Vehicle steering system control device

Abstract

To provide a control device of a vehicle steering system which can obtain a steering feeling on which a state of a road surface and a state of a vehicle are reflected.SOLUTION: A steering torque target value generation unit 200 comprises: a steering reaction force torque value generation part 210 which generates a first torque value Tref_a that increases / decreases according to at least an actual steering angle θh_act; a road surface reaction force induction torque compensation value generation part 220 which generates a second torque value Tref_d that increases / decreases according to a road surface reaction force torque estimation value estimated on the basis of at least a first turning motor current command value Iref_a; and a gain ratio generation part 230 which generates a first gain Ga that increases / decreases according to a vehicle speed Vs of a vehicle and a second gain Gb whose sum with the first gain Ga becomes 1. A steering torque target value Th_ref is generated by adding a value obtained by multiplying the first torque value Tref_a by the first gain Ga and a value obtained by multiplying the second torque value Tref_d by the second gain Gb.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a control device for a steering system for a vehicle. [Background technology]

[0002] One type of vehicle steering system is the steer-by-wire (SBW) system, which mechanically separates a steering mechanism (Force Feedback Actuator: FFA) with a steering wheel operated by the driver from a road wheel actuator (Road Wheel Actuator: RWA) that steers the steered wheels. In an SBW system, the steering mechanism and the road wheel actuator are electrically connected via an electronic control unit (ECU). Steering wheel operation is transmitted to the road wheel actuator via an electrical signal to steer the steered wheels, and the road wheel actuator generates a steering reaction force to give the driver an appropriate steering feel. The steering mechanism generates a steering reaction force using a reaction actuator equipped with a reaction motor, and the road wheel actuator steers the steered wheels using a steering actuator equipped with a steering motor. The reaction actuator and the road wheel are mechanically connected via a column shaft, and the reaction force (torque) generated by the reaction actuator is transmitted to the driver via the column shaft and the road wheel.

[0003] In SBW systems where the steering mechanism and the turning mechanism are mechanically separated, for example, when traveling on a frozen road or a low-μ road where the frictional resistance of the road surface has been significantly reduced due to hydroplaning in rainy weather, it is necessary to transmit oversteer or understeer to a reaction device as a steering reaction force. Patent Document 1 listed below discloses a vehicle steering device that estimates the reaction force (self-aligning torque) acting from the road surface and adds it to the reaction force generated in accordance with the steering angle, thereby reflecting the road surface conditions in the steering reaction force. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 167661 Summary of the Invention [Problem to be solved by the invention]

[0005] The self-aligning torque varies depending on the road surface conditions as well as vehicle conditions such as vehicle speed and steering angle. With the above-mentioned conventional technology, depending on the vehicle condition, it may not be possible to obtain a steering feel that reflects the road surface conditions.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a control device for a vehicle steering system that provides a steering feel that reflects road conditions and the state of the vehicle. [Means for solving the problem]

[0007] In order to achieve the above object, a control device for a vehicle steering system according to one aspect of the present invention is a control device for a vehicle steering system including a reaction device that drives a reaction motor that applies a steering reaction force to the steering wheel in accordance with the steering angle of the steering wheel, and a steering device that drives a steering motor that steers the steered wheels in accordance with the steering angle of the steering wheel, and the control device includes a steering torque target value generation unit that generates a steering torque target value that is a target value of the steering torque for obtaining the steering reaction force, a steering angle target value generation unit that generates a steering angle target value that is a target value of the steering angle of the steered wheels, based on the steering angle, and a first steering motor current command that is a target value of the current to be supplied to the steering motor, based on the steering angle target value. the steering torque target value generation unit comprises a steering reaction torque value generation unit that generates a first torque value that increases or decreases in accordance with at least the steering angle; a road surface reaction force sensitive torque compensation value generation unit that generates a second torque value that increases or decreases in accordance with a road surface reaction torque estimation value that is estimated based on at least the first steering motor current command value; and a gain ratio generation unit that generates a first gain that increases or decreases in accordance with at least one of a vehicle speed and a steering angle of the vehicle, and a second gain whose sum with the first gain is 1, and generates the steering torque target value by adding a value obtained by multiplying the first torque value by the first gain and a value obtained by multiplying the second torque value by the second gain.

[0008] According to the above configuration, a steering reaction force corresponding to the road surface reaction torque estimate can be applied to the steering wheel at a ratio according to at least one of the vehicle speed and steering angle, thereby providing a steering feel that reflects the road surface conditions and the vehicle state.

[0009] In a preferred embodiment of the control device for a vehicle steering system, the steering torque target value generating section preferably increases the second torque value as the vehicle speed increases.

[0010] According to the above configuration, a steering reaction force adapted to the road reaction force that increases as the vehicle speed increases can be applied to the steering wheel.

[0011] In a preferred embodiment of the control device for a vehicle steering system, the gain ratio generating section preferably decreases the first gain as the vehicle speed increases.

[0012] According to the above configuration, a steering reaction force corresponding to the road reaction torque estimate can be applied to the steering wheel at a ratio according to the vehicle speed, thereby providing a steering feel that reflects the road surface conditions and the vehicle speed.

[0013] In a preferred embodiment of the control device for a vehicle steering system, the gain ratio generating section preferably reduces the first gain within a range of a first vehicle speed or more and a second vehicle speed or less.

[0014] According to the above configuration, a steering reaction force according to the road surface reaction torque estimate value can be applied to the steering wheel at a ratio according to the vehicle speed within a range of not less than the first vehicle speed and not more than the second vehicle speed.

[0015] In a preferred embodiment of the control device for a vehicle steering system, the first gain in a range of vehicle speeds equal to or lower than the first vehicle speed may be greater than the second gain in a range of vehicle speeds equal to or higher than the second vehicle speed.

[0016] In a preferred embodiment of the control device for a vehicle steering system, a first gain in a range of vehicle speeds equal to or lower than the first vehicle speed may be equal to a second gain in a range of vehicle speeds equal to or higher than the second vehicle speed.

[0017] In a preferred embodiment of the control device for a vehicle steering system, the first gain in a range of vehicle speeds equal to or lower than the first vehicle speed may be smaller than the second gain in a range of vehicle speeds equal to or higher than the second vehicle speed.

[0018] In a preferred embodiment of the control device for a vehicle steering system, the gain ratio generating section preferably decreases the first gain as an actual steering angle, which is an actual steering angle of the steering wheel, increases.

[0019] According to the above configuration, a steering reaction force corresponding to the road surface reaction torque estimate can be applied to the steering wheel at a ratio corresponding to the actual steering angle, thereby providing a steering feel that reflects the road surface conditions and the actual steering angle.

[0020] In a preferred embodiment of the control device for a vehicle steering system, the gain ratio generating section preferably reduces the first gain within a range of a first steering angle or more and a second steering angle or less.

[0021] According to the above configuration, a steering reaction force according to the road surface reaction torque estimate value can be applied to the steering wheel at a ratio according to the actual steering angle within a range of not less than the first steering angle and not more than the second steering angle.

[0022] In a preferred embodiment of the control device for a vehicle steering system, a first gain in a range equal to or smaller than the first steering angle may be greater than a second gain in a range equal to or larger than the second steering angle.

[0023] In a preferred embodiment of the control device for a vehicle steering system, the first gain in a range equal to or smaller than the second steering angle may be equal to the second gain in a range equal to or larger than the second steering angle.

[0024] In a preferred embodiment of the control device for a vehicle steering system, the first gain in a range equal to or less than the second steering angle may be smaller than the second gain in a range equal to or greater than the second steering angle.

[0025] In a preferred embodiment of the control device for a vehicle steering system, the gain ratio generating section preferably decreases the first gain as an actual steering angle, which is an actual steering angle of the steered wheels, increases.

[0026] According to the above configuration, a steering reaction force corresponding to the road surface reaction torque estimate can be applied to the steering wheel at a ratio corresponding to the actual steering angle, thereby providing a steering feel that reflects the road surface conditions and the actual steering angle.

[0027] In a preferred embodiment of the control device for a vehicle steering system, the gain ratio generating section preferably reduces the first gain within a range of a first turning angle or more and a second turning angle or less.

[0028] According to the above configuration, a steering reaction force according to the road surface reaction torque estimate value can be applied to the steering wheel at a ratio according to the actual steering angle within a range of not less than the first steering angle and not more than the second steering angle.

[0029] In a preferred embodiment of the control device for a vehicle steering system, a first gain in a range equal to or smaller than the first steering angle may be greater than a second gain in a range equal to or larger than the second steering angle.

[0030] In a preferred embodiment of the control device for a vehicle steering system, the first gain in a range equal to or less than the second steering angle may be equal to the second gain in a range equal to or more than the second steering angle.

[0031] In a preferred embodiment of the control device for a vehicle steering system, the first gain in a range equal to or less than the second steering angle may be smaller than the second gain in a range equal to or greater than the second steering angle.

[0032] In a desirable aspect of the control device for a vehicle steering system, the steering angle control unit includes a friction compensation unit that calculates different steering motor current compensation values ​​for when the steered wheels are turned to the right and when they are turned to the left, based on the target steering angle value, and the steering angle control unit preferably generates a second steering motor current command value for driving the steering motor, based on the first steering motor current command value and the steering motor current compensation value.

[0033] According to the above configuration, friction compensation control can be performed effectively regardless of the steering speed of the driver, thereby reducing the sense of discomfort felt by the driver when the steering direction is changed from turning the steering wheel further to turning it back, or from turning it back to turning the steering wheel further.

[0034] In a preferred embodiment of the control device for a vehicle steering system, the steering motor current compensation value preferably has a hysteresis characteristic according to a change in the steering angle target value.

[0035] According to the above configuration, different turning motor current compensation values ​​are calculated when the steered wheels are turned right and when the steered wheels are turned left.

[0036] In a desirable aspect of the control device for a vehicle steering system, it is preferable that the steering motor current compensation value monotonically increases in a region from a first steering angle target value at the start of steering to a second steering angle target value obtained by adding a predetermined steering angle change amount threshold to the first steering angle target value, and becomes a constant value in a region greater than the second steering angle target value.

[0037] With the above configuration, friction compensation control can be performed effectively from a state in which the steered wheels are stationary, regardless of the steering speed of the driver. This reduces the sense of discomfort felt by the driver when the steering direction is changed from further turning to returning, or from returning to further turning, even in situations in which the driver's steering is extremely slow.

[0038] As a desirable aspect of the control device for a vehicle steering system, it is preferable that the friction compensation section increases or decreases the turning motor current compensation value in accordance with the second turning motor current command value.

[0039] According to the above configuration, it is possible to realize friction compensation control according to the friction force caused by the gear torque.

[0040] In a preferred embodiment of the control device for a vehicle steering system, the turning motor current compensation value preferably increases monotonically as the second turning motor current command value increases.

[0041] According to the above configuration, it is possible to realize friction compensation control according to the friction force caused by the gear torque that monotonically increases as the second turning motor current command value increases.

[0042] A desirable aspect of the control device for a vehicle steering system includes a current compensation value calculation unit that calculates a first current compensation value, and a current sensitive gain generation unit that generates a gain that monotonically increases as the second steering motor current command value increases, and it is preferable that the friction compensation unit calculates the second current compensation value by multiplying the first current compensation value by the gain.

[0043] According to the above configuration, it is possible to realize friction compensation control according to the friction force caused by the gear torque that monotonically increases as the second turning motor current command value increases.

[0044] In a desirable aspect of the control device for a vehicle steering system, it is preferable that the friction compensation section holds data that associates the second turning motor current command value with a gain that monotonically increases as the second turning motor current command value increases, and calculates the turning motor current compensation value based on the data.

[0045] According to the above configuration, it is possible to realize friction compensation control according to the friction force caused by the gear torque that monotonically increases as the second turning motor current command value increases. [Effects of the Invention]

[0046] According to the present invention, a steering reaction force corresponding to an estimated road reaction torque value can be applied to the steering wheel at a ratio according to the state of the vehicle, thereby providing a control device for a vehicle steering system that allows the driver to obtain a steering feel that reflects the road conditions and the state of the vehicle. [Brief explanation of the drawings]

