JP2022179082A - Controller for vehicular steering system and steer-by-wire system having the same - Google Patents

Abstract

To provide a controller for a vehicular steering system and an SBW system having the same, capable of suppressing an increase in the power consumption of a motor and a rise in the temperature of the motor by generating an appropriate reaction force according to a steering state.SOLUTION: A controller for a vehicular steering system, having a torsion bar and a steering final end and controlling a steering mechanism, comprises: a first target steering torque generating section including an elastic item generating section in which a first torque signal to be output functions as a steering reaction force when the magnitude of a steering angle exceeds a threshold value set at a neighbor of a final end angle, for computing a first target steering torque at least on the basis of the first torque signal; a first converting section for computing a first target twist angle at least on the basis of the first target steering torque; and a first twist angle control section for computing a first current command value at least on the basis of the first target twist angle. The elastic item generating section has a characteristic that a threshold value fluctuates following a steering angle and the proportion of the fluctuation of a threshold value to the fluctuation of a steering angle under a steering return increase state becomes smaller as a steering angle speed is higher.SELECTED DRAWING: Figure 8

Description

TECHNICAL FIELD The present invention relates to a control device for a vehicle steering system such as a steer-by-wire system in which a steering mechanism and a steering mechanism are mechanically separated, and in particular, controls a steering mechanism having a steering end that is the limit of steerability. The present invention relates to a control device for a vehicle steering system and a steer-by-wire system including the same.

As one vehicle steering system, there is a steer-by-wire (SBW) system in which a steering mechanism having a steering wheel operated by a driver and a steering mechanism for steering steered wheels are mechanically separated. In the SBW system, the operation of the steering wheel is transmitted to the steering mechanism by an electric signal to steer the steered wheels, and the steering mechanism generates a steering reaction force for giving an appropriate steering feeling to the driver. The steering mechanism generates a steering reaction force with a reaction force actuator having a reaction force motor, and the steering mechanism steers the steered wheels with a steering actuator having a steering motor. The reaction force actuator and the steering wheel are mechanically connected via the column shaft, and the reaction force (torque) generated by the reaction force actuator is transmitted to the driver via the column shaft and the steering wheel.

In the SBW system, there is a case where the steering mechanism is provided with a steering end, which is the steerable limit, and an upper limit value is set for the steering angle of the steering wheel. This is intended to avoid problems caused by cables when installing various electric parts on the steering wheel and connecting them with a controller fixed to the vehicle. For example, in Japanese Patent No. 6167634 (Patent Document 1), a first plate having a groove-shaped first rolling path extending in the radial direction of the steering shaft and a groove-shaped groove spirally formed in the circumferential direction of the steering shaft A steer-by-wire has been proposed in which a second plate having a second rolling path is superimposed and provided with a rotation limiting mechanism having a ball that is sandwiched between the two rolling paths and that can roll. Since the first plate rotates together with the steering shaft and the second plate does not rotate, when the steering wheel rotates and the first plate rotates together with the steering shaft, the balls move to the second rolling path. move along. When the ball comes into contact with the end surface of the second rolling path, the movement of the ball is restricted, so the rotation of the handle is also restricted.

When the steering mechanism is provided with the steering end in this manner, a collision occurs when the steering is steered to the steering end, and a collision noise is generated, which may make the driver feel uncomfortable.

As a countermeasure against this problem, the steer-by-wire of Patent Document 1 employs a physical method. That is, in the rotation limiting mechanism of Patent Document 1, the depth of the groove near the end face is made smaller than the others to increase the frictional force of the ball, thereby reducing the steering speed of the driver and causing the ball to collide with the end face. slowing down.

When a collision countermeasure is taken at the end of steering by a physical method as in Patent Document 1, it is not easy to make adjustments to give the driver an appropriate steering feeling, and even after the adjustment, the steering feeling deteriorates due to aging and the like. may change.

As another countermeasure against collision at the end of steering, there is a method of increasing the reaction force generated by the reaction force actuator before the steering angle reaches the maximum steering angle, which is the end of steering. In the case of this method, it is easier to adjust the steering feel than with a physical method. For example, in Japanese Patent Application Laid-Open No. 2017-24624 (Patent Document 2), the steering angle is set to the steering angle threshold value in order to suppress the steering operation in which both the turning angle and the steering angle exceed the upper limit values. A first reaction force that sharply increases when the turning angle exceeds the turning angle threshold value or a second reaction force that sharply increases when the turning angle becomes equal to or greater than the turning angle threshold is set. SBW systems have been proposed that set a target steering angle based on the sum. By setting the target steering angle in this way, the SBW system of Patent Literature 2 suppresses a steering operation that would cause the steering angle to exceed the upper limit.

Japanese Patent No. 6167634 JP 2017-24624 A

However, when the reaction force is increased according to the steering angle as in the SBW system of Patent Document 2, when the steering is slow or the steering torque is small, the increased reaction force acts too strongly and the steering angle becomes the maximum steering angle. There is a possibility that the driver will mistakenly think that the steering end has been reached before . Even if there is no misunderstanding, there is a possibility that a large steering torque must be applied in order to steer to the end of the steering. Also, when the steering wheel is turned back, kickback may occur due to the increased reaction force. When the inertial force acts on the fast steering or the steering torque is large, the possibility of erroneously identifying the end of the steering and the possibility of applying a large steering torque decrease, but the possibility of kickback occurring remains the same. In addition, generating an excessive reaction force may cause an unnecessary increase in the power consumption of the motor and an increase in the temperature of the motor.

SUMMARY OF THE INVENTION The present invention has been made in view of the circumstances described above. An object of the present invention is to provide a vehicle steering system control device and an SBW system including the same.

The present invention relates to a controller for a vehicle steering system, which includes a torsion bar, has a steering end that is the limit of steerability, and controls a steering mechanism by driving and controlling a reaction force actuator. An object of the present invention is to provide an elastic term generator that outputs a first torque signal that functions as a steering reaction force when the magnitude of the steering angle exceeds a threshold value set in the vicinity of the angle corresponding to the end of the steering, a first target steering torque generator for calculating a first target steering torque based on at least the first torque signal; and a first conversion unit for calculating a first target twist angle based on at least the first target steering torque. and a first torsion angle control unit for calculating a first current command value that follows the torsion angle of the torsion bar based on at least the first target torsion angle, wherein the elastic term generation unit The threshold value fluctuates in accordance with the steering angle, and when the steering mechanism is in a further turning state, the ratio of the fluctuation of the threshold value to the fluctuation of the steering angle becomes smaller when the steering angular velocity is high. , by driving and controlling the reaction force actuator based on the first current command value.

