JP2021142795A - Steering controller - Google Patents

Abstract

To provide a steering controller capable of properly implementing control of a turning angle of turning wheels.SOLUTION: A steering controller 1 includes a hydraulic actuator and an electric actuator, and treats as an object of control a steering unit whose cylinder tube is elastically supported by a vehicle body. The steering controller 1 includes a torque command value arithmetic unit 91, a correction unit 101, and a turning processing unit 93. The torque command value arithmetic unit 91 computes a torque command value T* which is a target value of a relative displacement quantity of a rack shaft in an axial direction with respect to the cylinder tube. The steering controller 1 uses the correction unit 101 to compute a correction value C on the basis of a rack shaft force Fa detected by a shaft force sensor. The steering controller 1 uses the turning processing unit 93 to control the electric actuator on the basis of the torque command value T* and the correction value C.SELECTED DRAWING: Figure 3

Description

The present invention relates to a steering control device.

Patent Document 1 discloses a steering device including a hydraulic actuator and an electric actuator. The hydraulic actuator applies a pressing force for axially relative displacement of the rack shaft by the hydraulic pressure of the hydraulic oil discharged from the pump. The electric actuator applies motor torque to rotate the steering shaft. The rack shaft is displaced relative to the axial direction according to the rotation of the steering shaft.

Such a steering device includes, for example, a steering gearbox as shown in Patent Document 2. The steering gearbox regulates the displacement in the direction intersecting the axial direction while allowing the relative displacement of the rack axis in the axial direction. Mounting holes are provided at a plurality of locations in the steering gearbox. A rubber mount bush is fitted in the mounting hole. The steering gearbox is fixed to the vehicle body via the mount bush by inserting a bolt into the mount bush. As a result, the steering gearbox is elastically supported by the vehicle body.

Japanese Unexamined Patent Publication No. 2005-254843 Japanese Unexamined Patent Publication No. 2009-236297

The steering device steers the steering wheels of a vehicle by displaced the rack shaft relative to the steering gearbox in the axial direction. The steering control device that controls such a steering device controls the steering angle of the steering wheel by controlling the amount of relative displacement of the rack shaft in the axial direction with respect to the steering gearbox. However, when the steering gearbox is elastically supported on the vehicle body by the mount bush as described above, the steering gearbox may be displaced relative to the vehicle body in the axial direction due to the elasticity of the mount bush. In this case, there is a difference between the amount of axial displacement of the rack shaft with respect to the steering gearbox and the amount of relative displacement of the rack shaft with respect to the vehicle body in the axial direction by the amount of relative displacement of the rack shaft with respect to the vehicle body. Occurs. That is, when the steering gearbox is not displaced relative to the vehicle body in the axial direction, the amount of relative displacement that the rack shaft originally wants to be displaced with respect to the vehicle body and the actual relative displacement of the rack shaft with respect to the vehicle body in the axial direction. There is a difference between the amount and the amount of displacement relative to the steering gearbox with respect to the vehicle body.

Specifically, when the steering wheel is steered in one direction, a motor torque for rotating the steering shaft is applied from the electric actuator so as to relatively displace the rack shaft in one direction away from the neutral position in the axial direction. , A pressing force is applied from the hydraulic actuator to relatively displace the rack shaft in the axial direction. At this time, a rack axle force as a load caused by the steering wheel trying to return to the neutral position acts on the rack axle. Since this rack axial force acts on the steering gearbox via the rack shaft, a force that causes the steering gearbox to be displaced relative to the vehicle body in the other direction is applied, and the steering gearbox is displaced relative to the vehicle body in the other direction. do. Here, the direction in which the steering gearbox is displaced relative to the vehicle body is opposite to the direction in which the rack shaft is displaced relative to the steering gearbox. Therefore, when the steering gearbox is displaced relative to the vehicle body in the axial direction, the original displacement of the rack axis with respect to the vehicle body in the axial direction when the steering gearbox is not displaced relative to the vehicle body in the axial direction. The relative displacement amount to be desired and the actual relative displacement amount of the rack axis with respect to the vehicle body in the axial direction will deviate from each other. The difference between the relative displacement amount of the rack shaft originally desired to be displaced and the actual relative displacement amount of the rack shaft generated in this way is determined by controlling the axial relative displacement amount of the rack shaft with respect to the steering gearbox. When controlling the steering angle, it may cause a decrease in the accuracy of the steering angle control and a delay in responsiveness.

The steering control device that solves the above problems reciprocates in the axial direction according to the rotation of the steering shaft to which the pump and the steering wheel are connected, thereby steering the steering wheel of the vehicle in the axial direction of the rack shaft. A cylinder tube that allows relative displacement and applies a pressing force for relative displacement of the rack shaft in the axial direction by the oil pressure of the hydraulic oil discharged from the pump, and a cylinder tube to the cylinder tube based on a steering operation. A hydraulic actuator having a control valve for controlling the supply and discharge of hydraulic oil, and
An electric actuator having a motor for applying motor torque for rotating the steering shaft, and the like.
A steering control device for controlling a steering device in which the cylinder tube is elastically supported by a vehicle body, and a target value calculation for calculating a target value of a relative displacement amount of the rack shaft with respect to the cylinder tube in the axial direction. A unit, a correction unit that calculates a correction value based on a rack axial force as a load applied to the rack axis in the axial direction, and a target value calculated by the target value calculation unit and a correction unit calculated by the correction unit. A steering processing unit that controls the electric actuator based on the correction value is provided.

