Motor control device

Abstract

This motor control device includes: a manual steering command value calculation unit that calculates a manual steering command value using torsion bar torque; an integrated angle command value calculation unit that calculates an integrated angle command value by adding the manual steering command value to an automatic steering command value for driving assistance; and a control unit that performs drive control of an electric motor on the basis of the integrated angle command value. The manual steering command value calculation unit is configured so that, while in a driving assistance mode, the manual steering command value is calculated using an equation of motion from a reference model for a steering device. The manual steering command value calculation unit calculates the manual steering command value at least while under a predetermined condition using a target virtual spring reaction force corresponding to the lateral position of a vehicle reference position with respect to a vehicle lane as a virtual spring reaction force in the equation of motion.

Description

Motor control device

[0001] The present disclosure relates to a control device for an electric motor for steering angle control.

[0002] Patent Document 1 listed below discloses a motor control device that includes an assist torque command value setting unit that generates an assist torque command value using torsion bar torque, a manual steering command value generation unit that generates a manual steering command value using torsion bar torque and the assist torque command value, an integrated angle command value calculation unit that calculates an integrated angle command value by adding the manual steering command value to the automatic steering command value, and a switching unit that switches, based on a switching signal, between first control that controls the electric motor based only on the assist torque command value and second control that controls the electric motor based on the integrated angle command value.

[0003] International Publication No. 2023 / 286169

[0004] In the second control described in Patent Document 1, the manual steering command value generator generates a manual steering command value using an equation of motion of a reference model of the steering device. The equation of motion of the reference model of the steering device includes a moment of inertia, a virtual spring reaction force, and a virtual damper reaction force. The virtual spring reaction force is a value obtained by multiplying the spring constant of the virtual spring by the rotation angle of the lower column (manual steering command value). Therefore, even if a value corresponding to the lateral position of the vehicle reference position is used as the spring constant, it is not possible to set a torque corresponding to the vehicle reference position as the virtual spring reaction force. Therefore, in the second control described in Patent Document 1, the virtual spring reaction force is a reaction force that is determined by the natural course of events.

[0005] An object of the present disclosure is to provide a motor control device that is capable of setting a virtual spring reaction force according to the lateral position of the vehicle reference position at least under predetermined conditions.

[0006] One embodiment of the present disclosure provides a motor control device for drive-controlling an electric motor of a steering device, the motor control device including: a manual steering command value calculation unit that calculates a manual steering command value using a torsion bar torque; an integrated angle command value calculation unit that calculates an integrated angle command value by adding the manual steering command value to an automatic steering command value for driving assistance; and a control unit that drive-controls the electric motor based on the integrated angle command value, wherein in a driving assistance mode, the manual steering command value calculation unit is configured to calculate the manual steering command value by utilizing an equation of motion of a reference model of the steering device, and the manual steering command value calculation unit calculates the manual steering command value by using, at least under predetermined conditions, a target virtual spring reaction force according to the lateral position of a vehicle reference position with respect to a driving lane as a virtual spring reaction force in the equation of motion.

[0007] With this configuration, it is possible to apply a virtual spring reaction force to the driver according to the lateral position of the vehicle reference position, at least under predetermined conditions.

[0008] The above and other objects, features, and advantages of the present disclosure will become apparent from the following description of the embodiments with reference to the accompanying drawings.

[0009] Fig. 1 is a schematic diagram showing the general configuration of an electric power steering system to which a motor control device according to an embodiment of the present disclosure is applied. Fig. 2 is a block diagram for explaining the electrical configuration of a motor control ECU. Fig. 3 is a diagram showing the torsion bar torque T ｔｂ Assist torque command value T ａｓ 4 is a graph showing an example of setting the lateral deviation e ｌ Target virtual spring reaction force T ｔｂ，ｄ (e ｌ) setting example. FIG. 5 is a schematic diagram showing an example of a reference EPS model. FIG. 6 is a block diagram showing the configuration of a manual steering command value calculation unit. FIG. 7 is a block diagram showing the configuration of an angle control unit. FIG. 8 is a schematic diagram showing an example of the configuration of a physical model of an electric power steering system. FIG. 9 is a block diagram showing the configuration of a disturbance torque estimator. FIG. 10 is a schematic diagram showing the configuration of a torque control unit. FIG. 11 is a block diagram showing first and second modified examples of a motor control ECU. FIG. 12 is a block diagram showing the configuration of a manual steering command value calculation unit used in the first modified example of the motor control ECU. FIG. 13A is a part of a flowchart for explaining the operation of an LKA target virtual spring reaction force / weight setting unit. FIG. 13B is a part of a flowchart for explaining the operation of an LKA target virtual spring reaction force / weight setting unit. FIG. 14 is a graph for explaining the operation of the LKA target virtual spring reaction force / weight setting unit. FIG. 15 is a block diagram showing the configuration of a manual steering command value calculation unit used in the second modified example of the motor control ECU. Fig. 16 is a block diagram showing a third modified example of the motor control ECU. ｌ LCA target virtual spring reaction force T ｔｂ，ｄ＿ＬＣＡ (e ｌ ) setting example and target virtual spring reaction force T for LKA ｔｂ，ｄ＿ＬＫＡ (e ｌ 18 is a block diagram showing the configuration of a manual steering command value calculation unit used in a third modified example of the motor control ECU.

[0010] [Description of an embodiment of the present disclosure] One embodiment of the present disclosure provides a motor control device for drive-controlling an electric motor of a steering device, the motor control device including: a manual steering command value calculation unit that calculates a manual steering command value using a torsion bar torque; an integrated angle command value calculation unit that calculates an integrated angle command value by adding the manual steering command value to an automatic steering command value for driving assistance; and a control unit that drive-controls the electric motor based on the integrated angle command value, wherein in a driving assistance mode, the manual steering command value calculation unit is configured to calculate the manual steering command value by utilizing an equation of motion of a reference model of the steering device, and the manual steering command value calculation unit calculates the manual steering command value by using, at least under predetermined conditions, a target virtual spring reaction force that corresponds to the lateral position of a vehicle reference position with respect to a driving lane, as a virtual spring reaction force in the equation of motion.

[0011] With this configuration, it is possible to apply a virtual spring reaction force to the driver according to the lateral position of the vehicle reference position, at least under predetermined conditions.

[0012] In one embodiment of the present disclosure, when the driving assistance mode is a lane keeping assist mode that assists in steering so that the vehicle stays within the driving lane, the manual steering command value calculation unit calculates the manual steering command value using a target virtual spring reaction force corresponding to the lateral position of the vehicle reference position with respect to the driving lane as the virtual spring reaction force in the equation of motion.

[0013] In one embodiment of the present disclosure, the driving assistance modes include the lane keeping assist mode and a driving mode other than the lane keeping assist mode, and when transitioning from a driving mode other than the lane keeping assist mode to the lane keeping assist mode, the target virtual spring reaction force is set so as to match the torsion bar torque immediately before transitioning from the other driving mode to the lane keeping assist mode.

[0014] In one embodiment of the present disclosure, the other driving mode is a lane centering assist mode that assists in steering the vehicle so that it travels in the center of the driving lane, and when the vehicle reference position is within a range of a predetermined distance from the center of the driving lane, the driving mode is set to the lane centering assist mode, and when the vehicle reference position is outside the range of the predetermined distance from the center of the driving lane, the driving mode is set to the lane keeping assist mode, and in the lane centering assist mode, the manual steering command value calculation unit calculates the manual steering command value using a virtual spring reaction force that is set using a spring constant of a virtual spring as a virtual spring reaction force in the equation of motion, and when transitioning from the lane centering assist mode to the lane keeping assist mode, the target virtual spring reaction force at the time of transition is set to match the torsion bar torque immediately before the transition.

[0015] DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT DISCLOSURE Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0016] FIG. 1 is a schematic diagram showing a general configuration of an electric power steering system to which a motor control device according to an embodiment of the present disclosure is applied.

[0017] The electric power steering system 1 includes a steering wheel (handle) 2 as a steering member for steering the vehicle, a steering mechanism 4 that steers steered wheels 3 in conjunction with the rotation of the steering wheel 2, and a steering assist mechanism 5 that assists the driver in steering. The steering wheel 2 and the steering mechanism 4 are mechanically connected via a steering shaft 6 and an intermediate shaft 7.

[0018] The steering shaft 6 includes an input shaft 8 connected to the steering wheel 2 and an output shaft 9 connected to the intermediate shaft 7. The input shaft 8 and the output shaft 9 are connected via a torsion bar 10 so as to be capable of relative rotation.

[0019] A torque sensor 12 is disposed near the torsion bar 10. The torque sensor 12 detects the torsion bar torque (steering torque) T applied to the steering wheel 2 based on the amount of relative rotational displacement between the input shaft 8 and the output shaft 9. ｔｂ In this embodiment, the torsion bar torque T ｔｂ For example, the torque for steering to the right is detected as a positive value, and the torque for steering to the left is detected as a negative value. The larger the absolute value of the torque, the greater the torsion bar torque T ｔｂ The magnitude of is assumed to be large.

[0020] The steering mechanism 4 is made up of a rack-and-pinion mechanism including a pinion shaft 13 and a rack shaft 14 as a steering shaft. The steered wheels 3 are connected to each end of the rack shaft 14 via tie rods 15 and knuckle arms (not shown). The pinion shaft 13 is connected to the intermediate shaft 7. The pinion shaft 13 rotates in conjunction with the steering of the steering wheel 2. A pinion 16 is connected to the tip of the pinion shaft 13.

[0021] The rack shaft 14 extends linearly in the left-right direction of the vehicle. A rack 17 that meshes with the pinion 16 is formed in the axial middle of the rack shaft 14. The pinion 16 and the rack 17 convert the rotation of the pinion shaft 13 into axial movement of the rack shaft 14. By moving the rack shaft 14 in the axial direction, the steered wheels 3 can be steered.

[0022] When the steering wheel 2 is steered (rotated), this rotation is transmitted to the pinion shaft 13 via the steering shaft 6 and the intermediate shaft 7. The rotation of the pinion shaft 13 is then converted into axial movement of the rack shaft 14 by the pinion 16 and the rack 17. As a result, the steered wheels 3 are steered.

[0023] The steering assist mechanism 5 includes an electric motor 18 for generating a steering assist force (assist torque), and a reducer 19 for amplifying the output torque of the electric motor 18 and transmitting it to the steering mechanism 4. The reducer 19 is made up of a worm gear mechanism including a worm gear 20 and a worm wheel 21 that meshes with the worm gear 20. The reducer 19 is housed in a gear housing 22 that serves as a transmission mechanism housing.

[0024] In the following description, the reduction ratio (gear ratio) of the reducer 19 is represented by N. The reduction ratio N is a function of the worm wheel angle θ, which is the rotation angle of the worm wheel 21. ｗｗ The worm gear angle θ is the rotation angle of the worm gear 20 relative to the ｗｇ The ratio (θ ｗｇ / θ ｗｗ ) is defined as

[0025] The worm gear 20 is rotationally driven by the electric motor 18. The worm wheel 21 is connected to the output shaft 9 so as to be rotatable integrally therewith.

[0026] When the worm gear 20 is rotationally driven by the electric motor 18, the worm wheel 21 is rotationally driven, and motor torque is applied to the steering shaft 6, causing the steering shaft 6 (output shaft 9) to rotate. The rotation of the steering shaft 6 is then transmitted to the pinion shaft 13 via the intermediate shaft 7. The rotation of the pinion shaft 13 is converted into axial movement of the rack shaft 14, thereby turning the steered wheels 3. In other words, by rotating the worm gear 20 with the electric motor 18, steering assistance by the electric motor 18 and steering of the steered wheels 3 become possible. The electric motor 18 is provided with a rotation angle sensor 23 for detecting the rotation angle of the rotor of the electric motor 18.