Further, the above object of the present invention is characterized in that the characteristic of the elastic term generator is such that when the steering angular velocity is high, the ratio when the steering mechanism is in the return state is higher than that when the steering mechanism is in the additional steering state. or the elastic term generating unit determines the threshold value using a value obtained by applying a low-pass filter to the steering angle; The cut-off frequency of the low-pass filter at is set higher than that in the additional steering state, or the elastic term generation unit increases as the magnitude of the steering angle exceeds the threshold value. or the first target steering torque generating section further comprises a phase compensating section for performing phase lead compensation on the first torque signal. Alternatively, a second target for outputting a second target steering torque based on at least the second torque signal, which includes a basic map section that obtains a second torque signal corresponding to the steering angle using a basic map. A steering torque generator is further provided, and the first target steering torque is calculated from the output from the first target steering torque generator and the second target steering torque, or the steering angle is calculated using a basic map. a second target steering torque generator for outputting a second target steering torque based on at least the second torque signal; a second conversion unit that converts to a target twist angle, and by calculating the first target twist angle from the output from the first conversion unit and the second target twist angle, or using a basic map a second target steering torque generation unit including a basic map unit for obtaining a second torque signal corresponding to the steering angle and outputting a second target steering torque based on at least the second torque signal; and the second target steering. a second conversion section for converting torque into a second target torsion angle; and a second torsion angle control section for calculating a second current command value based on the first target torsion angle, wherein the first torsion angle control By calculating the first current command value from the output from the unit and the second current command value, or by the second target steering torque generating unit based on the angular velocity information using a damper gain map sensitive to vehicle speed further comprising a damper calculation section for obtaining a third torque signal from the second torque signal and calculating the second target steering torque from the second torque signal and the third torque signal. achieved more effectively.

Further, the above object of the present invention is achieved by a steer-by-wire system comprising the vehicle steering system controller and the steering mechanism controlled by the controller.

According to the vehicle steering system control device of the present invention, an elastic term is generated that outputs a torque signal that functions as a steering reaction force when the steering angle exceeds a threshold value set near the angle corresponding to the steering end. By changing the characteristics in the additional turning state of the part according to the steering angular velocity, it is possible to generate an appropriate reaction force and suppress an increase in the power consumption of the motor and an increase in the temperature of the motor.

1 is a configuration diagram showing an example of an outline of an SBW system provided with a control device according to the present invention; FIG. FIG. 4 is a structural diagram showing an example of arrangement of various sensors on a column shaft; It is a block diagram which shows the structural example (1st Embodiment) of this invention. 2 is a block diagram showing a configuration example of a target steering torque generation unit 100; FIG. FIG. 3 is a diagram showing a configuration example of a basic map unit and a characteristic example of a basic map; FIG. 5 is a diagram showing an example of characteristics of a damper gain map; 2 is a block diagram showing a configuration example of a target steering torque generation unit 200; FIG. 4 is a block diagram showing a configuration example of an elastic term generator; FIG. FIG. 5 is a diagram for explaining additional steering/return determination; 3 is a block diagram showing a configuration example of a variable gain section; FIG. FIG. 11 is a diagram for explaining threshold fluctuations in a turning-further state; FIG. FIG. 5 is a diagram for explaining threshold fluctuations in a switchback state; FIG. 11 is a diagram showing an example of characteristics of a map used in a modification of the elastic term generator; It is a block diagram which shows the structural example of a target steering angle production|generation part. FIG. 5 is a diagram showing an example of setting upper and lower limit values in a limiter; It is a flowchart which shows the operation example (1st Embodiment) of this invention. 4 is a flowchart showing an operation example of a target steering torque generation unit 100; 4 is a flowchart showing an operation example of a target steering torque generation unit 200; 4 is a flow chart showing an operation example of a target steering angle generator; FIG. 4 is a block diagram showing an example of insertion of a phase compensator; It is a block diagram which shows the structural example (2nd Embodiment) of a reaction force control system. 9 is a flow chart showing part of an operation example (second embodiment) of a reaction force control system; It is a block diagram which shows the structural example (3rd Embodiment) of a reaction force control system. It is a flow chart which shows a part of example (3rd Embodiment) of operation of a reaction force control system.

The present invention sets a threshold at which the steering angle is set near the terminal angle before the steering angle reaches the angle corresponding to the steering terminal end (hereinafter referred to as the "terminal angle"), which is the limit of steerability. The characteristic of the torque signal, which becomes the target steering torque for increasing the reaction force generated by the reaction force actuator when it exceeds the steering angular velocity, is changed according to the steering angular velocity. Specifically, in the present invention, the threshold is changed to follow the steering angle, and the ratio of the change in the threshold to the change in the steering angle in a state in which the steering wheel is further turned to increase the magnitude of the steering angle (state of increased steering). is changed according to the steering angular velocity to increase the reaction force based on the torque signal calculated. As a result, an appropriate reaction force is generated as necessary, and an increase in motor power consumption and a rise in motor temperature can be suppressed. The above function is implemented in the elastic term generator in the target steering torque generator.

BEST MODE FOR CARRYING OUT THE INVENTION Below, embodiments of the present invention will be described with reference to the drawings.

First, a configuration example of an SBW system including a control device according to the present invention will be described.

FIG. 1 is a diagram showing a configuration example of the SBW system. The SBW system includes a reaction force device 30 that constitutes a steering mechanism having a steering wheel 1 operated by a driver, a steering device 40 that constitutes a steering mechanism that turns steered wheels, and a control device 50 that controls both devices. Prepare. The SBW system does not have an intermediate shaft that is mechanically coupled with a column shaft (steering shaft, handle shaft) 2, which is provided in a general electric power steering device. Specifically, the steering angle θh output from the reaction force device 30 is transmitted as an electrical signal.

The reaction force device 30 includes a reaction force motor 31 and a speed reduction mechanism 32 that reduces the rotation speed of the reaction force motor 31. is transmitted to the driver as a reaction force (torque). The reaction force device 30 further includes a steering angle sensor 33 and an angle sensor 34 provided on the column shaft 2 . Specifically, the arrangement of the steering angle sensor 33 and the angle sensor 34 on the column shaft 2 is as shown in FIG. That is, the steering angle sensor 33 is provided above the column shaft 2 and detects the steering angle θh. A torsion bar 2A is inserted in the column shaft 2, and as an angle sensor 34, an upper angle sensor 34A is provided on the handle 1 side of the column shaft 2 with the torsion bar 2A interposed therebetween. 2, a lower angle sensor 34B is provided on the opposite side of the steering wheel 1. The upper angle sensor 34A detects the steering wheel angle _.theta.1 , and the lower angle sensor 34B detects the column angle _.theta.2 . The steering wheel angle _.theta.1 and the column angle _.theta.2 are input to the torsion angle calculator 36, and the torsion angle calculator 36 obtains the torsion bar torsion angle .DELTA..theta.

なお、磁歪式や光学式等の公知のセンサを用いて、捩れ角Δθを直接求めても良い。

Note that the torsion angle Δθ may be obtained directly using a known sensor such as a magnetostrictive sensor or an optical sensor.

The column shaft 2 is provided with a stopper 35 that physically sets the steering end, which is the steerable limit. The steering angle .theta.h when the vehicle is steered to the end of the steering is the terminal angle, which is the limit value of the magnitude of the steering angle .theta.h. As the stopper 35, for example, a rotation limiting mechanism or the like disclosed in Patent Document 1 is used. The reaction force actuator is composed of the reaction force motor 31, the reduction mechanism 32, and the like, but the reaction force motor 31 alone may be called the reaction force actuator.

