JP2022150399A - Controller of vehicle steering system, and steer by wire system with the same - Google Patents

Abstract

To provide an SBW system capable of suppressing an increase in power consumption, heat generation, or the like in a reaction actuator in a state of having steered to a steering end.SOLUTION: A controller of a vehicle steering system has an end-hitting determination unit for determining whether a steering state is an end-hitting ON state being a state of having steered to a steering end or an end-hitting OFF state being a state of having not steered to the steering end, using steering-related information detected in a steering mechanism. The end-hitting determination unit determines the steering state using a first threshold value for determining whether the steering state has turned to the end-hitting ON state and a second threshold value for determining whether the steering state has turned to the end-hitting OFF state, being set with respect for the steering-related information. When the second threshold value is set in a range of values of the steering-related information in which it is not determined that the steering state has turned to the end-hitting ON state by a determination using the first threshold value, and the steering state is the end-hitting ON state, the end-hitting determination unit reduces control information being the basis for adjusting current, in order to reduce a current fed to a reaction actuator.SELECTED DRAWING: Figure 3

Description

TECHNICAL FIELD The present invention relates to a control device for a steering system for a vehicle, such as a steer-by-wire (SBW) system, in which the steering mechanism and the steering mechanism are mechanically separated, and more particularly to a steering system having a steering end that is the limit of steerability. The present invention relates to a vehicle steering system control device for controlling a mechanism and an SBW 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 Application Laid-Open No. 2016-30521 (Patent Document 1), a first groove having a semicircular cross-sectional shape recessed in the axial direction of the steering shaft and formed in a straight shape in the radial direction of the steering shaft is provided. A first plate and a second plate having a second groove that has a semicircular cross section recessed in the axial direction of the steering shaft and is formed in a helical shape in plan view are superimposed, and the second plate is sandwiched between the two grooves. A vehicle steering system has been proposed that includes a rotation limiting mechanism having a movable guide ball. An inner regulating member and an outer regulating member are arranged on both sides of the guide ball along the first groove. Since the first plate rotates with the steering shaft and the second plate does not rotate, when the steering component rotates and the first plate rotates with the steering shaft, the guide ball moves into the second groove. and along the first groove in the radial direction of the steering shaft. When the guide ball comes into contact with the end of the inner diameter side restricting member or the outer diameter side restricting member, the movement of the guide ball is restricted, and the rotation of the steering component is also restricted.

Further, as described above, the steering mechanism in the SBW system generates steering reaction force, and the steering reaction force is generated by supplying current to the reaction force actuator. For example, in Japanese Patent No. 5867612 (Patent Document 2), the steering reaction force is generated according to the steering state such as the steering angle of the steered wheels.

JP 2016-30521 A Japanese Patent No. 5867612

However, in the case of the SBW system in which the steering mechanism is provided with the steering end, the operation of the steering wheel is restrained by the steering end when the vehicle is steered to the steering end. In other words, since the reaction force received from the steering end acts as a reaction force on the steering wheel, the steering reaction force by the reaction force actuator is not particularly necessary. That is, if the reaction force actuator continues to generate a reaction force even after reaching the end of the steering, an unnecessary load is applied to the reaction force actuator, power consumption increases, and problems such as heat generation may occur. be.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle steering system capable of suppressing an increase in power consumption, heat generation, etc., in a reaction force actuator in a state in which steering is performed to the end of steering. and a SBW system equipped with the same.

The present invention relates to a control device for a vehicle steering system that has a steering end that is the steerable limit, drives and controls a reaction force actuator by adjusting a supplied current, and controls a steering mechanism. The above-mentioned object of (1) uses the steering-related information detected in the steering mechanism to determine whether the steering state is an end contact ON state, which is a state in which the steering is performed to the end of the steering, or a state in which the steering is not performed to the end of the steering. An end reliance determining unit that determines whether the end reliance is OFF state is provided, and the end reliance determination unit determines whether the steering state has become the end reliance ON state, which is set for the steering related information. The steering state is determined using the first threshold of and the second threshold for determining whether the steering state has become the end rest OFF state, and the second threshold is the steering in the determination by the first threshold When the state is set to the range of the value of the steering-related information in which it is not determined that the state is the end contact ON state, and the steering state is the end contact ON state, the current is adjusted in order to decrease the current. This is achieved by reducing the control information such that

Further, the above-mentioned object of the present invention is to increase the control information in order to restore the reduced current when the steering state is the end contact OFF state, or the end contact determination The unit has a gain that decreases with time when the steering state is the end contact ON state, and the control information is reduced by multiplying the gain, or the end contact determination unit and a gain that decreases with time when the steering state is the end contact ON state and increases with time when the steering state is the end contact OFF state, and the control is performed by multiplying the gain. Alternatively, the end contact determination unit uses the steering angle as the steering-related information and satisfies the condition that the magnitude of the steering angle is greater than or equal to a first steering angle threshold. case, if it is determined that the steering state is the end rest ON state and the magnitude of the steering angle is smaller than the first steering angle threshold value and smaller than the second steering angle threshold value, then the steering state is satisfied. is in the end-reliance OFF state, or the end-reliance determination unit further uses the steering angular velocity as the steering-related information, and the magnitude of the steering angular velocity is equal to or less than the first steering angular velocity threshold If the condition is further satisfied, it is determined that the steering state has become the end rest ON state, and the magnitude of the steering angular velocity is greater than the second steering angular velocity threshold greater than the first steering angular velocity threshold. Also when it is satisfied, by determining that the steering state has become the end reliance OFF state, or the end reliance determination unit further uses the steering torque as the steering related information, and the magnitude of the steering torque is the first When the condition that the steering torque is equal to or greater than one steering torque threshold is further satisfied, it is determined that the steering state is the end rest ON state, and the magnitude of the steering torque is a second steering torque that is smaller than the first steering torque threshold. Even when the condition that the threshold value is smaller than the threshold value is satisfied, by determining that the steering state has changed to the end reliance OFF state, or the end reliance determination unit uses the steering torque as the steering related information, the steering If the condition that the magnitude of the torque is equal to or greater than the first steering torque threshold is satisfied, it is determined that the steering state is the end rest ON state, and the magnitude of the steering torque is greater than the first steering torque threshold. When the condition that the steering torque is smaller than the small second steering torque threshold is satisfied, by determining that the steering state has changed to the end rest OFF state, Alternatively, when the end contact determining unit further uses a steering angular velocity as the steering-related information and further satisfies a condition that the magnitude of the steering angular velocity is equal to or less than a first steering angular velocity threshold, the steering state is determined to be the edge. Also when it is determined that the contact ON state is established and the condition that the magnitude of the steering angular velocity is larger than the second steering angular velocity threshold larger than the first steering angular velocity threshold is satisfied, the steering state is changed to the end contact OFF state. By determining that it has become, or when the end reliance determination unit further uses the current as the steering related information and further satisfies the condition that the magnitude of the current is equal to or greater than the first current threshold, the Also when it is determined that the steering state is the end reliance ON state and the magnitude of the current is smaller than the second current threshold smaller than the first current threshold, the steering state is the reliance OFF. By judging that a state is established, or when the end contact judging section continuously satisfies each of the above conditions for a predetermined time set for each of the above conditions, a judgment corresponding to each of the above conditions is made. Alternatively, a target steering torque generation unit that generates a target steering torque, a conversion unit that converts the target steering torque into a target torsion angle, and a torsion bar of the steering mechanism with respect to the target torsion angle. a torsion angle control unit that calculates a current command value that is a target value of the current so as to follow the angle; a target steering torque generation unit that generates a target steering torque; a conversion unit that converts the target steering torque into a target torsion angle; is further provided with a torsion angle control section for calculating a current command value, which is a target value of .