[0047] [Figure 1] FIG. 1 is a configuration diagram showing an example of an outline of an SBW system including a control device according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram showing the hardware configuration of the ECU. [Figure 3] FIG. 3 is a diagram illustrating an example of a control block configuration of the control device according to the present disclosure. [Figure 4] FIG. 4 is a block diagram showing an example of the configuration of the steering torque target value generating unit according to the first embodiment. [Figure 5] FIG. 5 is a block diagram showing an example of the configuration of the steering reaction torque value generating unit. [Figure 6A] FIG. 6A is a diagram showing an example of the characteristics of the basic map. [Figure 6B] FIG. 6B is a diagram showing an example of the characteristics of the torque value Tref_a. [Figure 7] FIG. 7 is a block diagram showing an example of the configuration of the damping torque value generating unit. [Figure 8A] FIG. 8A is a diagram showing an example of the characteristics of a damping gain map. [Figure 8B] FIG. 8B is a conceptual diagram showing an example of the characteristics of the torque value Tref_a+Tref_b. [Figure 9] FIG. 9 is a region diagram for explaining the steering direction in the present disclosure. [Figure 10] FIG. 10 is a block diagram showing an example of the configuration of the hysteresis compensator. [Figure 11] FIG. 11 is a diagram showing an example of the output characteristics of the hysteresis compensator. [Figure 12] FIG. 12 is a block diagram showing an example of the configuration of the road surface reaction force sensitive torque compensation value generating unit according to the first embodiment. [Figure 13] FIG. 13 is an image diagram showing the state of torque generated between the road surface and the steering motor. [Figure 14] FIG. 14 is a block diagram showing an example of the configuration of the road surface reaction torque estimating unit. [Figure 15] FIG. 15 is a conceptual diagram for explaining a method for calculating the actual road surface reaction torque acting on the steering mechanism. [Figure 16] FIG. 16 is a conceptual diagram showing a configuration for executing a simulation for deriving the transfer function Gfil. [Figure 17] FIG. 17 is a diagram showing an example of the characteristics of a road surface reaction force sensitive torque map. [Figure 18]FIG. 18 is a diagram conceptually showing an example of the characteristics of the second torque value after sign conversion. [Figure 19A] FIG. 19A is a diagram conceptually showing a first example of a gain ratio setting example in the gain ratio generating section according to the first embodiment. [Figure 19B] FIG. 19B is a diagram conceptually showing a second example of a gain ratio setting example in the gain ratio generating section according to the first embodiment. [Figure 19C] FIG. 19C is a diagram conceptually illustrating a third example of setting the gain ratio in the gain ratio generating section according to the first embodiment. [Figure 20] FIG. 20 is a block diagram showing an example of the configuration of a steering torque target value generating unit according to the second embodiment. [Figure 21] FIG. 21 is a diagram conceptually illustrating an example of a gain ratio setting example in the gain ratio generating unit according to the second embodiment. [Figure 22] FIG. 22 is a block diagram showing an example of the configuration of a steering torque target value generating unit according to the third embodiment. [Figure 23] FIG. 23 is a diagram conceptually illustrating an example of a gain ratio setting example in the gain ratio generating unit according to the third embodiment. [Figure 24] FIG. 24 is a block diagram showing an example of the configuration of a steering torque target value generating unit according to the fourth embodiment. [Figure 25] FIG. 25 is a block diagram illustrating an example of the configuration of a gain ratio generating unit according to the fourth embodiment. [Figure 26A] FIG. 26A is a diagram conceptually illustrating an example of a gain ratio setting example in the gain ratio generating unit according to the fourth embodiment. [Figure 26B] FIG. 26B is a diagram conceptually illustrating an example of a gain ratio setting example in the gain ratio generating section according to the fourth embodiment. [Figure 27] FIG. 27 is a block diagram showing an example of the configuration of a steering torque target value generating unit according to the fifth embodiment. [Figure 28] FIG. 28 is a block diagram illustrating an example of the configuration of a gain ratio generating unit according to the fifth embodiment. [Figure 29A]FIG. 29A is a diagram conceptually illustrating an example of a gain ratio setting example in the gain ratio generating unit according to the fifth embodiment. [Figure 29B] FIG. 29B is a diagram conceptually illustrating an example of a gain ratio setting example in the gain ratio generating section according to the fifth embodiment. [Figure 30] FIG. 30 is a block diagram showing an example of the configuration of a steering torque target value generating unit according to the sixth embodiment. [Figure 31] FIG. 31 is a 3D map showing an example of a gain ratio generation method according to the sixth embodiment. [Figure 32] FIG. 32 is a block diagram showing an example of the configuration of the steering angle control unit. [Figure 33] FIG. 33 is a block diagram showing an example of the configuration of the friction compensation unit. [Figure 34] FIG. 34 is a diagram showing an example of the characteristics of the first current compensation value in the current compensation value calculation unit. [Figure 35A] FIG. 35A is a diagram showing a first example of a current-sensitive gain map. [Figure 35B] FIG. 35B is a diagram showing a second example of a current-sensitive gain map. [Figure 36] FIG. 36 is a diagram showing an example of the output characteristics of the friction compensation unit. [Figure 37] FIG. 37 is a block diagram showing an example of the configuration of a friction compensation unit according to a modified example. [Figure 38A] FIG. 38A is a first conceptual diagram illustrating a specific example of friction compensation control by the friction compensation unit. [Figure 38B] FIG. 38B is a first conceptual diagram illustrating a specific example of friction compensation control by the friction compensation unit. [Figure 39A] FIG. 39A is a second conceptual diagram illustrating a specific example of friction compensation control by the friction compensation unit. [Figure 39B] FIG. 39B is a second conceptual diagram illustrating a specific example of friction compensation control by the friction compensation unit. DETAILED DESCRIPTION OF THE INVENTION

[0048] Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments. Furthermore, the components in the following embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiments can be combined as appropriate.

[0049] (Embodiment 1) 1 is a block diagram showing an example of an outline of an SBW system equipped with a control device according to the present disclosure, which includes a reaction force device 30 constituting a steering mechanism having a steering wheel operated by a driver, a steering device 40 constituting a steering mechanism for steering steered wheels, and a control device 50 for controlling both devices.

[0050] The SBW system does not have an intermediate shaft that is mechanically connected to the column shaft (steering shaft, handle shaft) 2, which is found in general electric power steering devices, and instead transmits the driver's operation of the steering wheel 1 as an electrical signal, specifically the steering angle θh output from the reaction force device 30, as an electrical signal.

[0051] The reaction force device 30 includes a reaction force motor 31 and a speed reduction mechanism 32 that reduces the rotational speed of the reaction force motor 31. The reaction force device 30 transmits the vehicle's motion state, which is transmitted from the steered wheels 5L, 5R, to the driver as a steering reaction force. The reaction force motor 31 applies the steering reaction force to the steering wheel 1 via the speed reduction mechanism 32.

[0052] The reaction force device 30 further includes a steering angle sensor 33 and a torque sensor 34. The steering angle sensor 33 detects the steering angle θh of the steering wheel 1. The torque sensor 34 detects the steering torque Th of the steering wheel 1. Hereinafter, the steering angle θh detected by the steering angle sensor 33 will also be referred to as the "actual steering angle θh_act," and the steering torque Th detected by the torque sensor 34 will also be referred to as the "actual steering torque Th_act."

[0053] In the present disclosure, a stopper (rotation limiting mechanism) 35 that physically sets a steering end point, which is the limit of possible steering, is provided on the column shaft 2. That is, the magnitude (absolute value) of the steering angle θh is limited by the stopper 35.

[0054] The steering device 40 includes a steering motor 41, a speed reduction mechanism 42 that reduces the rotational speed of the steering motor 41, and a pinion rack mechanism 44 that converts the rotational motion of the steering motor 41 into linear motion. The steering device 40 drives the steering motor 41 in accordance with the steering angle θh, and the resulting drive force is applied to the pinion rack mechanism 44 via the speed reduction mechanism 42, and the drive force is passed through the tie rods 3a and 3b to steer the steerable wheels 5L and 5R. An angle sensor 43 is disposed near the pinion rack mechanism 44 and detects the steering angle θt of the steerable wheels 5L and 5R. Instead of the steering angle θt of the steerable wheels 5L and 5R, for example, the motor angle of the steering motor 41 or the position of the rack may be detected and the detected value may be used. Hereinafter, the steering angle θt detected by the angle sensor 43 will also be referred to as the "actual steering angle θt_act."

[0055] In the present disclosure, the actual steering angle θh_act and the actual turning angle θt_act are also collectively referred to simply as the "steering angle" of the vehicle.

[0056] In order to cooperatively control the reaction force device 30 and the steering device 40, the control device 50 generates 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 based on information such as the steering angle θh and the turning angle θt output from both devices, as well as the vehicle speed Vs detected by the vehicle speed sensor 10.

[0057] The control device 50 is supplied with power from the battery 12 and receives an ignition key signal via the ignition key 11. A CAN (Controller Area Network) 20 that transmits and receives various vehicle information is also connected to the control device 50, and the vehicle speed Vs can also be received from the CAN 20. Furthermore, a non-CAN 21 that transmits and receives communications other than the CAN 20, analog / digital signals, radio waves, etc. can also be connected to the control device 50.

[0058] Specifically, the control device 50 is, for example, an ECU (Electronic Control Unit) mounted on a vehicle. The ECU is mainly composed of a CPU (including an MCU, an MPU, etc.). FIG. 2 is a schematic diagram showing the hardware configuration of an ECU. As shown in FIG. 2, the control device 50 of the vehicle steering system according to the embodiment includes a control computer (Electronic Control Unit, hereinafter also referred to as "ECU") 110.

[0059] ECU 110 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an EEPROM (Electrically Erasable Programmable ROM) 104, etc., which are connected to a bus 105. CPU 101 executes a control program stored in ROM 102. Reaction force device 30 and steering device 40 are cooperatively controlled by a control program executed mainly by ECU 110. Note that control device 50 may be configured as a single ECU, or may include a reaction force control ECU that controls reaction force device 30 and a steering control ECU that controls steering device 40.

[0060] The ROM 102 is used as a memory for storing the control program and control data used when the control program is executed, and the RAM 103 is used as a work memory for running the control program.

[0061] The EEPROM 104 is a nonvolatile memory that can retain its contents even after power is cut off, and stores control data and the like used by the CPU 101 to execute a control program. The various data stored in the EEPROM 104 is used in the control program loaded in the RAM 103 after power is turned on to the ECU 110, and is overwritten in the EEPROM 104 at a predetermined timing. Note that, although an EEPROM is used as the nonvolatile memory here, the present invention is not limited to this, and other nonvolatile memories such as a FLASH-ROM (registered trademark) or an SDRAM may also be used.

[0062] FIG. 3 is a diagram showing an example of a control block configuration of a control device according to the present disclosure. In FIG. 3, reaction force device 30 includes, in addition to reaction force motor 31 and the above-described configuration, a PWM (pulse width modulation) control unit 37, an inverter 38, and a motor current detector 39. Furthermore, turning device 40 includes, in addition to steering motor 41 and the above-described configuration, a PWM control unit 47, an inverter 48, and a motor current detector 49. Control device 50 implements the control blocks of reaction force control system 60, which controls reaction force device 30, and steering control system 70, which controls steering device 40. Reaction force control system 60 and steering control system 70 cooperate to control reaction force device 30 and steering device 40. Note that when control device 50 is configured to include a reaction force control ECU and a steering control ECU, reaction force control system 60 may be implemented by the reaction force control ECU, and steering control system 70 may be implemented by the steering control ECU. In this case, reaction force control system 60 in the following description may be read as a reaction force control ECU, and turning control system 70 may be read as a turning control ECU.

[0063] Each control block in reaction force control system 60 is realized by a reaction force control program executed in ECU 110. Also, each control block in turning control system 70 is realized by a turning control program executed in ECU 110. Note that some or all of the control blocks of control device 50 may be realized by hardware. Also, a mode in which control device 50 includes PWM control section 37, inverter 38, motor current detector 39, PWM control section 47, inverter 48, and motor current detector 49 may be used.

[0064] As shown in Fig. 3, control device 50 includes, as control blocks, steering torque target value generation section 200, road surface reaction force sensitive torque compensation value generation section 220, steering torque control section 400, current control section 500, turning angle target value generation section 600, turning angle control section 700, and current control section 800. Steering torque target value generation section 200, road surface reaction force sensitive torque compensation value generation section 220, steering torque control section 400, and current control section 500 are control blocks that make up reaction force control system 60. Turning angle target value generation section 600, turning angle control section 700, and current control section 800 are control blocks that make up steering control system 70.

[0065] The reaction force control system 60 performs control such that the actual steering torque Th_act detected by the torque sensor 34 follows the steering torque target value Th_ref, which is the target value of the steering torque of the reaction force device 30.

[0066] The steering torque target value generating section 200 generates a steering torque target value Th_ref.

[0067] The steering torque control unit 400 generates a reaction force motor current command value Ih_ref for driving the reaction force motor 31. The steering torque control unit 400 generates a current command value that makes the deviation Th_err between the steering torque target value Th_ref and the actual steering torque Th_act approach zero, and limits the output of the current command value by an output limiting unit to the upper and lower limit values, thereby calculating the reaction force motor current command value Ih_ref.

[0068] The current control unit 500 controls the current of the reaction force motor 31. The current control unit 500 calculates a voltage control command value Vh_ref such that the deviation Ih_err between the reaction force motor current command value Ih_ref output from the steering torque control unit 400 and the actual current value (motor current value) Ih_act of the reaction force motor 31 detected by the motor current detector 39 approaches zero.

[0069] In the reaction force device 30, the reaction force motor 31 is controlled and driven via a PWM control unit 37 and an inverter 38 based on the voltage control command value Vh_ref.

[0070] The steering control system 70 performs control such that the actual steering angle θt_act detected by the angle sensor 43 follows the target steering angle value θt_ref.

[0071] A steering angle target value generating section 600 generates a steering angle target value θt_ref based on the steering angle θh.

[0072] Steering angle control unit 700 generates second steering motor current command value It_ref for driving steering motor 41. Specifically, steering angle control unit 700 generates first steering motor current command value Iref_a, which is a control target value for current supplied to steering motor 41, so that deviation θt_err between steering angle target value θt_ref and actual steering angle θt_act approaches zero, and performs friction compensation control by a friction compensation unit on first steering motor current command value Iref_a to calculate second steering motor current command value It_ref. Below, an example in which a friction compensation unit is provided in steering angle control unit 700 will be described, but a configuration that does not include a friction compensation unit may also be used. Note that in a configuration that does not include a friction compensation unit, first steering motor current command value Iref_a after PID control is generated as second steering motor current command value It_ref.

[0073] Current control section 800 controls the current of steering motor 41. Current control section 800 calculates a voltage control command value Vt_ref such that deviation It_err between second steering motor current command value It_ref output from steering angle control section 700 and actual current value (motor current value) It_act of steering motor 41 detected by motor current detector 49 approaches zero.

[0074] In the steering device 40, the steering motor 41 is controlled and driven via a PWM control unit 47 and an inverter 48 based on the voltage control command value Vt_ref.

[0075] In this embodiment, steering torque control section 400, current control section 500, turning angle target value generation section 600, turning angle control section 700 and current control section 800 may have any configuration that can realize each control in reaction force control system 60 or turning control system 70, and are not limited by the configuration of each control block. The configuration of steering torque target value generation section 200 according to this embodiment will now be described with reference to Figure 4.

[0076] Fig. 4 is a block diagram showing an example of the configuration of the steering torque target value generator according to embodiment 1. As shown in Fig. 4, the steering torque target value generator 200 according to this embodiment includes, as main components, a steering reaction torque value generator 210, a road surface reaction force sensitive torque compensation value generator 220, a gain ratio generator 230, a damping torque value generator 240, and a hysteresis compensator 250.

[0077] First, the steering reaction torque value generating unit 210 will be described with reference to Figures 5, 6A and 6B. Figure 5 is a block diagram showing an example of the configuration of the steering reaction torque value generating unit.

[0078] In the present disclosure, the sign extraction unit 213 shown in Fig. 5 extracts the sign of the actual steering angle θh_act. Specifically, for example, the value of the actual steering angle θh_a is divided by the absolute value of the actual steering angle θh_a. As a result, the sign extraction unit 213 outputs "1" when the sign of the actual steering angle θh_act is "+", and outputs "-1" when the sign of the actual steering angle θh_act is "-". Specifically, the sign extraction unit 213 generates, for example, a sign function Sgn(θh) of the actual steering angle θh_act.

[0079] Fig. 6A is a diagram showing an example of the characteristics of the basic map. The steering angle |θh| and vehicle speed Vs that have been subjected to absolute value processing in the absolute value calculation unit 212 are input to the steering reaction torque map unit 211. The steering reaction torque value generation unit 210 generates a torque value Tref_a0 using the basic map shown in Fig. 6A with the vehicle speed Vs as a parameter. The torque value Tref_a0 is used to generate a basic steering reaction force according to the steering angle |θh| and the vehicle speed Vs.

[0080] The torque value Tref_a0 has an angle-sensitive characteristic that increases or decreases according to the steering angle |θh|. More specifically, as shown in FIG. 6A, the torque value Tref_a0 increases as the steering angle |θh| increases. Furthermore, the torque value Tref_a0 has a vehicle-speed-sensitive characteristic that increases or decreases according to the vehicle speed Vs. More specifically, as shown in FIG. 6A, the torque value Tref_a0 increases as the vehicle speed Vs increases. In other words, the reaction force obtained by the torque value Tref_a0 derived from the basic map shown in FIG. 6A increases as the amount of operation of the steering wheel 1 by the driver (steering angle θh) increases, and also increases as the vehicle speed (vehicle speed Vs) increases. Note that although the basic map shown in FIG. 6A has a vehicle-speed-sensitive characteristic, the present invention is not limited to this.