The steering device 40 includes a steering motor 41, a deceleration mechanism 42 for reducing the rotational speed of the steering motor 41, and a pinion rack mechanism 44 for converting rotational motion into linear motion. The steering motor 41 is driven in accordance with the change in the steering angle θh, and the driving force thereof is applied to the pinion rack mechanism 44 via the speed reduction mechanism 42, and the steered wheels 5L, 5R are driven via the tie rods 3a, 3b. steer. An angle sensor 43 is arranged near the pinion rack mechanism 44 to detect the turning angle θt of the steerable wheels 5L and 5R. As the steering angle θt, the motor angle of the steering motor 41, the position of the rack, or the like may be used.

In order to cooperatively control the reaction force device 30 and the steering device 40, the control device 50 controls the vehicle speed Vs detected by the vehicle speed sensor 10 in addition to information such as the steering angle θh and the steering angle θt output from both devices. Based on the above, a voltage control command value Vref1 for driving and controlling the reaction force motor 31 and a voltage control command value Vref2 for driving and controlling the steering motor 41 are generated. The control device 50 is supplied with power from the battery 12 and receives an ignition key signal through the ignition key 11 . Further, the controller 50 is connected to a CAN (Controller Area Network) 20 for exchanging various types of vehicle information, and the vehicle speed Vs can also be received from the CAN 20 . Further, the control device 50 can be connected to a non-CAN 21 that exchanges communication other than the CAN 20, analog/digital signals, radio waves, and the like.

The control device 50 has a CPU (including MCU, MPU, etc.), and coordinated control of the reaction force device 30 and the steering device 40 is mainly executed by a program inside the CPU. FIG. 3 shows a configuration example (first embodiment) for performing the control. In FIG. 3, a reaction force device 30 includes a reaction force motor 31, a steering angle sensor 33, an angle sensor 34, a PWM (pulse width modulation) control unit 37, an inverter 38, and a motor current detector 39. 41 , an angle sensor 43 , a PWM control unit 47 , an inverter 48 and a motor current detector 49 , the steering device 40 is provided, and other components are realized by the control device 50 . A part or all of the constituent elements of the control device 50 may be realized by hardware. The control device 50 may be equipped with a RAM (random access memory), a ROM (read only memory), or the like to store data, programs, and the like. Also, the control device 50 may include part or all of the PWM control section 37 , the inverter 38 , the motor current detector 39 , the PWM control section 47 , the inverter 48 and the motor current detector 49 .

The control device 50 has a configuration for controlling the reaction force device 30 (hereinafter referred to as a “reaction force control system”) and a configuration for controlling the steering device 40 (hereinafter referred to as a “steering control system”). The reaction force control system 60 and the steering control system 70 cooperate to control the reaction force device 30 and the steering device 40 .

The reaction force control system 60 includes a target steering torque generation unit 100 (second target steering torque generation unit) and 200 (first target steering torque generation unit), a conversion unit 300 (first conversion unit), a torsion angle control unit 400 ( a first torsion angle control section), a current control section 500, an addition section 510, and subtraction sections 520 and 530, and performs control such that the torsion angle of the torsion bar 2A follows the target torsion angle. A target steering torque generation unit 100 generates a target steering torque TrefA based on the steering angle θh and the vehicle speed Vs. A target steering torque generation unit 200 generates a target steering torque TrefB based on the steering angle θh. Target steering torque Tref, which is the sum of TrefA and TrefB, is converted into target torsion angle Δθref by conversion unit 300 . A deviation dΔθ (=Δθref−Δθ) between the target torsion angle Δθref and the torsion angle Δθ is input to the torsion angle control unit 400, and the torsion angle control unit 400 sets a current command value such that the torsion angle Δθ becomes the target torsion angle Δθref. Imc is computed. Then, a deviation I1 (=Imc−Imr) between the current command value Imc and the current value (motor current value) Imr of the reaction force motor 41 detected by the motor current detector 39 is calculated by the subtraction unit 530. Based on this, the current control unit 500 obtains the voltage control command value Vref1. In the reaction force device 30, the reaction force motor 31 is driven and controlled via the PWM control section 37 and the inverter 38 based on the voltage control command value Vref1. The target steering torque TrefA corresponds to the second target steering torque, the target steering torque Tref to the first target steering torque, the target twist angle Δθref to the first target twist angle, and the current command value Imc to the first current command value.

FIG. 4 shows a configuration example of the target steering torque generator 100. As shown in FIG. The target steering torque generation section 100 includes a basic map section 110 , a differentiation section 120 , a damper gain section 130 , a multiplication section 140 and an addition section 150 . The steering angle θh is input to the basic map portion 110 and the differentiating portion 120, and the vehicle speed Vs is input to the basic map portion 110 and the damper gain portion .

The basic map unit 110 has a basic map, and uses the basic map to output a torque signal Tref_a (second torque signal) having the vehicle speed Vs as a parameter. Torque signal Tref_a is used to generate a basic reaction force. The basic map is adjusted by tuning. For example, as shown in FIG. 5A, the magnitude of the torque signal Tref_a increases as the steering angle θh magnitude |θh| It also increases as it increases. That is, as the steering angle θh increases and as the vehicle speed Vs increases, the reaction force increases. In FIG. 5A, sign section 111 outputs the sign (+1, -1) of steering angle θh to multiplication section 112, and the magnitude of torque signal Tref_a is calculated from a map based on the magnitude of steering angle θh. and multiplied by the sign of the steering angle θh to obtain the torque signal Tref_a. Alternatively, as shown in FIG. 5(B), the map may be configured according to the positive and negative steering angles θh. can be Further, although the basic map shown in FIG. 5 is vehicle speed sensitive, it does not have to be vehicle speed sensitive.

The differentiation unit 120 differentiates the steering angle θh to calculate a steering angular velocity ωh1 as angular velocity information, and the steering angular velocity ωh1 is input to the multiplication unit 140 . The motor angular velocity of the reaction force motor 31 may be used as the angular velocity information instead of the steering angular velocity ωh1. In this case, the differentiating section 120 becomes unnecessary.

A damper gain section 130 outputs a damper gain _DG to be multiplied by the steering angular velocity ωh1. The steering angular velocity ωh1 multiplied by the damper gain _DG in the multiplier 140 is input to the adder 150 as the torque signal Tref_b (third torque signal). The damper gain _DG is obtained according to the vehicle speed Vs using a vehicle speed sensitive damper gain map of the damper gain section 130 . The damper gain map has a characteristic of gradually increasing as the vehicle speed Vs increases, as shown in FIG. 6, for example. By multiplying the steering angular velocity ωh1 by such a damper gain _DG and compensating for the target steering torque proportional to the steering angular velocity ωh1, it is possible to give a viscous feeling as a feeling, and the steering is turned off. When the handle is released from the handle, the steering wheel does not oscillate and has convergence, improving system stability. The damper gain map may be variable according to the steering angle θh. The damper gain section 130 and the multiplication section 140 constitute a damper calculation section.

The torque signals Tref_a and Tref_b are added by the adder 150, and the addition result is output as the target steering torque TrefA.

FIG. 7 shows a configuration example of the target steering torque generator 200. As shown in FIG. Target steering torque generator 200 includes elastic term generator 210 and phase compensator 220 , and steering angle θh is input to elastic term generator 210 .