According to the above configuration, the correction unit calculates the correction value based on the rack axial force. This rack axial force corresponds to the force that causes the cylinder tube to be displaced relative to the vehicle body. Therefore, it is possible to calculate a correction value for bringing the amount of relative displacement of the rack axis with respect to the vehicle body in the axial direction closer to the amount of relative displacement that is originally desired to be displaced. The steering processing unit controls the electric actuator based on the target value and the correction value. As a result, the motor torque for rotating the steering shaft from the electric actuator can be appropriately applied through the control of the electric actuator, and the push for axially displaced the rack shaft from the hydraulic actuator through the control of the electric actuator. The pressure can be applied appropriately. In this way, the steering processing unit controls the relative displacement amount of the rack shaft with respect to the cylinder tube in the axial direction based on the target value and the correction value, and therefore uses the correction value based on the rack axial force for the relative displacement amount. Compared with the case where the control is performed based only on the uncorrected target value, it is possible to suppress the influence of elastically supporting the cylinder tube on the vehicle body on the control of the steering angle of the steering wheel.

In the above steering control device, it is preferable that the cylinder tube is elastically supported with respect to the vehicle body by a bush provided with an elastic portion.
When the cylinder tube is fixed to the vehicle body via a bush having an elastic portion, the rack axle force due to the load from the steering wheel acts on the rack shaft causes the cylinder tube to act on the vehicle body. There is a risk of relative displacement. When controlling the amount of axial displacement of the rack shaft with respect to the cylinder tube based only on the uncorrected target value without using the correction value based on the rack axial force, the cylinder tube is displaced relative to the vehicle body. Then, the amount of relative displacement of the rack shaft with respect to the vehicle body in the axial direction is smaller than the amount of relative displacement of the rack shaft with respect to the cylinder tube in the axial direction. In the above configuration, since the control is performed based on the correction value based on the rack axial force in addition to the target value, it is possible to suppress the occurrence of such a situation.

In the steering control device, the correction unit multiplies the rack axial force by a coefficient set according to the elastic coefficient of the elastic portion, thereby causing a relative displacement amount of the cylinder tube with respect to the vehicle body in the axial direction. The displacement amount calculation unit that calculates the correction value, the correction value calculation unit that calculates the correction value based on the axial relative displacement amount of the cylinder tube with respect to the vehicle body calculated by the displacement amount calculation unit, and the target value calculation. It has a correction processing unit that corrects the target value based on the target value calculated by the unit and the correction value calculated by the correction value calculation unit, and the steering processing unit is corrected. It is preferable to control the electric actuator based on the target value.

Since the rack axial force corresponds to the force that relatively displaces the cylinder tube with respect to the vehicle body, the displacement amount calculation unit calculates the amount of axial displacement of the cylinder tube with respect to the vehicle body based on the rack axial force. can do. The correction value calculation unit calculates the correction value based on the relative displacement amount calculated in this way. As described above, the above configuration can be adopted as a specific configuration of the correction unit.

In the steering control device, the target value calculation unit calculates the target value that reflects the driving support command value for executing the driving support control that supports the driver's driving, and the correction unit calculates the target value. It is preferable to correct the target value by correcting the driving support command value with the correction value calculated based on the rack axial force.

Even when the driving support control is executed, the effect of elastically supporting the cylinder tube on the vehicle body on the control of the steering angle of the steering wheel occurs. According to the above configuration, even when the driving support control is executed, the steering wheel by elastically supporting the cylinder tube to the vehicle body in order to correct the target value by correcting the driving support command value based on the rack axial force. It is possible to suppress the influence on the control of the steering angle.

According to the steering control device of the present invention, it is possible to more appropriately control the steering angle of the steering wheel.

Schematic configuration diagram of the steering device. Schematic cross-sectional view of the mount and bush. Block diagram of the steering control device. The graph which shows the relationship between the rack axial force and the relative displacement amount. The figure which shows the processing flow of the correction part.

An embodiment of the steering control device will be described with reference to the drawings.
As shown in FIG. 1, the steering device 2 to be controlled by the steering control device 1 has a steering mechanism 5 that steers the steering wheel 4 based on an operation of the steering wheel 3 by the driver, and a pressing force on the steering mechanism 5. The hydraulic actuator 6 for applying the motor torque to the steering mechanism 5 and the electric actuator 7 for applying the motor torque to the steering mechanism 5 are provided.

The steering mechanism 5 includes a steering shaft 11 to which the steering wheel 3 is fixed, and a rack shaft 12 that reciprocates in the axial direction X according to the rotation of the steering shaft 11. The steering shaft 11 is configured by connecting a column shaft 14, an intermediate shaft 15, and a pinion shaft 16 in this order from the steering wheel 3 side.

The rack shaft 12 and the pinion shaft 16 are arranged at a predetermined crossing angle, and the rack and pinion teeth 12a formed on the rack shaft 12 and the pinion teeth 16a formed on the pinion shaft 16 are meshed with each other to rack and pinion. The pinion mechanism 17 is configured. Further, tie rods 18 are connected to both ends of the rack shaft 12, and the tip of the tie rod 18 is connected to a knuckle (not shown) to which the steering wheel 4 is assembled. Therefore, in the steering device 2, the rotation of the steering shaft 11 accompanying the steering operation is converted into the movement of the rack shaft 12 in the axial direction X by the rack and pinion mechanism 17, and the movement of the rack shaft 12 in the axial direction X causes the tie rod 18. By being transmitted to the knuckle via the steering wheel 4, the steering angle of the steering wheel 4, that is, the traveling direction of the vehicle is changed.

A first torsion bar 14a is provided in the middle of the column shaft 14. The first torsion bar 14a is provided between the input shaft on the steering wheel 3 side of the column shaft 14 and the output shaft on the steering wheel 4 side of the column shaft 14. The first torsion bar 14a is twisted when the input shaft of the column shaft 14 rotates with the steering of the steering wheel 3. A second torsion bar 16b is provided in the middle of the pinion shaft 16. The second torsion bar 16b is provided between the input shaft on the steering wheel 3 side of the pinion shaft 16 and the output shaft on the steering wheel 4 side of the pinion shaft 16. The second torsion bar 16b is twisted when the input shaft of the pinion shaft 16 rotates.