[0081] Fig. 6B is a diagram showing an example of the characteristics of the torque value Tref_a. The torque value Tref_a (first torque value) shown in Fig. 6B is obtained by multiplying the torque value Tref_a0 output from the steering reaction force torque map unit 211 by the sign function Sgn(θh) output from the sign extraction unit 213 in the multiplication unit 293. Note that a configuration without the sign extraction unit 213 may also be adopted in which the torque value Tref_a (first torque value) is obtained using a basic map corresponding to the positive and negative steering angles θh, as shown in Fig. 6B.

[0082] Next, the damping torque value generating unit 240 will be described with reference to Figures 7, 8A and 8B. Figure 7 is a block diagram showing an example of the configuration of the damping torque value generating unit.

[0083] The damping torque value generation unit 240 includes a damping gain map unit 241, a differentiation unit 242, and a multiplication unit 243. Fig. 8A is a diagram showing an example of the characteristics of the damping gain map. The vehicle speed Vs is input to the damping gain map unit 241. The damping gain map unit 241 generates the damping gain DG using the damping gain map shown in Fig. 8A.

[0084] As shown in Fig. 8A, the damping gain DG has a vehicle speed-sensitive characteristic that increases or decreases according to the vehicle speed Vs. In the damping torque value generation unit 240, a differentiating unit 242 multiplies the angular velocity of the steering wheel 1 (hereinafter also referred to as "steering angular velocity ωh") calculated by differentiating the steering angle θh by the damper gain DG output from the damping gain map unit 241, and outputs the result as a torque value Tref_b.

[0085] By adding the torque value Tref_b output from the damping torque value generation unit 240 to the torque value Tref_a (first torque value) output from the steering reaction torque value generation unit 210, it becomes possible to compensate for the steering reaction force in proportion to the steering angular velocity ωh.

[0086] Fig. 8B is a conceptual diagram showing an example of the characteristics of the torque value Tref_a+Tref_b. In Fig. 8B, the solid line indicates the torque value Tref_a+Tref_b when the steering angular velocity ωh is a positive value (ωh>0), and the dashed line indicates the torque value Tref_a+Tref_b when the steering angular velocity ωh is a negative value (ωh<0). Also in Fig. 8B, the dashed line indicates the torque value Tref_a (first torque value).

[0087] 9 is a region diagram for explaining the steering direction in the present disclosure, in which the horizontal axis represents the steering angle θh and the vertical axis represents the steering angular velocity ωh.

[0088] Area A ((θh, ωh) = (+, +)) shown in FIG. 9 indicates that the steering wheel 1 is turned to the right (θh > 0) and is being turned further to the right (ωh > 0). Area B ((θh, ωh) = (+, -)) shown in FIG. 9 indicates that the steering wheel 1 is turned to the right (θh > 0) and is being turned back to the left (ωh < 0). Area C ((θh, ωh) = (-, -)) shown in FIG. 9 indicates that the steering wheel 1 is turned to the left (θh < 0) and is being turned further to the left (ωh < 0). Area D ((θh, ωh) = (-, +)) shown in FIG. 9 indicates that the steering wheel 1 is turned to the left (θh < 0) and is being turned back to the right (ωh > 0). Also, in Figure 9, on the steering angle θh axis (ωh=0), it is shown that the steering wheel 1 is neither being turned further nor turned back ((θh, ωh)=(θh,0)), and on the steering angular velocity ωh axis (θh=0), it is shown that the steering wheel 1 is in the center position ((θh, ωh)=(0, ωh)).

[0089] The torque value Tref_b output from the damping torque value generation unit 240 is a positive value in regions A and D where the steering angular velocity ωh>0, and a negative value in regions B and C where the steering angular velocity ωh<0. As a result, when the steering angular velocity ωh>0, that is, in region A where the steering wheel 1 is turned to the right (θh>0) and further turned to the right, or in region D where the steering wheel 1 is turned to the left (θh<0) and turned back to the right, the torque value Tref_b is a value obtained by adding |Tref_b| to Tref_a, as shown by the solid line in Fig. 8B. On the other hand, when the steering angular velocity ωh<0, that is, in region B where the steering wheel 1 is turned to the right (θh>0) and turned back to the left, or in region C where the steering wheel 1 is turned to the left (θh<0) and further turned to the left, the torque value Tref_b is a value obtained by subtracting |Tref_b| from Tref_a, as shown by the dashed line in Fig. 8B.

[0090] 8B, the torque value Tref_a+Tref_b increases with increasing steering angle θ as the steering angle θh increases and approaches the steering end point limited by the stopper (rotation limiting mechanism) 35. In other words, the torque value Tref_a+Tref_b has a characteristic that the rate of change gradually decreases as the steering angle θh increases.

[0091] Next, the hysteresis compensation unit 250 will be described with reference to Fig. 10, Fig. 11 and Fig. 12. Fig. 10 is a block diagram showing an example of the configuration of the hysteresis compensation unit.

[0092] The actual steering angle θh_act and the actual steering speed ωh_act calculated by differentiating the actual steering angle θh_act by a differentiator 252 are input to the hysteresis compensation value calculation unit 251. The hysteresis compensation value calculation unit 251 calculates a torque compensation value Tref_c based on the actual steering angle θh_act and the actual steering speed ωh_act. A method for calculating the torque compensation value Tref_c in the hysteresis compensation value calculation unit 251 will be described below.

[0093] FIG. 11 is a diagram showing an example of the output characteristics of the hysteresis compensation unit. In FIG. 11, the horizontal axis represents the actual steering angle θh_act, and the vertical axis represents the torque compensation value Tref_c. Also in FIG. 11, the solid line represents the torque compensation value Tref_c when steering to the right, and the dashed line represents the torque compensation value Tref_c when steering to the left. As shown in FIG. 11, the torque compensation value Tref_c calculated in the hysteresis compensation value calculation unit 251 has a hysteresis characteristic in which the value is different when steering to the left and when steering to the right. In FIG. 11, L1 represents the trajectory when steering to the right from the center position (origin (0,0)) of the steering wheel 1, L2 represents the trajectory when switching from right steering to left steering occurs at coordinate A (x1, y1), and L3 represents the trajectory when switching from right steering to left steering occurs at coordinate B (x2, y2).

[0094] The hysteresis compensation value calculation unit 251 calculates the torque compensation value Tref_c using the following equations (1) and (2) based on the actual steering angle θh_act and the actual steering speed ωh_act. Specifically, when the sign ωh_act(sgn) of the actual steering speed ωh_act is a positive value ("+"), the torque compensation value Tref_c is calculated using the following equation (1), and when the sign ωh_act(sgn) of the actual steering speed ωh_act is a negative value ("-"), the torque compensation value Tref_c is calculated using the following equation (2). In the following equations (1) and (2), x represents the actual steering speed ωh_act, y represents the R is the torque compensation value when steering to the right, Tref_c, y L is the torque compensation value Tref_c when steering to the left. The coefficient a is greater than 1, and the coefficient c is greater than 0. The coefficient Ahys indicates the output width of the hysteresis characteristic (the width of the torque compensation value Tref_c), and the coefficient c is a coefficient that indicates the roundness of the hysteresis characteristic.

[0095] y R =Ahys{1-a -c(x-b)}···(1)

[0096] y L =-Ahys{1-a c(x-b’)}···(2)

[0097] That is, when steering to the right (ωh_act(sgn)="+"), the hysteresis compensation value calculation unit 251 calculates the torque compensation value Tref_c(y R ) is calculated, and when steering to the left (ωh_act(sgn) = "-"), the torque compensation value Tref_c(y L ) is calculated.

[0098] When a switch from right steering to left steering occurs (ωh_act(sgn) = "+" → "-"), or when a switch from left steering to right steering occurs (ωh_act(sgn) = "-" → "+"), the hysteresis compensation value calculation unit 251 takes over the previous values ​​of the actual steering angle θh_act and the torque compensation value Tref_c, and substitutes the coefficient b or b' shown in the following equation (3) or (4) into the above equation (1) or (2) that is applied after the steering switch. This maintains continuity before and after the steering switch. Specifically, when a switch from right steering to left steering occurs (ωh_act(sgn) = "+" → "-"), the hysteresis compensation value calculation unit 251 applies the actual steering angle θh_act and the previous value of the torque compensation value Tref_c (coordinate A(x1, y1) shown in FIG. 11) to the above equation (2), and substitutes the coefficient b' shown in the following equation (4) to calculate the torque compensation value Tref_c. Also, when a switch from left steering to right steering occurs (ωh_act(sgn) = "-" → "+"), the hysteresis compensation value calculation unit 251 applies the actual steering angle θh_act and the previous value of the torque compensation value Tref_c (coordinate B(x2, y2) shown in FIG. 11) to the above equation (1), and substitutes the coefficient b shown in the following equation (3) to calculate the torque compensation value Tref_c.

[0099] b=x1+(1 / c)log a {1-(y1 / Ahys)} (3)

[0100] b'=x1-(1 / c)log a {1-(y1 / Ahys)} (4)

[0101] The above formulas (3) and (4) are obtained by substituting x1 for x in the above formulas (1) and (2) and R and y L can be derived by substituting y1 into

[0102] When Napier's constant e is used as the coefficient a, the above equations (1), (2), (3), and (4) can be expressed as the following equations (5), (6), (7), and (8), respectively.

[0103] y R =Ahys[1-exp{-c(xb)}] (5)

[0104] y L =-Ahys[{1-exp{c(x-b')}]···(6)

[0105] b=x1+(1 / c)log e {1-(y1 / Ahys)}···(7)

[0106] b'=x1-(1 / c)log e {1-(y1 / Ahys)} (8)

[0107] As described above, the SBW system does not have an intermediate shaft mechanically coupled to the column shaft 2. In other words, the steering mechanism and the turning mechanism are mechanically separated. For this reason, it is necessary to transmit to the reaction device 30 the steering reaction force when the vehicle is oversteered or understeered, for example, when traveling on a low-μ road where the frictional resistance of the road surface is significantly reduced due to an icy road surface or hydroplaning during rainy weather.

[0108] In the present disclosure, as shown in Fig. 4, a component of steering torque target value generation section 200 estimates a road surface reaction torque corresponding to first steering motor current command value Iref_a generated by steering angle control section 700, and applies a torque value (second torque value) corresponding to the estimated road surface reaction torque to steering torque target value Th_ref. This makes it possible to apply a steering reaction force corresponding to the estimated value of road surface reaction torque to steering wheel 1. Below, a detailed description will be given of the configuration and operation that can apply a steering reaction force corresponding to the estimated value of road surface reaction torque to steering wheel 1.

[0109] Incidentally, in a mode in which steering angle control section 700 does not include a friction compensation section, a mode in which road surface reaction torque corresponding to second steering motor current command value It_ref is estimated instead of first steering motor current command value Iref_a in the following description may be adopted.

[0110] Fig. 12 is a block diagram showing an example of the configuration of a road surface reaction force sensitive torque compensation value generation unit according to embodiment 1. In the example configuration shown in Fig. 12, the road surface reaction force sensitive torque compensation value generation unit 220 includes, as main components, a road surface reaction force torque estimating unit 221 and a road surface reaction force sensitive torque map unit 222.

[0111] First, a method for estimating the road surface reaction torque estimated value Tsat_est in the road surface reaction torque estimator 221 will be described with reference to FIGS.

[0112] FIG. 12 is an image diagram showing the state of torque generated between the road surface and the steering motor.

[0113] When the driver steers the steering wheel, a target steering angle value θt_ref is generated, and in accordance with the target steering angle value θt_ref, the steering motor 41 generates a steering motor torque Tm that steers the steerable wheels 5L, 5R. As a result, the steerable wheels 5L, 5R are steered, and the road surface reaction torque T SATAt this time, torque is generated as a resistance due to the inertia (pinion shaft converted inertia) J acting on the pinion shaft from the (rotor of) the steering motor 41, the reduction mechanism, etc. Furthermore, the damper term (damper coefficient D M ) A physical torque (viscous torque) is generated. The balance of these forces gives the equation of motion shown in equation (9) below.

[0114] J×α M +D M ×ω M =Tm-T SAT ···(9)

[0115] In the above equation (9), ω M is the motor angular velocity converted to the pinion axis (value relative to the pinion axis), and α M is the motor angular acceleration converted to the pinion shaft. Then, the above equation (9) is used to calculate the road reaction torque T SAT When solving, the following equation (10) is obtained.

[0116] T SAT =Tm-J×α M -D M ×ω M ···(10)

[0117] As can be seen from the above equation (10), the pinion shaft converted inertia J and the damper coefficient D M is calculated as a constant in advance, the motor angular velocity ω M , motor angular acceleration α M , and the road reaction torque T SAT The pinion shaft converted inertia J may be simply converted to a value for the pinion shaft using the relational expression between the motor inertia and the reduction ratio.

[0118] Road surface reaction torque estimating section 221 receives as input first steering motor current command value Iref_a and actual steering angle θt_act generated by steering angle control section 700. Road surface reaction torque estimating section 221 estimates road surface reaction torque T SATis replaced with the road surface reaction torque estimated value Tsat_est to calculate the road surface reaction torque estimated value Tsat_est.

[0119] 14 is a block diagram showing an example of the configuration of the road surface reaction torque estimating unit 221. The road surface reaction torque estimating unit 221 includes a conversion unit 311, an angular velocity calculation unit 312, an angular acceleration calculation unit 313, a block 315, a block 317, and a subtraction unit 318.

[0120] First turning motor current command value Iref_a is input to conversion section 311. Conversion section 311 calculates pinion shaft converted turning motor torque Tm by multiplying it by a predetermined gear ratio and torque constant.

[0121] Actual steering angle θt_act is input to angular velocity calculation section 312. Angular velocity calculation section 312 converts actual steering angle θt_act into the angle of steering motor 41, performs differential calculation processing on this angle of steering motor 41, and further divides by the gear ratio to obtain pinion shaft converted motor angular velocity ω M Calculate.

[0122] The angular acceleration calculation unit 313 calculates the motor angular velocity ω M The angular acceleration calculation unit 313 calculates the motor angular velocity ω M is differentiated, and the motor angular acceleration converted to the pinion shaft is M Calculate.

[0123] The steering motor torque Tm and the motor angular velocity ω M , and motor angular acceleration α M Using the above, the road surface reaction torque estimated value Tsat_est is calculated based on the above equation (10) by the configuration shown in FIG.

[0124] The block 315 receives the motor angular velocity ω output from the angular velocity calculation unit 312. M is input. Block 315 adds the damper coefficient D M Multiply and output.