The elastic term generator 210 generates a torque signal TrefB0 (first torque signal) for increasing the reaction force after the magnitude |θh| of the steering angle θh exceeds a predetermined threshold θth set near the terminal angle. Generate. That is, when the magnitude |θh| of the steering angle θh exceeds the threshold θth, the magnitude of the torque signal TrefB0 is increased.

The elastic term generation unit 210 varies the threshold θth following the steering angle θh, and the ratio of the variation of the threshold θth to the variation of the steering angle θh in the increased steering state (hereinafter referred to as “threshold variation rate”) is Make it smaller when the angular velocity is fast. As an image, the threshold θth operates so as to escape from the steering angle θh, and for slow steering, it operates approximately the same as the steering angle θh and escapes, but for fast steering, it lags behind the steering angle θh. Move to prevent escape. This increases the reaction force only during fast steering.

The threshold change rate in the state where the steering angle is reduced by turning the steering wheel back (steering back state) is different from that in the additional steering state. As an image, the threshold .theta.th follows the steering angle .theta.h. Unlike the case of the additional steering state, the steering angle .theta. That is, in the case of fast steering, the threshold fluctuation rate in the return state is larger than that in the additional steering state. If the threshold fluctuation rate in the steering return state changes in the same manner as in the additional steering state, the threshold θth cannot catch up with the steering angle θh, the reaction force cannot be increased sufficiently. In order to solve this problem, in the return state, the threshold value θth is operated to catch up with the steering angle θh even in the case of fast steering.

In order to operate the threshold θth as described above, the elastic term generator 210 determines the threshold θth by filtering the steering angle θh with a low-pass filter (LPF), and increases the cutoff frequency of the LPF. Different values are used for the state and the revertive state. The LPF gives the threshold θth a change with a delay with respect to the steering angle θh to change the followability of the threshold θth. Further, by setting the cutoff frequency in the return state to be higher than the cutoff frequency in the additional steering state, the threshold θth catches up with the steering angle θh even for fast steering in the return state.

FIG. 8 shows a configuration example of the elastic term generator 210 . The elastic term generation unit 210 includes a differentiation unit 211, an additional steering/return determination unit 212, a filter unit 213, and a variable gain unit 214, and the steering angle θh is input to all of these components.

A differentiating section 211 differentiates the steering angle θh to calculate a steering angular velocity ωh 2 , and the steering angular velocity ωh 2 is input to an additional steering/return determination section 212 .

The additional steering/return determination unit 212 determines whether the steering mechanism is in the additional steering state or the return state (hereinafter referred to as "determination of additional steering/return"). For example, as shown in FIG. 9, the steering angle .theta.h and the steering angular velocity .omega.h2 are positive or negative to determine whether the steering angle is increased or not. The determination result is output to filter section 213 as steering state STs. The additional steering/return determination may be made using the steering torque. That is, as disclosed in Japanese Unexamined Patent Application Publication No. 2003-170856, when the sign of the steering torque and the sign of the rate of change of the steering torque are the same, and the absolute value of the rate of change of the steering torque is equal to or greater than a predetermined value, the steering state is the additional steering state. If the sign of the steering torque and the sign of the rate of change of the steering torque are different from each other and the absolute value of the rate of change of the steering torque is equal to or greater than a predetermined value, it may be determined that the steering wheel is in the return state. Alternatively, using the steering torque and the steering angular velocity ωh2, the steering torque and the steering angular velocity ωh
2 may be determined to be in the additional steering state when the signs of the two are the same, and may be determined to be in the return state when the signs are different.

The filter unit 213 has an LPF, performs filter processing with the LPF on the steering angle θh, and outputs the result as a threshold value θth. As the LPF, an LPF represented by an arbitrary transfer function such as a first-order transfer function or a second-order transfer function may be used. The cutoff frequency of the LPF is set to different values in the additional steering state and the return state, and the cutoff frequency in the return state is made higher than the cutoff frequency in the additional steering state. For example, as an empirical value, the cutoff frequency in the additional steering state is set to 1 to 5 Hz, and the cutoff frequency in the return state is set to 5 to 10 Hz. Whether the steering is in the additional steering state or the steering back state is determined from the steering state STs. Note that the threshold θth is used as a threshold for the magnitude of the steering angle θh in the variable gain section 214, so if the value after filtering is a negative number, a positive value is output as the threshold θth.

Variable gain section 214 creates a characteristic map (hereinafter referred to as “variable gain map”) that outputs torque signal TrefB0 after the magnitude of steering angle θh exceeds threshold θth output from filter section 213 . have. For example, as shown in FIG. 10, the variable gain map has the characteristic that the magnitude of the torque signal TrefB0 increases linearly from zero as the magnitude of the steering angle θh increases after exceeding the threshold value θth. By giving a sudden change to the reaction force based on such an increasing characteristic, the collision at the end of the steering can be suppressed. In FIG. 10, .theta.lim is the end angle, which is the mechanical limit value of the steering angle, or the measurement limit value of the steering angle detection, and the variable gain map is defined in the area below .theta.lim. Thus, according to the variable gain section 214, it is possible to apply the target steering torque that becomes a large reaction force when the magnitude of the steering angle θh exceeds the threshold value θth. Note that the variable gain map may be a curvilinear characteristic as long as it monotonically increases instead of the linear characteristic shown in FIG. Also, instead of maps, the characteristics may be defined by mathematical formulas such as linear functions. Further, in FIG. 10, the sign section 215 outputs the sign (+1, -1) of the steering angle θh to the multiplication section 216, and the magnitude of the torque signal TrefB0 is obtained from the magnitude of the steering angle θh using a map. is multiplied by the sign of the steering angle θh to obtain the torque signal TrefB0. In this case, the mode of change may be changed depending on whether the steering angle .theta.h is positive or negative.

Fluctuations in the threshold θth in the elastic term generator 210 having such a configuration will be described.

First, the variation of the threshold value θth in the additional steering state will be described.

When the steering angular velocity is slow, the frequency component of the variation in the steering angle θh passes through the LPF of the filter unit 213 without being blocked by the filter unit 213. Therefore, the threshold θth output from the filter unit 213 has substantially the same magnitude as the steering angle θh. Become. Therefore, as shown in FIG. 11A, the threshold θth moves following the steering angle θh, so the torque signal TrefB0 becomes a value close to zero, and no reaction force is generated based on the torque signal TrefB0. On the other hand, when the steering angular velocity increases, some of the frequency components of the variation of the steering angle θh are cut off, so that the variation of the threshold θth is suppressed more than the variation of the steering angle θh. . Therefore, as shown in FIG. 11B, the threshold .theta.th follows the steering angle .theta.h slowly, the value of the torque signal TrefB0 increases, and a reaction force is generated based thereon. That is, when the steering angular velocity is slow, the threshold θth moves to follow the steering angle θh, suppressing an increase in the reaction force. Since the possibility that the steering torque must be applied becomes low and the reaction force increases when the steering angular velocity is high, the collision at the end of the steering can be suppressed. If the steering is held in a state where a reaction force based on the torque signal TrefB0 is generated, the threshold θth approaches the steering angle θh, so the torque signal TrefB0 becomes smaller and the reaction force based on it becomes weaker. When the steering wheel is turned back, the steering angular velocity becomes zero and the operation returns to the starting state shown in FIG. 11(A), so the reaction force based on the torque signal TrefB0 also starts from zero. Therefore, the occurrence of kickback is suppressed.