[0027] The torque applied to the output shaft 9 (an example of a drive target of the electric motor 18) includes a motor torque by the electric motor 18 and a disturbance torque T ｌｃ Disturbance torque other than the motor torque T ｌｃ Torsion bar torque T ｔｂ , road reaction torque (road load torque) T ｒｌ , friction torque Tｆ etc. are included.

[0028] Torsion bar torque T ｔｂ is the torque applied to the output shaft 9 from the steering wheel 2 side by the force applied to the steering wheel 2 by the driver, the force generated by steering inertia, etc.

[0029] Road reaction torque T ｒｌ is the torque applied to the output shaft 9 from the steered wheels 3 side via the rack shaft 14 due to the self-aligning torque generated in the tire, the force generated by the suspension and tire / wheel alignment, the frictional force of the rack and pinion mechanism, etc.

[0030] The vehicle is equipped with a CCD (Charge Coupled Device) camera 25 that captures images of the road ahead in the direction of travel of the vehicle, a GPS (Global Positioning System) 26 for detecting the vehicle's position, a radar 27 for detecting road shapes and obstacles, and a map information memory 28 that stores map information. The vehicle is also equipped with two mode switches 31 and 32 for manually switching steering modes.

[0031] As will be described later, the steering modes include a manual steering mode in which steering is performed by manual driving, and a cooperative steering mode in which steering based on both manual driving and automatic driving is possible.

[0032] The CCD camera 25, GPS 26, radar 27, and map information memory 28 are connected to a host ECU (Electronic Control Unit) 201 for performing driving assistance control and automatic driving control. Based on the information obtained by the CCD camera 25, GPS 26, and radar 27 and the map information, the host ECU 201 performs surrounding environment recognition, vehicle position estimation, route planning, etc., and determines control target values ​​for steering and drive actuators.

[0033] In this embodiment, the host ECU 201 controls the automatic steering command value θ ａｄIn this embodiment, the automatic steering control is, for example, a control for driving the vehicle along a target driving line. ａｄ is the target value of the steering angle for automatically driving the vehicle along the target driving line.

[0034] In this embodiment, the automatic steering command value θ ａｄ is expressed as the amount of rotation (rotation angle) of the output shaft 9 from the neutral position, and the amount of rotation from the neutral position in the right steering direction is expressed as a positive value, and the amount of rotation from the neutral position in the left steering direction is expressed as a negative value. ａｄ is set based on, for example, the vehicle speed, the lateral deviation from the target driving line (the center line of the lane), and the yaw deviation of the vehicle from the target driving line. ａｄ The process of setting the value is well known, so a detailed description will be omitted here.

[0035] The automatic steering control (driving assistance control) may be, for example, lane keeping assist (LKA) control, which assists in steering so that the vehicle stays within the driving lane, or lane centering assist (LCA) control, which assists in steering so that the vehicle stays in the center of the driving lane.

[0036] The host ECU 201 also calculates the lateral deviation e from the currently set target driving line. ｌ In this embodiment, the lateral deviation e ｌ is the distance from the currently set target driving line (lane center line) to the vehicle's reference position (hereinafter referred to as the "vehicle reference position"). The vehicle reference position is set at a predetermined position in the center of the vehicle's width.

[0037] In this embodiment, the lateral deviation e ｌ is 0 (e ｌ = 0), and when the vehicle reference position is on the right side of the target driving line in the direction of travel, it becomes a positive value (e ｌ >0), and when the vehicle reference position is on the left side of the target driving line in the direction of travel, it becomes a negative value (e ｌ <0).

[0038] Furthermore, the host ECU 201 generates a steering mode signal S , which indicates whether the steering mode (driving mode) is a manual steering mode (manual driving mode) or a cooperative steering mode (driving assistance mode), based on the operation of the first mode switch 31 and the second mode switch 32. ｍｏｄｅ Specifically, when the first mode switch 31 is turned on by the driver, the host ECU 201 outputs a steering mode signal S ｍｏｄｅ On the other hand, when the second mode switch 32 is turned on by the driver, the host ECU 201 outputs a steering mode signal S ｍｏｄｅ Output.

[0039] Automatic steering command value θ ａｄ , lateral deviation e ｌ and steering mode signal S ｍｏｄｅ is given to the motor control ECU 202 via the in-vehicle network. ｔｂ The output signal of the rotation angle sensor 23 is input to the motor control ECU 202. The motor control ECU 202 controls the electric motor 18 based on these input signals and information provided by the host ECU 201.

[0040] FIG. 2 is a block diagram for explaining the electrical configuration of the motor control ECU 202. As shown in FIG.

[0041] The motor control ECU 202 includes a microcomputer 50, a drive circuit (inverter circuit) 41 controlled by the microcomputer 50 to supply power to the electric motor 18, and a current (hereinafter, "motor current I ｍ and a current detection circuit 42 for detecting the current.

[0042] The microcomputer 50 includes a CPU and memory (ROM, RAM, non-volatile memory, etc.), and functions as a plurality of functional processing sections by executing predetermined programs. The functional processing sections include an assist torque command value setting section 51, a target virtual spring reaction force setting section 52, a manual steering command value calculation section 53, an integrated angle command value calculation section 54, an angle control section 55, a first switch 56, a second switch 57, an adder 58, and a torque control section (current control section) 59.

[0043] The assist torque command value setting unit 51 sets the assist torque command value T ａｓ The assist torque command value setting unit 51 sets the torsion bar torque T ｔｂ Based on this, the assist torque command value T ａｓ Set.

[0044] FIG. 3 shows the torsion bar torque T ｔｂ Assist torque command value T ａｓ 10 is a graph showing an example of setting the

[0045] Assist torque command value T ａｓ is set to a positive value when the electric motor 18 is to generate a steering assist force for steering in the right direction, and is set to a negative value when the electric motor 18 is to generate a steering assist force for steering in the left direction. ａｓ is the torsion bar torque T ｔｂ The torsion bar torque T ｔｂ The assist torque command value T ａｓ is the torsion bar torque T ｔｂ The larger the absolute value of , the larger the absolute value is set.

[0046] The assist torque command value setting unit 51 calculates the torsion bar torque T ｔｂ is multiplied by a preset constant to obtain the assist torque command value T ａｓ The assist torque command value T ａｓmay be set taking into consideration the vehicle speed.

[0047] In the cooperative steering mode, the target virtual spring reaction force setting unit 52 sets the lateral deviation e given by the host ECU 201. ｌ Based on this, the target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) to set the

[0048] FIG. 4 shows the lateral deviation e ｌ Target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) is a graph showing an example of setting.

[0049] Lateral deviation e ｌ Ga-e ｌ，ｓ (However, e ｌ，ｓ >0) to e ｌ，ｓ In the range up to ｔｂ，ｄ (e ｌ ) is -T ｔｂ，ｄ，ｓ (However, T ｔｂ，ｄ，ｓ >0) to T ｔｂ，ｄ，ｓ Until, lateral deviation e ｌ In this example, the target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) varies linearly, but may vary nonlinearly.

[0050] Lateral deviation e ｌ，ｓ From e ｌ，ｍ (However, e ｌ，ｍ >e ｌ，ｓ ) in the range up to the target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) is T ｔｂ，ｄ，ｓ From T ｔｂ，ｄ，ｍ (However, T ｔｂ，ｄ，ｍ >T ｔｂ，ｄ，ｓ ) and lateral deviation e ｌ The larger the lateral deviation e ｌ Ga-e ｌ，ｓ From e ｌ，ｓ In this example, the slope of the line is set to be larger than the range up to the target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) changes linearly, but may change nonlinearly. ｌ Gaeｌ，ｍ In the larger range, the target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) is T ｔｂ，ｄ，ｍ is set to.

[0051] Lateral deviation e ｌ Ga-e ｌ，ｓ From -e ｌ，ｍ (However, -e ｌ，ｍ <-e ｌ，ｓ ) in the range up to the target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) is -T ｔｂ，ｄ，ｓ From -T ｔｂ，ｄ，ｍ (However, -T ｔｂ，ｄ，ｍ <-T ｔｂ，ｄ，ｓ ) and lateral deviation e ｌ The smaller the lateral deviation e ｌ Ga-e ｌ，ｓ From e ｌ，ｓ In this example, the slope of the line is set to be larger than the range up to the target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) changes linearly, but may change nonlinearly. ｌ Ga-e ｌ，ｍ In a smaller range, the target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) is -T ｔｂ，ｄ，ｍ is set to.

[0052] When the driver operates the steering wheel 2 in the cooperative steering mode, the manual steering command value calculation unit 53 calculates a steering angle (more precisely, a rotation angle θ of the output shaft 9) corresponding to the steering wheel operation. ｃ ) is the manual steering command value θ ｍｄ The manual steering command value calculation unit 53 is provided to set the torsion bar torque T ｔｂ and the target virtual spring reaction force T set by the target virtual spring reaction force setting unit 52. ｔｂ，ｄ (e ｌ ) and the manual steering command value θ ｍｄ The manual steering command value calculation unit 53 will be described in detail later.

[0053] The integrated angle command value calculation unit 54 calculates the automatic steering command value θ set by the host ECU 201. ａｄ Manual steering command value θ ｍｄ The integrated angle command value θ ｃｍｄ Calculate the following.

[0054] The angle control unit 55 calculates an integrated angle command value θ ｃｍｄ Based on this, the integrated motor torque command value T ｃｏｍ The angle control unit 55 will be described in detail later.

[0055] The first switch 56 and the second switch 57 are connected to the steering mode signal S ｍｏｄｅ Specifically, the steering mode signal S indicates that the steering mode is the manual steering mode. ｍｏｄｅ is input, the first switch 56 is turned on and the second switch 57 is turned off.

[0056] On the other hand, the steering mode signal S ｍｏｄｅ is input, the first switch 56 is turned off and the second switch 57 is turned on.

[0057] When the first switch 56 is in the ON state and the second switch 57 is in the OFF state, the adder 58 calculates the assist torque command value T ａｓ , the motor torque command value T ｍ，ｃｍｄ (=T ａｓ On the other hand, when the second switch 57 is in the ON state and the first switch 56 is in the OFF state, the adder 58 outputs the integrated motor torque command value T ｃｏｍ The motor torque command value T ｍ，ｃｍｄ (=T ｃｏｍ ) is output.

[0058] The motor torque command value T ｍ，ｃｍｄ is given to the torque control section 59.

[0059] The torque control unit 59 controls the motor torque of the electric motor 18 to be equal to the motor torque command value T ｍ，ｃｍｄ The torque control unit 59 drives the drive circuit 41 so that the torque approaches the torque. Details of the torque control unit 59 will be described later.

[0060] The manual steering command value calculation unit 53 will now be described in detail.

[0061] First, the manual steering command value θ generated by the manual steering command value generating unit described in Patent Document 1 ｍｄ This section explains how to set this up.

[0062] The manual steering command value generating unit calculates the manual steering command value θ using the reference EPS model shown in FIG. ｍｄ The reference EPS model in FIG. 5 is an example of the "reference model of the steering device" of the present disclosure.

[0063] This reference EPS model is a single inertia model including a lower column. The lower column corresponds to the output shaft 9 and the worm wheel 21. However, this model is only an example, and an inertia model including a configuration other than the above (for example, a rack bar) may also be used. In FIG. 5, J ｍｄ is the inertia of the lower column (hereinafter referred to as "column inertia"), and θ ｃｏｌ is the rotation angle of the lower column, and T ｔｂ is the torsion bar torque. ｔｂ , torque N·T acting on the output shaft 9 from the electric motor 18 ｍ and road reaction torque (virtual reaction force) T ｒｌ is given.