Alternatively, the above-described object of the present invention is to decrease the current after the state in which the magnitude of the steering torque is equal to or greater than the first steering torque threshold is continued for a first predetermined time, and after decreasing the current, the This is achieved by increasing the current after a state in which the magnitude of the steering torque is less than the first steering torque threshold and less than the second steering torque threshold continues for a second predetermined time.

Alternatively, the above-described object of the present invention is to decrease the current after the state in which the magnitude of the steering angle is equal to or greater than the first steering angle threshold continues for a first predetermined time, and decrease the current after the current is decreased. This is achieved by increasing the current after the magnitude of the steering angle remains smaller than the first steering angle threshold and smaller than the second steering angle threshold for a second predetermined time.

Moreover, the above object of the present invention can be achieved more effectively by providing the steering mechanism with an elastic body or a torsion bar between the steering wheel and the reaction force actuator.

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 control device of the steering system for a vehicle of the present invention, the steering state is determined, and when the steering state is the state in which the steering is steered to the end of the steering (end contact ON state), the current supplied to the reaction force actuator is reduced. By taking measures, it is possible to suppress an increase in power consumption and heat generation in the reaction force actuator.

In addition, by differentiating the threshold for determining whether the steering state has become the end contact ON state and the threshold for determining whether the steering state has not been steered to the end of the steering (end contact OFF state), Hunting phenomenon can be suppressed.

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. FIG. 3 is a block diagram showing a configuration example of a target steering torque generator; 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; It is a block diagram which shows the structural example (1st Embodiment) of an end contact determination part. FIG. 5 is a diagram for explaining changes in steering state when a first steering angle threshold and a second steering angle threshold are set; FIG. 10 is a diagram showing an image of temporal changes in the steering angle and the motor current value when the end reliance determination is performed using the threshold of the same value and the threshold of a different value. 4 is a block diagram showing a configuration example of a twist angle control unit; FIG. 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 generator; It is a flowchart which shows the example (1st Embodiment) of operation of an end contact determination part. 4 is a flow chart showing an operation example of a target steering angle generator; 9 is a flow chart showing a modification of the operation of the steering state determination section; It is a block diagram which shows the structural example (2nd Embodiment) of an end contact determination part. It is a block diagram which shows the structural example (3rd Embodiment) of an end contact determination part. It is a block diagram which shows the structural example (4th Embodiment) of an end contact determination part. FIG. 11 is a flowchart showing an operation example (fifth embodiment) of a steering state determination unit; FIG. FIG. 11 is a block diagram showing a configuration example (sixth embodiment) of a reaction force control system; FIG. 11 is a flow chart showing a part of an operation example (sixth embodiment) of a reaction force control system; FIG.

The present invention uses steering-related information such as the steering angle and steering torque detected by the steering mechanism to detect that the steering has reached the end of the steering that is the steerable limit (end rest ON state). Intermediate data (control information). As a result, the supplied current is reduced, so that it is possible to suppress an increase in power consumption and heat generation in the reaction force actuator in the end contact ON state. Reduction of power consumption leads to climate change countermeasures and reduction of global environmental load by reducing environmental load. A target steering torque or the like can be used as the control information.

Further, in the present invention, a threshold value (first threshold value) for determining whether the steering state has turned to the end contact ON state, and a threshold value for determining whether the steering state has not been steered to the end of the steering (end contact OFF state) ( second threshold) are set to different values. For example, when the steering angle is used as the steering-related information for determination, the first threshold is set to a value larger than the second threshold. When the same value is used for the first threshold and the second threshold, if the steering-related information fluctuates at the threshold boundary, a hunting phenomenon occurs in which the steering state is frequently switched between the end contact ON state and the end contact OFF state. Due to the occurrence of the hunting phenomenon, the current supplied to the reaction force actuator becomes unstable, which affects the steering reaction force and may make the driver feel uncomfortable. By using different values for the first threshold and the second threshold, the hunting phenomenon at the threshold boundary can be suppressed.

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 a steer-by-wire (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 operated by a driver, a steering device 40 that constitutes a steering mechanism that turns the 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 θh when the steering is steered to the end of the steering becomes the limit value (hereinafter referred to as the “end angle”) of the magnitude (absolute value) of the steering angle θh. 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 section 100, an end contact determination section 200, a conversion section 300, a torsion angle control section 400, a current control section 500, a multiplication section 510 and a subtraction section 520. Control is performed so that the angle follows the target twist angle. Also, the target steering torque is used as control information. A target steering torque generation unit 100 generates a target steering torque TrefA based on the steering angle θh and the vehicle speed Vs. The conversion unit 300 converts the target steering torque Tref, which is the result of multiplying the torque TrefA by the end contact determination gain Ge, into the target twist angle Δθref. The target torsion angle Δθref is input together with the torsion angle Δθ to the torsion angle control unit 400, and the torsion angle control unit 400 calculates a current command value Imc that makes the torsion angle Δθ equal to the target torsion angle Δθref. 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 subtractor 520, and the deviation I1 is 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.

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 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. 5(A), the torque signal Tref_a increases as the steering angle θh magnitude |θh| is also increasing. That is, as the magnitude |θh| of 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 torque signal Tref_a is calculated from the magnitude |θh| of steering angle θh using a map. The magnitude is obtained 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.

Differentiating section 120 differentiates steering angle θh to calculate steering angular velocity ωh1 , and steering angular velocity ωh1 is input to multiplying section 140 . In calculating the steering angular velocity ωh1, low-pass filter (LPF) processing may be appropriately performed in order to reduce the influence of high-frequency noise. You can implement it. Further, the steering angular velocity ωh1 may be calculated by performing differential operation 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. good. The motor angular velocity of the steering motor 41 may be used 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. 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 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.

The end contact determination section 200 determines the steering state St using the steering angle θh as the steering related information, and determines the end contact determination gain Ge based on the steering state St. Since the motor current value Imr of the reaction force motor 41 is adjusted based on the target steering torque Tref obtained by multiplying the target steering torque TrefA by the end contact determination gain Ge, the end contact determination gain Ge is adjusted in the end contact ON state. is decreased, the magnitude of the target steering torque Tref is also decreased, and finally the motor current value Imr can be decreased.