Next, variation of the threshold value θth in the switchback state will be described. In order to explain the effect of setting the cut-off frequency to different values in the return state and the additional turn-on state, a comparison with the case where the cut-off frequency is set to the same value will be described.

If the same cutoff frequency is set in the return state and the increased steering state, the threshold value θth in the return state operates in the same manner as in the increased steering state. That is, when the steering angular speed is slow, the threshold θth is substantially the same as the steering angle θh, and the threshold θth follows the steering angle θh. As shown in FIG. 12A, the threshold θth follows the steering angle θh slowly, and the gap between the steering angle θh and the threshold θth (for example, FIG. 12A) WG) occurs. In this state, when shifting to the additional steering state by fast steering, the torque signal TrefB0 becomes substantially zero until the gap disappears, and the reaction force based on the torque signal TrefB0 does not occur, so the effect of suppressing the collision at the end of the steering. is insufficient. On the other hand, when the cutoff frequency in the steering-back state is increased, the threshold θth in the steering-back state hardly cuts off the frequency component of the fluctuation of the steering angle θh even when the steering angular velocity is high. , moves following the steering angle θh. Therefore, in this state, even if the steering is shifted to the additional steering state by fast steering, the threshold value θth can shift to the operation shown in FIG. 11(B). can be suppressed.

By using a value obtained by subtracting the threshold θth from the magnitude (absolute value) of the steering angle θh instead of varying the threshold θth in the elastic term generator 210, the threshold θth substantially follows the steering angle θh. You can do it. That is, the difference dθ (=|θh|-θth) between the magnitude |θh| of the steering angle θh and the threshold value θth is obtained. A map defining the magnitude may be used to determine the torque signal TrefB0. The map shown in FIG. 13 has characteristics obtained by moving the variable gain map so that the threshold value θth becomes the origin.

Note that the elastic term generation unit 210 uses the output from the filter unit 213 as the threshold θth, but the threshold θth may be obtained by adding a predetermined value to the output from the filter unit 213 in order to provide a margin for the threshold θth. A value obtained by adding a margin to the steering angle θh may be processed by the filter unit 213, and the output from the filter unit 213 may be used as the threshold value θth. Further, the tracking of the threshold value θth to the steering angle θh may be started when the steering angle θh exceeds a predetermined angle. In that case, when the steering angle θh is within a predetermined angle, the threshold θth may be fixed at a predetermined angle. As the predetermined angle, for example, an angle 10 degrees before the end angle is set.

Phase compensation section 220 performs phase lead compensation on torque signal TrefB0 to calculate target steering torque TrefB. If the elastic term generating section 210 suppresses the steering until the end of the steering operation, there is a possibility that a rebound event may occur. Try to reduce. The phase compensation section 220 has a first-order phase compensation filter represented by Equation 2 below, and sets the phase lead by setting the cutoff frequency of the numerator to a value smaller than the cutoff frequency of the denominator.

ここで、Ｔｎ＝１／（２π・ｆｎ）、Ｔｄ＝１／（２π・ｆｄ）で、ｆｎ及びｆｄは遮断周波数であり、ｆｎ＜ｆｄとなっている。位相補償部２２０は、入力したトルク信号ＴｒｅｆＢ０に対して、上記数２で表される位相補償フィルタによる位相進み補償を行い、目標操舵トルクＴｒｅｆＢを算出する。操舵角θｈの大きさが閾値θｔｈ以下の場合、図１０に示されるようにトルク信号ＴｒｅｆＢ０はゼロであるから、位相補償部２２０から出力される目標操舵トルクＴｒｅｆＢもゼロとなり、位相進み補償は機能しないことになる。このように、弾性項生成部２１０と位相補償部２２０を組み合わせることにより、操舵終端での衝突抑制と同時に跳ね返り低減を実現することができる。位相補償フィルタは１次ではなく、２次以上でも良く、位相進み補償を実現するのであれば、ＰＤ（比例微分）制御等で位相進み補償を行っても良い。位相補償フィルタの特性を車速及び／又は舵角速度に応じて変更しても良い。例えば、車速又は舵角速度が速いときには応答性が速くなるように、Ｔｎを大きくするか、Ｔｄを小さくする。これにより、より適切な跳ね返り低減を実現することができる。なお、跳ね返り低減を他の手段で実現する場合等では、位相補償部２２０はなくても良い。

Here, Tn=1/(2π·fn), Td=1/(2π·fd), fn and fd are cutoff frequencies, and fn<fd. Phase compensator 220 performs phase lead compensation on the input torque signal TrefB0 using the phase compensating filter represented by Equation 2 above to calculate target steering torque TrefB. When the magnitude of the steering angle θh is equal to or less than the threshold θth, the torque signal TrefB0 is zero as shown in FIG. I will not. In this manner, by combining the elastic term generator 210 and the phase compensator 220, it is possible to suppress the collision at the end of the steering and reduce the rebound. The phase compensation filter may be of a second or higher order instead of a first order, and if phase lead compensation is to be realized, phase lead compensation may be performed by PD (proportional differential) control or the like. The characteristics of the phase compensation filter may be changed according to vehicle speed and/or steering angular velocity. For example, when the vehicle speed or the steering angular velocity is high, Tn is increased or Td is decreased so as to increase the responsiveness. As a result, more appropriate bounce reduction can be achieved. It should be noted that the phase compensator 220 may be omitted if the rebound reduction is achieved by other means.

Returning to FIG. 3, the target steering torques TrefA and TrefB respectively output from the target steering torque generators 100 and 200 are added by the adder 510, and the addition result is output as the target steering torque Tref.

The conversion unit 300 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 the target twist angle Δθref.

In the subtraction unit 520, the target torsion angle Δθref is added, the torsion angle Δθ of the torsion bar 2A is subtracted, and the subtraction result dΔθ is input to the torsion angle control unit 400.

The torsion angle control unit 400 multiplies the deviation dΔθ by a compensation value C _FB (transfer function) and outputs a current command value Imc such that the torsion angle Δθ follows the target torsion angle Δθref. The compensation value _CFB may be a simple gain or a generally used compensation value such as a compensation value for PI (proportional-integral) control or PID (proportional-integral-derivative) control.

The current command value Imc is added to the subtraction unit 530, and the subtraction unit 530 calculates the deviation I1 from the motor current value Imr being fed back. A current control unit 500 inputs the deviation I1, performs current control by PI control or the like, and outputs a current-controlled voltage control command value Vref1.

The voltage control command value Vref1 is sent to the reaction force device 30, input to the PWM control unit 37, and the duty is calculated. be done. A motor current value Imr of the reaction force motor 31 is detected by the motor current detector 39 and fed back to the subtractor 530 of the reaction force control system 60 .