[0064] Road reaction torque T ｒｌ is the spring constant k of the virtual spring ｍｄ and the viscous damping coefficient c of the virtual damper ｍｄ Using the above, it is expressed by the following equation (1).

[0065]

[0066] Spring constant k ｍｄ and the viscous damping coefficient c ｍｄ has been obtained in advance through experiments, analysis, etc. In the following, k ｍｄ ・θ ｃｏｌ is called the virtual spring reaction force, and c ｍｄ (dθ ｃｏｌ / dt) is sometimes called a virtual damper reaction force.

[0067] The equation of motion of the reference EPS model is expressed by the following equation (2).

[0068]

[0069] In formula (2), J ｍｄ ・d ２ θ ｃｏｌ / dt ２ is the moment of inertia acting on the lower column.

[0070] The manual steering command value generating unit is T ｔｂ The torsion bar torque T detected by the torque sensor 12 ｔｂ Substituting, T ｍ The assist torque command value T ａｓ By substituting the above and solving the differential equation (2), the rotation angle θ of the lower column is obtained. ｃｏｌ Then, the manual steering command value generating unit calculates the obtained rotation angle θ of the lower column. ｃｏｌ The manual steering command value θ ｍｄ In this way, the manual steering command value θ ｍｄ The method of setting is called the comparison method.

[0071] The equation of motion in equation (2) is T ｍ T ａｓ and θ ｃｏｌ θ ｍｄ is equivalent to the equation of motion in which

[0072] In the comparative method, the spring constant k of the virtual spring is used as the virtual spring reaction force. ｍｄ Low Column J ｍｄ Rotation angle θ ｃｏｌ (Manual steering command value θ ｍｄ ) is used. Therefore, the spring constant k ｍｄ Even if a value corresponding to the lateral position of the vehicle reference position is used as the virtual spring reaction force, it is not possible to set a torque corresponding to the lateral position of the vehicle reference position as the virtual spring reaction force. ｍｄ ・θ ｃｏｌ (= k ｍｄ ・θ ｍｄ) is a reaction force that is left to chance.

[0073] In this embodiment, the manual steering command value calculation unit 53 calculates the manual steering command value θ using the equation of motion (2) of the reference EPS model described above. ｍｄ Specifically, in this embodiment, the manual steering command value calculation unit 53 calculates the manual steering command value θ based on the equation of motion obtained by modifying the equation of motion (2) of the reference EPS model described above. ｍｄ Calculate the following.

[0074] FIG. 6 is a block diagram showing the configuration of the manual steering command value calculation unit 53.

[0075] In FIG. ｍｄ is the column inertia. s is the differential operator. θ ｍｄ is the manual steering command value, and the rotation angle θ of the lower column in the comparison method ｃｏｌ Equivalent to: ｍｄ is the viscous damping coefficient of the virtual damper, which is obtained in advance by experiment, analysis, etc.

[0076] The manual steering command value calculation unit 53 includes an addition / subtraction unit 101 , an inertia division unit 102 , a first integration unit 103 , a second integration unit 104 , and a virtual damper reaction force calculation unit 105 .

[0077] The addition / subtraction unit 101 receives the torsion bar torque T ｔｂ and the target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) and the virtual damper reaction force c given by the virtual damper reaction force calculation unit 105 ｍｄ ・dθ ｍｄ / dt is input.

[0078] The addition / subtraction unit 101 calculates the torsion bar torque T ｔｂ From the above, the target virtual spring reaction force T ｔｂ，ｄ (e ｌ ) and virtual damper reaction force c ｍｄ ・dθ ｍｄ As a result, the adder / subtractor 101 subtracts J on the left side of the equation (2). ｍｄ ・d ２ θ ｃｏｌ / dt ２ The moment of inertia J corresponds to ｍｄ ・d２ θ ｍｄ / dt ２ (=T ｔｂ -c ｍｄ ・dθ ｍｄ / dt-T ｔｂ，ｄ (e ｌ )) is calculated.

[0079] The inertia division unit 102 calculates the moment of inertia J calculated by the addition / subtraction unit 101. ｍｄ ・d ２ θ ｍｄ / dt ２ The column inertia J ｍｄ By dividing by , the manual steering command value θ ｍｄ The second derivative d ２ θ ｍｄ / dt ２ Calculate the following.

[0080] The first integration unit 103 calculates the manual steering command value θ ｍｄ The second derivative d ２ θ ｍｄ / dt ２ By integrating the manual steering command value θ ｍｄ The first derivative dθ ｍｄ / dt is calculated.

[0081] The second integration unit 104 calculates the manual steering command value θ ｍｄ The first derivative dθ ｍｄ By integrating / dt, the manual steering command value θ ｍｄ This manual steering command value θ ｍｄ is output from the manual steering command value calculation unit 53.

[0082] The virtual damper reaction force calculation unit 105 calculates the manual steering command value θ calculated by the first integration unit 103. ｍｄ The first derivative dθ ｍｄ / dt with viscous damping coefficient c ｍｄ By multiplying by ｍｄ ・dθ ｍｄ / dt is calculated. This virtual damper reaction force c ｍｄ ・dθ ｍｄ / dt is fed back to the addition / subtraction unit 101 .

[0083] That is, the manual steering command value calculation unit 53 calculates the manual steering command value θ based on the equation of motion shown in the following equation (3). ｍｄ Calculate the following.

[0084]

[0085] In formula (3), J ｍｄ ・d ２ θ ｍｄ / dt ２ is the moment of inertia. ｍｄ ・dθ ｍｄ / dt is the virtual damper reaction force. ｔｂ，ｄ (e ｌ ) is the target virtual spring reaction force.

[0086] In this embodiment, the manual steering command value calculation unit 53 calculates the N·T ｍ (= N.T. ａｓ ) is set to 0, and the virtual spring reaction force k θ in the equation of motion of the above equation (2) is ｍｄ As a result, the lateral deviation e ｌ Target virtual spring reaction force T according to ｔｂ，ｄ (e ｌ ) to obtain the manual steering command value θ ｍｄ Calculate the following.

[0087] The manual steering command value calculation unit 53 calculates the assist torque command value T ａｓ By multiplying this by the reduction ratio N, we get N・T ａｓ Calculate the obtained N.T. ａｓ In this case, the addition / subtraction unit 101 calculates the torsion bar torque T ｔｂ N.T. ａｓ From the sum of these values, the virtual damper reaction force c ｍｄ ・dθ ｍｄ / dt and target virtual spring reaction force T ｔｂ，ｄ (e ｌ In this case, the manual steering command value calculation unit 53 subtracts N·T from the right side of the equation (3). ａｓ Based on the equation of motion to which is added, the manual steering command value θ ｍｄ The following calculation is performed.

[0088] FIG. 7 is a block diagram showing the configuration of the angle control unit 55.

[0089] The angle control unit 55 calculates an integrated angle command value θ ｃｍｄ Based on this, the integrated motor torque command value T ｃｏｍ The angle control unit 55 includes a low-pass filter (LPF) 61, a feedback control unit 62, a feedforward control unit 63, a disturbance torque estimating unit 64, a torque adding unit 65, a disturbance torque compensating unit 66, a first reduction ratio dividing unit 67, a reduction ratio multiplying unit 68, a rotation angle calculating unit 69, and a second reduction ratio dividing unit 70.

[0090] The reduction ratio multiplication unit 68 multiplies the motor torque command value T ｍ，ｃｍｄ is multiplied by the reduction ratio N of the reducer 19 to obtain the motor torque command value T ｍ，ｃｍｄ is the output shaft torque command value N·T acting on the output shaft 9 (worm wheel 21). ｍ，ｃｍｄ Convert to.

[0091] The rotation angle calculation unit 69 calculates the rotor rotation angle θ of the electric motor 18 based on the output signal of the rotation angle sensor 23. ｍ The second reduction ratio division unit 70 calculates the rotor rotation angle θ calculated by the rotation angle calculation unit 69. ｍ By dividing by the reduction ratio N, the rotor rotation angle θ ｍ The rotation angle (actual steering angle) θ of the output shaft 9 ｃ Convert to.

[0092] In this embodiment, the actual steering angle θ ｃ is expressed as the amount of rotation (rotation angle) of the output shaft 9 from the neutral position, and the amount of rotation from the neutral position in the right steering direction is expressed as a positive value, and the amount of rotation from the neutral position in the left steering direction is expressed as a negative value.

[0093] The low-pass filter 61 calculates the integrated angle command value θ ｃｍｄ The integrated angle command value θ after low-pass filtering is ｃｍｄｌ is given to the feedback control section 62 and the feedforward control section 63. The low-pass filter 61 does not have to be provided.

[0094] The feedback control unit 62 converts the steering angle estimated value ^θ calculated by the disturbance torque estimating unit 64 into an integrated angle command value θ after low-pass filtering. ｃｍｄｌ The feedback control unit 62 includes an angle deviation calculation unit 62A and a PD control unit 62B. The angle deviation calculation unit 62A calculates an integrated angle command value θ ｃｍｄｌ and the estimated steering angle ^θ ｃ Deviation Δθ (= θ ｃｍｄｌ -^θ ｃ ) is calculated. The angle deviation calculation unit 62A calculates the integrated angle command value θ ｃｍｄｌ and the actual steering angle θ calculated by the second reduction ratio division unit 70. ｃ deviation from (θ ｃｍｄｌ -θ ｃ ) may be calculated as the angle deviation Δθ.

[0095] The PD control unit 62B performs a PD calculation (proportional differential calculation) on the angle deviation Δθ calculated by the angle deviation calculation unit 62A, thereby obtaining a feedback control torque T ｆｂ The feedback control torque T ｆｂ is given to the torque adder 65.

[0096] The feedforward control unit 63 is provided to compensate for a delay in response due to the inertia of the electric power steering system 1, thereby improving the response of the control. The feedforward control unit 63 includes an angular acceleration calculation unit 63A and an inertia multiplication unit 63B. The angular acceleration calculation unit 63A calculates an integrated angle command value θ ｃｍｄｌ By differentiating twice, the target angular acceleration d ２ θ ｃｍｄｌ / dt ２ Calculate the following.

[0097] The inertia multiplication unit 63B multiplies the target angular acceleration d calculated by the angular acceleration calculation unit 63A by ２ θ ｃｍｄｌ / dt ２ is multiplied by the inertia J of the electric power steering system 1 to obtain the feedforward control torque T ｆｆ (=J.d ２ θ ｃｍｄｌ / dt ２The inertia J can be calculated from, for example, a physical model (see FIG. 8) of the electric power steering system 1, which will be described later. The feedforward control torque T ｆｆ is given to the torque adder 65 as an inertia compensation value.

[0098] The torque adder 65 calculates the feedback control torque T ｆｂ The feedforward control torque T ｆｆ By adding ｆｂ +T ｆｆ ) is calculated.

[0099] The disturbance torque estimating unit 64 is provided to estimate a nonlinear torque (disturbance torque: torque other than motor torque) that occurs as a disturbance in the plant (the object to be controlled by the electric motor 18). The disturbance torque estimating unit 64 estimates the output shaft torque command value N·T ｍ，ｃｍｄ and the actual steering angle θ ｃ Based on this, the disturbance torque (disturbance load) T ｌｃ , steering angle θ and steering angle differential value (angular velocity) dθ ｃ / dt is estimated. ｌｃ , steering angle θ ｃ and steering angle differential value (angular velocity) dθ ｃ The estimated values ​​of / dt are respectively ｌｃ , ^θ ｃ and d^θ ｃ The disturbance torque estimation unit 64 will be described in detail later.

