detects the turning angle θt of the steered wheels 8L, 8R. In order to cooperatively control the reaction force device 60 and the drive device 70, the ECU 50 uses information such as the steering angle θh and turning angle θt outputted from both devices, as well as the vehicle speed Vs from the vehicle speed sensor 12, to A voltage control command value Vref1 for driving and controlling the reaction motor 61 and a voltage control command value Vref2 for driving and controlling the driving motor 71 are generated.

The configuration of a sixth embodiment in which the present invention is applied to such an SBW system will be described.

FIG. 26 is a block diagram showing the configuration of the sixth embodiment. The sixth embodiment controls the torsion angle Δθ (hereinafter referred to as "torsion angle control") and controls the steering angle θt (hereinafter referred to as "steering angle control"), and twists the reaction force device. It is controlled by angle control, and the drive device is controlled by steering angle control. Note that the drive device may be controlled using other control methods.

In the torsion angle control, the torsion angle Δθ follows the target torsion angle Δθref calculated via the target steering torque generation unit 120 and the conversion unit 130 using the steering angle θh etc. using the same configuration and operation as the first embodiment. control. The motor angle θm is detected by the angle sensor 74, and the motor angular velocity ωm is calculated by differentiating the motor angle θm by the angular velocity calculating section 951. The steering angle θt is detected by an angle sensor 73. Further, in the first embodiment, detailed explanation is not provided as processing within the EPS steering system/vehicle system 100, but the current control section 180 includes the subtraction section 32B, the PI control section 35, and the PWM control shown in FIG. With the same configuration and operation as the section 36 and the inverter 37, based on the motor current command value Imc output from the torsion angle control section 140 and the current value Imr of the reaction force motor 61 detected by the motor current detector 190, The reaction force motor 61 is driven to perform current control.

In the turning angle control, a target turning angle θtref is generated based on the steering angle θh in a target turning angle generation unit 910, and the target turning angle θtref is input to the turning angle control unit 920 together with the turning angle θt. The steering angle control unit 920 calculates a motor current command value Imct such that the steering angle θt becomes the target steering angle θtref. Then, based on the motor current command value Imct and the current value Imd of the drive motor 71 detected by the motor current detector 940, the current control unit 930 controls the drive motor 71 with the same configuration and operation as the current control unit 160. 71 to perform current control.

FIG. 27 shows a configuration example of the target turning angle generation section 910. The target turning angle generation section 910 includes a restriction section 931, a rate restriction section 932, and a correction section 933.

The limiting unit 931 limits the upper and lower limits of the steering angle θh and outputs the steering angle θh1. Similar to the input limiting section 141 and the output limiting section 145 in the torsion angle control section, an upper limit value and a lower limit value for the steering angle θh are set in advance to apply a limit.

In order to avoid sudden changes in the steering angle, the rate limiting unit 932 sets a limit value to limit the amount of change in the steering angle θh1, and outputs the steering angle θh2. For example, if the difference between the steering angle θh2 of one sample before and the steering angle θh1 of the current sample is the amount of change, and the absolute value of the amount of change is larger than a predetermined value (limit value), the absolute value of the amount of change is the limit value. The steering angle θh1 is added or subtracted so that the steering angle θh1 becomes the value, and is output as the steering angle θh2. If the steering angle θh1 is less than the limit value, the steering angle θh1 is output as is as the steering angle θh2. Note that instead of setting a limit value for the absolute value of the amount of change, it is also possible to set an upper limit value and a lower limit value for the amount of change. A limit may be placed on the rate.

The correction unit 933 corrects the steering angle θh2 and outputs the target turning angle θtref. For example, like the basic map section 121 in the target steering torque generation section 120, a map that defines the characteristics of the target turning angle θtref with respect to the magnitude of the steering angle θh2 |θh2| Find the angle θtref. Alternatively, the target turning angle θtref may be obtained by simply multiplying the steering angle θh2 by a predetermined gain.

A configuration example of the steering angle control section 920 is shown in FIG. 28. The steering angle control section 920 includes a steering angle feedback (FB) compensating section 921, a steering angular velocity calculation section 922, a speed control section 923, an output limiting section 926, and a subtracting section 927, and includes a steering angle feedback (FB) compensating section 921, a steering angular velocity calculation section 922, a speed control section 923, an output limiting section 926, and a subtracting section 927. A motor current command value Imct is calculated based on the angle θt.