The hydraulic actuator 6 is a hydraulic cylinder 23 that applies a pressing force to the rack shaft 12 via a pump 21 that is a supply source of hydraulic oil, a reservoir tank 22 that stores hydraulic oil, and a piston 35 that will be described later based on a hydraulic difference. And a control valve 24 for controlling the supply and discharge of hydraulic oil to the hydraulic cylinder 23. Further, the hydraulic actuator 6 includes oil passages L1 to L5 for connecting the pump 21, the reservoir tank 22, the hydraulic cylinder 23, and the control valve 24. The pump 21 employs an engine-driven pump driven by the rotation of the crankshaft of the internal combustion engine 31.

The hydraulic cylinder 23 includes a cylindrical cylinder tube 32 into which a rack shaft 12 is reciprocally inserted in the axial direction X, and a piston 35 that divides the inside of the cylinder tube 32 into a first hydraulic chamber 33 and a second hydraulic chamber 34. And have. The piston 35 is fixed to the rack shaft 12 so that it can move in the axial direction X integrally with the rack shaft 12. In the present embodiment, the cylinder tube 32 regulates the displacement of the rack shaft 12 in the direction intersecting the axial direction X while allowing the relative displacement of the rack shaft 12 in the axial direction X.

The control valve 24 is configured as a well-known rotary valve that controls the supply and discharge of hydraulic oil to the first hydraulic chamber 33 and the second hydraulic chamber 34 of the hydraulic cylinder 23 in conjunction with the steering operation. The control valve 24 is provided so as to rotatably surround the pinion shaft 16 so as to include the second torsion bar 16b. When the input shaft of the pinion shaft 16 rotates, the second torsion bar 16b is twisted by the rotation. When an angle difference occurs between the rotation angle of the input shaft of the pinion shaft 16 and the rotation angle of the output shaft of the pinion shaft 16 due to this twist, the hydraulic cylinder 23 operates in the first hydraulic chamber 33 and the second hydraulic chamber 34. The amount of oil supplied and discharged changes. Specifically, the control valve 24 is provided with a supply port 36, a discharge port 37, a first supply / discharge port 38, and a second supply / discharge port 39. The supply port 36 is connected to the pump 21 via the supply oil passage L1. The discharge port 37 is connected to the reservoir tank 22 via the discharge oil passage L2. The first supply / discharge port 38 is connected to the first oil supply / drainage chamber 33 via the first oil supply / discharge passage L3. The second supply / discharge port 39 is connected to the second hydraulic chamber 34 via the second oil supply / discharge passage L4. The pump 21 and the reservoir tank 22 are connected to each other via a suction oil passage L5.

In the present embodiment, as a configuration for fixing the cylinder tube 32 to the vehicle body, a configuration for elastically supporting the cylinder tube 32 with respect to the vehicle body is adopted. Specifically, a mount portion 61 is provided on the outer surface of the cylinder tube 32. The cylinder tube 32 is elastically supported with respect to the vehicle body by the mount portion 61 and the bush 71 provided on the outer surface of the cylinder tube 32. Here, the suspension member 62 is illustrated as a part of the vehicle body.

As shown in FIG. 2, the mount portion 61 is fastened and fixed to the suspension member 62 via the bush 71. The bush 71 has a tubular portion 72, a flange portion 73, and an elastic portion 74. The elastic portion 74 and the tubular portion 72 are inserted into the inner peripheral surface 61a of the mount portion 61 with the elastic portion 74 covering the radial outer side of the tubular portion 72. Here, both of the elastic portion 74 and the tubular portion 72 have both end portions protruding outward from the inner peripheral surface 61a. The protruding portion of the elastic portion 74 extends radially outward of the tubular portion 72. On the other hand, the flange portions 73 are provided on both sides in a direction parallel to the direction Y advancing to the suspension member 62, protruding from the inner peripheral surface 61a of the mount portion 61. The flange portion 73 extends radially outward of the tubular portion 72 so as to follow the elastic portion 74. Here, the tubular portion 72 and the flange portion 73 are a hard solid such as a metal or a rigid body such as a polycrystalline body having "hardness" and "strength". The elastic portion 74 is an elastic body such as rubber that is easily elastically deformed.

The mounting portion 61 is fastened to the suspension member 62 by inserting the fastening member 63 into the inner peripheral surface of the hole 72a penetrating the tubular portion 72 and the hole 73a penetrating the flange portion 73. Therefore, the mount portion 61 is elastically supported by the suspension member 62. As a result, the cylinder tube 32 is elastically supported by the vehicle body.

As shown in FIG. 1, the electric actuator 7 includes a motor 41 which is a drive source, and a reduction mechanism 42 such as a worm and wheel which is connected to the motor 41 and also to the column shaft 14. The connecting portion of the column shaft 14 with the speed reduction mechanism 42 is provided on the steering wheel 4 side of the first torsion bar 14a. The electric actuator 7 decelerates the motor torque output by the motor 41 by the reduction mechanism 42 and transmits it to the column shaft 14. For the motor 41 of the present embodiment, for example, a three-phase brushless motor is adopted.