[0100] The disturbance torque estimated value ^T calculated by the disturbance torque estimator 64 ｌｃ is given to the disturbance torque compensator 66 as a disturbance torque compensation value. The steering angle estimated value ^θ calculated by the disturbance torque estimator 64 ｃ is given to the angle deviation calculation unit 62A.

[0101] The disturbance torque compensator 66 calculates the basic torque command value (T ｆｂ +T ｆｆ ) to the estimated disturbance torque value ^T ｌｃ By subtracting ｃｏ (=T ｆｂ +T ｆｆ -^Tｌｃ ) is calculated. As a result, the integrated torque command value T ｃｏ (torque command value for the output shaft 9) is obtained.

[0102] Integrated torque command value T ｃｏ is given to the first reduction ratio division unit 67. The first reduction ratio division unit 67 calculates the integrated torque command value T ｃｏ is divided by the reduction ratio N to obtain the integrated motor torque command value T ｃｏｍ (torque command value for the electric motor 18). This integrated motor torque command value T ｃｏｍ is applied to the second switch 57 (see FIG. 2).

[0103] The disturbance torque estimation unit 64 will be described in detail. The disturbance torque estimation unit 64 uses, for example, a physical model 300 of the electric power steering system 1 shown in FIG. 8 to estimate the disturbance torque T ｌｃ , steering angle θ ｃ and angular velocity dθ ｃ It is composed of a disturbance observer that estimates / dt.

[0104] This physical model 300 includes a plant (an example of a motor-driven object) 301 including an output shaft 9 and a worm wheel 21 fixed to the output shaft 9. The plant 301 receives a torsion bar torque T ｔｂ is applied, and a road reaction torque T ｒｌ is given.

[0105] Furthermore, the plant 301 receives an output shaft torque command value N·T via a worm gear 20. ｍ，ｃｍｄ is applied, and friction torque T ｆ is given.

[0106] When the inertia of the plant 301 is J, the equation of motion for the inertia of the physical model 300 is expressed by the following equation (4).

[0107]

[0108] d ２ θ ｃ / dt ２ is the angular acceleration of the plant 301. N is the reduction ratio of the reducer 19. T ｌｃ represents a disturbance torque other than the motor torque applied to the plant 301. In this embodiment, the disturbance torque T ｌｃ is the torsion bar torque T ｔｂ and road reaction torque T ｒｌ and friction torque T ｆ However, in reality, the disturbance torque T ｌｃ includes torques other than these.

[0109] The state equation for the physical model 300 in FIG. 8 is expressed by the following equation (5).

[0110]

[0111] In the above formula (5), x is the state variable vector, u １ is the known input vector, u ２ is the unknown input vector, y is the output vector (measurement value). In addition, in the above formula (5), A is the system matrix, B １ is the first input matrix, B ２ is the second input matrix, C is the output matrix, and D is the direct feedthrough matrix.

[0112] The state equation is expressed as follows: ２ The state equation of the extended system (extended state equation) is expressed by the following equation (6).

[0113]

[0114] In the formula (6), x ｅ is the state variable vector of the extended system, and is expressed by the following equation (7).

[0115]

[0116] In the formula (6), A ｅ is the system matrix of the extended system, B ｅ is the known input matrix of the extended system, C ｅ is the output matrix of the augmented system.

[0117] From the extended state equation of the above-mentioned equation (6), a disturbance observer (extended state observer) expressed by the following equation (8) is constructed.

[0118]

[0119] In equation (8), ^x ｅ Ha x ｅ represents the estimated value of . Also, L is the observer gain. Also, ^y represents the estimated value of y. ^x ｅ is expressed by the following equation (9).

[0120]

[0121] In equation (9), ^θ ｃ is θ ｃ is an estimate of ^T ｌｃ is T ｌｃ is an estimate of

[0122] The disturbance torque estimation unit 64 calculates the state variable vector ^x based on the equation (8). ｅ Calculate the following.

[0123] FIG. 9 is a block diagram showing the configuration of the disturbance torque estimating section 64.

[0124] The disturbance torque estimation unit 64 includes an input vector input unit 81, an output matrix multiplication unit 82, a first addition unit 83, a gain multiplication unit 84, an input matrix multiplication unit 85, a system matrix multiplication unit 86, a second addition unit 87, an integration unit 88, and a state variable vector output unit 89.

[0125] The output shaft torque command value N·T calculated by the reduction ratio multiplication unit 68 (see FIG. 7) ｍ，ｃｍｄ is given to the input vector input unit 81. The input vector input unit 81 receives the input vector u １ Output.

[0126] The output of the integrator 88 is the state variable vector ^x ｅ (See the above equation (9)). At the start of the calculation, the state variable vector ^x ｅ The initial value is given as the state variable vector ^x ｅ The initial value of is, for example, 0.

[0127] The system matrix multiplication unit 86 multiplies the state variable vector ^x ｅ system matrix A ｅ The output matrix multiplication unit 82 multiplies the state variable vector ^x ｅ into the output matrix C ｅ Multiply by.

[0128] The first adder 83 calculates the actual steering angle θ calculated by the second reduction ratio divider 70 (see FIG. 7). ｃ From the output vector (measurement value) y, the output of the output matrix multiplication unit 82 (C ｅ ・^x ｅ ) is subtracted from the output vector y. That is, the first adder 83 subtracts the output vector estimate ^y (=C ｅ ・^x ｅ The gain multiplication unit 84 multiplies the output (y−^y) of the first addition unit 83 by the observer gain L (see equation (8) above).

[0129] The input matrix multiplication unit 85 multiplies the input vector u output from the input vector input unit 81. １ Input matrix B ｅ The second adder 87 multiplies the output (B ｅ ・u １ ), and the output of the system matrix multiplication unit 86 (A ｅ ・^x ｅ ) and the output (L(y-^y)) of the gain multiplication unit 84, the differential value d^x of the state variable vector is obtained. ｅ The integrator 88 calculates the output of the second adder 87 (d^x ｅ / dt), the state variable vector ^x ｅ The state variable vector output unit 89 calculates the state variable vector ^x ｅ Based on this, the disturbance torque estimate ^T ｌｃ , steering angle estimate ^θ ｃ and the estimated angular velocity d^θ ｃ / dt is calculated.

[0130] Unlike the aforementioned extended state observer, a general disturbance observer consists of an inverse model of the plant and a low-pass filter. The equation of motion of the plant is expressed by equation (3) as mentioned above. Therefore, the inverse model of the plant is expressed by the following equation (10).

[0131]

[0132] The input to a general disturbance observer is J·d ２ θ ｃ / dt ２ and N.T. ｍ，ｃｍｄ and the actual steering angle θ ｃ Since the second-order differential value of is used, it is significantly affected by noise from the rotation angle sensor 23. In contrast, the extended state observer of the above-described embodiment estimates the disturbance torque in an integral manner, so that it is possible to reduce the influence of noise due to differentiation.

[0133] The disturbance torque estimating unit 64 may be a general disturbance observer configured with an inverse model of the plant and a low-pass filter.

[0134] FIG. 10 is a schematic diagram showing the configuration of the torque control unit 59.

[0135] The torque control unit 59 (see FIG. 2) includes a motor current command value calculation unit 91 , a current deviation calculation unit 92 , a PI control unit 93 , and a PWM (Pulse Width Modulation) control unit 94 .

[0136] The motor current command value calculation unit 91 calculates the motor torque command value T ｍ，ｃｍｄ is the torque constant K of the electric motor 18. ｔ By dividing by , the motor current command value I ｍ，ｃｍｄ Calculate the following.

[0137] The current deviation calculation unit 92 calculates the motor current command value I obtained by the motor current command value calculation unit 91. ｍ，ｃｍｄ and the motor current I detected by the current detection circuit 42. ｍ Deviation ΔI (=I ｍ，ｃｍｄ -I ｍ ) is calculated.

[0138] The PI control unit 93 performs a PI calculation (proportional integral calculation) on the current deviation ΔI calculated by the current deviation calculation unit 92, thereby calculating the motor current I flowing through the electric motor 18 as a motor current command value I ｍ，ｃｍｄ The PWM control unit 94 generates a drive command value for guiding the electric motor 18 to the above-described drive command value. The PWM control unit 94 generates a PWM control signal with a duty ratio corresponding to the drive command value and supplies the PWM control signal to the drive circuit 41. As a result, electric power corresponding to the drive command value is supplied to the electric motor 18.

[0139] The operation of this embodiment will be described below with reference to FIG.

[0140] In this embodiment, the manual steering mode is defined as the assist torque command value T ａｓ The cooperative steering mode refers to a steering mode in which the electric motor 18 is controlled based only on the automatic steering command value θ ａｄ and manual steering command value θ ｍｄ The integrated angle command value θ ｃｍｄ This refers to a steering mode in which the electric motor 18 is controlled based on the steering angle.

[0141] When the steering mode is set to the manual steering mode, the first switch 56 is turned on and the second switch 57 is turned off. When the steering mode is set to the cooperative steering mode, the first switch 56 is turned off and the second switch 57 is turned on. In other words, the motor control ECU 202 can switch the steering mode between the manual steering mode and the cooperative steering mode by the driver operating the mode switches 31, 32.

[0142] Although the steering mode is switched by mode switches 31 and 32, host ECU 201 may switch the steering mode in response to an ON / OFF signal for the driving assistance function or the automatic driving function, obstacles, the driver's state, driver operations such as accelerator and brake, and the running state of the vehicle. In this case, host ECU 201 generates a mode setting signal in response to an ON / OFF signal for the driving assistance function or the automatic driving function, obstacles, the driver's state, driver operations such as accelerator and brake, and the running state of the vehicle, and provides the signal to motor control ECU 202.

[0143] For example, when lane keeping assist control is performed to keep the vehicle within the lane, the host ECU 201 may automatically switch the steering mode as follows.

[0144] Referring to FIG. 4, the lateral deviation e ｌ But, -e ｌ，ｓ From e ｌ，ｓ If the steering angle is within the range of -e in FIG. 4, the host ECU 201 sets the steering mode to the manual steering mode. This causes the first switch 56 to be turned on and the second switch 57 to be turned off. In this case, the second switch 57 is turned off, so that the steering angle is -e in FIG. ｌ，ｓ From e ｌ，ｓ Target virtual spring reaction force T within the range ｔｂ，ｄ (e ｌ ) will no longer be reflected as steering reaction force.

[0145] On the other hand, lateral deviation e ｌ But, -e ｌ，ｓ From e ｌ，ｓ If the steering angle is outside the range of -e in FIG. 4, the host ECU 201 sets the steering mode to the cooperative steering mode. This causes the second switch 57 to be turned on and the first switch 56 to be turned off. In this case, the second switch 57 is turned on, so that the -e in FIG. ｌ，ｓ From e ｌ，ｓ Target virtual spring reaction force T outside the range ｔｂ，ｄ (e ｌ ) is reflected as steering reaction force.

[0146] When the steering mode is automatically switched in this way, the lateral deviation e ｌ But, -e ｌ，ｓ From e ｌ，ｓ Under the condition that the steering angle is outside the range of 1 / 2 to 1 / 3, the manual steering command value calculation unit 53 calculates the virtual spring reaction force k·θ in the equation of motion of the above-mentioned formula (2). ｍｄ As a result, the lateral deviation e ｌ Target virtual spring reaction force T according to ｔｂ，ｄ (e ｌ ) to obtain the manual steering command value θ ｍｄ Calculate the following.