The steering angular velocity ωh1 calculated by the differentiating section 120 of the target steering torque generating section 100 and the steering angular velocity ωh2 calculated by the differentiating section 211 of the elastic term generating section 210 are obtained by differential calculation with respect to the steering angle θh. However, in order to reduce the influence of high-frequency noise, LPF processing is performed appropriately. Also, a high-pass filter (HPF) and a gain may be used to perform differential calculation and LPF processing. Further, the steering angular velocities ωh1 and ωh2 are not calculated from the steering angle θh, but are calculated by performing differentiation 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. can be Differential units 120 and 211 may be combined into one and shared.

The steering control system 70 includes a target steering angle generator 600, a steering angle controller 700, a current controller 800, and subtractors 810 and 820. control. A target steering angle θtref is generated based on the steering angle θh in the target steering angle generation unit 600, and the deviation dθt (=θtref−θt) between the target steering angle θtref and the steering angle θt is obtained by the steering angle control unit 700. , and a steering angle control unit 700 calculates a current command value Imct such that the steering angle θt becomes the target steering angle θtref. Then, a deviation I2 (=Imct-Imd) between the current command value Imct and the current value (motor current value) Imd of the steering motor 41 detected by the motor current detector 49 is calculated by the subtractor 820. Based on this, voltage control command value Vref2 is obtained in current control unit 800 . In the steering device 40, the driving of the steering motor 41 is controlled via the PWM control section 47 and the inverter 48 based on the voltage control command value Vref2.

FIG. 14 shows a configuration example of the target turning angle generator 600. As shown in FIG. The target steering angle generator 600 includes a limiter 610 , a rate limiter 620 and a corrector 630 .

Limiting unit 610 limits the upper and lower limits of steering angle θh and outputs steering angle θh1. By limiting the upper and lower limits of the steering angle .theta.h, output of an abnormal value is suppressed when the steering angle .theta.h becomes an abnormal value due to data corruption in the RAM due to a hardware error or the like, a communication error, or the like. As shown in FIG. 15, an upper limit value and a lower limit value for the steering angle are set in advance. , the steering angle θh is output as the steering angle θh1. Note that the limiting unit 610 can be omitted when the steering angle does not become an abnormal value or when suppressing the output of an abnormal value by other means.

Rate limiter 620 controls the amount of change in steering angle θh1 in order to prevent a sudden change in the steering angle when the steering is performed very abruptly or when the steering angle becomes an abnormal value as described above. A limit value is set for , and the steering angle θh2 is output. For example, if the amount of change is the difference from the steering angle θh1 one sample before, and the absolute value of the amount of change is greater than a predetermined value (limit value), the steering angle The steering angle .theta.h2 is output by adding or subtracting .theta.h1. If the steering angle .theta.h2 is equal to or less than the limit value, the steering angle .theta.h1 is directly output as the steering angle .theta.h2. By limiting the amount of change in the steering angle θh1, sudden changes in the target steering angle are prevented and unstable behavior of the vehicle is suppressed. Instead of setting a limit value for the absolute value of the amount of change, an upper limit value and a lower limit value may be set for the amount of change to limit the amount of change. You may make it restrict|limit with respect to a rate. Also, the rate limiter 620 can be omitted if the steering angle does not change suddenly or if the sudden change is avoided by other means.

Correction unit 630 corrects steering angle θh2 and outputs target steering angle θtref. For example, using a map such as the basic map section 110 in the target steering torque generation section 100 that defines the characteristic of the target steering angle θtref with respect to the magnitude |θh2| of the steering angle θh2, the target steering angle Find the angle θtref. Alternatively, the target steering angle θtref may be obtained simply by multiplying the steering angle θh2 by a predetermined gain.

The subtraction unit 810 receives the target turning angle θtref for addition, subtracts the turning angle θt, and inputs the difference dθt, which is the subtraction result, to the turning angle control unit 700 .

Similarly to the torsion angle control unit 400, the turning angle control unit 700 multiplies the deviation dθt by a compensation value Ct _FB (transfer function), and determines the current so that the turning angle θt follows the target turning angle θtref. Output the command value Imct.

Subtractor 820, current controller 800, PWM controller 47, inverter 48, and motor current detector 49 are similar to subtractor 530, current controller 500, PWM controller 37, inverter 38, and motor current detector 39, respectively. Do the same with configuration.

In such a configuration, an operation example of this embodiment will be described with reference to the flow charts of FIGS. 16 to 19. FIG.

When the operation starts, the steering angle θh, vehicle speed Vs, torsion angle Δθ, and turning angle θt are detected or calculated (step S10). Furthermore, the vehicle speed Vs is input to the target steering torque generator 100, the torsion angle .DELTA..theta.

The target steering torque generator 100, which receives the steering angle θh and the vehicle speed Vs, generates a target steering torque TrefA (step S20). An example of the operation of the target steering torque generator 100 will be described with reference to the flowchart of FIG.

The steering angle θh inputted to the target steering torque generating section 100 is inputted to the basic map section 110 and the differentiating section 120, and the vehicle speed Vs is inputted to the basic map section 110 and the damper gain section 130 (step S21).

The basic map unit 110 uses the basic map shown in FIG. 5A or 5B to generate a torque signal Tref_a corresponding to the steering angle θh and the vehicle speed Vs, and outputs the torque signal Tref_a to the addition unit 150 (step S22). ).

The differentiating section 120 differentiates the steering angle θh to output the steering angular velocity ωh1 (step S23), and the damper gain section 130 outputs the damper gain _DG according to the vehicle speed Vs using the damper gain map shown in FIG. 6 (step S24), the multiplier 140 multiplies the steering angular velocity ωh1 and the damper gain _DG to calculate the torque signal Tref_b, and outputs it to the adder 150 (step S25). Then, the addition unit 150 adds the torque signals Tref_a and Tref_b to calculate the target steering torque TrefA (step S26).

The target steering torque generator 200 that receives the steering angle θh generates a target steering torque TrefB (step S30). An example of the operation of the target steering torque generator 200 will be described with reference to the flowchart of FIG.

The steering angle θh inputted to the target steering torque generating section 200 is inputted to the differentiating section 211, the steering/return determining section 212, the filtering section 213 and the variable gain section 214 in the elastic term generating section 210 (step S31). .

The differentiating section 211 differentiates the steering angle θh to calculate a steering angular velocity ωh2, and outputs the calculated steering angular velocity ωh2 to the additional steering/reverse steering determination section 212 (step S32).

Based on the steering angle θh and the steering angular velocity ωh, the additional steering/reverse steering determination unit 212 performs additional steering/reverse steering determination according to the characteristics shown in FIG. step S33).

The filter unit 213 determines whether the steering mechanism is in the additional steering state or the steering back state from the steering state STs (step S34). LPF processing is performed (step S 35 ), and the threshold θth is output to the variable gain section 214 .

Variable gain section 214 sets the input threshold value θth in the variable gain map shown in FIG. (step S37).

Phase compensator 220 performs phase advance compensation on torque signal TrefB0 to calculate target steering torque TrefB and outputs it to adder 510 (step S38).

Target steering torques TrefA and TrefB are added in addition section 510, and target steering torque Tref is output to conversion section 300 (step S40).