In the steering device 2 configured in this way, the hydraulic oil delivered from the pump 21 is controlled via the supply oil passage L1 after the flow rate is controlled to a predetermined amount by a solenoid valve (not shown) built in the pump 21. It is supplied to the valve 24. Then, the hydraulic oil supplied to the control valve 24 fills either the first oil supply / drainage passage L3 or the second oil supply / drainage passage L4 in response to the twist of the second torsion bar 16b due to the rotation of the steering shaft 11. It is supplied to either the first hydraulic chamber 33 or the second hydraulic chamber 34 via the first hydraulic chamber 33. At this time, the hydraulic oil is discharged from either the first hydraulic chamber 33 or the second hydraulic chamber 34. This hydraulic oil is discharged to the reservoir tank 22 via the control valve 24 and the drainage oil passage L2, whichever of the first oil supply / drainage passage L3 and the second oil supply / drainage passage L4. As a result, a hydraulic difference is generated between the first hydraulic chamber 33 and the second hydraulic chamber 34, and based on this hydraulic difference, it is applied as a pressing force in the axial direction X acting on the piston 35 and the rack shaft 12. The pressing force in the axial direction X based on this hydraulic pressure difference is a force that causes the rack shaft 12 to be displaced relative to the cylinder tube 32 in the axial direction X. The pressing force in the axial direction X based on the hydraulic pressure difference is applied to the steering mechanism 5 as an assist force, so that the steering operation is assisted. Further, in the steering device 2, even when the steering shaft 11 is rotated by the motor torque applied from the electric actuator 7, a pressing force in the axial direction X similar to that when the steering operation is performed on the hydraulic cylinder 23 is generated. The pressing force in the axial direction X based on this hydraulic pressure difference is a force that causes the rack shaft 12 to be displaced relative to the cylinder tube 32 in the axial direction X. The steering angle of the steering wheel 4 can be changed by moving the rack shaft 12 in the axial direction X by the pressing force in the axial direction X based on the hydraulic pressure difference. The pressing force applied to the rack shaft 12 increases as the amount of rotation from the neutral position of the steering shaft 11 increases.

The configuration of the steering control device 1 will be described.
As shown in FIG. 1, the steering control device 1 is connected to the motor 41 and controls its operation. The steering control device 1 includes a central processing unit and a memory (not shown), and the central processing unit executes a program stored in the memory at predetermined calculation cycles to execute various controls.

The steering control device 1 is connected to a vehicle speed sensor 51 that detects the vehicle speed V, which is the traveling speed of the vehicle, and a torque sensor 52 that detects the steering torque Th applied to the steering shaft 11. The torque sensor 52 detects the steering torque Th based on the twist of the first torsion bar 14a. Further, the steering control device 1 is connected to a rotation angle sensor 54 that detects the rotation angle θm of the motor 41 at a relative angle within a range of 360 degrees. The steering torque Th and the rotation angle θm are detected as positive values when steering in one direction and as negative values when steering in the other direction. Further, a pressure sensor 55 for detecting the discharge pressure Pd of the pump 21 is connected to the steering control device 1. The pressure sensor 55 has another control device (not shown) of the internal combustion engine 31 so that the internal combustion engine 31 does not stop due to an increase in the discharge pressure Pd of the pump 21 when, for example, a steering operation is performed when the vehicle is idle. Used to control operation. That is, the pressure sensor 55 is a sensor used for performing so-called idle-up control. Further, the steering control device 1 is connected to an axial force sensor 56 that detects the rack axial force Fa, which is a detection value of the axial force acting on the rack shaft 12. The axial force sensor 56 is a sensor that detects the rack axial force Fa based on, for example, the movement of the rack shaft 12 in the axial direction X. The rack axial force Fa is a load applied to the rack shaft 12 in the axial direction X. The steering control device 1 acquires the rack axial force Fa from the axial force sensor 56 in the dimension of torque.

The steering control device 1 is connected to a driving support control device 57 provided outside the steering control device 1. The driving support control device 57 is connected to a camera 58 that captures image data and an operation switch 59 that is provided near the driver's seat of the vehicle to execute driving support control. As the driving support control, the driving support control device 57 of the present embodiment executes, for example, lane departure prevention support control that assists the driver's steering operation so as to maintain the traveling lane in which the vehicle is traveling and facilitate the driving. .. The driving support control device 57 calculates an ideal steering angle at which the vehicle can maintain driving in the lane based on the image data captured by the camera 58 when the lane departure prevention support control is executed, and this ideal. The driving support command value θ * is calculated according to the deviation between the typical steering angle and the actual steering angle of the steering wheel 4. The driving support command value θ * of the present embodiment is an angle command value indicating a target value of the rotation angle of the pinion shaft 16. The driving support control device 57 executes driving support control according to the on / off of the operation switch 59. The driving support control device 57 outputs the driving support command value θ * to the steering control device 1 when the driving support control is executed.

The steering control device 1 operates the electric actuator 7 by supplying driving power to the motor 41 based on the signal indicating each state amount input from each of these sensors and the signal input from the driving support control device 57. To control.

The configuration of the steering control device 1 will be described.
As shown in FIG. 3, the steering control device 1 includes a microcomputer 81 that outputs a control signal and a drive circuit 82 that supplies drive power to the motor 41 based on the control signal. The drive circuit 82 of this embodiment employs a well-known PWM inverter having a plurality of switching elements. The control signal output by the microcomputer 81 defines the on / off state of each switching element. As a result, each switching element is turned on and off in response to the control signal, and the energization pattern of each phase to the motor coil is switched, so that the driving power of the three phases is output to the motor 41.

The vehicle speed V, steering torque Th, rotation angle θm, rack axial force Fa, and driving support command value θ * are input to the microcomputer 81. Further, each phase current value Iu, Iv, Iw of the motor 41 detected by the current sensor 84 provided on the connection line 83 between the drive circuit 82 and the motor coil of each phase is input to the microcomputer 81. .. In FIG. 3, for convenience of explanation, the connection line 83 of each phase and the current sensor 84 of each phase are shown together. Then, the microcomputer 81 outputs a control signal based on each of these state quantities.

Specifically, the microcomputer 81 includes a torque command value calculation unit 91 that calculates a torque command value T * that is a target value of the motor torque output by the motor 41, and current command values Id * and Iq corresponding to the torque command value T *. It has a current command value calculation unit 92 that calculates *, and a steering processing unit 93 that outputs a control signal based on the current command values Id * and Iq *. The current command values Id * and Iq * are target values of the current to be supplied to the motor 41. The current command value Id * indicates the current command value on the d-axis in the d / q coordinate system. The current command value Iq * indicates the current command value on the q axis in the d / q coordinate system.