[0125] Block 317 receives the motor angular acceleration α output from the angular acceleration calculation unit 313. M is input. Block 317 multiplies the input data by the pinion shaft converted inertia J and outputs the result.

[0126] Subtraction section 318 subtracts the output of block 317 and the output of block 315 from the turning motor torque Tm output from conversion section 311 .

[0127] The above configuration can realize the above equation (10). That is, the road surface reaction torque estimation value Tsat_est is calculated by the configuration of the road surface reaction torque estimating unit 221 shown in Fig. 14 .

[0128] In the case where the angle of the steering motor 41 is detected, the angular velocity calculation unit 312 performs a differential calculation process on the detected angle of the steering motor 41, and further divides it by the gear ratio to obtain the pinion shaft converted motor angular velocity ω M Furthermore, if the column angle can be detected directly, the column angle may be used as angle information instead of the actual turning angle θt_act or the angle of the turning motor 41. In this case, pinion shaft conversion is not necessary. Furthermore, instead of the actual turning angle θt_act or the angle of the turning motor 41, a signal obtained by converting the turning angular velocity or the turning motor angular velocity into a pinion shaft is used as the motor angular velocity ω M and omit the differentiation process for the angle of the steering motor 41. Furthermore, the road surface reaction force torque estimated value Tsat_est may be calculated by a method other than the above, or an estimated value equivalent to the road surface reaction force torque estimated value Tsat_est may be used. Below, a method for calculating the road surface reaction force torque estimated value Tsat_est that is different from the above method will be described.

[0129] In a method of calculating road surface reaction force torque estimated value Tsat_est that is different from the above-described method, first steering motor current command value Iref_a generated by steering angle control unit 700 is input to road surface reaction force torque estimating section 221. Also, a transfer function Gfil shown in the following equation (11) is set in road surface reaction force torque estimating section 221. Transfer function Gfil is stored, for example, in a ROM of an ECU that constitutes control device 50.

[0130] Gfil=N(s) / D(s)=(Ds+E) / (As 2 +Bs+C)···(11)

[0131] In the above equation (11), the linear function N(s) = Ds + E and the quadratic function D(s) = As 2 A, B, C, D, and E in +Bs+C are coefficients set by the simulation shown below.

[0132] In the present disclosure, the transfer function Gfil is assumed to be a transfer function with a first order numerator and a second order denominator, but the order of the numerator and denominator can be changed as appropriate depending on the allowable error between the actual road surface reaction torque Tsat_act and the road surface reaction torque estimate value Tsat_est, the load on the ECU, etc.

[0133] For example, if the orders of the numerator and denominator are increased, the relationship between the first steering motor current command value Iref_a obtained by an experiment, which will be described later, and the actual road surface reaction torque Tsat_act can be made to match well with the transfer characteristics of the transfer function Gfil, and therefore it is possible to estimate a road surface reaction torque estimated value Tsat_est that is close to the actually measured value.

[0134] On the other hand, if the order of the numerator and denominator is reduced, the load on the ECU can be reduced.

[0135] Road reaction torque T SAT It is assumed that the relational expression shown in the following equation (12) holds between the first steering motor current command value Iref_a and the road surface reaction torque T SATis defined as the road surface reaction torque estimated value Tsat_est in this disclosure.

[0136] In other words, transfer function Gfil calculates road surface reaction torque estimated value Tsat_est from first turning motor current command value Iref_a by simulating the relationship between first turning motor current command value Iref_a and actual road surface reaction torque Tsat_act obtained through experiments.

[0137] T SAT =Gfil×Iref_a=Tsat_est···(12)

[0138] On the other hand, the actual road surface reaction torque Tsat_act acting on the steering mechanism can be calculated from the axial force applied to the tie rod. Fig. 15 is a conceptual diagram for explaining a method for calculating the actual road surface reaction torque acting on the steering mechanism.

[0139] The actual road surface reaction torque Tsat_act can be calculated by the following equation (13) using the axial forces FL and FR applied to the tie rods 3a and 3b and the length L of the arms 6a and 6b determined for each vehicle type.

[0140] Tsat_act=FL×L-FR×L···(13)

[0141] In the present disclosure, the actual road surface reaction torque Tsat_act is calculated using the above formula (13) that uses the axial forces FL and FR measured in advance through experiments using an actual vehicle. The axial forces FL and FR can be measured, for example, by attaching force sensors to the tie rods 3 a and 3 b.

[0142] FIG. 16 is a conceptual diagram showing a configuration for executing a simulation for deriving the transfer function Gfil.

[0143] The first steering motor current command value Iref_a and axial forces FL and FR are input to the processing device shown in Figure 16. The processing device derives a transfer function Gfil such that the road surface reaction torque estimated value Tsat_est shown in equation (12) above approximates the actual road surface reaction torque Tsat_act calculated by equation (13) above. An example of the processing device shown in Figure 16 is one that includes a frequency characteristics analysis device (servo analyzer).

[0144] Specifically, the processing device performs curve fitting using a sweep method to derive the coefficients A, B, C, D, and E of the transfer function Gfil shown in the above equation (11). An example of the curve fitting method is the least squares approximation method. The curve fitting method is not limited to the least squares approximation method.

[0145] Road surface reaction torque estimating section 221 performs filtering on first steering motor current command value Iref_a generated by steering angle control section 700 using transfer function Gfil derived as described above, and calculates road surface reaction torque estimated value Tsat_est shown in equation (12) above. This provides road surface reaction torque estimated value Tsat_est that corresponds to the behavior of actual road surface reaction torque Tsat_act when the vehicle is actually traveling.

[0146] The transfer function used when calculating the road surface reaction torque estimated value Tsat_est in the road surface reaction torque estimator 221 is not limited to the form shown in (11) above. Specifically, for example, the present disclosure is not limited by the orders of the function N(s) or the function D(s).

[0147] Returning to FIG. 12 , the sign extraction unit 224 extracts the sign of the road reaction force torque estimated value Tsat_est obtained by the calculation method described above. Specifically, for example, the value of the road reaction force torque estimated value Tsat_est is divided by the absolute value of the road reaction force torque estimated value Tsat_est. As a result, the sign extraction unit 224 outputs "1" when the sign of the road reaction force torque estimated value Tsat_est is "+", and outputs "-1" when the sign of the road reaction force torque estimated value Tsat_est is "-". Specifically, the sign extraction unit 224 generates, for example, a sign function Sgn(Tsat_est) of the road reaction force torque estimated value Tsat_est.

[0148] 17 is a diagram showing an example of the characteristics of a road reaction force sensitive torque map. The road reaction force torque estimated value |Tsat_est| and vehicle speed Vs that have been subjected to absolute value processing in absolute value calculation section 223 are input to road reaction force sensitive torque map section 222. Road reaction force sensitive torque map section 222 generates a torque value Tref_d0 using the road reaction force sensitive torque map shown in FIG. 17 with vehicle speed Vs as a parameter.

[0149] As shown in FIG. 17, the torque value Tref_d0 has a torque-sensitive characteristic that increases or decreases according to the road surface reaction torque estimated value |Tsat_est|.

[0150] More specifically, the torque value Tref_d0 increases as the road surface reaction torque estimated value |Tsat_est| increases, and the rate of increase decreases as the road surface reaction torque estimated value |Tsat_est| increases.

[0151] Furthermore, the torque value Tref_d0 has a vehicle speed-sensitive characteristic that increases and decreases according to the vehicle speed Vs. More specifically, the torque value Tref_d0 increases as the vehicle speed Vs increases, as shown in Fig. 17 .

[0152] That is, the reaction force obtained by the torque value Tref_d0 derived from the road reaction force sensitive torque map shown in Fig. 17 becomes larger as the road reaction force torque estimated value |Tsat_est| becomes larger and as the vehicle speed (vehicle speed Vs) becomes faster. Note that although the road reaction force sensitive torque map shown in Fig. 17 has a vehicle speed sensitive characteristic, the present invention is not limited to this.

[0153] The road reaction force sensitive torque compensation value generation unit 220 multiplies the torque value Tref_d0, which is the output value of the road reaction force sensitive torque map unit 222, by the sign function Sgn(Tsat_est) of the road reaction force torque estimation value Tsat_est in a multiplication unit 225, and outputs the sign-converted torque value Tref_d (second torque value).

[0154] Fig. 18 is a diagram conceptually showing an example of the characteristics of the second torque value after sign conversion. As shown in Fig. 18, the torque value Tref_d (second torque value) output from road reaction force sensitive torque compensation value generation unit 220 increases or decreases according to the road reaction force torque estimated value Tsat_est, which is an estimate of the reaction force (self-aligning torque) acting from the road surface. By applying the torque value Tref_d (second torque value), which increases or decreases according to the road reaction force torque estimated value Tsat_est, to the steering torque target value Th_ref, it is possible to obtain a steering reaction force according to the road reaction force torque estimated value Tsat_est.

[0155] The characteristics of the road reaction force sensitive torque map are not limited to the aspects shown in Fig. 17 or 18. Furthermore, for example, instead of the aspects of the maps shown in Fig. 17 or 18, the characteristics may be defined by a predetermined transfer function.

[0156] Here, the road reaction torque estimated value Tsat_est changes depending on the road surface condition as well as the vehicle state such as the vehicle speed and steering angle. Therefore, depending on the vehicle state, the road surface condition may not be fully reflected, and it may not be possible to obtain a steering feel that corresponds to the road surface condition and the vehicle state.

[0157] The configuration and operation according to the first embodiment, which can provide a steering feel according to road conditions and vehicle state, will be described below with reference to Fig. 4, Fig. 19A, Fig. 19B, and Fig. 19C. Fig. 19A is a diagram conceptually showing a first example of a gain ratio setting example in the gain ratio generation unit according to the first embodiment. Fig. 19B is a diagram conceptually showing a second example of a gain ratio setting example in the gain ratio generation unit according to the first embodiment. Fig. 19C is a diagram conceptually showing a third example of a gain ratio setting example in the gain ratio generation unit according to the first embodiment.

[0158] In this embodiment, a first gain Ga and a second gain Gb are generated using the vehicle speed Vs as a parameter. As shown in Fig. 4, the vehicle speed Vs is input to a gain ratio generation unit 230 of the steering torque target value generation unit 200 according to the first embodiment. The gain ratio generation unit 230 generates a first gain Ga that increases or decreases according to the vehicle speed Vs, and a second gain Gb whose sum with the first gain Ga is 1. A multiplication unit 261 multiplies a torque value Tref_a (first torque value) by the first gain Ga. A multiplication unit 262 multiplies a torque value Tref_d (second torque value) by the second gain Gb.

[0159] The gain ratio generation unit 230 monotonically decreases the first gain Ga by which the torque value Tref_a (first torque value) is multiplied within a range of the first vehicle speed Vs_A or more and the second vehicle speed Vs_B or less. Accordingly, the second gain Gb by which the torque value Tref_d (second torque value) is multiplied monotonically within a range of the first vehicle speed Vs_A or more and the second vehicle speed Vs_B or less. The first vehicle speed Vs_A is set to, for example, 5 [km / h]. The second vehicle speed Vs_B is set to, for example, 30 [km / h]. The present disclosure is not limited to the values ​​of the first vehicle speed Vs_A and the second vehicle speed Vs_B.

[0160] 19A shows an example in which the maximum value Ga_max of the first gain Ga in the range equal to or less than the first vehicle speed Vs_A is greater than the maximum value Gb_max of the second gain Gb in the range equal to or greater than the second vehicle speed Vs_B. In this case, the minimum value Gb_min of the second gain Gb in the range equal to or less than the first vehicle speed Vs_A is greater than the minimum value Ga_min of the first gain Ga in the range equal to or greater than the second vehicle speed Vs_B.

[0161] 19B shows an example in which the maximum value Ga_max of the first gain Ga in the range equal to or less than the first vehicle speed Vs_A is smaller than the maximum value Gb_max of the second gain Gb in the range equal to or greater than the second vehicle speed Vs_B. In this case, the minimum value Gb_min of the second gain Gb in the range equal to or less than the first vehicle speed Vs_A is smaller than the minimum value Ga_min of the first gain Ga in the range equal to or greater than the second vehicle speed Vs_B.

[0162] 19C shows an example in which the maximum value Ga_max of the first gain Ga in the range equal to or less than the first vehicle speed Vs_A is equal to the maximum value Gb_max of the second gain Gb in the range equal to or greater than the second vehicle speed Vs_B. In this case, the minimum value Gb_min of the second gain Gb in the range equal to or less than the first vehicle speed Vs_A is equal to the minimum value Ga_min of the first gain Ga in the range equal to or greater than the second vehicle speed Vs_B.

[0163] The maximum value Ga_max of the first gain Ga, the minimum value Ga_min of the first gain Ga, the maximum value Gb_max of the second gain Gb, and the minimum value Gb_min of the second gain Gb, and the magnitude relationship between these values ​​may be set appropriately depending on the dynamic performance and vehicle specifications of the vehicle in which the control device 50 according to the present disclosure is installed.

[0164] The steering torque target value generation unit 200 adds (at multiplication unit 261) the torque value Tref_a (first torque value) output from the steering reaction torque value generation unit 210 by the first gain Ga to obtain a torque value Ga×Tref_a, (at multiplication unit 262) the torque value Tref_d (second torque value) output from the road surface reaction force sensitive torque compensation value generation unit 220 by the second gain Gb to obtain a torque value Gb×Tref_d, (at multiplication unit 262) the torque value Tref_b output from the damping torque value generation unit 240, and the torque compensation value Tref_c output from the hysteresis compensation unit 250, and outputs the result as the steering torque target value Th_ref.

[0165] In the first embodiment, a steering reaction force corresponding to the road reaction torque estimated value Tsat_est can be applied to the steering wheel 1 at a ratio corresponding to the vehicle speed Vs. Specifically, in a region where the vehicle speed Vs is relatively low, the steering torque target value generating unit 200 generates the steering torque target value Th_ref by multiplying the torque value Tref_a (first torque value) output from the steering reaction torque value generating unit 210 by a relatively large first gain Ga, and in a region where the vehicle speed Vs is relatively high, the steering torque target value generating unit 200 generates the steering torque target value Th_ref by multiplying the torque value Tref_d (second torque value) output from the road reaction force sensitive torque compensating value generating unit 220 by a relatively large second gain Gb. In a low-speed region where the vehicle speed Vs is relatively low, the reaction torque component due to elastic deformation of the tires is the main component of the road reaction torque, and the reaction torque component due to the road surface condition accounts for a small proportion of the road reaction torque. That is, if the output of road reaction force sensitive torque generation unit 220 is relatively large in the low speed range, a heavy steering torque is applied even though it is difficult to obtain road surface conditions, and the steering feel for the driver deteriorates. Therefore, in the low speed range where vehicle speed Vs is relatively low, by using a relatively large first gain Ga and a relatively small second gain Gb, it is possible to obtain a steering feel that reflects the road surface conditions and vehicle speed Vs.