Conversion unit 300 converts target steering torque Tref into target twist angle Δθref (step S 50 ), and target twist angle Δθref is added to subtraction unit 520 .

The torsion angle Δθ is subtracted from the subtractor 520, and the deviation dΔθ is calculated by subtracting the torsion angle Δθ from the target torsion angle Δθref (step S60). The deviation dΔθ is input to the torsion angle control section 400, and the torsion angle control section 400 obtains the current command value Imc by multiplying the deviation dΔθ by the compensation value _CFB (step S70).

The current command value Imc is added to the subtractor 530, and the deviation I1 from the motor current value Imr detected by the motor current detector 39 is calculated by the subtractor 530 (step S80). The deviation I1 is input to the current control unit 500, and the current control unit 500 calculates the voltage control command value Vref1 by current control (step S90). After that, based on the voltage control command value Vref1, the reaction force motor 31 is driven and controlled via the PWM control section 37 and the inverter 38 (step S100).

On the other hand, the target turning angle generator 600, which receives the steering angle θh, generates a target turning angle θtref (step S110). An example of the operation of the target steering angle generator 600 will be described with reference to the flowchart of FIG.

The steering angle θh input to the target steering angle generation section 600 is input to the limit section 610 . Limiting unit 610 limits the upper and lower limits of steering angle θh using preset upper and lower limits (step S111), and outputs the result to rate limiting unit 620 as steering angle θh1. Rate limiter 620 limits the amount of change in steering angle θh1 by a preset limit value (step S112), and outputs the result to correction unit 630 as steering angle θh2. The correction unit 630 corrects the steering angle θh2 to obtain the target turning angle θtref (step S113). Target steering angle θtref is added to subtraction section 810 .

The steering angle θt is subtracted from the subtraction unit 810, and the deviation dθt is calculated by subtracting the steering angle θt from the target steering angle θtref (step S120). The deviation dθt is input to the turning angle control section 700, and the turning angle control section 700 multiplies the deviation dθt by the compensation value Ct _FB to obtain the current command value Imct (step S130).

The current command value Imct is added to the subtractor 820, and the deviation I2 from the motor current value Imd detected by the motor current detector 49 is calculated by the subtractor 820 (step S140). Deviation I2 is input to current control section 800, and current control section 800 calculates voltage control command value Vref2 by current control (step S150). After that, based on the voltage control command value Vref2, the driving of the steering motor 41 is controlled via the PWM control section 47 and the inverter 48 (step S160).

Note that the order of data input and calculation in FIGS. 16 to 19 can be changed as appropriate.

In the above-described embodiment, the target steering torque generation unit 100 includes a damper calculation unit (damper gain unit 130, multiplication unit 140). In some cases, the damper calculation unit may be omitted. In this case, the differentiating section 120 and the adding section 150 can also be eliminated. In order to add a hysteresis characteristic to the reaction force generated based on the target steering torque TrefA, that is, to generate a different reaction force between the additional steering and the return steering of the steering wheel, a torque signal having a hysteresis characteristic is set as a target. It may be added to the steering torque TrefA. Furthermore, a phase compensator 160 that performs phase compensation may be inserted before or after the basic map unit 110 . That is, the configuration of the region R surrounded by the dashed line in FIG. 4 may be changed to the configuration shown in FIG. 20(A) or (B). In the phase compensation unit 160, phase lead compensation is set as phase compensation. For example, when the phase lead compensation is performed by a first-order filter with a numerator cutoff frequency of 1.0 Hz and a denominator cutoff frequency of 1.3 Hz, the phase lead compensation is clear. feel can be realized. The target steering torque generating section 100 is not limited to the above configuration as long as it is based on the steering angle.

Further, when the function of the reaction force control system 60 is specialized to generate a reaction force based on the target steering torque TrefB, the target steering torque generation section 100 may be omitted. In this case, addition section 510 can also be omitted, and target steering torque TrefB output from target steering torque generation section 200 is input to conversion section 300 .

The elastic term generation unit 210 described above sets the cutoff frequency of the LPF of the filter unit 213 to different values in the increased steering state and the reversal state. The steering angle θh may be used as the threshold θth without filtering. By not performing filter processing in the return state, the threshold θth can catch up with the steering angle θh not only for slow steering but also for fast steering.

Another embodiment of the present invention will be described. In addition, in each subsequent embodiment, the same code|symbol is attached|subjected to the same structure as other embodiment of existing appearance, and a part or all of the description is abbreviate|omitted.

In the first embodiment, the target steering torque TrefB for increasing the reaction force is added to the target steering torque TrefA. It is possible to perform addition of the underlying elements of .

In the configuration example (second embodiment) of the reaction force control system shown in FIG. 21, the addition is performed after the calculation of the target torsion angle. In the reaction force control system 60A of the second embodiment, compared with the reaction force control system 60 of the first embodiment shown in FIG. The adding section 510 arranged after the sections 100 and 200 is eliminated, and instead, an adding section 511 is arranged after the transforming sections 300 and 310 .

Conversion unit 310, like conversion unit 300, has a characteristic of −1/Kt obtained by reversing the sign of the reciprocal of the spring constant Kt of torsion bar 2A. Torque TrefA is converted into target twist angle ΔθrefA. The target twist angle ΔθrefA is input to the adder 511 . Conversion unit 300 converts target steering torque TrefB output from target steering torque generation unit 200 into target twist angle ΔθrefB, and target twist angle ΔθrefB is input to addition unit 511 . Then, the addition result of the target twist angles ΔθrefA and ΔθrefB becomes the target twist angle Δθref. In this embodiment, the target steering torque TrefB corresponds to the first target steering torque, and the target twist angle ΔθrefA corresponds to the second target twist angle.

Compared with the operation of the first embodiment, the operation of the second embodiment is the operation from after generation of the target steering torques TrefA and TrefB to before calculation of the deviation dΔθ in the reaction force control system (steps S40 to S50 in FIG. 16). ) are different. Different operations will be described with reference to the flow chart of FIG.

After step S30, conversion unit 310 converts target steering torque TrefA into target twist angle ΔθrefA (step S41), and conversion unit 300 converts target steering torque TrefB into target twist angle ΔθrefB (step S42). Then, the adder 511 adds the target twist angles ΔθrefA and ΔθrefB and outputs the target twist angle Δθref (step S43). The target twist angle Δθref is added to the subtractor 520, and the process continues to step S60.

In the configuration example (third embodiment) of the reaction force control system shown in FIG. 23, the addition is performed after the current command value is calculated. Compared to the reaction force control system 60A of the second embodiment shown in FIG. 21, the reaction force control system 60B of the third embodiment further includes a twist angle control section 410 (second twist angle control section). , the addition section is moved to the stage after the twist angle control sections 400 and 410 .