FIG. 7 shows a configuration example of the end contact determination unit 200. As shown in FIG. The end contact determination section 200 includes a steering state determination section 210 and a gain calculation section 220 . The steering angle θh is input to the steering state determination section 210 .

The steering state determination unit 210 uses the steering angle θh to determine whether the steering state St is in the end reliance ON state (hereinafter referred to as “end reliance ON determination”), and to determine whether the steering state St is in the end reliance OFF state. (hereinafter referred to as "end contact OFF determination") is performed, and the steering state St is output.

of the steering angle θh is greater than or equal to a predetermined threshold value (first steering angle threshold value) θth1, the steering state St is assumed to be in the ON state. state St=end contact ON state”. As the first steering angle threshold θth1, an angle slightly before the terminal angle, for example, an angle 2 degrees before the terminal angle is used. By setting the first steering angle threshold θth1 before the terminal angle, it is possible to absorb the time lag that may occur from the time when the steering terminal is reached until the motor current value Imr starts decreasing. A terminal angle may be used as the first steering angle threshold θth1.

of the steering angle θh is smaller than a predetermined threshold value (second steering angle threshold value) θth2, the steering state St is assumed to be in the off state. state St=end contact OFF state”. The second steering angle threshold value θth2 is set within a range of the magnitude |θh| of the steering angle θh in which it is not determined that the steering state St is in the end contact ON state in the end contact ON determination, that is, a range smaller than the first steering angle threshold value θth1. be done. That is, the second steering angle threshold θth2 is set to a value smaller than the first steering angle threshold θth1. For example, an angle 5 degrees before the terminal angle is used as the second steering angle threshold θth2.

FIG. 8 shows changes in the steering state when the steering wheel 1 is operated with the first steering angle threshold .theta.th1 and the second steering angle threshold .theta.th2 thus set. When the steering wheel 1 is operated from the neutral position, the steering state is the "end contact OFF state" (arrow A) until the magnitude |θh| of the steering angle θh becomes greater than or equal to the first steering angle threshold value θth1. of the steering angle θh becomes greater than or equal to the first steering angle threshold value θth1, the steering state becomes the “end contact ON state” (arrow B). Then, the steering wheel 1 is returned and the steering state remains in the "end contact ON state" (arrow C) until the steering angle .theta.h magnitude |.theta.h| becomes smaller than the second steering angle threshold value .theta.th2. When the magnitude |θh| of the steering angle θh becomes smaller than the second steering angle threshold value θth2, the steering state becomes the “end contact OFF state” (arrow D). Therefore, immediately after the magnitude |θh| of the steering angle θh becomes greater than or equal to the first steering angle threshold value θth1 and the steering state becomes the “end contact ON state”, the magnitude of the steering angle θh |θh| Even if it becomes smaller than the threshold value θth1, the steering state remains in the “end contact ON state”. Further, immediately after the steering angle θh magnitude |θh| becomes smaller than the second steering angle threshold value θth2 and the steering state becomes the “end contact OFF state”, the steering angle θh magnitude |θh| Even when the angle threshold value θth2 or more is reached, the steering state remains in the “end contact OFF state”. By using the first steering angle threshold value θth1 and the second steering angle threshold value θth2 in this way, even if the magnitude |θh| It is possible to suppress the hunting phenomenon that frequently switches to the contact OFF state.

The steering state determination unit 210 performs end reliance ON determination and end reliance OFF determination (hereinafter, these two determinations are collectively referred to as “end reliance determination”) in the following procedure. First, the end contact ON determination is performed, and if the magnitude of the steering angle θh |θh| I do. If the magnitude |θh| of the steering angle θh is smaller than the second steering angle threshold value θth2 in the end contact OFF determination, the steering state St is determined to be the end contact OFF state. When the magnitude |θh| is equal to or greater than the second steering angle threshold θth2 and smaller than the first steering angle threshold θth1, the steering state St is not changed.

The gain calculator 220 determines the end contact determination gain Ge based on the steering state St. As described above, in the end contact ON state, the end contact determination gain Ge is decreased in order to reduce the magnitude of the target steering torque Tref. In the end contact OFF state, the end contact determination gain Ge is increased in order to restore the reduced target steering torque.

When the steering state St is the “end reliance ON state”, the gain calculation unit 220 decreases the end reliance determination gain Ge over time in order to monotonically decrease the target steering torque by multiplication of the end reliance determination gain Ge. Specifically, in order to gradually decrease the end contact determination gain Ge from 1 at a constant rate after the end contact ON state, the immediately preceding end contact determination gain Ge (hereinafter referred to as “immediate end contact determination gain Gep”) A value obtained by subtracting a constant value FR1 (for example, 0.2) from the value FR1 is set as a new end contact determination gain Ge. That is, a new end contact determination gain Ge is obtained by setting Ge=Gep-FR1. If the subtracted value is 0 or less, the end contact determination gain Ge is set to 0. The immediately preceding end contact determination gain Gep is updated to the newly obtained end contact determination gain Ge.

When the steering state St is the “end reliance OFF state”, the gain calculation unit 220 increases the end reliance determination gain Ge over time in order to monotonically increase the target steering torque by multiplication of the end reliance determination gain Ge. Specifically, in order to gradually increase the end contact determination gain Ge at a constant rate until the end contact determination gain Ge becomes 1 after the end contact OFF state, a constant value FR2 (for example, 0.2 ) is added as a new end contact determination gain Ge. That is, a new edge contact determination gain Ge is obtained by setting Ge=Gep+FR2. If the added value is 1 or more, the end contact determination gain Ge is set to 1. The immediately preceding end contact determination gain Gep is updated to the newly obtained end contact determination gain Ge. The constant values FR1 and FR2 may be the same value or different values.

The end contact determination gain Ge output from the end contact determination unit 200 is multiplied by the target steering torque TrefA in the multiplication unit 510, and the multiplication result is output as the target steering torque Tref.

By obtaining the target steering torque Tref in this way, it is possible to reduce the motor current value Imr in the end reliance ON state and to suppress the hunting phenomenon at the threshold boundary. For example, FIG. 9 shows the steering angle θh when the steering wheel 1 starts to be turned from the neutral position at time t1, reaches the terminal angle at time t2, and then operates the steering wheel 1 around a threshold set before the terminal angle. and the motor current value Imr. The effect will be described using this figure. FIG. 9A shows a case where the first steering angle threshold θth1 and the second steering angle threshold θth2 are set to the same value (referred to as steering angle threshold). FIG. 9B shows the first steering angle threshold θth1 and the second steering angle threshold θth2. It is a figure in the case of this embodiment which set 2 steering angle threshold value (theta)th2 to a different value. When the first steering angle threshold value θth1 and the second steering angle threshold value θth2 are set to the same value, as shown in FIG. The contact ON state and the end contact OFF state are alternately switched, and the motor current value Imr repeats increase and decrease. In addition, in FIG. 9A, for convenience of explanation, the steering angle θh and the motor current value Imr are displayed so as to overlap each other. On the other hand, when the first steering angle threshold θth1 and the second steering angle threshold θth2 are set to different values, the steering angle θh fluctuates at the boundary of the first steering angle threshold θth1 as shown in FIG. 9B. Also (see the dashed line), if the steering angle does not become smaller than the second steering angle threshold θth2, the steering state remains in the end contact ON state, so the motor current value Imr gradually decreases and becomes 0 at time t3 (see the solid line). ).