[0147] In the above embodiment, the integrated angle command value θ ｃｍｄand a cooperative steering mode in which the electric motor 18 can be controlled based on the assist torque command value T ａｓ This allows switching between a manual steering mode in which the electric motor 18 can be controlled based only on the steering angle.

[0148] That is, the integrated angle command value θ ｃｍｄ In the electric power steering system 1, the electric motor 18 can be controlled based on the assist torque command value T ａｓ Therefore, the electric motor 18 can be controlled based only on the above.

[0149] In the above-described embodiment, in the manual steering mode, the assist torque command value T ａｓ Since the electric motor 18 is controlled based only on the road surface reaction torque, the driver can receive the actual road surface reaction torque.

[0150] In the above-described embodiment, in the cooperative steering mode, the manual steering command value calculation unit 53 calculates the virtual spring reaction force k·θ in the equation of motion of the above-described formula (2). ｍｄ As a result, the lateral deviation e ｌ Target virtual spring reaction force T according to ｔｂ，ｄ (e ｌ ) to obtain the manual steering command value θ ｍｄ As a result, in the cooperative steering mode, the lateral deviation e ｌ This allows the driver to easily recognize the distance from the center of the lane or the distance to the lane.

[0151] In the above embodiment, the integrated angle command value θ ｃｍｄ Based on the basic torque command value (T ｆｂ +T ｆｆ ) is calculated, and the disturbance torque estimated value ^T calculated by the disturbance torque estimating unit 64 ｌｃ The basic torque command value (T ｆｂ +T ｆｆ ) is corrected, the effect of disturbance torque on angle control performance can be suppressed, thereby realizing highly accurate angle control.

[0152] Below, we will explain modified examples of the motor control ECU 202. In the following modified examples of the motor control ECU 202, the operation in the manual steering mode is the same as in the above-described embodiment, so below we will explain the operation in the cooperative steering mode.

[0153] 11 is a block diagram showing a first modified example of the motor control ECU, in which parts corresponding to those in FIG. 2 are denoted by the same reference numerals as in FIG.

[0154] The motor control ECU 202A in Figure 11 differs from the motor control ECU 202 in Figure 2 in the following (1) and (2): (1) The configuration of the manual steering command value calculation unit 53A is different from the configuration of the manual steering command value calculation unit 53 in Figure 2. (2) A target virtual spring reaction force / weight setting unit 52A for LKA (hereinafter referred to as the "reaction force / weight setting unit 52A") is used instead of the target virtual spring reaction force setting unit 52 in Figure 2.

[0155] The reaction force / weight setting unit 52A calculates the target virtual spring reaction force T for lane keeping assist (LKA). ｔｂ，ｄ＿ＬＫＡ (e ｌ ), and also sets a first weight W1 and a second weight W2, which will be described later. ｌ In addition, torsion bar torque T ｔｂ is given.

[0156] The manual steering command value calculation unit 53A receives the torsion bar torque T ｔｂ and the target virtual spring reaction force T for LKA set by the reaction force / weight setting unit 52A. ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is given to the manual steering command value calculation unit 53A. ａｓ and a first weight W1 and a second weight W2 set by the reaction force / weight setting unit 52A.

[0157] 12 is a block diagram showing the configuration of the manual steering command value calculation unit 53 A. In FIG. 12, parts corresponding to those in FIG. 6 are denoted by the same reference numerals as in FIG.

[0158] In FIG. ｍｄ is the spring constant of the virtual spring, which is determined in advance by experiment, analysis, etc. ａｓ is the assist torque command value T set by the assist torque command value setting unit 51 ａｓ is.

[0159] The manual steering command value calculation unit 53A includes a reduction ratio multiplication unit 131, an addition / subtraction unit 101, an inertia division unit 102, a first integration unit 103, a second integration unit 104, a virtual damper reaction force calculation unit 105, a virtual spring reaction force calculation unit 106, a first weight multiplication unit 107, a first addition unit 108, a second weight multiplication unit 109, and a second addition unit 110.

[0160] The reduction ratio multiplication unit 131 calculates the assist torque command value T ａｓ is multiplied by the reduction ratio N of the reducer 19 to obtain the assist torque command value T ａｓ is the assist torque command value N·T for the output shaft 9. ａｓ The assist torque command value N·T for the output shaft 9 calculated by the reduction ratio multiplication unit 131 is converted into ａｓ is given to the adder / subtractor 101 and also to the first adder 108 .

[0161] The addition / subtraction unit 101 receives the torsion bar torque T ｔｂ and the assist torque command value N·T for the output shaft 9 calculated by the reduction ratio multiplication unit 131. ａｓ and the virtual damper reaction force c given by the virtual damper reaction force calculation unit 105. ｍｄ ・dθ ｍｄ / dt and the addition result X of the second adder 110 are given.

[0162] The addition / subtraction unit 101 calculates the torsion bar torque T ｔｂ Assist torque command value N·T for output shaft 9 ａｓ The virtual damper reaction force θ is calculated from the result of the addition. ｍｄ ・dθ ｍｄ / dt and X. As a result, the adder / subtractor 101 subtracts J on the left side of the above equation (2). ｍｄ ・d ２ θ ｃｏｌ / dt ２The moment of inertia J corresponds to ｍｄ ・d ２ θ ｍｄ / dt ２ (=T ｔｂ +N.T. ａｓ -c ｍｄ ・dθ ｍｄ / dt-X) is calculated.

[0163] The inertia division unit 102 calculates the moment of inertia J calculated by the addition / subtraction unit 101. ｍｄ ・d ２ θ ｍｄ / dt ２ The column inertia J ｍｄ By dividing by , the manual steering command value θ ｍｄ The second derivative d ２ θ ｍｄ / dt ２ Calculate the following.

[0164] The first integration unit 103 calculates the manual steering command value θ ｍｄ The second derivative d ２ θ ｍｄ / dt ２ By integrating the manual steering command value θ ｍｄ The first derivative dθ ｍｄ / dt is calculated.

[0165] The second integration unit 104 calculates the manual steering command value θ ｍｄ The first derivative dθ ｍｄ By integrating / dt, the manual steering command value θ ｍｄ This manual steering command value θ ｍｄ is output from the manual steering command value calculation unit 53A.

[0166] The virtual damper reaction force calculation unit 105 calculates the manual steering command value θ calculated by the first integration unit 103. ｍｄ The first derivative dθ ｍｄ / dt with viscous damping coefficient c ｍｄ By multiplying by ｍｄ ・dθ ｍｄ / dt is calculated. This virtual damper reaction force c ｍｄ ・dθ ｍｄ / dt is fed back to the addition / subtraction unit 101 .

[0167] The virtual spring reaction force calculation unit 106 calculates the manual steering command value θ ｍｄ Spring constant k ｍｄ By multiplying by ｍｄ ・θ ｍｄ Calculate the following.

[0168] The first weight multiplier 107 calculates the virtual spring reaction force k ｍｄ ・θ ｍｄ is multiplied by a first weight W1.

[0169] The first adder 108 calculates the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) and the assist torque command value N·T for the output shaft 9 calculated by the reduction ratio multiplication unit 131. ａｓ The second weight multiplication unit 109 adds the calculation result (T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) + N.T. ａｓ ) is multiplied by a second weight W2.

[0170] The second adder 110 multiplies the result of calculation W1·k by the first weight multiplier 107 by ｍｄ ・θ ｍｄ and the calculation result W2·(T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) + N.T. ａｓ The sum of the second adder 110 {W1·k ｍｄ ・θ ｍｄ +W2・(T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) + N.T. ａｓ )} is fed back to the addition / subtraction unit 101 as X.

[0171] Referring to FIG. ｌ，ｑ is set to a predetermined value that is greater than zero and smaller than half the width of the travel lane. ｌ Ga-e ｌ，ｑ is greater than e ｌ，ｑ If the difference is smaller than 1, the driving assistance mode is the lane centering assist mode (LCA mode), the first weight W1 is set to 1, and the second weight W2 is set to zero.

[0172] On the other hand, lateral deviation eｌ Ga-e ｌ，ｑ If the following occurs or e ｌ，ｑ If this is the case, the driving assistance mode is set to the lane keeping assist mode (LKA mode), the first weight W1 is set to 0, and the second weight W2 is set to 1.

[0173] In the LCA mode, the addition result X of the second adder 110 is k ｍｄ ・θ ｍｄ Therefore, the calculation result of the addition / subtraction unit 101 is (T ｔｂ +N.T. ａｓ -c ｍｄ ・dθ ｍｄ / dt-k ｍｄ ・θ ｍｄ )

[0174] Therefore, in the LCA mode, the manual steering command value calculation unit 53A calculates the manual steering command value θ based on the equation of motion of the following equation (11): ｍｄ Calculate the following.

[0175]

[0176] In formula (11), J ｍｄ ・d ２ θ ｍｄ / dt ２ is the moment of inertia. ｍｄ ・dθ ｍｄ / dt is the virtual damper reaction force. ｍｄ ・θ ｍｄ is the virtual spring reaction force k in the above equation (2). ｍｄ ・θ ｃｏｌ is the virtual spring reaction force equivalent to

[0177] That is, in the LCA mode, the manual steering command value calculation unit 53A calculates the manual steering command value θ based on a motion equation similar to the motion equation of the above-mentioned equation (2). ｍｄ Calculate the following.

[0178] In the LKA mode, the addition result X of the first adder 108 is (T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) + N.T. ａｓ ) Therefore, the calculation result of the addition / subtraction unit 101 is {T ｔｂ -c ｍｄ ・dθｍｄ / dt-T ｔｂ，ｄ＿ＬＫＡ (e ｌ )}.

[0179] Therefore, in the LKA mode, the manual steering command value calculation unit 53A calculates the manual steering command value θ based on the equation of motion of the following equation (12), which is similar to the above equation (3). ｍｄ Calculate the following.

[0180]

[0181] In formula (12), J ｍｄ ・d ２ θ ｍｄ / dt ２ is the moment of inertia. ｍｄ ・dθ ｍｄ / dt is the virtual damper reaction force. ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is the target virtual spring reaction force for LKA.

[0182] That is, in the LKA mode, the manual steering command value calculation unit 53A calculates the N·T in the equation of motion of the above-mentioned formula (2). ｍ (= N.T. ａｓ ) is set to 0, and the virtual spring reaction force k ｍｄ ・θ ｃｏｌ As a result, the lateral deviation (e ｌ ) Target virtual spring reaction force T for LKA according to ｔｂ，ｄ＿ＬＫＡ (e ｌ ) to obtain the manual steering command value θ ｍｄ Calculate the following.

[0183] The manual steering command value calculation unit 53A calculates the N·T ａｓ In this case, in the LKA mode, the manual steering command value calculation unit 53A may add N·T to the right side of the above equation (12). ａｓ Based on the equation of motion to which is added, the manual steering command value θ ｍｄ The following calculation is performed.

[0184] 13A and 13B are flowcharts for explaining the operation of the reaction force / weight setting unit 52A.

[0185] When the power is turned on, the reaction force / weight setting unit 52A performs initialization (step S1). Specifically, the reaction force / weight setting unit 52A resets a flag F (F=0) for storing whether the driving assistance mode is the LCA mode or the LKA mode. The reaction force / weight setting unit 52A also sets the first weight W1 to 1 and the second weight W2 to 0.

[0186] In addition, the reaction force / weight setting unit 52A sets the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ In this modification, an initial calculation formula or a map storing initial characteristics for calculating the parameter (i.e., the initial calculation formula is set). The initial calculation formula may be stored in a preset memory.

[0187] The flag F is set (F=1) if the driving assistance mode is the LCA mode, and is reset (F=0) if the driving assistance mode is the LKA mode.