[0166] 19A, 19B, and 19C. For example, within a range of the first vehicle speed Vs_A or higher and the second vehicle speed Vs_B or lower, the first gain Ga by which the torque value Tref_a (first torque value) is multiplied may gradually decrease as the vehicle speed Vs increases, and accordingly, the second gain Gb by which the torque value Tref_d (second torque value) is multiplied may gradually increase as the vehicle speed Vs increases. Alternatively, within a range of the first vehicle speed Vs_A or higher and the second vehicle speed Vs_B or lower, the first gain Ga by which the torque value Tref_a (first torque value) is multiplied may gradually increase as the vehicle speed Vs decreases, and accordingly, the second gain Gb by which the torque value Tref_d (second torque value) is multiplied may gradually decrease as the vehicle speed Vs decreases.

[0167] (Embodiment 2) The configuration and operation according to the second embodiment, which can provide a steering feel according to road conditions and vehicle state, will be described below with reference to Fig. 20 and Fig. 21. Fig. 20 is a block diagram showing an example of the configuration of a steering torque target value generator according to the second embodiment. Fig. 21 is a diagram conceptually showing an example of gain ratio setting in the gain ratio generator according to the second embodiment.

[0168] In this embodiment, a first gain Ga and a second gain Gb are generated using the actual steering angle θh_act as a parameter. As shown in Fig. 20, the actual steering angle θh_act is input to a gain ratio generation unit 230a of a steering torque target value generation unit 200a according to the second embodiment. The gain ratio generation unit 230a generates a first gain Ga that increases or decreases according to the actual steering angle θh_act, and a second gain Gb whose sum with the first gain Ga is 1. A multiplication unit 261 multiplies a torque value Tref_a (first torque value) by the first gain Ga. A multiplication unit 262 multiplies a torque value Tref_d (second torque value) by the second gain Gb.

[0169] The gain ratio generation unit 230a monotonically decreases the first gain Ga by which the torque value Tref_a (first torque value) is multiplied within a range of the first steering angle θh_A or more and the second steering angle θh_B or less. Accordingly, the second gain Gb by which the torque value Tref_d (second torque value) is multiplied monotonically within a range of the first steering angle θh_A or more and the second steering angle θh_B or less. The first steering angle θh_A is set to, for example, 3 [deg]. The second steering angle θh_B is set to, for example, 20 [deg]. The present disclosure is not limited to the values ​​of the first steering angle θh_A and the second steering angle θh_B.

[0170] 21 shows an example in which the maximum value Ga_max of the first gain Ga in the range equal to or less than the first steering angle θh_A is greater than the maximum value Gb_max of the second gain Gb in the range equal to or greater than the second steering angle θh_B. In this case, the minimum value Gb_min of the second gain Gb in the range equal to or less than the first steering angle θh_A is greater than the minimum value Ga_min of the first gain Ga in the range equal to or greater than the second steering angle θh_B.

[0171] In addition, the maximum value Ga_max of the first gain Ga in the range equal to or less than the first steering angle θh_A may be smaller than the maximum value Gb_max of the second gain Gb in the range equal to or greater than the second steering angle θh_B, and the minimum value Gb_min of the second gain Gb in the range equal to or less than the first steering angle θh_A may be smaller than the minimum value Ga_min of the first gain Ga in the range equal to or greater than the second steering angle θh_B.

[0172] In addition, the maximum value Ga_max of the first gain Ga in the range equal to or less than the first steering angle θh_A may be equal to the maximum value Gb_max of the second gain Gb in the range equal to or greater than the second steering angle θh_B, and the minimum value Gb_min of the second gain Gb in the range equal to or less than the first steering angle θh_A may be equal to the minimum value Ga_min of the first gain Ga in the range equal to or greater than the second steering angle θh_B.

[0173] The maximum value Ga_max of the first gain Ga, the minimum value Ga_min of the first gain Ga, the maximum value Gb_max of the second gain Gb, and the minimum value Gb_min of the second gain Gb, and the magnitude relationship between these values ​​may be set appropriately depending on the dynamic performance and vehicle specifications of the vehicle in which the control device 50 according to the present disclosure is installed.

[0174] The steering torque target value generation unit 200a adds (at multiplication unit 261) the torque value Ga×Tref_a obtained by multiplying the torque value Tref_a (first torque value) output from the steering reaction torque value generation unit 210 by the first gain Ga to (to obtain a torque value Ga×Tref_a), (at multiplication unit 262) the torque value Tref_d (second torque value) output from the road surface reaction force sensitive torque compensation value generation unit 220 by the second gain Gb to (to obtain a torque value Gb×Tref_d), (at multiplication unit 262) the torque value Tref_b output from the damping torque value generation unit 240, and the torque compensation value Tref_c output from the hysteresis compensation unit 250 to (addition units 271, 272, 273), and outputs the result as the steering torque target value Th_ref.

[0175] In the second embodiment, a steering reaction force corresponding to the road surface reaction torque estimated value Tsat_est can be applied to the steering wheel 1 at a ratio corresponding to the actual steering angle θh_act. Specifically, in a region where the actual steering angle θh_act is relatively small, the steering torque target value generating unit 200a generates the steering torque target value Th_ref by multiplying the torque value Tref_a (first torque value) output from the steering reaction force torque value generating unit 210 by a relatively large first gain Ga, and in a region where the actual steering angle θh_act is relatively large, the steering torque target value generating unit 200a generates the steering torque target value Th_ref by multiplying the torque value Tref_d (second torque value) output from the road surface reaction force sensitive torque compensation value generating unit 220 by a relatively large second gain Gb. This makes it possible to obtain a steering feel that reflects the road surface conditions and the actual steering angle θh_act.

[0176] The gain ratio setting example in the gain ratio generation unit 230a according to the second embodiment is merely an example and is not limited to the example shown in Fig. 21. For example, within a range of the first steering angle θh_A or more and the second steering angle θh_B or less, the first gain Ga by which the torque value Tref_a (first torque value) is multiplied may gradually decrease as the actual steering angle θh_act increases, and accordingly, the second gain Gb by which the torque value Tref_d (second torque value) is multiplied may gradually increase as the actual steering angle θh_act increases. Furthermore, within a range of the first steering angle θh_A or more and the second steering angle θh_B or less, the first gain Ga by which the torque value Tref_a (first torque value) is multiplied may gradually increase as the actual steering angle θh_act decreases, and accordingly, the second gain Gb by which the torque value Tref_d (second torque value) is multiplied may gradually decrease as the actual steering angle θh_act decreases.

[0177] (Embodiment 3) The configuration and operation according to the third embodiment, which can provide a steering feel according to road conditions and vehicle state, will be described below with reference to Fig. 22 and Fig. 23. Fig. 22 is a block diagram showing an example of the configuration of a steering torque target value generator according to the third embodiment. Fig. 23 is a diagram conceptually showing an example of gain ratio setting in the gain ratio generator according to the third embodiment.

[0178] In the present embodiment, a first gain Ga and a second gain Gb are generated using the actual turning angle θt_act as a parameter. As shown in Fig. 22, the actual turning angle θt_act is input to a gain ratio generation section 230b of a steering torque target value generation section 200b according to the third embodiment. Gain ratio generation section 230b generates a first gain Ga that increases or decreases according to the actual turning angle θt_act, and a second gain Gb whose sum with the first gain Ga is 1. A multiplication section 261 multiplies a torque value Tref_a (first torque value) by the first gain Ga. A multiplication section 262 multiplies a torque value Tref_d (second torque value) by the second gain Gb.

[0179] Gain ratio generation section 230b monotonically decreases first gain Ga, by which torque value Tref_a (first torque value) is multiplied, within the range of not less than first turning angle θt_A and not more than second turning angle θt_B. Accordingly, second gain Gb, by which torque value Tref_d (second torque value) is multiplied, monotonically increases within the range of not less than first turning angle θt_A and not more than second turning angle θt_B. First turning angle θt_A is set to, for example, 3 [deg]. Second turning angle θt_B is set to, for example, 20 [deg]. The present disclosure is not limited to the values ​​of first turning angle θt_A and second turning angle θt_B.

[0180] 23 shows an example in which the maximum value Ga_max of the first gain Ga in the range equal to or less than the first turning angle θt_A is greater than the maximum value Gb_max of the second gain Gb in the range equal to or greater than the second turning angle θt_B. In this case, the minimum value Gb_min of the second gain Gb in the range equal to or less than the first turning angle θt_A is greater than the minimum value Ga_min of the first gain Ga in the range equal to or greater than the second turning angle θt_B.

[0181] Note that the maximum value Ga_max of the first gain Ga in the range equal to or less than the first steering angle θt_A may be smaller than the maximum value Gb_max of the second gain Gb in the range equal to or greater than the second steering angle θt_B, and the minimum value Gb_min of the second gain Gb in the range equal to or less than the first steering angle θt_A may be smaller than the minimum value Ga_min of the first gain Ga in the range equal to or greater than the second steering angle θt_B.

[0182] In addition, the maximum value Ga_max of the first gain Ga in the range equal to or less than the first steering angle θt_A may be equal to the maximum value Gb_max of the second gain Gb in the range equal to or more than the second steering angle θt_B, and the minimum value Gb_min of the second gain Gb in the range equal to or less than the first steering angle θt_A may be equal to the minimum value Ga_min of the first gain Ga in the range equal to or more than the second steering angle θt_B.

[0183] The maximum value Ga_max of the first gain Ga, the minimum value Ga_min of the first gain Ga, the maximum value Gb_max of the second gain Gb, and the minimum value Gb_min of the second gain Gb, and the magnitude relationship between these values ​​may be set appropriately depending on the dynamic performance and vehicle specifications of the vehicle in which the control device 50 according to the present disclosure is installed.

[0184] The steering torque target value generation unit 200b adds (at multiplication unit 261) the torque value Ga×Tref_a obtained by multiplying the torque value Tref_a (first torque value) output from the steering reaction torque value generation unit 210 by the first gain Ga to (to obtain a torque value Ga×Tref_a), (at multiplication unit 262) the torque value Tref_d (second torque value) output from the road surface reaction force sensitive torque compensation value generation unit 220 by the second gain Gb to (to obtain a torque value Gb×Tref_d), (at multiplication unit 262) the torque value Tref_b output from the damping torque value generation unit 240, and the torque compensation value Tref_c output from the hysteresis compensation unit 250 to (addition units 271, 272, 273), and outputs the result as the steering torque target value Th_ref.

[0185] In the third embodiment, a steering reaction force corresponding to road surface reaction force torque estimated value Tsat_est can be applied to steering wheel 1 at a ratio corresponding to actual turning angle θt_act. Specifically, in a region where actual turning angle θt_act is relatively small, steering torque target value generation section 200b generates steering torque target value Th_ref by multiplying torque value Tref_a (first torque value) output from steering reaction force torque value generation section 210 by a relatively large first gain Ga, and in a region where actual turning angle θt_act is relatively large, generates steering torque target value Th_ref by multiplying torque value Tref_d (second torque value) output from road surface reaction force sensitive torque compensation value generation section 220 by a relatively large second gain Gb. This makes it possible to obtain a steering feel that reflects the road surface conditions and actual turning angle θt_act.

[0186] The example of setting the gain ratios in gain ratio generation unit 230b according to the third embodiment is just one example, and is not limited to the aspect shown in Fig. 23 described above. For example, an aspect may be such that, within a range of not less than the first turning angle θt_A and not more than the second turning angle θt_B, the first gain Ga by which the torque value Tref_a (first torque value) is multiplied gradually decreases as the actual turning angle θt_act increases, and accordingly, the second gain Gb by which the torque value Tref_d (second torque value) is multiplied gradually increases as the actual turning angle θt_act increases. Furthermore, for example, an aspect may be such that, within a range of not less than the first turning angle θt_A and not more than the second turning angle θt_B, the first gain Ga by which the torque value Tref_a (first torque value) is multiplied gradually increases as the actual turning angle θt_act decreases, and accordingly, the second gain Gb by which the torque value Tref_d (second torque value) is multiplied gradually decreases as the actual turning angle θt_act decreases.

[0187] (Embodiment 4) The configuration and operation according to the fourth embodiment, which can provide a steering feel according to road conditions and vehicle state, will be described below with reference to Fig. 24, Fig. 25, Fig. 26A, and Fig. 26B. Fig. 24 is a block diagram showing an example of the configuration of a steering torque target value generator according to the fourth embodiment. Fig. 25 is a block diagram showing an example of the configuration of a gain ratio generator according to the fourth embodiment. Figs. 26A and 26B are diagrams conceptually showing an example of gain ratio setting in the gain ratio generator according to the fourth embodiment.

[0188] In this embodiment, a first gain Ga and a second gain Gb are generated using the vehicle speed Vs and the actual steering angle θh_act as parameters. As shown in Fig. 24, the vehicle speed Vs and the actual steering angle θh_act are input to a gain ratio generation unit 230c of a steering torque target value generation unit 200c according to the fourth embodiment. Furthermore, as shown in Fig. 25, the gain ratio generation unit 230c includes a first gain ratio generation unit 230, a second gain ratio generation unit 230a, and a gain ratio calculation unit 231.

[0189] The first gain ratio generation unit 230 of the gain ratio generation unit 230c has substantially the same components as the gain ratio generation unit 230 according to embodiment 1. The first gain ratio generation unit 230 generates a first gain Ga1 that increases or decreases according to the vehicle speed Vs, and a second gain Gb1 whose sum with the first gain Ga1 is 1.

[0190] The first gain ratio generation unit 230 monotonically decreases the first gain Ga1 within a range of the first vehicle speed Vs_A or more and the second vehicle speed Vs_B or less. Accordingly, the second gain Gb1 monotonically increases within a range of the first vehicle speed Vs_A or more and the second vehicle speed Vs_B or less. The first vehicle speed Vs_A is set to, for example, 5 km / h. The second vehicle speed Vs_B is set to, for example, 30 km / h. The present disclosure is not limited to the values ​​of the first vehicle speed Vs_A and the second vehicle speed Vs_B.

[0191] 26A shows an example in which the maximum value Ga1_max of the first gain Ga1 in the range equal to or less than the first vehicle speed Vs_A is greater than the maximum value Gb1_max of the second gain Gb1 in the range equal to or greater than the second vehicle speed Vs_B. In this case, the minimum value Gb1_min of the second gain Gb1 in the range equal to or less than the first vehicle speed Vs_A is greater than the minimum value Ga1_min of the first gain Ga1 in the range equal to or greater than the second vehicle speed Vs_B.

[0192] In addition, the maximum value Ga1_max of the first gain Ga1 in the range below the first vehicle speed Vs_A may be smaller than the maximum value Gb1_max of the second gain Gb1 in the range above the second vehicle speed Vs_B, and the minimum value Gb1_min of the second gain Gb1 in the range below the first vehicle speed Vs_A may be smaller than the minimum value Ga1_min of the first gain Ga1 in the range above the second vehicle speed Vs_B.