Although the minimum value of the end contact determination gain Ge is set to 0, any small value may be set as the minimum value. Further, although the end contact determination gain Ge is linearly decreased and increased at a constant rate, the shape of the change may be arbitrary as long as the end contact determination gain Ge is monotonously decreased and increased. you can go to The end contact determination gain Ge may be increased or decreased based on a map or function. Further, the end contact determination gain Ge may be set to 0 or an arbitrary small value when it is determined that the end contact is ON, and the end contact determination gain Ge is set when it is determined that the end contact is OFF. It can be set to 1. In this case, instead of multiplying the target steering torque TrefA by the end contact determination gain Ge, the target steering torque TrefA and 0 or any small value are switched by a switch according to the steering state St, and output as the target steering torque Tref. You can make it work.

The conversion unit 300 has a characteristic of the reciprocal "1/Kt" of the spring constant Kt of the torsion bar 2A, and converts the target steering torque Tref into the target twist angle Δθref.

The torsion angle control unit 400 inputs the target torsion angle Δθref and the torsion angle Δθ, and calculates the current command value Imc such that the torsion angle Δθ becomes the target torsion angle Δθref. A desired steering reaction force is realized by controlling the torsion angle Δθ so as to follow a value corresponding to the steering angle θh.

FIG. 10 is a block diagram showing a configuration example of the torsion angle control section 400. The torsion angle control section 400 includes gain sections 420, 440 and 470, an integration section 450, a differentiation section 460, subtraction sections 410 and 480, and an addition section 430. and calculates a current command value Imc using a target torsion angle Δθref and a torsion angle Δθ by derivative-preceding PID (proportional-integral-derivative) control (PI-D control). The target twist angle Δθref is added to the subtraction unit 410 , and the twist angle Δθ is subtracted from the subtraction unit 410 and input to the differentiating unit 460 .

An angle deviation dΔθ between the target twist angle Δθref and the twist angle Δθ is calculated by the subtractor 410 , and the angle deviation dΔθ is input to the gain units 420 and 440 . Gain unit 420 multiplies angle deviation dΔθ by proportional gain Kp, and the multiplication result is input to addition unit 430 as current command value Imc1. The angular deviation dΔθ is multiplied by integral gain Ki in gain section 440, the multiplication result is input to integration section 450 and integrated (1/s), and the integration result is input to addition section 430 as current command value Imc2. The addition unit 430 adds the current command values Imc1 and Imc2, and the current command value Imc3, which is the addition result, is input to the subtraction unit 480 for addition. The differentiating section 460 that receives the torsion angle Δθ differentiates (s) the torsion angle Δθ. The differentiation result is input to the gain section 470 and multiplied by the differentiation gain Kd. is entered. Subtraction unit 480 subtracts current command value Imc4 from current command value Imc3, and outputs the subtraction result as current command value Imc.

Note that the control by the torsion angle control unit 400 is not limited to PI-D control, and may be controlled so that the torsion angle Δθ follows the target torsion angle Δθref. PI (proportional integral) control, P Commonly used controls such as (proportional) control, PID control, IP control (proportional leading PI control), model matching control, and model reference control may be used. Also, a limiter that limits the maximum value of the current command value Imc may be provided in the subsequent stage of the torsion angle control section 400 .

The current command value Imc is added to the subtraction unit 520, and the subtraction unit 520 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 520 of the reaction force control system 60 .

The steering control system 70 includes a target steering angle generator 600, a steering angle controller 700, a current controller 800, and a subtractor 810, and controls the steering angle θt to follow the target steering angle θtref. conduct. A target turning angle θtref is generated based on the steering angle θh in the target turning angle generation unit 600, and the target turning angle θtref is input to the turning angle control unit 700 together with the turning angle θt. At 700, a current command value Imct is calculated so 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 810. 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. 11 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. 12, 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 steering angle control unit 700 has the same configuration and operation as the torsion angle control unit 400, and uses the target steering angle θtref and the steering angle θt to obtain the target steering angle θtref by PI-D control. A current command value Imct that θt follows is calculated.

Subtractor 810, current controller 800, PWM controller 47, inverter 48, and motor current detector 49 are similar to subtractor 520, 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. 13 to 16. FIG.

When the operation is started, the steering angle θh, vehicle speed Vs, torsion angle Δθ, and turning angle θt are detected or calculated (step S10), and the steering angle θh is calculated by the target steering torque generation unit 100, the end contact determination unit 200, and the target turning angle θh. The vehicle speed Vs is input to the target steering torque generator 100, the twist angle Δθ is input to the twist angle controller 400, and the steering angle θt is input to the steering angle controller 700, respectively.

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).

After inputting the steering angle θh, the end contact determination section 200 obtains the end contact determination gain Ge (step S30). An operation example of the end contact determination unit 200 will be described with reference to the flowchart of FIG. 15 . The initial value of the steering state St output by the steering state determination unit 210 is the “end contact OFF state”, and the immediately preceding end contact determination gain Gep used in the gain calculation unit 220 is set to 1 in advance as an initial value. ing.

The steering angle θh input to the end contact determining section 200 is input to the steering state determining section 210 (step S31).

of the steering angle θh is greater than or equal to the first steering angle threshold value θth1 (step S32), the steering state determination unit 210 determines that the steering state St is in the end contact ON state, and sets the steering state St to " end contact ON state" (step S33). If the magnitude |θh| of the steering angle θh is smaller than the first steering angle threshold θth1 (step S32), it is checked whether the magnitude |θh| of the steering angle θh is smaller than the second steering angle threshold θth2 (step S34). When the magnitude |θh| of the steering angle θh is smaller than the second steering angle threshold value θth2, it is determined that the steering state St is in the end contact OFF state, and the steering state St is set to the “end contact OFF state” (step S35). ), otherwise the steering state St remains unchanged. The steering state determination unit 210 outputs the steering state St to the gain calculation unit 220 (step S36).