[0188] The method for calculating the initial calculation formula will be described below.

[0189] The dashed line L0 in FIG. 14 represents the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is a schematic diagram showing the initial characteristics.

[0190] Lateral deviation (e ｌ ) is e ｌ，ｑ If it is equal to or greater than this, the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is the lateral deviation (e ｌ ) is e ｌ，ｑ is set to zero when ｌ ) corresponds to the right lane boundary e ｌ，ｍａｘ When ｔｂ，ｄ＿ＬＫＡ，ｍａｘ Lateral deviation (e ｌ ) is e ｌ，ｑ From e ｌ，ｍａｘ In the range up to ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is from 0 to T ｔｂ，ｄ＿ＬＫＡ，ｍａｘ Until the lateral deviation (e ｌ ) is set to be larger as the

[0191] Lateral deviation (e ｌ ) is -e ｌ，ｑ If the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is the lateral deviation (e ｌ ) is -e ｌ，ｑ is set to zero when ｌ ) corresponds to the left lane boundary - e ｌ，ｍａｘ When -T ｔｂ，ｄ＿ＬＫＡ，ｍａｘ Lateral deviation (e ｌ ) is -e ｌ，ｑ From -e ｌ，ｍａｘ In the range up to ｔｂ，ｄ＿ＬＫＡ (e ｌ ) ranges from 0 to -T ｔｂ，ｄ＿ＬＫＡ，ｍａｘ Until the lateral deviation (e ｌ ) is set to be smaller as

[0192] {(e ｌ，ｍａｘ -e ｌ，ｑ ) = L}, the target virtual spring reaction force for LKA T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is expressed by the following equation (13).

[0193]

[0194] Next, the reaction force / weight setting unit 52A calculates the lateral deviation e ｌ Ga-e ｌ，ｑ <e ｌ <e ｌ，ｑ It is determined whether the lateral deviation e is within the range of ｌ Ga-e ｌ，ｑ <e ｌ <e ｌ，ｑ If it is within the range (step S2: YES), the reaction force / weight setting unit 52A sets the flag F (F=1) (step S3).

[0195] Next, the reaction force / weight setting unit 52A sets the first weight W1 to 1 and the second weight W2 to 0 (step S4), thereby setting the driving assistance mode to the LCA mode.

[0196] Next, the reaction force / weight setting unit 52A calculates the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ) is set to zero (step S5).

[0197] Next, the reaction force / weight setting unit 52A calculates the actual torsion bar torque value T immediately before the transition from the LCA mode to the LKA mode. ｔｂ，ｂｅｆｏｒｅ As the current torsion bar torque T ｔｂ (Step S6). After that, the reaction force / weight setting unit 52A returns to Step S2.

[0198] In step S2, the lateral deviation e ｌ Ga-e ｌ，ｑ <e ｌ <e ｌ，ｑ If it is determined that the lateral deviation e is outside the range (step S2: NO), the reaction force / weight setting unit 52A ｌ Gae ｌ，ｑ It is determined whether or not it is equal to or greater than this (step S7).

[0199] Lateral deviation e ｌ Gae ｌ，ｑ If so (step S7: YES), the reaction force / weight setting unit 52A determines whether or not flag F is set (step S8). If flag F is set (step S8: YES), the reaction force / weight setting unit 52A resets flag F (F=0) (step S9).

[0200] Then, the reaction force / weight setting unit 52A sets the first weight W1 to 0 and the second weight W2 to 1 (step S10), thereby switching the driving assistance mode from the LCA mode to the LKA mode.

[0201] The reaction force / weight setting unit 52A also calculates the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) as T ｔｂ，ｂｅｆｏｒｅ is set (step S11). ｔｂ，ｂｅｆｏｒｅ is the torsion bar torque T just before the driving assistance mode is switched to the LKA mode. ｔｂ is.

[0202] Next, the reaction force / weight setting unit 52A calculates the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ) is updated (step S12). Specifically, the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ The formula for calculating (14) is changed to the following formula (14).

[0203]

[0204] The solid line L1 in FIG. ｔｂ，ｂｅｆｏｒｅ T ｔｂ１ (> 0) when the lateral deviation e after the change ｌ Target virtual spring reaction force T for LKA ｔｂ，ｄ＿ＬＫＡ (e ｌ ) characteristics.

[0205] In step S12, the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ Instead of changing the formula for calculating the lateral deviation e ｌ Target virtual spring reaction force T for LKA ｔｂ，ｄ＿ＬＫＡ (e ｌ ) may be modified.

[0206] Thereafter, the reaction force / weight setting unit 52A returns to step S2.

[0207] If it is determined in step S8 that the flag F has been reset (step S8: NO), the reaction force / weight setting unit 52A sets the first weight W1 to 0 and the second weight W2 to 1 (step S13). This sets the driving assistance mode to the LKA mode. Note that the driving assistance mode may already be set to the LKA mode when a negative determination is made in step S8.

[0208] Next, the reaction force / weight setting unit 52A calculates the currently set calculation formula and the lateral deviation e ｌ Based on this, the target virtual spring reaction force T for LKA is calculated. ｔｂ，ｄ＿ＬＫＡ (e ｌ ) (step S14). After that, the reaction force / weight setting unit 52A returns to step S2.

[0209] In step S7, the lateral deviation e ｌ Gae ｌ，ｑIf it is determined that the lateral deviation e is not equal to or greater than the predetermined value (step S7: NO), the reaction force / weight setting unit 52A calculates the lateral deviation e ｌ Ga-e ｌ，ｑ If the flag F is set (step S15: YES), the reaction force / weight setting unit 52A resets the flag F (F=0) (step S16).

[0210] Next, the reaction force / weight setting unit 52A sets the first weight W1 to 0 and the second weight W2 to 1 (step S16), thereby switching the driving assistance mode from the LCA mode to the LKA mode.

[0211] The reaction force / weight setting unit 52A also calculates the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) as T ｔｂ，ｂｅｆｏｒｅ is set (step S18). ｔｂ，ｂｅｆｏｒｅ is the torsion bar torque T just before the driving assistance mode is switched to the LKA mode. ｔｂ is.

[0212] Next, the reaction force / weight setting unit 52A calculates the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is updated (step S19). Specifically, the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ The formula for calculating (15) is changed to the following formula (15).

[0213]

[0214] The solid line L2 in FIG. ｔｂ，ｂｅｆｏｒｅ T ｔｂ２ (< 0) ｌ Target virtual spring reaction force T for LKA ｔｂ，ｄ＿ＬＫＡ (e ｌ ) characteristics.

[0215] In step S19, the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ Instead of changing the formula for calculating the lateral deviation e ｌTarget virtual spring reaction force T for LKA ｔｂ，ｄ＿ＬＫＡ (e ｌ ) may be modified.

[0216] Thereafter, the reaction force / weight setting unit 52A returns to step S2.

[0217] If it is determined in step S15 that the flag F has been reset (step S15: NO), the reaction force / weight setting unit 52A sets the first weight W1 to 0 and the second weight W2 to 1 (step S20). This sets the driving assistance mode to the LKA mode. Note that the driving assistance mode may already be set to the LKA mode when a negative determination is made in step S15.

[0218] Next, the reaction force / weight setting unit 52A calculates the currently set calculation formula and the lateral deviation e ｌ Based on this, the target virtual spring reaction force T for LKA is calculated. ｔｂ，ｄ＿ＬＫＡ (e ｌ ) (step S21). Then, the reaction force / weight setting unit 52A returns to step S2.

[0219] In this first modified example, when the steering mode is the cooperative steering mode, the lateral deviation e ｌ Ga-e ｌ，ｑ <e ｌ <e ｌ，ｑ When the virtual spring reaction force k is within the range, the driving assistance mode is set to the LCA mode. ｍｄ ・θ ｍｄ Based on the equation of motion (11) including ｍｄ This provides the driver with a steering reaction force to guide the vehicle to the center of the lane.

[0220] On the other hand, lateral deviation e ｌ Ga-e ｌ，ｑ <e ｌ <e ｌ，ｑ When the virtual spring reaction force k is outside the range of the manual steering command value, the driving assistance mode is set to the LKA mode. ｍｄ ・θ ｃｏｌ As a result, the lateral deviation (e ｌ) Target virtual spring reaction force T for LKA according to ｔｂ，ｄ＿ＬＫＡ (e ｌ ) based on the equation of motion (12) using the manual steering command value θ ｍｄ This calculates the lateral deviation e ｌ This allows the driver to easily recognize the distance from the center of the lane (the distance to the lane).

[0221] In addition, when the driving assistance mode is changed from the LCA mode to the LKA mode, the target virtual spring reaction force T for LKA immediately after the change is ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is the torsion bar torque T just before the transition ｔｂ，ｂｅｆｏｒｅ The target virtual spring reaction force T for LKA is set to match ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is set, and the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is updated (see equations (14) and (15)).

[0222] As a result, when the driving assistance mode is changed from the LCA mode to the LKA mode, the torsion bar torque T ｔｂ This makes it possible to prevent the steering feeling from suddenly becoming lighter or the driver from feeling a shock when switching from the LCA mode to the LKA mode.

[0223] When the driving assistance mode is changed from the LCA mode to the LKA mode, the virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is the virtual spring reaction force k just before the transition ｍｄ ・θ ｍｄ The target virtual spring reaction force T for LKA is set to match ｔｂ，ｄ＿ＬＫＡ (e ｌ ) may be set.

[0224] In this case, in step S6 of FIG. 13A, the reaction force / weight setting unit 52A calculates the virtual spring reaction force (k ｍｄ ・θ ｍｄ -) ｂｅｆｏｒｅ As the current virtual spring reaction force k ｍｄ ・θｍｄ In step S11 of FIG. 13A and step S18 of FIG. 13B, the reaction force / weight setting unit 52A sets the target virtual spring reaction force for LKA T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) as (k ｍｄ ・θ ｍｄ -) ｂｅｆｏｒｅ Set.

[0225] In step S12 of FIG. 13A, the reaction force / weight setting unit 52A calculates the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ The formula for calculating (16) is changed to the following formula (16).

[0226]

[0227] In step S19 of FIG. 13B, the reaction force / weight setting unit 52A calculates the target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ The formula for calculating (17) is changed to the following formula (17).

[0228]

[0229] Instead of the manual steering command value calculation unit 53A in FIG. 11, an automatic steering command value θ ａｄ Hereinafter, the motor control ECU 202B in which the manual steering command value calculation unit 53B is used instead of the manual steering command value calculation unit 53A will be referred to as a second modified example of the motor control ECU.

[0230] Fig. 15 is a block diagram showing the configuration of the manual steering command value calculation unit 53B. In Fig. 15, parts corresponding to those in Fig. 12 are denoted by the same reference numerals as in Fig. 12.

[0231] The manual steering command value calculation unit 53B includes a reduction ratio multiplication unit 131, a first-order differentiation unit 111, a second-order differentiation unit 112, an addition / subtraction unit 101, an inertia division unit 102, a first integration unit 103, a second integration unit 104, a first virtual damper reaction force calculation unit 105, a virtual spring reaction force calculation unit 106, a first weight multiplication unit 107, a second virtual damper reaction force calculation unit 113, an inertia multiplication unit 114, a first addition unit 108, a second weight multiplication unit 109, and a second addition unit 110.

[0232] The reduction ratio multiplication unit 131 calculates the assist torque command value T ａｓ is multiplied by the reduction ratio N of the reducer 19 to obtain the assist torque command value T ａｓ is the assist torque command value N·T for the output shaft 9. ａｓ The assist torque command value N·T for the output shaft 9 calculated by the reduction ratio multiplication unit 131 is converted into ａｓ is given to the adder / subtractor 101 and also to the first adder 108 .