The torque command value calculation unit 91 has a basic command value calculation unit 94 that calculates the basic command value Tb *, which is a basic component of the torque command value T *. The steering torque Th, the vehicle speed V, and the driving support command value θ * are input to the basic command value calculation unit 94. When the basic command value calculation unit 94 is not executing the driving support control, the motor is based on the steering torque Th so that the internal friction of the electric actuator 7 itself does not affect the steering operation of the driver. Calculate the basic command value Tb * that operates 41. In the present embodiment, the basic command value calculation unit 94 determines whether or not the driving support control is being executed based on whether or not the driving support command value θ * is input. The calculated basic command value Tb * is output to the adder 95. In addition to the basic command value Tb *, the driving support torque command value Tad * for executing the driving support control described later is input to the adder 95. The torque command value calculation unit 91 calculates the torque command value T * by adding the operation support torque command value Tad * to the basic command value Tb * in the adder 95. When the driving support control is being executed, the basic command value calculation unit 94 sets the component that assists the steering operation to substantially zero. Then, the torque command value calculation unit 91 calculates the operation support torque command value Tad * for executing the operation support control as the torque command value T * in the adder 95.

The torque command value T * is input to the current command value calculation unit 92. The current command value calculation unit 92 calculates the q-axis current command value Iq * corresponding to the torque command value T * and outputs it to the steering processing unit 93. In the present embodiment, the current command value Id * on the d-axis is basically fixed to zero.

The steering processing unit 93 executes current feedback control in the d / q coordinate system based on the current command values Id *, Iq *, the phase current values Iu, Iv, Iw, and the rotation angle θm of the motor 41. Generates a control signal. Specifically, the steering processing unit 93 maps each phase current value Iu, Iv, Iw to the d / q coordinate system based on the rotation angle θm, so that the actual current of the motor 41 in the d / q coordinate system The d-axis current value and the q-axis current value, which are the values, are calculated. The steering processing unit 93 executes current feedback control so that the d-axis current value follows the d-axis current command value Id * and the q-axis current value follows the q-axis current command value Iq *. By doing so, a control signal is generated. When this control signal is output to the drive circuit 82, drive power corresponding to the control signal is supplied to the motor 41. As a result, the drive of the motor 41 is controlled so that the motor torque output by the motor 41 follows the torque command value corresponding to the current command value Iq * of the q-axis.

The microcomputer 81 further includes a correction unit 101 that corrects the operation support command value θ * based on the rack axial force Fa acquired by the axial force sensor 56, and a rotation angle calculation unit 96 that calculates the rotation angle θp of the pinion shaft 16. It has an angle feedback control unit 97 that executes angle feedback control based on the corrected driving support command value θp * and the rotation angle θp.

The correction unit 101 includes a displacement amount calculation unit 102, a correction value calculation unit 103, and an adder 104. The displacement amount calculation unit 102 acquires the rack axial force Fa detected by the axial force sensor 56. The displacement amount calculation unit 102 multiplies the rack axial force Fa by a coefficient set according to the configuration for fixing the cylinder tube 32 to the vehicle body, thereby causing the cylinder tube 32 to be displaced relative to the vehicle body in the axial direction X. Calculate the quantity D. In the present embodiment, the coefficient set according to the configuration for fixing the cylinder tube 32 to the vehicle body is set based on the rigidity of the mount portion 61 for fixing the cylinder tube 32 to the vehicle body, that is, the elastic modulus. It is a coefficient.

As shown in FIG. 4, there is a proportional relationship between the rack axial force Fa and the relative displacement amount D. The inclination of the relative displacement amount D with respect to the rack axial force Fa is a coefficient set according to the configuration in which the cylinder tube 32 is fixed to the vehicle body. The absolute value of the axial force applied to the rack shaft 12 and the absolute value of the rack axial force Fa can be regarded as equal.

As shown in FIG. 3, the correction value calculation unit 103 acquires the relative displacement amount D calculated by the displacement amount calculation unit 102. The correction value calculation unit 103 calculates the correction value C by multiplying the relative displacement amount D by the conversion coefficient. The conversion coefficient is a coefficient set based on the ratio of the rotation angle of the pinion shaft 16 to the amount of relative displacement of the rack shaft 12 with respect to the cylinder tube 32 in the axial direction X. When setting the conversion coefficient, the change in the rotation angle of the pinion shaft 16 when the cylinder tube 32 is displaced relative to the vehicle body in the axial direction X, and the rack shaft 12 is displaced relative to the cylinder tube 32 in the axial direction X. It is considered that the change in the rotation angle of the pinion shaft 16 at the time of this is the same. In this way, the correction value calculation unit 103 calculates the amount of change in the rotation angle of the pinion shaft 16 with respect to the relative displacement amount D as the correction value C. In other words, the correction value calculation unit 103 calculates a correction value C that eliminates the difference between the original relative displacement amount of the rack shaft 12 with respect to the vehicle body in the axial direction X and the actual relative displacement amount of the rack shaft 12. .. The original relative displacement amount of the rack shaft 12 with respect to the cylinder tube 32 in the axial direction X is when the cylinder tube 32 is not displaced relative to the vehicle body in the axial direction X, that is, when the relative displacement amount D is zero. It is a relative displacement amount that the rack shaft 12 is originally desired to be displaced in the axial direction X with respect to the vehicle body.

The adder 104 acquires the driving support command value θ * calculated by the driving support control device 57 and the correction value C calculated by the correction value calculation unit 103. The adder 104 calculates the corrected driving support command value θp * by adding the correction value C to the driving support command value θ *. The correction processing unit described in the claims corresponds to the adder 104.

The rotation angle calculation unit 96 calculates the rotation angle θp of the pinion shaft 16 based on the rotation angle θm detected by the rotation angle sensor 54.
The angle feedback control unit 97 acquires the corrected driving support command value θp * calculated by the correction unit 101 and the rotation angle θp calculated by the rotation angle calculation unit 96. The angle feedback control unit 97 executes angle feedback control based on the deviation between the corrected driving support command value θp * and the rotation angle θp in order to make the rotation angle θp follow the corrected driving support command value θp *. Calculate the driving support torque command value Tad *.