[0193] In addition, the maximum value Ga1_max of the first gain Ga1 in the range below the first vehicle speed Vs_A may be equal to the maximum value Gb1_max of the second gain Gb1 in the range above the second vehicle speed Vs_B, and the minimum value Gb1_min of the second gain Gb1 in the range below the first vehicle speed Vs_A may be equal to the minimum value Ga1_min of the first gain Ga1 in the range above the second vehicle speed Vs_B.

[0194] The maximum value Ga_max of the first gain Ga, the minimum value Ga_min of the first gain Ga, the maximum value Gb_max of the second gain Gb, and the minimum value Gb_min of the second gain Gb, and the magnitude relationship between these values ​​may be set appropriately depending on the dynamic performance and vehicle specifications of the vehicle in which the control device 50 according to the present disclosure is installed.

[0195] A second gain ratio generation section 230a of the gain ratio generation section 230c has substantially the same components as the gain ratio generation section 230a according to embodiment 2. The second gain ratio generation section 230a generates a first gain Ga2 that increases or decreases according to the actual turning angle θt_act, and a second gain Gb2 whose sum with the first gain Ga2 is 1.

[0196] The second gain ratio generation unit 230a monotonically decreases the first gain Ga2 within a range of the first steering angle θh_A or more and the second steering angle θh_B or less. Accordingly, the second gain Gb2 monotonically increases within a range of the first steering angle θh_A or more and the second steering angle θh_B or less. The first steering angle θh_A is set to, for example, 3 degrees. The second steering angle θh_B is set to, for example, 20 degrees. The present disclosure is not limited to the values ​​of the first steering angle θh_A and the second steering angle θh_B.

[0197] 26B shows an example in which the maximum value Ga2_max of the first gain Ga2 in the range equal to or less than the first steering angle θh_A is greater than the maximum value Gb2_max of the second gain Gb2 in the range equal to or greater than the second steering angle θh_B. In this case, the minimum value Gb2_min of the second gain Gb2 in the range equal to or less than the first steering angle θh_A is greater than the minimum value Ga2_min of the first gain Ga2 in the range equal to or greater than the second steering angle θh_B.

[0198] In addition, the maximum value Ga2_max of the first gain Ga2 in the range equal to or less than the first steering angle θh_A may be smaller than the maximum value Gb2_max of the second gain Gb2 in the range equal to or greater than the second steering angle θh_B, and the minimum value Gb2_min of the second gain Gb2 in the range equal to or less than the first steering angle θh_A may be smaller than the minimum value Ga2_min of the first gain Ga2 in the range equal to or greater than the second steering angle θh_B.

[0199] In addition, the maximum value Ga2_max of the first gain Ga2 in the range equal to or less than the first steering angle θh_A may be equal to the maximum value Gb2_max of the second gain Gb2 in the range equal to or greater than the second steering angle θh_B, and the minimum value Gb2_min of the second gain Gb2 in the range equal to or less than the first steering angle θh_A may be equal to the minimum value Ga2_min of the first gain Ga2 in the range equal to or greater than the second steering angle θh_B.

[0200] The gain ratio calculation unit 231 receives the first gain Ga1 and second gain Gb1 output from the first gain ratio generation unit 230, and the first gain Ga2 and second gain Gb2 output from the second gain ratio generation unit 230a. The gain ratio calculation unit 231 calculates the first gain Ga using the following equation (14), and calculates the second gain Gb using the following equation (15).

[0201] Ga=(Ga1×Ga2) / {(Ga1×Ga2)+(Gb1×Gb2)} ···(14)

[0202] Gb=(Gb1×Gb2) / {(Ga1×Ga2)+(Gb1×Gb2)} ···(15)

[0203] The torque value Tref_a (first torque value) is multiplied by the first gain Ga by the multiplication unit 261. The torque value Tref_d (second torque value) is multiplied by the second gain Gb by the multiplication unit 262.

[0204] The steering torque target value generation unit 200c adds (at multiplication unit 261) the torque value Ga×Tref_a obtained by multiplying the torque value Tref_a (first torque value) output from the steering reaction torque value generation unit 210 by the first gain Ga to (a result of multiplication unit 261), (at multiplication unit 262) the torque value Tref_d (second torque value) output from the road surface reaction force sensitive torque compensation value generation unit 220 by the second gain Gb to (a result of multiplication unit 262), the torque value Tref_b output from the damping torque value generation unit 240, and the torque compensation value Tref_c output from the hysteresis compensation unit 250 to (at addition units 271, 272, 273), and outputs the result as the steering torque target value Th_ref.

[0205] In the fourth embodiment, a steering reaction force corresponding to the road reaction torque estimated value Tsat_est can be applied to the steering wheel 1 at a ratio corresponding to both the vehicle speed Vs and the actual steering angle θh_act. Specifically, in a region where the vehicle speed Vs or the actual steering angle θh_act is relatively small, the steering torque target value generating unit 200c generates the steering torque target value Th_ref by multiplying the torque value Tref_a (first torque value) output from the steering reaction torque value generating unit 210 by a relatively large first gain Ga, and in a region where the vehicle speed Vs or the actual steering angle θh_act is relatively large, the steering torque target value generating unit 200c generates the steering torque target value Th_ref by multiplying the torque value Tref_d (second torque value) output from the road reaction force sensitive torque compensation value generating unit 220 by a relatively large second gain Gb. This makes it possible to obtain a steering feel that reflects the road surface conditions, the vehicle speed Vs, and the actual steering angle θh_act.

[0206] Note that the gain ratio setting example in the first gain ratio generation unit 230 according to the fourth embodiment is merely an example and is not limited to the example shown in Fig. 26A described above. For example, the first gain Ga1 may be gradually decreased as the vehicle speed Vs increases within a range of the first vehicle speed Vs_A or higher and the second vehicle speed Vs_B or lower, and the second gain Gb1 may be gradually increased accordingly as the vehicle speed Vs increases. Alternatively, the first gain Ga1 may be gradually increased as the vehicle speed Vs decreases within a range of the first vehicle speed Vs_A or higher and the second vehicle speed Vs_B or lower, and the second gain Gb1 may be gradually decreased accordingly as the vehicle speed Vs decreases.

[0207] Furthermore, the gain ratio setting example in the second gain ratio generation unit 230a according to the fourth embodiment is merely an example and is not limited to the aspect shown in Fig. 26B described above. For example, an aspect may be adopted in which the first gain Ga2 gradually decreases as the actual steering angle θh_act increases within a range of the first steering angle θh_A or more and the second steering angle θh_B or less, and the second gain Gb2 gradually increases accordingly as the actual steering angle θh_act increases. Furthermore, for example, an aspect may be adopted in which the first gain Ga2 gradually increases as the actual steering angle θh_act decreases within a range of the first steering angle θh_A or more and the second steering angle θh_B or less, and the second gain Gb2 gradually decreases accordingly as the actual steering angle θh_act decreases.

[0208] (Embodiment 5) The configuration and operation according to the fifth embodiment, which can provide a steering feel according to road conditions and vehicle state, will be described below with reference to Figs. 27, 28, 29A, and 29B. Fig. 27 is a block diagram showing an example of the configuration of a steering torque target value generator according to the fifth embodiment. Fig. 28 is a block diagram showing an example of the configuration of a gain ratio generator according to the fifth embodiment. Figs. 29A and 29B are diagrams conceptually showing an example of gain ratio setting in the gain ratio generator according to the fifth embodiment.

[0209] In the present embodiment, a first gain Ga and a second gain Gb are generated using vehicle speed Vs and actual steering angle θt_act as parameters. As shown in Fig. 27, vehicle speed Vs and actual steering angle θt_act are input to gain ratio generation section 230d of steering torque target value generation section 200d according to embodiment 5. Further, gain ratio generation section 230d includes first gain ratio generation section 230, second gain ratio generation section 230b, and gain ratio calculation section 231, as shown in Fig. 25.

[0210] The first gain ratio generation unit 230 of the gain ratio generation unit 230d has substantially the same components as the gain ratio generation unit 230 according to embodiment 1. The first gain ratio generation unit 230 generates a first gain Ga1 that increases or decreases according to the vehicle speed Vs, and a second gain Gb1 whose sum with the first gain Ga1 is 1.

[0211] The first gain ratio generation unit 230 monotonically decreases the first gain Ga1 within a range of the first vehicle speed Vs_A or more and the second vehicle speed Vs_B or less. Accordingly, the second gain Gb1 monotonically increases within a range of the first vehicle speed Vs_A or more and the second vehicle speed Vs_B or less. The first vehicle speed Vs_A is set to, for example, 5 km / h. The second vehicle speed Vs_B is set to, for example, 30 km / h. The present disclosure is not limited to the values ​​of the first vehicle speed Vs_A and the second vehicle speed Vs_B.

[0212] 29A shows an example in which the maximum value Ga1_max of the first gain Ga1 in the range equal to or less than the first vehicle speed Vs_A is greater than the maximum value Gb1_max of the second gain Gb1 in the range equal to or greater than the second vehicle speed Vs_B. In this case, the minimum value Gb1_min of the second gain Gb1 in the range equal to or less than the first vehicle speed Vs_A is greater than the minimum value Ga1_min of the first gain Ga1 in the range equal to or greater than the second vehicle speed Vs_B.

[0213] In addition, the maximum value Ga1_max of the first gain Ga1 in the range below the first vehicle speed Vs_A may be smaller than the maximum value Gb1_max of the second gain Gb1 in the range above the second vehicle speed Vs_B, and the minimum value Gb1_min of the second gain Gb1 in the range below the first vehicle speed Vs_A may be smaller than the minimum value Ga1_min of the first gain Ga1 in the range above the second vehicle speed Vs_B.

[0214] In addition, the maximum value Ga1_max of the first gain Ga1 in the range below the first vehicle speed Vs_A may be equal to the maximum value Gb1_max of the second gain Gb1 in the range above the second vehicle speed Vs_B, and the minimum value Gb1_min of the second gain Gb1 in the range below the first vehicle speed Vs_A may be equal to the minimum value Ga1_min of the first gain Ga1 in the range above the second vehicle speed Vs_B.

[0215] The maximum value Ga_max of the first gain Ga, the minimum value Ga_min of the first gain Ga, the maximum value Gb_max of the second gain Gb, and the minimum value Gb_min of the second gain Gb, and the magnitude relationship between these values ​​may be set appropriately depending on the dynamic performance and vehicle specifications of the vehicle in which the control device 50 according to the present disclosure is installed.

[0216] A second gain ratio generation section 230b of the gain ratio generation section 230c has substantially the same components as the gain ratio generation section 230b according to embodiment 3. The second gain ratio generation section 230b generates a first gain Ga2 that increases or decreases according to the actual turning angle θt_act, and a second gain Gb2 whose sum with the first gain Ga2 is 1.

[0217] Second gain ratio generation section 230b monotonically decreases first gain Ga2 within a range of not less than first turning angle θt_A and not more than second turning angle θt_B. Accordingly, second gain Gb2 monotonically increases within a range of not less than first turning angle θt_A and not more than second turning angle θt_B. First turning angle θt_A is set to, for example, 3 [deg]. Second turning angle θt_B is set to, for example, 20 [deg]. The present disclosure is not limited to the values ​​of first turning angle θt_A and second turning angle θt_B.

[0218] 29B shows an example in which the maximum value Ga2_max of the first gain Ga2 in the range equal to or less than the first turning angle θt_A is greater than the maximum value Gb2_max of the second gain Gb2 in the range equal to or greater than the second turning angle θt_B. In this case, the minimum value Gb2_min of the second gain Gb2 in the range equal to or less than the first turning angle θt_A is greater than the minimum value Ga2_min of the first gain Ga2 in the range equal to or greater than the second turning angle θt_B.

[0219] Note that the maximum value Ga2_max of the first gain Ga2 in the range equal to or less than the first steering angle θt_A may be smaller than the maximum value Gb2_max of the second gain Gb2 in the range equal to or greater than the second steering angle θt_B, and the minimum value Gb2_min of the second gain Gb2 in the range equal to or less than the first steering angle θt_A may be smaller than the minimum value Ga2_min of the first gain Ga2 in the range equal to or greater than the second steering angle θt_B.

[0220] In addition, the maximum value Ga2_max of the first gain Ga2 in the range equal to or less than the first steering angle θt_A may be equal to the maximum value Gb2_max of the second gain Gb2 in the range equal to or greater than the second steering angle θt_B, and the minimum value Gb2_min of the second gain Gb2 in the range equal to or less than the first steering angle θt_A may be equal to the minimum value Ga2_min of the first gain Ga2 in the range equal to or greater than the second steering angle θt_B.

[0221] The gain ratio calculation unit 231 calculates the first gain Ga and the second gain Gb using the equations (14) and (15) described in the fourth embodiment.

[0222] The torque value Tref_a (first torque value) is multiplied by the first gain Ga by the multiplication unit 261. The torque value Tref_d (second torque value) is multiplied by the second gain Gb by the multiplication unit 262.

[0223] The steering torque target value generation unit 200d adds (at multiplication unit 261) the torque value Ga×Tref_a obtained by multiplying the torque value Tref_a (first torque value) output from the steering reaction torque value generation unit 210 by the first gain Ga to (to obtain a torque value Ga×Tref_a), (at multiplication unit 262) the torque value Tref_d (second torque value) output from the road surface reaction force sensitive torque compensation value generation unit 220 by the second gain Gb to (to obtain a torque value Gb×Tref_d), (at multiplication unit 262) the torque value Tref_b output from the damping torque value generation unit 240, and the torque compensation value Tref_c output from the hysteresis compensation unit 250 to (addition units 271, 272, 273), and outputs the result as the steering torque target value Th_ref.

[0224] In the fifth embodiment, a steering reaction force corresponding to road surface reaction force torque estimated value Tsat_est can be applied to the steering wheel 1 at a ratio corresponding to both the vehicle speed Vs and the actual turning angle θt_act. Specifically, in a region where the vehicle speed Vs or the actual turning angle θt_act is relatively small, steering torque target value generation section 200d generates steering torque target value Th_ref by multiplying torque value Tref_a (first torque value) output from steering reaction force torque value generation section 210 by a relatively large first gain Ga, and in a region where the vehicle speed Vs or the actual turning angle θt_act is relatively large, multiplying torque value Tref_d (second torque value) output from road surface reaction force sensitive torque compensation value generation section 220 by a relatively large second gain Gb to generate steering torque target value Th_ref. This makes it possible to obtain a steering feel that reflects the road surface conditions, vehicle speed Vs, and actual turning angle θt_act.