[0233] The addition / subtraction unit 101 receives the torsion bar torque T ｔｂ and the assist torque command value N·T for the output shaft 9. ａｓ and the first virtual damper reaction force c calculated by the first virtual damper reaction force calculation unit 105. ｍｄ ・dθ ｍｄ / dt and the addition result Y of the second adder 110 are given.

[0234] The addition / subtraction unit 101 calculates the torsion bar torque T ｔｂ Assist torque command value N·T for output shaft 9 ａｓ From the result of the addition, the first virtual damper reaction force c ｍｄ ・dθ ｍｄ / dt and Y. As a result, the adder / subtractor 101 subtracts J on the left side of the above equation (2). ｍｄ ・d ２ θ ｃｏｌ / dt ２ The moment of inertia J corresponds to ｍｄ ・d ２ θ ｍｄ / dt ２ (=T ｔｂ +N.T. ａｓ -c ｍｄ・dθ ｍｄ / dt-Y) is calculated.

[0235] The inertia division unit 102 calculates the moment of inertia J calculated by the addition / subtraction unit 101. ｍｄ ・d ２ θ ｍｄ / dt ２ The column inertia J ｍｄ By dividing by , the manual steering command value θ ｍｄ The second derivative d ２ θ ｍｄ / dt ２ Calculate the following.

[0236] The first integration unit 103 calculates the manual steering command value θ ｍｄ The second derivative d ２ θ ｍｄ / dt ２ By integrating the manual steering command value θ ｍｄ The first derivative dθ ｍｄ / dt is calculated.

[0237] The second integration unit 104 calculates the manual steering command value θ ｍｄ The first derivative dθ ｍｄ By integrating / dt, the manual steering command value θ ｍｄ This manual steering command value θ ｍｄ is output from the manual steering command value calculation unit 53B.

[0238] The first virtual damper reaction force calculation unit 105 calculates the manual steering command value θ calculated by the first integration unit 103. ｍｄ The first derivative dθ ｍｄ / dt with viscous damping coefficient c ｍｄ By multiplying by ｍｄ ・dθ ｍｄ / dt is calculated. ｍｄ ・dθ ｍｄ / dt is fed back to the addition / subtraction unit 101 .

[0239] The virtual spring reaction force calculation unit 106 calculates the manual steering command value θ ｍｄ Spring constant k ｍｄ By multiplying by ｍｄ ・θ ｍｄThe first weight multiplier 107 calculates the virtual spring reaction force k ｍｄ ・θ ｍｄ is multiplied by a first weight W1.

[0240] The first-order differentiation unit 111 calculates the automatic steering command value θ ａｄ The second virtual damper reaction force calculation unit 113 calculates the first derivative of the automatic steering command value θ ａｄ The first derivative dθ ａｄ / dt with viscous damping coefficient c ｍｄ By multiplying this, the second virtual damper reaction force c ｍｄ ・dθ ａｄ / dt is calculated. ｍｄ ・dθ ａｄ / dt is the automatic steering command value θ ａｄ is the virtual damper reaction force against

[0241] The second-order differentiation unit 112 calculates the automatic steering command value θ ａｄ The inertia multiplication unit 114 calculates the second-order derivative of the automatic steering command value θ ａｄ The second derivative d ２ θ ａｄ / dt ２ Column inertia J ｍｄ By multiplying by , the automatic steering command value θ ａｄ Moment of inertia J ｍｄ ・d ２ θ ａｄ / dt ２ Calculate the following.

[0242] The first adder 108 calculates the automatic steering command value θ ａｄ Virtual damper reaction force (second virtual damper reaction force) c ｍｄ ・dθ ａｄ / dt, the automatic steering command value θ ａｄ Moment of inertia J ｍｄ ・d ２ θ ａｄ / dt ２ , LKA target virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) and the assist torque command value N·T for the output shaft 9 ａｓ Add.

[0243] The second weight multiplier 109 multiplies the calculation result (c ｍｄ ・dθａｄ / dt+J ｍｄ ・d ２ θ ａｄ / dt ２ +T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) + N.T. ａｓ ) is multiplied by a second weight W2.

[0244] The second adder 110 multiplies the result of calculation W1·k by the first weight multiplier 107 by ｍｄ ・θ ｍｄ and the calculation result W2·(c ｍｄ ・dθ ａｄ / dt+J ｍｄ ・d ２ θ ａｄ / dt ２ +T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) + N.T. ａｓ The addition result {W1·k ｍｄ ・θ ｍｄ +W2·(c ｍｄ ・dθ ａｄ / dt+J ｍｄ ・d ２ θ ａｄ / dt ２ +T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) + N.T. ａｓ )} is fed back as Y to the addition / subtraction unit 101 .

[0245] In this modification, the reaction force / weight setting unit 52A performs the same operation as that described with reference to Figures 13A and 13B. However, as described above, when the driving assistance mode is shifted from the LCA mode to the LKA mode, the virtual spring reaction force T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is the virtual spring reaction force k just before the transition ｍｄ ・θ ｍｄ The target virtual spring reaction force T for LKA is set to match ｔｂ，ｄ＿ＬＫＡ (e ｌ ) may be set.

[0246] Therefore, the lateral deviation e ｌ Ga-e ｌ，ｑ is greater than e ｌ，ｑIf the difference is smaller than 1, the driving assistance mode is the lane centering assist mode (LCA mode), the first weight W1 is set to 1, and the second weight W2 is set to zero.

[0247] On the other hand, lateral deviation e ｌ Ga-e ｌ，ｑ If the following occurs or e ｌ，ｑ If this is the case, the driving assistance mode is set to the lane keeping assist mode (LKA mode), the first weight W1 is set to 0, and the second weight W2 is set to 1.

[0248] In the LCA mode, the addition result Y of the second addition unit 110 is calculated as k ｍｄ ・θ ｍｄ Therefore, the calculation result Y of the addition / subtraction unit 101 is T ｔｂ +N.T. ａｓ -c ｍｄ ・dθ ｍｄ / dt-k ｍｄ ・θ ｍｄ This becomes:

[0249] Therefore, in the LCA mode, the manual steering command value calculation unit 53B calculates the manual steering command value θ based on the equation of motion of the following equation (18), which is the same as the above equation (11). ｍｄ Calculate the following.

[0250]

[0251] That is, in the LCA mode, the manual steering command value calculation unit 53B calculates the manual steering command value θ using a motion equation similar to the above-mentioned equation (2). ｍｄ Calculate the following.

[0252] In the LKA mode, the addition result Y of the second adder 110 is (c ｍｄ ・dθ ａｄ / dt+J ｍｄ ・d ２ θ ａｄ / dt ２ +T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) + N.T. ａｓ ) Therefore, the calculation result of the addition / subtraction unit 101 is T ｔｂ -c ｍｄ ・dθ ｍｄ / dt-c ｍｄ ・dθ ａｄ / dt-J ｍｄ ・d ２ θ ａｄ / dt ２ -T ｔｂ，ｄ＿ＬＫＡ (e ｌ )

[0253] Therefore, in the LCA mode, the manual steering command value calculation unit 53B calculates the manual steering command value θ based on the equation of motion of the following equation (19): ｍｄ Calculate the following.

[0254]

[0255] In formula (19), (J ｍｄ ・d ２ θ ｍｄ / dt ２ +J ｍｄ ・d ２ θ ａｄ / dt ２ ) is the moment of inertia. ｍｄ ・dθ ｍｄ / dt+c ｍｄ ・dθ ａｄ / dt) is the virtual damper reaction force. ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is the target virtual spring reaction force for LKA.

[0256] That is, in the LKA mode, the manual steering command value calculation unit 53B calculates the N·T in the equation of motion of the above-mentioned formula (2). ｍ (= N.T. ａｓ ) is set to 0, and the moment of inertia J ｍｄ ・d ２ θ ｃｏｌ / dt ２ , virtual damper reaction force c ｍｄ ・dθ ｃｏｌ / dt and virtual spring reaction force k ｍｄ ・θ ｃｏｌ As such, (J ｍｄ ・d ２ θ ｍｄ / dt ２ +J ｍｄ ・d ２ θ ａｄ / dt ２ ), (c ｍｄ ・dθｍｄ / dt+c ｍｄ ・dθ ａｄ / dt) and T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) to obtain the manual steering command value θ ｍｄ Calculate the following.

[0257] The manual steering command value calculation unit 53B calculates the N·T ａｓ In this case, in the LKA mode, the manual steering command value calculation unit 53B may add N·T to the right side of the above equation (19). ａｓ Based on the equation of motion to which is added, the manual steering command value θ ｍｄ The following calculation is performed.

[0258] The second modification has the same effect as the first modification. The second modification also has the effect of reducing the sense of discomfort felt by the driver in the LKA mode. This will be described below.

[0259] 11 and 7, in the cooperative steering mode, the actual steering angle θ ｃ is the integrated angle command value θ ｃｍｄ The electric motor 18 is controlled so as to follow the actual steering angle θ ｃ is the integrated angle command value θ ｃｍｄ Assuming that the system follows the ｍｄ = θ ｃ -θ ａｄ The following relationship holds.

[0260] In this case, the manual steering command value θ in the above equation (19) ｍｄ Virtual damper reaction force c ｍｄ ・dθ ｍｄ / dt is expressed by the following equation (20).

[0261]

[0262] Furthermore, the manual steering command value θ ｍｄ Moment of inertia J ｍｄ ・d ２ θ ｍｄ / dt ２ is expressed by the following equation (21).

[0263]

[0264] That is, c ｍｄ ・dθ ｍｄ / dt is the actual steering angle θ ｃ The actual steering angle component c according to the first derivative of ｍｄ ・dθ ｃ / dt and the automatic steering command value θ ａｄ Automatic steering component -c according to the first derivative of ｍｄ ・dθ ａｄ / dt. Similarly, J ｍｄ ・d ２ θ ｍｄ / dt ２ is the actual steering angle θ ｃ Actual steering angle component J corresponding to the second derivative of ｍｄ ・d ２ θ ｃ / dt ２ and the automatic steering command value θ ａｄ Automatic steering component according to the second derivative of -J ｍｄ ・d ２ θ ａｄ / dt ２ Includes:

[0265] These actual steering angle components c ｍｄ ・dθ ｃ / dt and J ｍｄ ・d ２ θ ｃ / dt ２ Since the automatic steering component -c corresponds to the driver's behavior, the driver does not feel uncomfortable. ｍｄ ・dθ ａｄ / dt and -J ｍｄ ・d ２ θ ａｄ / dt ２ Since −dθ is not related to the driver's behavior, the driver may feel uncomfortable. ａｄ The absolute value of / dt is -d ２ θ ａｄ / dt ２ Since the absolute value of the virtual damper reaction force is larger than the absolute value of ｍｄ ・dθ ａｄ / dθ is likely to have a negative effect on the steering feel.

[0266] In the second modification, the equation of motion of the above-mentioned equation (19) is expressed as a virtual damper reaction force, and the manual steering command value θｍｄ Virtual damper reaction force c ｍｄ ・dθ ｍｄ / dt plus the automatic steering command value θ ａｄ Virtual damper reaction force c ｍｄ ・dθ ａｄ The equation of motion of the above equation (19) includes the manual steering command value θ ｍｄ Moment of inertia J ｍｄ ・d ２ θ ｍｄ / dt ２ In addition to the automatic steering command value θ ａｄ Moment of inertia J ｍｄ ・d ２ θ ａｄ / dt ２ Includes:

[0267] As a result, the manual steering command value θ ｍｄ Virtual damper reaction force c ｍｄ ・dθ ｍｄ Automatic steering component -c included in / dt ｍｄ ・dθ ａｄ Similarly, the manual steering command value θ ｍｄ Moment of inertia J ｍｄ ・d ２ θ ｍｄ / dt ２ Automatic steering component contained in -J ｍｄ ・d ２ θ ａｄ / dt ２ This can reduce the sense of discomfort felt by the driver in the LKA mode.