FIG. 5 shows the processing of the correction unit 101. The correction unit 101 repeatedly executes the process shown in FIG. 5 at a predetermined cycle.
As shown in FIG. 5, the correction unit 101 acquires the rack axial force Fa detected by the axial force sensor 56 (step S11), calculates the relative displacement amount D based on the rack axial force Fa (step S12), and calculates the relative displacement amount D (step S12). The correction value C is calculated based on the relative displacement amount D (step S13). Then, the correction unit 101 adds the correction value C to the driving support command value θ * calculated by the driving support control device 57 (step S14). As a result, the correction unit 101 calculates the corrected driving support command value θp * that corrects the driving support command value θ *, and outputs the calculated corrected driving support command value θp * to the angle feedback control unit 97.

The target value calculation unit described in the claims corresponds to the torque command value calculation unit 91. The operation support command value θ * is a value that is the basis of the torque command value T *, which is a target value of the amount of relative displacement of the rack shaft 12 with respect to the cylinder tube 32 in the axial direction X. That is, the torque command value T * is a value that reflects the driving support command value θ *. The target value described in the claims is an uncorrected torque command value that reflects the driving support command value θ * that has not been corrected by the correction value C. The uncorrected torque command value is the driving support torque command value Tad * obtained by controlling the angle feedback between the uncorrected driving support command value θ * and the rotation angle θp by the angle feedback control unit 97. It is a value obtained by adding the basic command value Tb * and the basic command value Tb *. In the present embodiment, the torque is obtained by adding the correction value C to the driving support command value θ * which is the base value of the torque command value T * which is the target value, that is, the value reflected in the torque command value T *. The command value T * is corrected. The steering processing unit 93 controls the electric actuator 7 based on the corrected torque command value T * that reflects the corrected driving support command value θp * corrected by the correction value C. That is, the steering processing unit 93 uses the torque command value T * in which the corrected driving support command value θp * is reflected by the correction value C, and is based on the torque command value and the correction value C that have not been corrected. It controls the electric actuator 7.

The operation of this embodiment will be described.
When the driving support control is executed, the steering wheel 4 is controlled based on the driving support command value θ *. For example, when the steering wheel 4 is steered in one direction based on the driving support command value θ *, the steering shaft 11 is rotated from the electric actuator 7 so as to relatively displace the rack shaft 12 in one direction from the neutral position. The motor torque for this purpose is applied, and a pressing force for relative displacement of the rack shaft 12 in the axial direction X is applied from the hydraulic actuator 6. As a result, the rack shaft 12 is displaced relative to the cylinder tube 32 in one direction. At this time, a load caused by the steering wheel 4 trying to return to the neutral position acts on the rack shaft 12. Since the relative displacement force acts on the cylinder tube 32, the cylinder tube 32 is displaced relative to the vehicle body in the axial direction X. Here, the direction in which the cylinder tube 32 is relative to the vehicle body is opposite to the direction in which the rack shaft 12 is relative to the cylinder tube 32. That is, when the rack shaft 12 is displaced relative to the cylinder tube 32 in one direction, the cylinder tube 32 is displaced relative to the vehicle body in the other direction. In this case, the actual relative displacement amount of the rack shaft 12 with respect to the vehicle body in the axial direction X is the axial direction X of the rack shaft 12 with respect to the vehicle body by the amount of the relative displacement D of the cylinder tube 32 with respect to the vehicle body. It becomes smaller than the relative displacement amount that is originally desired to be displaced.

In the present embodiment, the correction unit 101 corrects the operation support command value θ * based on the rack axial force Fa. Since this rack axial force Fa corresponds to a force that relatively displaces the cylinder tube 32 with respect to the vehicle body, the amount D of the relative displacement of the cylinder tube 32 with respect to the vehicle body in the axial direction X due to the rack axial force Fa is calculated. can do. The correction unit 101 has a relative displacement amount of the rack shaft 12 with respect to the cylinder tube 32 in one direction as compared with the case where the steering angle of the steering wheel 4 is controlled based on the uncorrected driving support command value θ *. The driving support command value θ * is corrected so that it becomes a large value. The torque command value calculation unit 91 is relative to the cylinder tube 32 in one direction as compared with the case where the steering angle of the steering wheel 4 is controlled based on the uncorrected driving support command value θ *. The torque command value T * is calculated so that the displacement amount becomes a large value. Therefore, by correcting the driving support command value θ * based on the rack axial force Fa, the actual relative displacement amount of the rack shaft 12 with respect to the vehicle body in the axial direction X is changed to the axial direction X of the rack shaft 12 with respect to the vehicle body. It is possible to approach the relative displacement amount that is originally desired to be displaced. The current command value calculation unit 92 calculates the current command values Id * and Iq * corresponding to the torque command value T * that reflects the corrected corrected operation support command value θp *. The steering processing unit 93 generates a control signal according to the current command values Id * and Iq *. Thereby, the motor torque for rotating the steering shaft 11 from the electric actuator 7 can be appropriately applied through the control of the electric actuator 7. Further, through the control of the electric actuator 7, it is possible to appropriately apply a pressing force for displaced the rack shaft 12 relative to the axial direction X from the hydraulic actuator 6. By doing so, the steering wheel 4 is elastically supported by the cylinder tube 32 as compared with the case where the steering angle of the steering wheel 4 is controlled based on the uncorrected driving support command value θ *. The influence on the control of the steering angle can be suppressed.

The effect of this embodiment will be described.
(1) Since it is possible to suppress the influence of elastically supporting the cylinder tube 32 on the control of the steering angle of the steering wheel 4, it is possible to more appropriately control the steering angle of the steering wheel 4. can.