Similar to torsion angle control unit 400, torsion angle control unit 410 multiplies target torsion angle ΔθrefB by compensation value C _FB (transfer function) and outputs current command value ImcB. Current command value ImcB is input to adder 512 . Subtraction unit 520 subtracts torsion angle Δθ of torsion bar 2A from target torsion angle ΔθrefA output from conversion unit 310 , and deviation dΔθA, which is the subtraction result, is input to torsion angle control unit 400 . A torsion angle control unit 400 multiplies the deviation dΔθA by a compensation value C _FB (transfer function) and outputs a current command value ImcA. Current command value ImcA is input to adder 512 . The addition result of the current command values ImcA and ImcB becomes the current command value Imc. Note that in the present embodiment, the target twist angle ΔθrefB corresponds to the first target twist angle, and the current command value ImcB corresponds to the second current command value.

Compared with the operation of the second embodiment, the operation of the third embodiment is the operation from after the calculation of the target torsion angles ΔθrefA and ΔθrefB to before the calculation of the deviation I1 in the reaction force control system (the steps in FIGS. 16 and 22). S43 to S70) are different. Different operations will be described with reference to the flow chart of FIG.

After step S42, the subtraction unit 520 calculates the deviation dΔθA by subtracting the torsion angle Δθ from the target torsion angle ΔθrefA (step S51). The deviation dΔθA is input to the torsion angle control unit 400, and the torsion angle control unit 400 multiplies the deviation dΔθA by the compensation value _CFB to obtain the current command value ImcA (step S52). On the other hand, the torsion angle control unit 410 obtains the current command value ImcB by multiplying the target torsion angle ΔθrefB by the compensation value _CFB (step S53). Adder 512 then adds current command values ImcA and ImcB and outputs current command value Imc (step S54). Current command value Imc is added to subtraction unit 530, and the process continues to step S80.

In the above-described embodiments (first to third embodiments), one control device has a reaction force control system and a steering control system. may be provided respectively. In this case, the control devices transmit and receive data through communication. Further, the SBW system shown in FIG. 1 does not have a mechanical connection between the reaction force device 30 and the steering device 40, but when an abnormality occurs in the system, the column shaft 2 and the steering mechanism are clutched. The present invention can also be applied to an SBW system provided with a mechanical torque transmission mechanism that is mechanically coupled by e.g. In such an SBW system, when the system is normal, the clutch is turned off to disengage mechanical torque transmission, and when the system is abnormal, the clutch is turned on to enable mechanical torque transmission. Furthermore, although the reaction force device 30 has a torsion bar, any mechanism having an arbitrary spring constant between the handle 1 and the reaction force motor 31 is not limited to the torsion bar.

The torsion angle control unit in the above-described embodiment directly calculates the current command value. A value may be calculated. In this case, a commonly used relationship between motor current and motor torque is used to obtain the current command value from the motor torque.

The diagrams used above are conceptual diagrams for qualitatively explaining the present invention, and the present invention is not limited to these. Moreover, although the above-described embodiment is a preferred example of the present invention, it is not limited to this, and various modifications can be made without departing from the gist of the present invention.

A main object of the present invention is to provide means for realizing a target steering torque for suppressing a collision at the end of steering. It does not have to be limited to departments.

1 steering wheel 2 column axis (steering shaft, steering wheel axis)
2A torsion bar 10 vehicle speed sensor 30 reaction force device 31 reaction force motors 32, 42 reduction mechanism 33 steering angle sensors 34, 43 angle sensor 35 stopper 36 torsion angle calculation units 37, 47 PWM control units 38, 48 inverters 39, 49 motor Current detector 40 Steering device 41 Steering motor 50 Control device 60, 60A, 60B Reaction force control system 70 Steering control system 100, 200 Target steering torque generation unit 110 Basic map units 120, 211 Differentiation unit 130 Damper gain unit 160 , 220 phase compensator 210 elastic term generator 212 steering/return determination unit 213 filter unit 214 variable gain units 300 and 310 converters 400 and 410 twist angle controllers 500 and 800 current controller 600 target steering angle generator 610 restriction unit 620 rate restriction unit 630 correction unit 700 steering angle control unit

Claims (11)

A control device for a vehicle steering system that includes a torsion bar, has a steering end that is the limit of steerability, and controls a steering mechanism by driving and controlling a reaction force actuator,
an elastic term generation unit that outputs a first torque signal that functions as a steering reaction force when the magnitude of the steering angle exceeds a threshold value that is set in the vicinity of the angle corresponding to the end of the steering; a first target steering torque generator for calculating a first target steering torque based on the 1 torque signal;
a first converter for calculating a first target twist angle based on at least the first target steering torque;
a first torsion angle control unit for calculating a first current command value that follows the torsion angle of the torsion bar based on at least the first target torsion angle;
When the elastic term generator changes the threshold value following the steering angle, and the steering mechanism is in a further steering state, the ratio of the change in the threshold value to the change in the steering angle is high when the steering angular velocity is high. has the characteristic of becoming smaller to
A control device for a steering system for a vehicle, wherein drive control is performed on the reaction force actuator based on the first current command value. The characteristics of the elastic term generator are
2. The controller for a vehicle steering system according to claim 1, further comprising a characteristic in which, when the steering angular velocity is high, the ratio in the steering mechanism in the return state is greater than in the steering mechanism in the additional steering state. The elastic term generator,
3. A controller for a vehicle steering system according to claim 2, wherein the threshold value is determined using a value obtained by applying a low-pass filter to the steering angle. 4. A controller for a vehicle steering system according to claim 3, wherein a cut-off frequency of said low-pass filter in said return state is set higher than in said additional steering state. The elastic term generator,
5. The vehicle steering system control according to any one of claims 1 to 4, further comprising a characteristic that the magnitude of the first torque signal increases as the magnitude of the steering angle increases after exceeding the threshold value. Device. The first target steering torque generation unit,
6. The control device for a vehicle steering system according to claim 1, further comprising a phase compensator that performs phase lead compensation on the first torque signal. A second target steering torque generator, comprising a basic map section for obtaining a second torque signal corresponding to the steering angle using a basic map, and outputting a second target steering torque based on at least the second torque signal. prepared,
7. A control device for a vehicle steering system according to claim 1, wherein said first target steering torque is calculated from an output from said first target steering torque generating section and said second target steering torque. a second target steering torque generation unit including a basic map unit that obtains a second torque signal corresponding to the steering angle using a basic map, and that outputs a second target steering torque based on at least the second torque signal;
a second conversion unit that converts the second target steering torque into a second target torsion angle;
7. The controller for a vehicle steering system according to claim 1, wherein the first target torsion angle is calculated from the output from the first conversion unit and the second target torsion angle. a second target steering torque generation unit including a basic map unit that obtains a second torque signal corresponding to the steering angle using a basic map, and that outputs a second target steering torque based on at least the second torque signal;
a second conversion unit that converts the second target steering torque into a second target twist angle;
a second torsion angle control unit that calculates a second current command value based on the first target torsion angle;
7. The controller for a vehicle steering system according to claim 1, wherein the first current command value is calculated from the output from the first torsion angle control section and the second current command value. The second target steering torque generating section,
further comprising a damper calculation unit that obtains a third torque signal based on angular velocity information using a damper gain map sensitive to vehicle speed;
10. A controller for a vehicle steering system according to claim 7, wherein said second target steering torque is calculated from said second torque signal and said third torque signal. a control device for a vehicle steering system according to any one of claims 1 to 10;
and the steering mechanism controlled by the controller.

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