The steering angle FB compensator 921 performs a calculation similar to the torsion angle FB compensator 143 in the torsion angle controller 140 for the deviation Δθt ₀ between the target steering angle θtref and the steering angle θt calculated by the subtraction unit 927. Through the operation, a target turning angular velocity ωtref is calculated such that the turning angle θt follows the target turning angle θtref. The target turning angular velocity ωtref is input to the speed control section 923.

The steering angular velocity calculation unit 922 calculates the steering angular velocity ωtt from the steering angle θt by the same operation as the torsion angular velocity calculation unit 144 in the torsion angle control unit 140. The steering angular velocity ωtt is input to the speed control section 923.

The speed control unit 923 calculates a motor current command value Imcta such that the turning angular velocity ωtt follows the target turning angular velocity ωtref by IP control (proportional advance type PI control). A subtraction unit 928 calculates the difference (ωtref−ωtt) between the target turning angular velocity ωtref and the turning angular velocity ωtt, the difference is integrated by an integration unit 924 having a gain Kti, and the integration result is added to a subtraction unit 929. is input. The steering angular velocity ωtt is also input to a proportional section 925, subjected to proportional processing using a gain Ktp, and subtracted and input to a subtracting section 929. The result of subtraction by subtractor 929 is output as motor current command value Imcta.

Output limiting section 926 limits the upper and lower limits of motor current command value Imcta and outputs motor current command value Imct. Similar to the input limiting section 141 and the output limiting section 145 in the torsion angle control section, the motor current command value Imcta is limited by setting an upper limit value and a lower limit value in advance.

In such a configuration, an example of the operation of the sixth embodiment will be described with reference to the flowchart of FIG. 29.

When the operation starts, the angle sensor 73 detects the steering angle θt, the angle sensor 74 detects the motor angle θm (step S110), the steering angle θt is sent to the steering angle control unit 920, and the motor angle θm is sent to the angular velocity. Each is input to the calculation unit 951.

The angular velocity calculation unit 951 calculates the motor angular velocity ωm by differentiating the motor angle θm, and outputs it to the right-turn/left-turn determination unit 110 (step S120).

Thereafter, the target steering torque generation unit 120 executes operations similar to steps S10 to S60 shown in FIG. 11, drives the reaction force motor 61, and performs current control (steps S130 to S170).

On the other hand, in the steering angle control, the target steering angle generation unit 910 inputs the steering angle θh, and the steering angle θh is input to the restriction unit 931. The limiting unit 931 limits the upper and lower limits of the steering angle θh using preset upper and lower limits (step S180), and outputs it to the rate limiting unit 932 as the steering angle θh1. The rate limiting unit 932 limits the amount of change in the steering angle θh1 using a preset limit value (step S190), and outputs it to the correcting unit 933 as a steering angle θh2. The correction unit 933 corrects the steering angle θh2 to obtain a target turning angle θtref (step S200), and outputs it to the turning angle control unit 920.

The steering angle control unit 920 that has input the steering angle θt and the target steering angle θtref calculates the deviation Δθt ₀ by subtracting the steering angle θt from the target steering angle θtref in the subtraction unit 927 (step S210). The deviation Δθt ₀ is input to the steering angle FB compensation unit 921, and the steering angle FB compensation unit 921 compensates for the deviation Δθt ₀ by multiplying the deviation Δθt ₀ by the compensation value (step S220), and sets the target steering angular velocity. ωtref is output to the speed control section 923. The steering angular velocity calculation unit 922 inputs the steering angle θt, calculates the steering angular velocity ωtt by differential calculation with respect to the steering angle θt (step S230), and outputs it to the speed control unit 923. The speed control unit 923 calculates the motor current command value Imcta by IP control (step S240), and outputs it to the output restriction unit 926. The output limiter 926 limits the upper and lower limits of the motor current command value Imcta using preset upper and lower limits (step S250), and outputs it as the motor current command value Imct (step S260).

The motor current command value Imct is input to the current control unit 930, and the current control unit 930 controls the drive motor 71 based on the motor current command value Imct and the current value Imd of the drive motor 71 detected by the motor current detector 940. 71 to perform current control (step S270).

Note that the order of data input, calculation, etc. in FIG. 29 can be changed as appropriate. In addition, the speed control section 923 in the steering angle control section 920 can realize PI control, P (proportional) control, PID control, PI-D control, etc. instead of IP control. Any one of the following controls may be used, and furthermore, the follow-up control in the turning angle control section 920 may be performed using a commonly used control structure. The steering angle control unit 920 can be used in a vehicle device as long as it has a control configuration in which the actual angle (here, the steering angle θt) follows the target angle (here, the target steering angle θtref). The present invention is not limited to the control configuration, and for example, a control configuration used in industrial positioning devices, industrial robots, etc. may be applied.