(2) When the cylinder tube 32 is fixed to the suspension member 62 which is a part of the vehicle body via the bush 71 provided with the elastic portion 74, the load from the steering wheel 4 acts on the rack shaft 12. The cylinder tube 32 may be displaced relative to the vehicle body due to the action of the rack axial force Fa. When controlling the steering angle of the steering wheel 4 based on the uncorrected driving support command value θ * without using the correction value C based on the rack axial force Fa, the cylinder tube 32 is displaced relative to the vehicle body. The amount of relative displacement of the rack shaft 12 with respect to the vehicle body in the axial direction X is smaller than the amount of relative displacement of the rack shaft 12 with respect to the cylinder tube 32 in the axial direction X. In the present embodiment, the torque command value T * is corrected by correcting the driving support command value θ * based on the rack axial force Fa, so that such a situation can be suppressed.

(3) Since the rack axial force Fa corresponds to a force that relatively displaces the cylinder tube 32 with respect to the vehicle body, the displacement amount calculation unit 102 determines the shaft of the cylinder tube 32 with respect to the vehicle body based on the rack axial force Fa. The relative displacement amount D in the direction X can be calculated. The correction value calculation unit 103 calculates the correction value C based on the relative displacement amount D calculated in this way. As described above, as a specific configuration of the correction unit 101 that corrects the driving support command value θ * based on the rack axial force Fa, the displacement amount calculation unit 102, the correction value calculation unit 103, and the adder 104 are provided. Things can be adopted.

(4) Even when the driving support control is executed, the effect of elastically supporting the cylinder tube 32 on the vehicle body on the control of the steering angle of the steering wheel 4 occurs. According to the present embodiment, even when the driving support control is executed, the cylinder tube 32 is mounted on the vehicle body in order to correct the torque command value T * by correcting the driving support command value θ * based on the rack axial force Fa. It is possible to suppress the influence on the control of the steering angle of the steering wheel 4 by elastically supporting the steering wheel 4.

(5) When the cylinder tube 32 is elastically supported by the vehicle body via the bush 71, the rack axial force Fa caused by the load from the steering wheel 4 acting on the rack shaft 12 acts on the cylinder tube. There is a risk that the 32 will be displaced relative to the vehicle body. When the cylinder tube 32 is displaced relative to the vehicle body due to the rack axial force Fa, the accuracy of controlling the steering angle of the steering wheel 4 is lowered and the response is delayed. In the present embodiment, the torque command value T * is corrected by correcting the driving support command value θ * based on the rack axial force Fa, so that such a situation can be suppressed.

(6) It is also conceivable to attach the cylinder tube 32 to the vehicle body so that the relative displacement amount of the cylinder tube 32 in the axial direction X with respect to the vehicle body does not occur without elastically supporting the cylinder tube 32 when it is attached to the vehicle body. In this case, when the steering angle of the steering wheel 4 is controlled, an impact may be transmitted from the steering wheel 4 to the cylinder tube 32 due to the load caused by the steering wheel 4 trying to return to the neutral position. In the present embodiment, since the cylinder tube 32 is elastically supported when it is attached to the vehicle body, the impact transmitted from the steering wheel 4 to the cylinder tube 32 can be alleviated.

The above embodiment may be modified as follows. In addition, the following other embodiments can be combined with each other to the extent that they are technically consistent.
A bush 71 having an elastic portion 74 and a mount portion 61 have been adopted as a configuration for fixing the cylinder tube 32 to the vehicle body, but the present invention is not limited to this. For example, as a configuration for fixing the cylinder tube 32 to the vehicle body, a configuration for adhesively fixing the cylinder tube 32 with an elastic body interposed between the cylinder tube 32 and the vehicle body may be adopted. That is, any configuration may be adopted for fixing the cylinder tube 32 to the vehicle body as long as the cylinder tube 32 can be elastically supported with respect to the vehicle body.

The correction unit 101 corrects the torque command value T * by correcting the driving support command value θ *, but the present invention is not limited to this. For example, the correction unit 101 may directly correct the torque command value T *. In this case, the angle feedback control unit 97 executes the angle feedback control based on the deviation between the uncorrected driving support command value θ * and the rotation angle θp, so that the uncorrected driving support torque command value Tad Calculate *. The adder 95 calculates the torque command value T * by adding the driving support torque command value Tad * to the basic command value Tb *. The correction unit 101 calculates a torque correction value for correcting the torque command value T * based on the rack axial force Fa, and adds the torque correction value to the torque command value T * to obtain the torque command value T. * Correct. In this case, the adder 95 adds the basic command value Tb *, the driving support torque command value Tad *, and the torque correction value calculated based on the rack axial force Fa to obtain the torque command value T. * May be calculated.

-The configuration of the correction unit 101 can be changed as appropriate. For example, instead of the displacement amount calculation unit 102 and the correction value calculation unit 103, a map calculation unit that performs map calculation of the correction value C based on the rack axial force Fa may be provided. Further, instead of the adder 104, a multiplier that multiplies the driving support command value θ * by using the correction value C as a gain may be provided.

-Although the axial force sensor 56 is connected to the steering control device 1, the axial force sensor 56 may not be provided. In this case, for example, the steering control device 1 may calculate the rack axial force Fa based on the discharge pressure Pd of the pump 21, that is, the hydraulic pressure of the hydraulic oil. Since there is a predetermined relationship between the discharge pressure Pd and the twist of the second torsion bar 16b, there is also a predetermined relationship between the discharge pressure Pd and the rack axial force Fa. Therefore, the rack axial force Fa can be calculated from the discharge pressure Pd. In this case, the portion where the steering control device 1 calculates the rack axial force Fa corresponds to the axial force acquisition unit.