When the steering state St is in the "end contact ON state" (step S37), the gain calculator 220 sets the end contact determination gain Ge to a value obtained by subtracting a constant value FR1 from the immediately preceding end contact determination gain Gep (step S38). If the end contact determination gain Ge is 0 or less (step S39), the end contact determination gain Ge is set to 0 (step S40). When the steering state St is the "end contact OFF state" (step S37), the end contact determination gain Ge is set to a value obtained by adding a constant value FR2 to the immediately preceding end contact determination gain Gep (step S41). is 1 or more (step S42), the end contact determination gain Ge is set to 1 (step S43). Then, the immediately preceding end contact determination gain Gep is updated to the newly obtained end contact determination gain Ge (step S44), and the end contact determination gain Ge is output to the multiplier 510 (step S45).

Target steering torque TrefA is multiplied by end contact determination gain Ge in multiplication section 510 (step S50), and the multiplication result is output to conversion section 300 as target steering torque Tref.

Conversion unit 300 converts target steering torque Tref into target twist angle Δθref (step S 60 ), and target twist angle Δθref is input to twist angle control unit 400 .

The torsion angle control unit 400 inputs the torsion angle Δθ together with the target torsion angle Δθref, performs PI-D control according to the configuration shown in FIG. 10, and calculates the current command value Imc (step S70).

The current command value Imc is added to the subtractor 520, and the deviation I1 from the motor current value Imr detected by the motor current detector 39 is calculated by the subtractor 520 (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). The target steering angle θtref is input to the steering angle control section 700 .

The turning angle control unit 700 inputs the turning angle θt together with the target turning angle θtref, and obtains the current command value Imct by PI-D control (step S120).

The current command value Imct is added to the subtractor 810, and the deviation I2 from the motor current value Imd detected by the motor current detector 49 is calculated by the subtractor 810 (step S130). Deviation I2 is input to current control section 800, and current control section 800 calculates voltage control command value Vref2 by current control (step S140). 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 S150).

Note that the order of data input and calculation in FIGS. 13 to 16 can be changed as appropriate.

In the above operation example, the steering state determination unit 210 may select the determination to be performed (end reliance ON determination, end reliance OFF determination) according to the steering state St at the time of performing the end reliance determination. . That is, the end contact ON determination is performed only when the steering state St is the end contact OFF state, and the end contact OFF determination is performed only when the steering state St is the end contact ON state. The operation of the steering state determination section in this case differs from that of steps S32 to S35 in the flow chart shown in FIG. That is, as shown in FIG. 17, the steering state determination unit confirms the steering state St after the steering angle θh is input (step S31A). If the steering state St is the “end contact OFF state”, the end contact ON determination is performed, and if the magnitude of the steering angle θh |θh| If not, the steering state St remains unchanged. If the steering state St is the “end contact ON state”, the end contact OFF determination is performed, and if the magnitude of the steering angle θh |θh| If not, the steering state St remains unchanged. After that, it continues to step S36.

Further, in the gain calculation unit 220, the operations of steps S38 to S40 may not be performed when the end contact determination gain Ge is zero. Similarly, the operations of steps S41 to S43 may not be performed when the end contact determination gain Ge is 1.

In the above-described embodiment, the target steering torque generation unit 100 includes the damper gain unit 130. However, the damper gain unit 130 may be omitted when the effect of the damper gain is realized by other means or when emphasis is placed on reducing the amount of calculation. Also good. In this case, the differentiating section 120, the multiplying section 140 and the adding section 150 can also be eliminated. The target steering torque generating section 100 is not limited to the above configuration as long as it is based on the steering angle.

In the above-described embodiment, the target steering torque is reduced by multiplying the target steering torque by the end reliance determination gain in the end reliance ON state. Alternatively, the target steering torque may be reduced by other methods. Similarly, in the end contact OFF state, the magnitude of the target steering torque is increased by multiplying the target steering torque by the end contact determination gain. The magnitude of the target steering torque may be increased by the method.

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.

The steering state determination unit 210 in the end-reliance determination unit 200 in the first embodiment uses the steering angle as the steering-related information to perform end-reliance determination. And the steering angular velocity can be used to determine the end contact. The steering angular velocity at the steering end is approximately 0, and the steering angular velocity near the steering end is also very small. Therefore, by adding the steering angular velocity to the end reliance determination, it is possible to perform end reliance determination in accordance with the actual situation.

FIG. 18 shows a configuration example (second embodiment) of the end contact determination section corresponding to the above. In the end reliance determination section 200A in the second embodiment, compared with the end reliance determination section 200 in the first embodiment shown in FIG. In addition to the steering angle θh, the steering angular velocity ωh2 is input to the state determination section 210A.

The steering angular velocity ωh2 is calculated by differentiating the steering angle θh in a differentiating section 900 newly added to the reaction force control system. The steering angular velocity ωh1 calculated by the differentiating section 120 in the target steering torque generating section 100 may be used instead of the steering angular velocity ωh2. In this case, the differentiation section 900 becomes unnecessary.

The steering state determination unit 210A uses the steering angle θh and the steering angular velocity ωh2 to perform end contact determination.

is equal to or greater than the first steering angle threshold value θth1, and the magnitude |ωh2| of the steering angular velocity ωh2 is a predetermined threshold value (first steering angular velocity threshold value). ) When ωth1 or less, it is assumed that the steering state St is in the end reliance ON state, and “steering state St = end reliance ON state” is set. For example, 2 deg/sec is used as the first steering angular velocity threshold ωth1.

is smaller than the second steering angle threshold value θth2, or the magnitude |ωh2| of the steering angle speed ωh2 is a predetermined threshold (second steering speed threshold ), if it is larger than ωth2, it is assumed that the steering state St is in the end reliance OFF state, and "steering state St = end reliance OFF state" is set. The second steering angular velocity threshold ωth2 is set within a range of the magnitude |ωh2| of the steering angular velocity ωh2 in which it is not determined that the steering state St is in the ON state of the end reliance in the reliance ON determination, that is, in a range larger than the first steering angular velocity threshold ωth1. be done. That is, the second steering angular velocity threshold ωth2 is set to a value larger than the first steering angular velocity threshold ωth1. For example, 5 deg/sec is used as the second steering angular velocity threshold ωth2.

210 A of steering state determination parts are the same procedures as the steering state determination part 210, and perform an edge reliance determination. That is, first, the end contact ON determination is performed, and the magnitude |θh| of the steering angle θh is equal to or greater than the first steering angle threshold θth1 and the magnitude |ωh2| If not, "steering state St = end contact ON state" is set, and if not, end contact OFF determination is performed. If the magnitude |θh| of the steering angle θh is smaller than the second steering angle threshold θth2 or the magnitude |ωh2| Steering state St=end contact OFF state", otherwise, the steering state St is not changed.

The operation of the second embodiment differs from the operation of the first embodiment by adding the operation of calculating the steering angular velocity ωh2 in the differentiating section 900, and changing the operation of the steering state determining section as described above. are the same.

As the steering-related information, in addition to the steering angle and the steering angular velocity, the steering torque can be used to perform the end-reliance determination. If the driver tries to further turn the steering wheel in the end reliance ON state, the steering torque increases. Therefore, by adding the steering torque to the reliance determination, the end reliance determination can be performed more accurately.