In the sixth embodiment, as shown in FIG. 25, one ECU 50 controls the reaction force device 60 and the drive device 70, but the ECU for the reaction force device 60 and the ECU for the drive device 70 are respectively It may be provided. In this case, the ECUs will transmit and receive data through communication. Furthermore, although the SBW system shown in FIG. 25 does not have a mechanical connection between the reaction device 60 and the drive device 70, if an abnormality occurs in the system, the column shaft 2 and the steering mechanism can be connected to each other using a clutch, etc. The present invention is also applicable to an SBW system that includes a mechanical torque transmission mechanism that is mechanically coupled to the SBW system. In such an SBW system, when the system is normal, the clutch is turned off to allow mechanical torque transmission to be released, and when the system is abnormal, the clutch is turned on to enable mechanical torque transmission.

The torsion angle control unit in the first to sixth embodiments and the assist control unit 500 in the fifth embodiment directly calculate the motor current command value Imc and the assist current command value Iac. Before calculating, the motor torque to be output (target torque) may be calculated first, and then the motor current command value and the assist current command value may be calculated. In this case, to obtain the motor current command value and the assist current command value from the motor torque, a commonly used relationship between motor current and motor torque is used.

Note that the figures used above are conceptual diagrams for qualitatively explaining the present invention, and the present invention is not limited thereto. Further, although the above-described embodiment is an example of a preferred implementation of the present invention, the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. Furthermore, the mechanism is not limited to a torsion bar as long as it has an arbitrary spring constant between the handle and the motor or reaction force motor.

1 Handle 2 Column shaft (steering shaft, handle shaft)
2A Torsion bar 3 Reduction mechanism 10 Torque sensor 12 Vehicle speed sensor 14 Rudder angle sensor 20 Motors 30, 50 Control unit (ECU)
31 Current command value calculation unit 33, 590 Current limiting unit 34 Compensation signal generation unit 38, 190, 940 Motor current detector 60 Reaction force device 61 Reaction force motor 70 Drive device 71 Drive motor 72 Gears 73, 74 Angle sensor 100 EPS steering system/vehicle system 110 Right turn/left turn determination unit 120 Target steering torque generation unit 121 Basic map unit 123 Damper gain unit 124 Hysteresis correction unit 128 Phase compensation unit 130 Conversion unit 140 Torsion angle control unit 141 Input restriction unit 142, 932 Rate limiting section 143 Torsion angle feedback (FB) compensation section 144 Torsion angular velocity calculation section 145, 926 Output limiting section 160, 260, 923 Speed control section 163, 353 Pseudo integration section 180, 930 Current control section 262 Phase lag filter section 471 Compensation Change flag setting section 500 Assist control section 910 Target turning angle generation section 920 Turning angle control section 921 Turning angle feedback (FB) compensation section 922 Turning angular velocity calculation section 931 Limiting section 933 Correction section 951 Angular velocity calculation section

Claims (6)

A vehicle steering device that includes at least a torsion bar having an arbitrary spring constant and a sensor that detects a torsion angle of the torsion bar, and that assists and controls a steering system by driving and controlling a motor based on a motor current command value. ,
a torsion angle control unit that calculates the motor current command value so that the torsion angle follows a target torsion angle obtained by converting a target steering torque calculated based on at least a steering angle and a steering state using the spring constant; Prepare,
The torsion angle control section calculates the motor current command value by performing proportional compensation and pseudo-integral compensation based on the target torsion angle and a deviation of the torsion angle, and performing differential compensation based on the torsion angle. ,
A vehicle steering device characterized in that the motor is drive-controlled based on the motor current command value. The torsion angle control section
2. The vehicle steering device according to claim 1, wherein the motor current command value is calculated by performing differential-preemptive PID control based on the target torsion angle , a deviation of the torsion angle, and the torsion angle . The torsion angle control section
further comprising a compensation change flag setting unit that sets a desired value to a compensation change flag that makes the pseudo-integral compensation variable;
The vehicle steering system according to claim 1 or 2, wherein the pseudo-integral compensation is made variable by multiplying the compensation change flag. The torsion angle control section
The vehicle steering system according to any one of claims 1 to 3, further comprising an input limiting section that limits upper and lower limits of the target torsion angle. The torsion angle control section
The vehicle steering device according to any one of claims 1 to 4, further comprising a rate limiting unit that limits the amount of change in the target torsion angle. The torsion angle control section
The vehicle steering device according to any one of claims 1 to 5, further comprising an output limiting section that limits upper and lower limits of the motor current command value.

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