-In the above embodiment, the driving support command value output by the driving support control device 57 is not limited to the angle command value. For example, the driving support command value output by the driving support control device 57 may be a torque command value. In this case, for example, the driving support command value as the torque command value is input to the adder 95, and the adder 95 calculates the sum of the basic command value Tb * and the driving support command value θ * converted into the torque value. It may be calculated as the torque command value T *. In this way, the command value output by the driving support control device 57 can be changed as appropriate. Further, the mode in which the driving support command value is reflected in the basic command value Tb * can be changed as appropriate.

-In the above embodiment, the steering control device 1 executes the driving support control using the driving support command value θ * output by the driving support control device 57, but the driving support command value θ output by the driving support control device 57. It may be the one that does not acquire *. In this case, for example, the correction unit 101 corrects the basic command value Tb *. As a result, it is possible to suppress the influence of elastically supporting the cylinder tube 32 on the vehicle body on the control of the steering angle of the steering wheel 4.

-In the above embodiment, the steering device 2 is provided with the hydraulic actuator 6, but it may not be provided.
-In the above embodiment, in the steering device 2, the electric actuator 7 applies the motor torque to the column shaft 14, but the present invention is not limited to this. For example, in the steering device 2, the electric actuator 7 may apply a motor torque to the intermediate shaft 15, or the electric actuator 7 may apply a force to move the rack shaft 12 in the axial direction. good. That is, any steering device may be used as long as it is provided with an electric actuator that applies motor torque to the steering mechanism 5 by a motor.

-In the above embodiment, the steering control device 1 is one or more dedicated hardware such as one or more processors that execute a computer program, or an integrated circuit for a specific application that executes at least a part of various processes. A computer configured as a circuit or a circuit including a combination of the processor and the dedicated hardware circuit. Each control unit constituting the steering control device 1 includes a CPU and a memory. A RAM, a ROM, or the like is adopted as the memory. The memory stores a program code or a command configured to cause the CPU to execute the process. The memory, in other words the computer-readable medium, may consist of any available medium accessible by a general purpose or dedicated computer. The configuration of the computer is the same for the driving support control device 57.

The technical ideas that can be grasped from each of the above-described embodiments and the above-mentioned other embodiments will be added below together with their effects.
(A) A steering control device including an axial force acquisition unit that calculates the rack axial force based on the hydraulic pressure of the hydraulic oil discharged from the pump. According to the above configuration, since there is a predetermined relationship between the hydraulic pressure of the hydraulic oil and the rack axial force, the hydraulic pressure of the hydraulic oil can be used as a value used for calculating the rack axial force.

(B) The steering device includes a bush that elastically supports the cylinder tube with respect to the vehicle body, and the correction unit is generated by the cylinder tube being displaced relative to the vehicle body due to the bending of the bush. A steering control device that corrects the target value so as to suppress a decrease in the accuracy of controlling the steering angle of the steering wheel. According to the above configuration, when the cylinder tube is elastically supported by the vehicle body via a bush, the cylinder tube is moved to the vehicle body by the rack axial force caused by the load from the steering wheel acting on the rack shaft. There is a risk of relative displacement with respect to. When the cylinder tube is displaced relative to the vehicle body due to the rack axial force, the accuracy of steering angle control based on the target value is lowered. In the above configuration, since control is performed based on the target value and the correction value, it is possible to suppress the occurrence of such a situation.

1 ... Steering control device 2 ... Steering device 3 ... Steering wheel 4 ... Steering wheel 6 ... Hydraulic actuator 7 ... Electric actuator 11 ... Steering shaft 12 ... Rack shaft 21 ... Pump 23 ... Hydraulic cylinder 24 ... Control valve 32 ... Cylinder tube 41 ... Motor 71 ... Bush 91 ... Torque command value calculation unit 93 ... Steering processing unit 101 ... Correction unit 102 ... Displacement amount calculation unit 103 ... Correction value calculation unit 104 ... Adder C ... Correction value D ... Relative displacement amount Fa ... Rack shaft Force θ *… Driving support command value

Claims (4)

By reciprocating in the axial direction according to the rotation of the steering shaft to which the pump and the steering wheel are connected, the rack shaft that steers the steering wheel of the vehicle is allowed to be relatively displaced in the axial direction, and from the pump. A cylinder tube that applies a pressing force for relative displacement of the rack shaft in the axial direction by the hydraulic pressure of the discharged hydraulic oil, and a control valve that controls the supply and discharge of the hydraulic oil to the cylinder tube based on the steering operation. With a hydraulic actuator and
An electric actuator having a motor for applying motor torque for rotating the steering shaft, and the like.
A steering control device for controlling a steering device in which the cylinder tube is elastically supported by a vehicle body.
A target value calculation unit that calculates a target value of a relative displacement amount of the rack shaft with respect to the cylinder tube in the axial direction, and a target value calculation unit.
A correction unit that calculates a correction value based on the rack axial force as a load applied in the axial direction to the rack shaft, and a correction unit.
A steering control device including a steering processing unit that controls the electric actuator based on the target value calculated by the target value calculation unit and the correction value calculated by the correction unit. The steering control device according to claim 1, wherein the cylinder tube is elastically supported with respect to a vehicle body by a bush having an elastic portion. The correction unit
A displacement amount calculation unit that calculates the amount of relative displacement of the cylinder tube in the axial direction with respect to the vehicle body by multiplying the rack axial force by a coefficient set according to the elastic modulus of the elastic portion.
A correction value calculation unit that calculates the correction value based on the axially relative displacement amount of the cylinder tube with respect to the vehicle body calculated by the displacement amount calculation unit.
It has a correction processing unit that corrects the target value based on the target value calculated by the target value calculation unit and the correction value calculated by the correction value calculation unit.
The steering control device according to claim 2, wherein the steering processing unit controls the electric actuator based on the corrected target value. The target value calculation unit calculates the target value that reflects the driving support command value for executing the driving support control that supports the driver's driving.
The steering control device according to any one of claims 1 to 3, wherein the correction unit corrects the target value by correcting the driving support command value with the correction value calculated based on the rack axial force. ..

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