FIG. 19 shows a configuration example (third embodiment) of the end contact determination section corresponding to the above. In the end contact determination section 200B of the third embodiment, compared with the end contact determination section 200A of the second embodiment shown in FIG. In addition to the steering angle θh and the steering angular velocity ωh2, the steering torque Th is input to the state determination section 210B.

The steering torque Th may be detected by a torque sensor provided on the column shaft 2, or may be obtained by multiplying the torsion angle Δθ by the spring constant Kt of the torsion bar 2A.

The steering state determination unit 210B uses the steering angle θh, the steering angular velocity ωh2, and the steering torque Th to perform end-reliance determination.

is equal to or greater than the first steering angle threshold value .theta.th1, the magnitude |.omega.h2| of the steering angle speed .omega.h2 is equal to or less than the first steering angle speed threshold value .omega.th1, and the steering torque When the magnitude |Th| of Th is equal to or greater than a predetermined threshold value (first steering torque threshold value) Tth1 set in advance, it is assumed that the steering state St is in the end contact ON state, and "steering state St = end contact ON state". and As the first steering torque threshold Tth1, for example, a value of 30% of the maximum value of the steering torque Th is used.

is smaller than the second steering angle threshold value θth2, or is larger than the second steering angular speed threshold value ωth2, or is greater than the second steering angular speed threshold value ωth2. When the magnitude of Th |Th| is smaller than a predetermined threshold value (second steering torque threshold value) Tth2 set in advance, it is assumed that the steering state St is in the end contact OFF state, and "steering state St = end contact OFF state". and The second steering torque threshold Tth2 is set to a range of the magnitude |Th| of the steering torque Th in which the steering state St is not determined to be in the end reliance ON state in the reliance ON determination, that is, a range smaller than the first steering torque threshold Tth1. be done. That is, the second steering torque threshold Tth2 is set to a value smaller than the first steering torque threshold Tth1. For example, a value of 15% of the maximum value of the steering torque Th is used as the second steering torque threshold Tth2.

The steering state determination section 210B performs end contact determination in the same procedure as the steering state determination section 210A. That is, first, the end contact ON determination is performed, and the magnitude |θh| of the steering angle θh is equal to or greater than the first steering angle threshold θth1 and the magnitude |ωh2| of the steering angular velocity ωh2 is equal to or less than the first steering angular velocity threshold ωth1. of the steering torque Th is greater than or equal to the first steering torque threshold value Tth1, the "steering state St=end reliance ON state" is determined; otherwise, reliance OFF determination is performed. Then, the magnitude |θh| of the steering angle θh is smaller than the second steering angle threshold θth2, or the magnitude |ωh2| of the steering angular velocity ωh2 is larger than the second steering angular velocity threshold ωth2, or When the magnitude |Th| of the steering torque Th is smaller than the second steering torque threshold value Tth2, the steering state St is set to "the end contact OFF state", and otherwise, the steering state St is not changed.

Compared to the operation of the second embodiment, the operation of the third embodiment is the same except that the operation of detecting or calculating the steering torque Th is added and the operation of the steering state determination unit is changed as described above. is.

As the steering-related information, in addition to the steering angle, the steering angular velocity, and the steering torque, the motor current value can be used to perform end-reliance determination. By using the motor current value Imr of the reaction force motor 41 to be finally reduced in the end reliance ON state for the reliance determination, more appropriate end reliance determination directly linked to the effect can be performed.

FIG. 20 shows a configuration example (fourth embodiment) of the end contact determination section corresponding to the above. In the end contact determination section 200C of the fourth embodiment, compared with the end contact determination section 200B of the third embodiment shown in FIG. In addition to the steering angle θh, the steering angular velocity ωh2, and the steering torque Th, the motor current value Imr is input to the state determination unit 210C.

The motor current value Imr detected by the motor current detector 39 is subtracted and input to the subtractor 520 and also input to the steering state determination section 210C.

210 C of steering state determination parts perform end reliance determination using steering angle (theta)h, steering angular velocity (omega)h2, steering torque Th, and motor electric current value Imr.

is equal to or greater than the first steering angle threshold value .theta.th1, the magnitude |.omega.h2| of the steering angle speed .omega.h2 is equal to or less than the first steering angle speed threshold value .omega.th1, and the steering torque is greater than or equal to the first steering torque threshold value Tth1 and the motor current value Imr is greater than or equal to a predetermined threshold value (first current threshold value) Ith1 set in advance, the steering state St is the end contact ON state. Then, it is assumed that "steering state St = end contact ON state". As the first current threshold value Ith1, for example, a value of 30% of the maximum value of the motor current value Imr is used.

is smaller than the second steering angle threshold value θth2, or is larger than the second steering angular speed threshold value ωth2, or is greater than the second steering angular speed threshold value ωth2. is smaller than the second steering torque threshold value Tth2, or the motor current value Imr is smaller than a preset threshold value (second current threshold value) Ith2, the steering state St is the end rest OFF state. Assuming that it becomes, "steering state St = end contact OFF state". The second current threshold Ith2 is set to a range of the motor current value Imr in which it is not determined that the steering state St is in the ON state of the end reliance in the reliance ON determination, that is, a range smaller than the first current threshold Ith1. That is, the second current threshold Ith2 is set to a value smaller than the first current threshold Ith1. For example, a value of 15% of the maximum value of the motor current value Imr is used as the second current threshold value Ith2.

The steering state determination section 210C performs end contact determination in the same procedure as the steering state determination section 210B. That is, first, the end contact ON determination is performed, and the magnitude |θh| of the steering angle θh is equal to or greater than the first steering angle threshold θth1 and the magnitude |ωh2| of the steering angular velocity ωh2 is equal to or less than the first steering angular velocity threshold ωth1. is equal to or greater than the first steering torque threshold value Tth1, and the motor current value Imr is equal to or greater than the first current threshold value Ith1, the steering state St is set to the end contact ON state, Otherwise, an end contact OFF determination is made. Then, the magnitude |θh| of the steering angle θh is smaller than the second steering angle threshold θth2, or the magnitude |ωh2| of the steering angular velocity ωh2 is larger than the second steering angular velocity threshold ωth2, or is smaller than the second steering torque threshold value Tth2, or the motor current value Imr is smaller than the second current threshold value Ith2, the "steering state St = end contact OFF state" is determined; In this case, the steering state St is not changed.

The operation of the fourth embodiment is the same as the operation of the third embodiment, except that the operation of the steering state determination unit is changed as described above.

Note that the current command value Imc may be used as the steering-related information instead of the motor current value Imr.