[0225] Note that the gain ratio setting example in the first gain ratio generation unit 230 according to the fifth embodiment is merely an example and is not limited to the example shown in Fig. 29A described above. For example, the first gain Ga1 may be gradually decreased as the vehicle speed Vs increases within a range of not less than the first vehicle speed Vs_A and not more than the second vehicle speed Vs_B, and the second gain Gb1 may be gradually increased accordingly as the vehicle speed Vs increases. Alternatively, the first gain Ga1 may be gradually increased as the vehicle speed Vs decreases within a range of not less than the first vehicle speed Vs_A and not more than the second vehicle speed Vs_B, and the second gain Gb1 may be gradually decreased accordingly as the vehicle speed Vs decreases.

[0226] Furthermore, the gain ratio setting example in second gain ratio generation section 230b according to embodiment 5 is merely an example and is not limited to the aspect shown in Fig. 29B described above. For example, an aspect may be such that, within a range of not less than the first turning angle θt_A and not more than the second turning angle θt_B, first gain Ga2 gradually decreases as the actual turning angle θt_act increases, and accordingly, second gain Gb2 gradually increases as the actual turning angle θt_act increases. Furthermore, for example, an aspect may be such that, within a range of not less than the first turning angle θt_A and not more than the second turning angle θt_B, first gain Ga2 gradually increases as the actual turning angle θt_act decreases, and accordingly, second gain Gb2 gradually decreases as the actual turning angle θt_act decreases.

[0227] (Embodiment 6) In this embodiment, a method for setting the first gain Ga and the second gain Gb that is different from that in the fourth embodiment will be described. Fig. 30 is a block diagram showing an example of the configuration of a steering torque target value generator according to the sixth embodiment. Fig. 31 is a 3D map showing an example of a gain ratio generation method according to the sixth embodiment.

[0228] The gain ratio generation unit 230e of the steering torque target value generation unit 200e according to the sixth embodiment has a gain ratio setting map shown in Fig. 31. The gain ratio generation unit 230e generates a second gain Gb using the gain ratio map shown in Fig. 31, with the vehicle speed Vs and the actual steering angle θh_act as parameters. In addition, the gain ratio generation unit 230e calculates a first gain Ga using the following equation (16).

[0229] Ga = 1 − Gb (16)

[0230] In the example shown in FIG. 31, the gain ratio generation unit 230e generates the second gain Gb using the gain ratio map shown in FIG. 31, and calculates the first gain Ga using the above equation (16). However, the gain ratio generation unit 230e may have a gain ratio map for generating the first gain Ga using the vehicle speed Vs and the actual steering angle θh_act as parameters, and may calculate the second gain Gb using the following equation (17), which is a modification of the above equation (16).

[0231] Gb = 1 − Ga (17)

[0232] Furthermore, in this embodiment, as in embodiment 4, an example has been described in which the first gain Ga and the second gain Gb are generated using the vehicle speed Vs and the actual steering angle θh_act as parameters. However, it is also possible to have a gain ratio map for generating the first gain Ga or the second gain Gb using the vehicle speed Vs and the actual steering angle θt_act as parameters, and to generate the first gain Ga and the second gain Gb using the vehicle speed Vs and the actual steering angle θt_act as parameters, as in embodiment 5.

[0233] (Embodiment 7) In this embodiment, we will explain steering angle control section 700. Fig. 32 is a block diagram showing an example configuration of the steering angle control section. As shown in Fig. 32, steering angle control section 700 includes a feedforward compensation section 710, a PID control section 730, a stabilization compensation section 740, an output limiting section 760, a friction compensation section 770, and addition sections 720 and 750.

[0234] Feedforward compensation section 710 is configured with a filter (FF filter) for improving the ability of actual turning angle θt_act to follow target turning angle value θt_ref. Feedforward compensation section 710 performs filtering on target turning angle value θt_ref. Specifically, for example, an LPF having a first-order or second-order lag transfer function is used, and the LPF is designed so that the time delay caused by filtering by the LPF is equivalent to the delay in the actual turning angle θt_act following target turning angle value θt_ref.

[0235] PID control section 730 performs PID control so that deviation θt_err between target turning angle value θt_ref, which is the calculation result of addition section 720, and actual turning angle θt_act approaches zero.

[0236] The stabilization compensation unit 740 is configured with a filter (stabilization filter) having transfer characteristics required for stabilizing control. The stabilization compensation unit 740 performs filtering on the output value of the PID control unit 730.

[0237] Output limiting section 760 performs output limiting processing on current command value Iref_c, which is the calculation result of adder 750, and outputs second turning motor current command value It_ref. Upper and lower limit values ​​for current command value Iref_c are set in advance for output limiting section 760. Output limiting section 760 limits the upper and lower limit values ​​of current command value Iref_c, and outputs turning motor current command value It_ref.

[0238] It should be noted that the above-described feedforward compensation section 710 and stabilization compensation section 740 are not necessarily required components, and for example, either one or both of the feedforward compensation section 710 and the stabilization compensation section 740 may be omitted.

[0239] Friction compensation section 770 calculates second current compensation value Iref_b based on steering angle target value θt_ref to compensate for the delay in response of actual steering angle θt_act to steering angle target value θt_ref caused by friction in the steering mechanism. The specific configuration and operation of friction compensation section 770 will be described in detail below.

[0240] Fig. 33 is a block diagram showing an example of the configuration of a friction compensation unit 770. As shown in Fig. 33, the friction compensation unit 770 includes, as its main components, a current compensation value calculation unit 771 and a current sensitive gain generation unit 773.

[0241] Current compensation value calculation section 771 receives as input the steering angle target value θt_ref and the turning speed target value ωt_ref calculated by differentiating the steering angle target value θt_ref by differentiating section 772. Current compensation value calculation section 771 calculates a first current compensation value Iref_b0 based on the steering angle target value θt_ref and the turning speed target value ωt_ref.

[0242] The method of calculating the first current compensation value Iref_b0 in the current compensation value calculation unit 771 will be described below.

[0243] Fig. 34 is a diagram showing an example of the characteristics of the first current compensation value in the current compensation value calculation unit. In Fig. 34, the horizontal axis represents the steering angle target value θt_ref, and the vertical axis represents the first current compensation value Iref_b0. Also in Fig. 34, the solid line represents the first current compensation value Iref_b0 when steering to the right, and the dashed line represents the first current compensation value Iref_b0 when steering to the left. As shown in Fig. 34, the first current compensation value Iref_b0 calculated in current compensation value calculation unit 771 has hysteresis characteristics that result in different values ​​when steering to the left and when steering to the right. L1 shown in Figure 34 indicates the trajectory when the steered wheels 5L and 5R are steered to the right from their center position (origin (0,0)), L2 indicates the trajectory when a switch from right steering to left steering occurs at coordinate A (x1, y1), and L3 indicates the trajectory when a switch from right steering to left steering occurs at coordinate B (x2, y2).

[0244] Current compensation value calculation unit 771 calculates first current compensation value Iref_b0 using the following equations (18) and (19) based on the steering angle target value θt_ref and the steering speed target value ωt_ref. Specifically, when the sign ωt_ref(sgn) of the steering speed target value ωt_ref is a positive value ("+"), it calculates first current compensation value Iref_b0 using the following equation (18), and when the sign ωt_ref(sgn) of the steering speed target value ωt_ref is a negative value ("-"), it calculates first current compensation value Iref_b0 using the following equation (19). In the following equations (18) and (19), x is the steering speed target value ωt_ref, y is the R is the first current compensation value Iref_b0 when steering to the right, y L is the first current compensation value Iref_b0 when steering left. Furthermore, the coefficient a is a value greater than 1, and the coefficient c is a value greater than 0. The coefficient Ahys indicates the output width of the hysteresis characteristic (the width of the first current compensation value Iref_b0), and the coefficient c is a coefficient that indicates the roundness of the hysteresis characteristic.

[0245] y R =Ahys{1-a -c(x-b)}···(18)

[0246] y L =-Ahys{1-a c(x-b’)}···(19)

[0247] That is, when steering to the right (ωt_ref(sgn)="+"), the current compensation value calculation unit 771 calculates the first current compensation value Iref_b0(y R ) is calculated, and when steering left (ωt_ref(sgn)="-"), the first current compensation value Iref_b0(y L ) is calculated.

[0248] When a switch from right steering to left steering occurs (ωt_ref(sgn) = "+" → "-"), or when a switch from left steering to right steering occurs (ωt_ref(sgn) = "-" → "+"), current compensation value calculation unit 771 takes over the previous values ​​of steering angle target value θt_ref and first current compensation value Iref_b0, and substitutes coefficient b or b' shown in equation (20) or (21) below into equation (18) or (19) above that is applied after the steering switch. This maintains continuity before and after the steering switch. Specifically, when a switch from right steering to left steering occurs (ωt_ref(sgn)="+"→"-"), current compensation value calculation unit 771 applies the previous values ​​of steering angle target value θt_ref and first current compensation value Iref_b0 (coordinate A(x1, y1) shown in FIG. 34) to equation (19) above, and substitutes coefficient b' shown in equation (21) below to calculate first current compensation value Iref_b0. Also, when a switch from left steering to right steering occurs (ωt_ref(sgn)="-"→"+"), current compensation value calculation unit 771 applies the previous values ​​of steering angle target value θt_ref and first current compensation value Iref_b0 (coordinate B(x2, y2) shown in FIG. 34) to equation (18) above, and substitutes coefficient b shown in equation (20) below to calculate first current compensation value Iref_b0.

[0249] b=x1+(1 / c)log a {1-(y1 / Ahys)} (20)

[0250] b'=x1-(1 / c)log a {1-(y1 / Ahys)} (21)

[0251] The above equations (20) and (21) are obtained by substituting x1 for x in the above equations (18) and (19) and R and y L can be derived by substituting y1 into

[0252] When Napier's constant e is used as the coefficient a, the above equations (18), (19), (20), and (21) can be expressed as the following equations (22), (23), (24), and (25), respectively.

[0253] y R =Ahys[1-exp{-c(xb)}]···(22)

[0254] y L =-Ahys[{1-exp{c(x-b')}]···(23)

[0255] b=x1+(1 / c)log e {1-(y1 / Ahys)} (24)

[0256] b'=x1-(1 / c)log e {1-(y1 / Ahys)} (25)

[0257] Returning to Figure 33, previous value hold section 774 holds the previous output value It_ref' of steering angle control section 700. Specifically, previous output value It_ref' is second steering motor current command value It_ref in the previous processing. Previous value hold section 774 is formed, for example, by a RAM of an ECU constituting control device 50.

[0258] In the present disclosure, absolute value calculation section 775 performs absolute value processing of the previous output value It_ref′ of turning angle control section 700 output from previous value holding section 774 .

[0259] Current sensitive gain generation section 773 receives as input the previous output value |It_ref'| of turning angle control section 700 which has been subjected to absolute value processing in absolute value calculation section 775. Current sensitive gain generation section 773 generates gain Gi according to the previous output value |It_ref'| of turning angle control section 700.

[0260] Current sensitive gain generation section 773 has a current sensitive gain map in which gain Gi is set according to previous output value |It_ref'| of steering angle control section 700. The current sensitive gain map is stored, for example, in the ROM of the ECU that constitutes control device 50. Fig. 35A is a diagram showing a first example of the current sensitive gain map. Fig. 35B is a diagram showing a second example of the current sensitive gain map.

[0261] The first example of the current-sensitive gain map shown in Figure 35A has a current-value-sensitive characteristic in which gain Gi increases or decreases in accordance with the previous output value |It_ref'| of turning angle control unit 700. More specifically, as shown in Figure 35A, gain Gi monotonically increases as the previous output value |It_ref'| of turning angle control unit 700 increases.

[0262] Fig. 36 is a diagram showing an example of the output characteristics of the friction compensation unit. In Fig. 36, the horizontal axis represents the target turning angle value θt_ref, and the vertical axis represents the second current compensation value Iref_b.

[0263] The frictional force generated in the steering mechanism includes friction due to gear torque between steering motor 41 and reduction mechanism 42. Gear torque refers to torque resulting from frictional force generated in the mechanical elements of the reduction gear. For example, in the case of a worm reduction gear, the frictional torque caused by frictional force generated at the meshing portion between the worm gear and the worm wheel can be defined as gear torque. The frictional force due to this gear torque increases monotonically with motor current.

[0264] In the present disclosure, friction compensation section 770 calculates second current compensation value Iref_b by multiplying (by multiplication section 776) first current compensation value Iref_b0 output from current compensation value calculation section 771 by gain Gi generated by current sensitive gain generation section 773. This provides a characteristic in which the output width of the hysteresis characteristic (width of second current compensation value Iref_b) increases and decreases in accordance with second turning motor current command value It_ref, as shown in Fig. 36, and makes it possible to realize friction compensation control in accordance with friction force caused by gear torque.

[0265] Specifically, when second turning motor current command value It_ref is relatively large, gear torque becomes relatively large and frictional force caused by the gear torque acts strongly. Under such circumstances, by multiplying first current compensation value Iref_b0 output from current compensation value calculation section 771 by gain Gi_H that is relatively larger than gain Gi_M, it is possible to increase the output width of the hysteresis characteristic (width of second current compensation value Iref_b), as shown by the dashed line.

[0266] Furthermore, when second turning motor current command value It_ref is relatively small, the gear torque becomes relatively small and the frictional force caused by the gear torque becomes smaller. Under such circumstances, by multiplying first current compensation value Iref_b0 output from current compensation value calculation section 771 by gain Gi_L that is relatively smaller than gain Gi_M, it is possible to narrow the output width of the hysteresis characteristic (width of second current compensation value Iref_b), as shown by the dashed dotted line.

[0267] The mode of the current sensitive gain map is not limited to the mode of the first example shown in Figure 35 A. For example, as in the second example shown in Figure 35B, the mode may be such that second current compensation value Iref_b is calculated by multiplying first current compensation value Iref_b0 output from current compensation value calculation section 771 by a constant gain Gi=k (for example, k=1), regardless of second turning motor current command value It_ref (previous output value |It_ref'| of turning angle control section 700).

[0268] Second current compensation value Iref_b output from friction compensation section 770 is added by addition section 750 shown in FIG. 32 to first turning motor current command value Iref_a output from stabilization compensation section 740, and second turning motor current command value It_ref, which has been output limited by output limiting section 760 with respect to current command value Iref_c after the addition, is output.

[0269] FIG. 37 is a block diagram showing an example configuration of a friction compensation section according to a modified example. In the example configuration of friction compensation section 770a shown in FIG. 33, first current compensation value Iref_b0 output from current compensation value calculation section 771 is multiplied by gain Gi generated by current sensitive gain generation section 773. However, in the modified example shown in FIG. 37, current compensation value calculation section 771a may be configured to hold a table (data) correlating second turning motor current command value It_ref (previous output value |It_ref'| of turning angle control section 700) with coefficient Ahys in equations (6) to (13) above, and to obtain a characteristic in which the output width of the hysteresis characteristic (width of second current compensation value Iref_b) increases or decreases according to second turning motor current command value It_ref, as shown in FIG. 36. This data, like the current sensitive gain map, can be stored, for example, in the ROM of the ECU constituting control device 50. This makes it possible to realize friction compensation control according to frictional force caused by gear torque, similar to the configuration shown in FIG. 33.