In the above-described embodiments (first to fourth embodiments), the steering-related information includes "steering angle", "steering angle, steering angular velocity", "steering angle, steering angular velocity, steering torque", "steering angle, steering Angular velocity, steering torque, and motor current value” are used in combination to perform end-reliance determination, but other combinations may be used to perform end-reliance determination. For example, "steering torque", "steering angle, steering torque", "steering torque, steering angular velocity", or a combination of these plus a "motor current value" may be used for end reliance determination.

Elapsed time can also be added as a condition for the end contact determination in the above-described embodiment. For example, in the end reliance ON determination in the first embodiment, when the steering angle θh magnitude |θh| of the steering angle θh is greater than or equal to the first steering angle threshold value θth1 for a predetermined period of time (first predetermined period of time), it is determined that the end contact is ON for the first time. . If the magnitude |θh| of the steering angle θh becomes smaller than the first steering angle threshold θth1 before the predetermined time elapses, it is not determined that the end contact ON state has occurred. Similarly, in addition to the elapsed time condition, the state where the magnitude of the steering angle θh |θh| Then, it is determined that the end contact OFF state is reached for the first time. Adding elapsed time to the condition has the effect of suppressing the hunting phenomenon at the threshold boundary, and by combining with the use of two different thresholds that are also effective in suppressing the hunting phenomenon, there is more flexibility with respect to the hunting phenomenon. can take appropriate action. Adding the elapsed time is also effective in suppressing sporadic and sudden fluctuations in values. A counter or the like can be used to determine whether or not it has continued for a predetermined period of time.

An operation example (fifth embodiment) in which the elapsed time is added to the conditions for the end contact determination in the first embodiment will be described with reference to the flowchart of FIG. 21 . Since the operation of the fifth embodiment differs from the operation of the first embodiment only in the operation of the steering state determination section, only the operation of the steering state determination section is shown in FIG. explain. The steering state determination unit has a counter (hereinafter referred to as an "ON counter") used for determining whether the end contact is ON and a counter used for determining whether the end contact is OFF (hereinafter referred to as an "OFF counter"). Each counter is set to 0 as an initial value in advance.

Subsequent to step S31 in the flowchart shown in FIG. 15, the steering state determination unit turns ON the counter when the input steering angle θh magnitude |θh| is equal to or greater than the first steering angle threshold θth1 (step S32). It is incremented by one (step S32A). When the ON counter is equal to or greater than a predetermined value Ft1 set in advance (step S32B), it is determined that the steering state St is in the end contact ON state, and the steering state St is set to the "end contact ON state" (step S33). ), the ON counter is reset to 0 (step S33A). When the ON counter is smaller than the predetermined value Ft1 (step S32B), it is determined that the end contact ON state has not yet occurred, and the steering state St is not changed. of the steering angle θh is smaller than the first steering angle threshold θth1 (step S32), the ON counter is reset to 0 (step S33B), and the magnitude of the steering angle θh |θh| It is checked whether it is smaller than the angle threshold θth2 (step S34). of the steering angle θh is smaller than the second steering angle threshold θth2, the OFF counter is incremented by one (step S34A). Then, when the OFF counter is equal to or greater than the predetermined value Ft2 set in advance (step S34B), it is determined that the steering state St has become the end contact OFF state, and the steering state St is set to the "end contact OFF state" (step S35). ), the OFF counter is reset to 0 (step S35A). When the OFF counter is smaller than the predetermined value Ft2 (step S34B), it is determined that the end contact OFF state has not yet occurred, and the steering state St is not changed. is greater than or equal to the second steering angle threshold value θth2 in step S34, the OFF counter is reset to 0 (step S35B), and the steering state St remains unchanged. After that, the process continues to step S36.

Note that the order of data input and calculation in FIG. 21 can be changed as appropriate.

In the above-described end contact determination, the preset predetermined values Ft1 and Ft2 may be the same value or different values. In addition, although the elapsed time is added to the conditions for both the end contact ON determination and the end contact OFF determination, it may be added to only one of them.

Elapsed time can also be added as a condition for end contact determination in the second to fourth embodiments. In this case, the predetermined time set in advance under each condition of the steering angular velocity ωh2, the steering torque Th, and the motor current value Imr may be the same as the predetermined time set under the condition of the steering angle θh, or may differ depending on each condition. Also good.

In the above-described embodiments (first to fifth embodiments), the target steering torque is used as control information, and the magnitude of the target steering torque is reduced to decrease the motor current value. Other data that is calculated before determining the value can also be used as control information. For example, a current command value can be used as control information.

FIG. 22 is a block diagram showing a configuration example (sixth embodiment) of a reaction force control system when using the current command value Imc as control information in contrast to the first embodiment. In the reaction force control system 60D of the sixth embodiment, as compared with the reaction force control system 60 of the first embodiment shown in FIG. The target steering torque TrefA output from the target steering torque generation unit 100 is installed after the control unit 400 and is input to the conversion unit 300. The end contact determination gain Ge output from the end contact determination unit 200 is is multiplied by the current command value Imc output from the multiplication unit 510, and the multiplication result is added to the subtraction unit 520 as the current command value ImcD.

An operation example of the reaction force control system 60D of the sixth embodiment having such a configuration will be described with reference to the flowchart of FIG. FIG. 23 shows only portions where the operation flow differs from the operation example of the first embodiment shown in FIG. 13 .

The target steering torque TrefA generated at step S20 in the flow chart shown in FIG.

Conversion unit 300 converts target steering torque TrefA into target twist angle Δθref (step S 60 ), and target twist angle Δθref is input to twist angle control unit 400 .

Similar to the first embodiment, the torsion angle control unit 400 inputs the torsion angle Δθ together with the target torsion angle Δθref, performs PI-D control, and calculates the current command value Imc (step S70).

Current command value Imc is input to multiplication unit 510, current command value Imc is multiplied by end contact determination gain Ge (step S70A), and the multiplication result is output as current command value ImcD.

The current command value ImcD is added to the subtractor 520, and the deviation I1 from the motor current value Imr detected by the motor current detector 39 is calculated by the subtractor 520 (step S80). After that, it continues to step S90.

Also in the second to fifth embodiments, the current command value can be used as the control information instead of the target steering torque. Further, as the control information, a target twist angle, etc. may be used in addition to the target steering torque and current command value.

In the above-described embodiments (first to sixth embodiments), the reaction force control system performs control such that the torsion angle follows the target torsion angle, but control in the reaction force control system is not limited to that. Control or the like may be performed such that the steering angle follows the target steering angle.

In the above-described embodiment, one control device has a reaction force control system and a steering control system. can be In this case, the control devices transmit and receive data through communication. 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 if an abnormality occurs in the system, the column shaft 2 and the steering mechanism can be connected by a clutch or the like. The present invention is also applicable to SBW systems with mechanically coupled mechanical torque transmission mechanisms. 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 includes a torsion bar, any elastic body or mechanism having an arbitrary spring constant between the handle 1 and the reaction force motor 31 may be used without being 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 generally 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.

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, 60D Reaction force control system 70 Steering control system 100 Target steering torque generation unit 110 Basic map unit 130 Damper gain unit 200, 200A, 200B, 200C End contact determination Units 210, 210A, 210B, 210C Steering state determination unit 220 Gain calculation unit 300 Conversion unit 400 Torsion angle control units 500 and 800 Current control unit 600 Target turning angle generation unit 610 Limiting unit 620 Rate limiting unit 630 Correction unit 700 Steering angle controller

Claims (18)

A control device for a vehicle steering system that has a steering end that is a steerable limit, drives and controls a reaction force actuator by adjusting a supplied current, and controls a steering mechanism,
Using the steering-related information detected in the steering mechanism, the steering state is an end reliance ON state in which the steering is performed to the end of the steering, or an end reliance OFF state in which the steering is not performed to the end of the steering. Equipped with an end contact determination unit that determines whether
A first threshold for determining whether the steering state is the end reliance ON state and whether the steering state is the end reliance OFF state, which are set for the steering-related information by the end reliance determination unit determining the steering state using a second threshold for determining;
The second threshold is set to a value range of the steering-related information in which it is not determined that the steering state is the end rest ON state by determination based on the first threshold,
A control device for a steering system for a vehicle, wherein when the steering state is the end rest ON state, control information that serves as a basis for adjusting the current is decreased in order to decrease the current. 2. A controller for a vehicle steering system according to claim 1, wherein, when said steering state is said end contact OFF state, said control information is increased in order to restore said decreased current. The end contact determination unit has a gain that decreases over time when the steering state is the end contact ON state,
2. A controller for a vehicle steering system according to claim 1, wherein said control information is reduced by multiplying said gain. The end contact determination unit has a gain that decreases with time when the steering state is the end contact ON state and increases with time when the steering state is the end contact OFF state,
3. A controller for a vehicle steering system according to claim 2, wherein said control information is decreased or increased by multiplying said gain. The end contact determination unit
using a steering angle as the steering-related information;
If the condition that the magnitude of the steering angle is greater than or equal to the first steering angle threshold is satisfied, it is determined that the steering state has become the end contact ON state,
5. The method according to any one of claims 1 to 4, wherein when a condition is satisfied that the magnitude of the steering angle is smaller than the first steering angle threshold and smaller than the second steering angle threshold, it is determined that the steering state has become the end rest OFF state. A control device for a steering system for a vehicle according to any one of the above. The end contact determination unit
Further using a steering angular velocity as the steering-related information,
determining that the steering state has become the end contact ON state when the condition that the magnitude of the steering angular speed is equal to or less than the first steering angular speed threshold value is further satisfied;
6. The method according to claim 5, wherein the steering state is determined to be the off state of the end support even when the condition that the magnitude of the steering angular velocity is larger than the second steering angular velocity threshold larger than the first steering angular velocity threshold is satisfied. vehicle steering system controller. The end contact determination unit
further using steering torque as the steering-related information;
If the condition that the magnitude of the steering torque is greater than or equal to the first steering torque threshold is further satisfied, it is determined that the steering state has become the end contact ON state,
7. It is determined that said steering state has become said end support OFF state also when the condition that said magnitude of said steering torque is smaller than said second steering torque threshold which is smaller than said first steering torque threshold is satisfied. The control device for the vehicle steering system according to 1. The end contact determination unit
using steering torque as the steering-related information;
If the condition that the magnitude of the steering torque is greater than or equal to the first steering torque threshold is satisfied, it is determined that the steering state is the end rest ON state,
5. The method according to any one of claims 1 to 4, wherein when the magnitude of said steering torque satisfies a condition that said steering torque is smaller than said first steering torque threshold and smaller than said second steering torque threshold, it is determined that said steering state has become said end rest OFF state. A control device for a steering system for a vehicle according to any one of the above. The end contact determination unit
Further using a steering angular velocity as the steering-related information,
determining that the steering state has become the end contact ON state when the condition that the magnitude of the steering angular speed is equal to or less than the first steering angular speed threshold value is further satisfied;
9. The system according to claim 8, wherein it is determined that said steering state has changed to said end support OFF state also when the condition that said magnitude of said steering angular velocity is greater than said first steering angular velocity threshold and greater than said second steering angular velocity threshold is satisfied. vehicle steering system controller. The end contact determination unit
further using said current as said steering-related information;
If the condition that the magnitude of the current is equal to or greater than the first current threshold is further satisfied, it is determined that the steering state is the end contact ON state,
10. Even when the condition that the magnitude of the current is smaller than the second current threshold smaller than the first current threshold is satisfied, it is determined that the steering state has become the end contact OFF state. The control device for the vehicle steering system according to 1. 11. The method according to any one of claims 5 to 10, wherein the end contact determination unit makes a determination corresponding to each condition when each condition is continuously satisfied for a predetermined time set for each condition. A controller for a vehicle steering system. a target steering torque generator that generates a target steering torque;
a conversion unit that converts the target steering torque into a target twist angle;
a torsion angle control unit that calculates a current command value, which is a target value of the current, such that the torsion bar of the steering mechanism follows the target torsion angle;
12. A controller for a vehicle steering system according to claim 1, wherein said target steering torque is used as said control information. a target steering torque generator that generates a target steering torque;
a conversion unit that converts the target steering torque into a target twist angle;
a torsion angle control unit that calculates a current command value, which is a target value of the current, such that the torsion bar of the steering mechanism follows the target torsion angle;
12. A controller for a vehicle steering system according to claim 1, wherein said current command value is used as said control information. 12. A control device for a vehicle steering system according to claim 1, wherein said steering mechanism has an elastic body or a torsion bar between said steering wheel and said reaction force actuator. A control device for a vehicle steering system that has a steering end that is a steerable limit, drives and controls a reaction force actuator by adjusting a supplied current, and controls a steering mechanism,
reducing the current after a state in which the magnitude of the steering torque is equal to or greater than the first steering torque threshold continues for a first predetermined time;
increasing the current after the magnitude of the steering torque continues to be smaller than the second steering torque threshold, which is smaller than the first steering torque threshold, for a second predetermined time period after the current is decreased; A controller for a steering system for a vehicle. A control device for a vehicle steering system that has a steering end that is a steerable limit, drives and controls a reaction force actuator by adjusting a supplied current, and controls a steering mechanism,
reducing the current after a state in which the magnitude of the steering angle is greater than or equal to the first steering angle threshold continues for a first predetermined time;
After decreasing the current, increasing the current after the magnitude of the steering angle continues to be less than the first steering angle threshold and less than the second steering angle threshold for a second predetermined time. A controller for a steering system for a vehicle. 17. A control device for a vehicle steering system according to claim 15 or 16, wherein said steering mechanism has an elastic member or a torsion bar between said steering wheel and said reaction force actuator. a control device for a vehicle steering system according to any one of claims 1 to 17;
and the steering mechanism controlled by the controller.

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