[0270] Note that the present invention is not limited to the aspect in which steering speed target value ωt_ref is obtained by differentiating steering angle target value θt_ref, and may alternatively be an aspect in which it is determined that the steering direction has been switched using the motor angular velocity of steering motor 41. Also, a configuration may be adopted in which a filter is provided in a stage preceding current compensation value calculation section 771 and current sensitive gain generation section 773, or a configuration in which a filter is provided in a stage subsequent to current sensitive gain generation section 773. Furthermore, a configuration may be adopted in which a limiter that performs output limiting processing on second current compensation value Iref_b is provided in a stage subsequent to friction compensation section 770, similar to output limiting section 760 described above.

[0271] Figures 38A and 38B are first conceptual diagrams illustrating a specific example of friction compensation control by a friction compensation unit. In Figures 38A and 38B, the horizontal axis represents time, and the vertical axis represents steering angle. The dashed lines in Figures 38A and 38B represent steering angle target value θt_ref, and the solid lines represent actual steering angle θt_act. Figure 38A illustrates a time response when friction compensation control by friction compensation unit 770 is not performed. Figure 38B illustrates a time response when friction compensation control by friction compensation unit 770 is performed.

[0272] The examples shown in Figures 38A and 38B show time responses when steered wheels 5L, 5R are steered left and right from their center positions at a relatively fast predetermined frequency. When friction compensation control is not performed by friction compensation unit 770, distortion occurs in actual steering angle θt_act when the steering direction is switched, as shown in Figure 38A, as enclosed by the dashed line. In this case, when the driver switches the steering direction from steering further to steering back, or from steering back to steering further, a discrepancy occurs between the operation (steering) of steering wheel 1 and the steering of steered wheels 5L, 5R, which may cause the driver to feel uncomfortable. In contrast, when friction compensation control is performed by friction compensation unit 770, distortion in actual steering angle θt_act is suppressed when the steering direction is switched, as shown in Figure 38B, as enclosed by the dashed line.

[0273] To explain in more detail, when the steering angle target value θt_ref is switched during a change in steering direction, the steering speed target value ωt_ref becomes approximately zero. However, since the first current compensation value Iref_b0 is determined in accordance with the steering angle target value θt_ref, the friction compensation unit 770 can perform predetermined friction compensation control even when the steering speed target value ωt_ref is approximately zero.

[0274] This reduces the sense of discomfort felt by the driver when the steering direction is switched from further turning to returning, or from returning to further turning.

[0275] 39A and 39B are second conceptual diagrams illustrating a specific example of friction compensation control by a friction compensation unit. In Fig. 39A and Fig. 39B, the horizontal axis represents time, and the vertical axis represents steering angle. The dashed lines in Fig. 39A and Fig. 39B represent steering angle target value θt_ref, and the solid lines represent actual steering angle θt_act. Fig. 39A illustrates a time response when friction compensation control is performed in accordance with steering speed target value ωt_ref, as a comparative example of friction compensation control according to the embodiment. Fig. 39B illustrates a time response when friction compensation control is performed by friction compensation unit 770.

[0276] The examples shown in Figures 39A and 39B show time responses when the steering is performed more slightly to the left or right than in Figures 38A and 38B. When friction compensation control is performed in accordance with steering speed target value ωt_ref according to the comparative example, as shown in Figure 39A, when the steering is performed slightly to the left or right, distortion occurs in actual steering angle θt_act when the steering direction is switched, as surrounded by a dashed line. In contrast, when friction compensation control is performed by friction compensation section 770, as shown in Figure 39B, distortion in actual steering angle θt_act is suppressed when the steering direction is switched, as surrounded by a dashed line, even when the steering is performed slightly to the left or right.

[0277] Explaining in more detail, if the steering wheel is operated slowly, minutely, and slowly, when the steering direction is switched, as with the example of Figures 38A and 38B, when the steering angle target value θt_ref switches, the steering speed target value ωt_ref becomes approximately zero. Here, unlike the example of Figures 38A and 38B, because the steering angle target value θt_ref also takes a value close to zero, the first current compensation value Iref_b0 output from current compensation value calculation unit 771 also becomes a small value, but by multiplying first current compensation value Iref_b0 by gain Gi calculated by current sensitive gain generation unit 773, it is possible to prevent second current compensation value Iref_b from becoming too small.

[0278] This reduces the sense of discomfort felt by the driver when the steering direction of the driver's steering wheel is changed from turning more to turning back, or from turning back to turning more, even in a situation where the driver's steering operation is slight.

[0279] As described above, steering angle control section 700 is provided with friction compensation section 770 and is configured to calculate, based on steering angle target value θt_ref, second current compensation value Iref_b for compensating for the delay in response of actual steering angle θt_act to steering angle target value θt_ref caused by friction in the steering mechanism, thereby enabling friction compensation control to be performed effectively and appropriately regardless of the steering wheel operation speed by the driver.

[0280] Furthermore, as described above, by setting the second current compensation value Iref_b to have a characteristic that increases or decreases according to the second turning motor current command value It_ref, it is possible to realize friction compensation control according to the friction force caused by the gear torque.

[0281] In the present disclosure, road surface reaction force sensitive torque compensation value generation section 220 calculates a road surface reaction force torque estimated value Tsat_est corresponding to first steering motor current command value Iref_a before adding second current compensation value Iref_b output from friction compensation section 770, thereby obtaining a road surface reaction force torque estimated value Tsat_est corresponding to the behavior of actual road surface reaction force torque Tsat_act when the vehicle is actually traveling, and making it possible to apply a steering reaction force corresponding to road surface reaction force torque estimated value Tsat_est.

[0282] In addition, in the present disclosure, the increase or decrease in the first gain Ga and the second gain Gb in the section from the first vehicle speed Vs_A to the second vehicle speed Vs_B may be changed linearly with respect to the vehicle speed, as shown in Figure 19, etc., or may be changed nonlinearly in some sections.

[0283] It should be noted that the drawings used in the above-described embodiments are conceptual diagrams for qualitatively explaining the present disclosure, and are not intended to be limiting. Furthermore, while the above-described embodiment is an example of a preferred embodiment of the present disclosure, the present disclosure is not limited thereto, and various modifications can be made within the scope of the gist of the present disclosure. [Explanation of symbols]

[0284] 1 handle 2 column axis 3a, 3b tie rod 5L,5R steered wheels 6a,6b Arms 10 Vehicle speed sensor 11 Ignition key 12 Battery 30 Reaction Device 31 Reaction motor 32 Reduction mechanism 33 Steering angle sensor 34 Torque sensor 35 Stopper (rotation limiting mechanism) 40 Steering gear 41 Steering motor 42 Reduction mechanism 43 Angle Sensor 44 Pinion rack mechanism 50 Control device 60 Reaction Force Control System 70 Steering control system 200, 200a, 200b, 200c, 200d, 200e Steering torque target value generation unit 210 Steering reaction torque value generation unit 211 Steering reaction torque map section 220 Road reaction force sensitive torque compensation value generation unit 221 Road reaction torque estimation unit 222 Road reaction force sensitive torque map section 230, 230a, 230b, 230c, 230d, 230e Gain ratio generation unit (first gain ratio generation unit, second gain ratio generation unit) 231 Gain ratio calculation unit 240 Damping torque value generator 241 Damping Gain Map Section 250 Hysteresis compensation section 251 Hysteresis compensation value calculation unit 400 Steering torque control unit 500 Current control section 600 steering angle target value generation unit 700 Steering angle control unit 710 Feedforward compensation section 720 Addition Section 730 PID control unit 740 Stabilization compensation section 750 Addition Section 760 Output Limiter 770,770a Friction compensation section 771,771a Current compensation value calculation unit 772 Differential part 773 Current Sensitive Gain Generator 774 Previous value storage unit 775 Absolute Value Calculation Unit 776 Multiplication Unit 800 Current control section

Claims

1. A control device for a vehicle steering system including a reaction device that drives a reaction motor that applies a steering reaction force to a steering wheel in accordance with a steering angle of the steering wheel, and a steering device that drives a steering motor that steers steered wheels in accordance with the steering angle of the steering wheel, a steering torque target value generating unit that generates a steering torque target value that is a target value of the steering torque for obtaining the steering reaction force; a steering angle target value generation unit that generates a steering angle target value that is a target value of the steering angle of the steered wheels based on the steering angle; a steering angle control unit that generates a first steering motor current command value that is a target value of a current to be supplied to the steering motor based on the steering angle target value; Equipped with The steering torque target value generation unit a steering reaction torque value generator that generates a first torque value that increases or decreases according to at least the steering angle; a road surface reaction force sensitive torque compensation value generation unit that generates a second torque value that increases or decreases in accordance with a road surface reaction force torque estimation value that is estimated based on at least the first steering motor current command value; a gain ratio generating unit that generates a first gain that increases or decreases according to at least one of a vehicle speed and a steering angle of the vehicle, and a second gain whose sum with the first gain is 1; Equipped with generating the steering torque target value by adding a value obtained by multiplying the first torque value by the first gain and a value obtained by multiplying the second torque value by the second gain; the steering torque target value generation unit increases the second torque value as the vehicle speed increases. A control device for a vehicle steering system.

2. the gain ratio generation unit decreases the first gain as the vehicle speed increases.

2. The control device for a vehicle steering system according to claim 1.

3. the gain ratio generating unit reduces the first gain when the vehicle speed is within a range of a first vehicle speed or more and a second vehicle speed or less.

3. The control device for a vehicle steering system according to claim 2.

4. The first gain in a range of vehicle speeds equal to or lower than the first vehicle speed is greater than the second gain in a range of vehicle speeds equal to or higher than the second vehicle speed.

4. The control device for a vehicle steering system according to claim 3.

5. a first gain in a range equal to or less than the first vehicle speed is equal to a second gain in a range equal to or more than the second vehicle speed; 4. The control device for a vehicle steering system according to claim 3.

6. The first gain in a range of vehicle speeds equal to or lower than the first vehicle speed is smaller than the second gain in a range of vehicle speeds equal to or higher than the second vehicle speed.

4. The control device for a vehicle steering system according to claim 3.

7. the gain ratio generation unit decreases the first gain as an actual steering angle, which is an actual steering angle of the steering wheel, increases.

2. The control device for a vehicle steering system according to claim 1.

8. the gain ratio generation unit reduces the first gain within a range of a first steering angle or more and a second steering angle or less. The control device for a vehicle steering system according to claim 7.

9. The first gain in a range equal to or smaller than the first steering angle is greater than the second gain in a range equal to or larger than the second steering angle. The control device for a vehicle steering system according to claim 8.

10. a first gain in a range equal to or smaller than the first steering angle is equal to a second gain in a range equal to or larger than the second steering angle; The control device for a vehicle steering system according to claim 8.

11. The first gain in a range equal to or smaller than the first steering angle is smaller than the second gain in a range equal to or larger than the second steering angle. The control device for a vehicle steering system according to claim 8.

12. A control device for a vehicle steering system including a reaction device that drives a reaction motor that applies a steering reaction force to a steering wheel in accordance with a steering angle of the steering wheel, and a steering device that drives a steering motor that steers steered wheels in accordance with the steering angle of the steering wheel, a steering torque target value generating unit that generates a steering torque target value that is a target value of the steering torque for obtaining the steering reaction force; a steering angle target value generation unit that generates a steering angle target value that is a target value of the steering angle of the steered wheels based on the steering angle; a steering angle control unit that generates a first steering motor current command value that is a target value of a current to be supplied to the steering motor based on the steering angle target value; Equipped with The steering torque target value generation unit a steering reaction torque value generator that generates a first torque value that increases or decreases according to at least the steering angle; a road surface reaction force sensitive torque compensation value generation unit that generates a second torque value that increases or decreases in accordance with a road surface reaction force torque estimation value that is estimated based on at least the first steering motor current command value; a gain ratio generating unit that generates a first gain that increases or decreases according to at least one of a vehicle speed and a steering angle of the vehicle, and a second gain whose sum with the first gain is 1; Equipped with generating the steering torque target value by adding a value obtained by multiplying the first torque value by the first gain and a value obtained by multiplying the second torque value by the second gain; the gain ratio generation unit decreases the first gain as an actual steering angle, which is an actual steering angle of the steered wheels, increases. A control device for a vehicle steering system.

13. the steering torque target value generation unit increases the second torque value as the vehicle speed increases. The control device for a vehicle steering system according to claim 12.

14. the gain ratio generation unit reduces the first gain within a range of a first turning angle or more and a second turning angle or less. The control device for a vehicle steering system according to claim 12.

15. The first gain in a range equal to or smaller than the first steering angle is greater than the second gain in a range equal to or larger than the second steering angle. The control device for a vehicle steering system according to claim 14.

16. a first gain in a range equal to or smaller than the first steering angle is equal to a second gain in a range equal to or larger than the second steering angle; The control device for a vehicle steering system according to claim 14.

17. The first gain in a range equal to or smaller than the first steering angle is smaller than the second gain in a range equal to or larger than the second steering angle. The control device for a vehicle steering system according to claim 14.

18. The steering angle control unit a friction compensation unit that calculates different steering motor current compensation values ​​depending on whether the steered wheels are steered to the right or left, based on the steering angle target value; The steering angle control unit generating a second turning motor current command value for driving the turning motor based on the first turning motor current command value and the turning motor current compensation value; A control device for a vehicle steering system according to any one of claims 1 to 17.

19. the steering motor current compensation value has a hysteresis characteristic according to a change in the steering angle target value, The control device for a vehicle steering system according to claim 18.

20. the steering motor current compensation value monotonically increases in a region where the steering motor current compensation value is equal to or smaller than a second steering angle target value obtained by adding a predetermined steering angle change amount threshold to a first steering angle target value when steering is started, and becomes a constant value in a region where the steering motor current compensation value is larger than the second steering angle target value. The control device for a vehicle steering system according to claim 18.

21. the friction compensation unit increases or decreases the turning motor current compensation value in accordance with the second turning motor current command value, The control device for a vehicle steering system according to claim 18.

22. the turning motor current compensation value monotonically increases as the second turning motor current command value increases.

22. The control device for a vehicle steering system according to claim 21.

23. a current compensation value calculation unit that calculates a first current compensation value; a current sensitive gain generating unit that generates a gain that monotonically increases as the second steering motor current command value increases; Equipped with the friction compensation unit calculates a second current compensation value by multiplying the first current compensation value by the gain; 23. The control device for a vehicle steering system according to claim 22.

24. the friction compensation section holds data in which the second turning motor current command value is associated with a gain that monotonically increases as the second turning motor current command value increases, and calculates the turning motor current compensation value based on the data.

23. The control device for a vehicle steering system according to claim 22.

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