[0268] θ ｍｄ = θ ｃ -θ ａｄ If it is assumed that the above relationship holds, the equation of motion of equation (19) becomes as shown in the following equation (22).

[0269]

[0270] In this case, c ｍｄ ・dθ ｍｄ Automatic steering component -c included in / dt ｍｄ ・dθ ａｄ / dt is compensated for, and the actual steering angle θｃ Actual steering angle component c ｍｄ ・dθ ｃ Only / dt remains, and J ｍｄ ・d ２ θ ｍｄ / dt ２ Automatic steering component contained in -J ｍｄ ・d ２ θ ａｄ / dt ２ is compensated, and the actual steering angle θ ｃ J against ｍｄ ・d ２ θ ｃ / dt ２ Only remains.

[0271] Fig. 16 is a block diagram showing a third modified example of the motor control ECU, in which parts corresponding to those in Fig. 11 are denoted by the same reference numerals as in Fig. 11 .

[0272] The motor control ECU 202C in FIG. 16 differs from the second modified example described with reference to FIG. 11 in the following (1) and (2): (1) The configuration of the manual steering command value calculation unit 53C differs from the configuration of the manual steering command value calculation unit 53B of the second modified example ( FIG. 15 ). (2) In addition to the LKA target virtual spring reaction force / weight setting unit 52A in FIG. 11 , an LCA target virtual spring reaction force setting unit 52B is provided for setting an LCA target virtual spring reaction force, which is a target virtual spring reaction force for lane centering assist.

[0273] The manual steering command value calculation unit 53C receives the torsion bar torque T ｔｂ and the target virtual spring reaction force T for LKA ｔｂ，ｄ＿ＬＫＡ (e ｌ ), the first weight W1 and the second weight W2, and the automatic steering command value θ ａｄ The manual steering command value calculation unit 53C further receives the LCA target virtual spring reaction force T ｔｂ，ｄ＿ＬＣＡ (e ｌ In this third modification, the manual steering command value calculation unit 53C receives the assist torque command value T ａｓ cannot be given.

[0274] The LCA target virtual spring reaction force setting unit 52B calculates the lateral deviation e ｌ Based on the LCA target virtual spring reaction force T ｔｂ，ｄ＿ＬＣＡ (e ｌ The solid line L3 in FIG. ｌ LCA target virtual spring reaction force T ｔｂ，ｄ＿ＬＣＡ (e ｌ ) is a graph showing an example of setting.

[0275] LCA target virtual spring reaction force T ｔｂ，ｄ＿ＬＣＡ (e ｌ ) is the lateral deviation (e ｌ ) is e ｌ，ｑ Range and lateral deviation (e ｌ ) is -e ｌ，ｑ In the range smaller than , it is set to 0. Also, the target virtual spring reaction force for LCA T ｔｂ，ｄ＿ＬＣＡ (e ｌ ) is the lateral deviation (e ｌ ) is set to 0.

[0276] LCA target virtual spring reaction force T ｔｂ，ｄ＿ＬＣＡ (e ｌ ) is the lateral deviation (e ｌ ) is e ｌ，ｑ When the predetermined maximum value T ｔｂ，ｄ＿ＬＣＡ，ｍａｘ The lateral deviation (e ｌ ) is -e ｌ，ｑ When -T ｔｂ，ｄ＿ＬＣＡ，ｍａｘ is set to

[0277] Lateral deviation (e ｌ ) is 0 to e ｌ，ｑ In the range up to ｔｂ，ｄ＿ＬＣＡ (e ｌ ) ranges from 0 to T ｔｂ，ｄ＿ＬＣＡ，ｍａｘ Until the lateral deviation (e ｌ The larger the lateral deviation e ｌ is 0 to -e ｌ，ｑ In the range up to ｔｂ，ｄ＿ＬＣＡ (e ｌ ) ranges from 0 to -T ｔｂ，ｄ＿ＬＣＡ，ｍａｘ Until the lateral deviation (e ｌ In this example, the LCA target virtual spring reaction force T ｔｂ，ｄ＿ＬＣＡ (eｌ ) varies linearly, but may vary nonlinearly.

[0278] The reaction force / weight setting unit 52A performs substantially the same operations as those described with reference to Figures 13A and 13B. However, the initial calculation formula set in step S1 in Figure 13A is different from the initial calculation formula described with reference to Figure 13A. Other operations of the reaction force / weight setting unit 52A are the same as those described above.

[0279] In this modification, the target virtual spring reaction force T for LKA is set to ｔｂ，ｄ＿ＬＫＡ (e ｌ The initial characteristics for determining the .times. ...

[0280] Therefore, in step S1 of FIG. 13A, the initial calculation formula shown in the following formula (23) is set.

[0281]

[0282] Fig. 18 is a block diagram showing the configuration of the manual steering command value calculation unit 53C. In Fig. 18, parts corresponding to those in Fig. 15 are denoted by the same reference numerals as in Fig. 15.

[0283] The manual steering command value calculation unit 53C includes a first-order differentiation unit 111, a second-order differentiation unit 112, an addition / subtraction unit 101, an inertia division unit 102, a first integration unit 103, a second integration unit 104, a third addition unit 121, a virtual damper reaction force calculation unit 105, a fourth addition unit 122, a virtual spring reaction force calculation unit 106, a fifth addition unit 123, a first weight multiplication unit 107, a sixth addition unit 124, a second weight multiplication unit 109, a second addition unit 110, and an inertia multiplication unit 125.

[0284] The second-order differentiation unit 112 calculates the automatic steering command value θ ａｄ The inertia multiplication unit 125 performs second-order differentiation on the differentiation result d ２ θ ａｄ / dt ２ Column inertia J ｍｄ By multiplying by , the automatic steering command value θ ａｄ Moment of inertia J ｍｄ ・ ２ θ ａｄ / dt ２ Calculate the following.

[0285] The addition / subtraction unit 101 receives the torsion bar torque T ｔｂ and the automatic steering command value θ ａｄ Moment of inertia J ｍｄ ・ ２ θ ａｄ / dt ２ and the addition result Z of the second addition unit 110 is given.

[0286] The addition / subtraction unit 101 calculates the torsion bar torque T ｔｂ From the above, the automatic steering command value θ ａｄ Moment of inertia J ｍｄ ・ ２ θ ａｄ / dt ２ and Z. As a result, the adder / subtractor 101 subtracts J on the left side of the above equation (2). ｍｄ ・d ２ θ ｃｏｌ / dt ２ The moment of inertia J corresponds to ｍｄ ・d ２ θ ｍｄ / dt ２ (=T ｔｂ -J ｍｄ ・ ２ θ ａｄ / dt ２ -Z).

[0287] The inertia division unit 102 calculates the moment of inertia J calculated by the addition / subtraction unit 101. ｍｄ ・d ２ θ ｍｄ / dt ２ The column inertia J ｍｄ By dividing by , the manual steering command value θ ｍｄ The second derivative d ２ θ ｍｄ / dt ２ Calculate the following.

[0288] The first integration unit 103 calculates the manual steering command value θ ｍｄ The second derivative d ２ θ ｍｄ / dt ２ By integrating the manual steering command value θ ｍｄ The first derivative dθ ｍｄ / dt is calculated.

[0289] The second integration unit 104 calculates the manual steering command value θ ｍｄ The first derivative dθ ｍｄ By integrating / dt, the manual steering command value θ ｍｄ This manual steering command value θ ｍｄ is output from the manual steering command value calculation unit 53C.

[0290] The first-order differentiation unit 111 calculates the automatic steering command value θ ａｄ The third adder 121 calculates the first derivative of the manual steering command value θ ｍｄ The differential value dθ ｍｄ / dt, the automatic steering command value θ ａｄ The differential value dθ ａｄ / dt is added.

[0291] The virtual damper reaction force calculation unit 105 calculates the sum (dθ ｍｄ / dt+dθ ａｄ / dt) with the viscous damping coefficient c ｍｄ By multiplying by ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) is calculated.

[0292] The fourth adder 122 calculates the manual steering command value θ ｍｄ Automatic steering command value θ ａｄ The virtual spring reaction force calculation unit 106 adds the sum (θ ｍｄ +θ ａｄ ) with spring constant k ｍｄ By multiplying by ｍｄ ・(θ ｍｄ +θ ａｄ ) is calculated.

[0293] The fifth adder 123 calculates the virtual damper reaction force c calculated by the virtual damper reaction force calculation unit 105. ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) and the virtual spring reaction force k calculated by the virtual spring reaction force calculation unit 106 ｍｄ ・(θ ｍｄ +θ ａｄ ) and the target virtual spring reaction force T for LCA ｔｂ，ｄ＿ＬＣＡ (e ｌ ) and add them together.

[0294] The first weight multiplier 107 multiplies the sum {c ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) + k ｍｄ ・(θ ｍｄ +θ ａｄ ) + T ｔｂ，ｄ＿ＬＣＡ (e ｌ )} is multiplied by a first weight W1.

[0295] The sixth adder 124 calculates the virtual damper reaction force c calculated by the virtual damper reaction force calculation unit 105. ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) and the target virtual spring reaction force T for LKA ｔｂ，ｄ＿ＬＫＡ (e ｌ ) and add them together.

[0296] The second weight multiplication unit 109 multiplies the sum {c ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) + T ｔｂ，ｄ＿ＬＫＡ (e ｌ )} is multiplied by a second weight W2.

[0297] The second adder 110 multiplies the result of calculation W1·{c ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) + k ｍｄ ・(θ ｍｄ +θ ａｄ ) + T ｔｂ，ｄ＿ＬＣＡ (e ｌ )} and the calculation result W2·{c ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) + T ｔｂ，ｄ＿ＬＫＡ (e ｌ )}. The addition result of the second adder 110 [W1·{c ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) + k ｍｄ ・(θ ｍｄ +θ ａｄ ) + T ｔｂ，ｄ＿ＬＣＡ (e ｌ )}+W2·{c ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) + T ｔｂ，ｄ＿ＬＫＡ (e ｌ )}] is fed back as Z to the addition / subtraction unit 101 .

[0298] In this modified example, the lateral deviation e ｌ Ga-e ｌ，ｑ is greater than e ｌ，ｑ If the difference is smaller than 1, the driving assistance mode is the lane centering assist mode (LCA mode), the first weight W1 is set to 1, and the second weight W2 is set to zero.

[0299] On the other hand, lateral deviation e ｌ Ga-e ｌ，ｑ If the following occurs or e ｌ，ｑ If this is the case, the driving assistance mode is set to the lane keeping assist mode (LKA mode), the first weight W1 is set to 0, and the second weight W2 is set to 1.

[0300] In the LCA mode, the addition result Z of the second adder 110 is expressed as {c ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) + k ｍｄ ・(θ ｍｄ +θ ａｄ ) + T ｔｂ，ｄ＿ＬＣＡ (e ｌ )}. Therefore, the calculation result of the addition / subtraction unit 101 is {(T ｔｂ -J ｍｄ ・d ２ θ ａｄ / dt ２ -c ｍｄ ・dθ ｍｄ / dt-c ｍｄ ・dθ ａｄ / dt-k ｍｄ ・θ ｍｄ -k ｍｄ ・θ ａｄ -T ｔｂ，ｄ＿ＬＣＡ (e ｌ )}.

[0301] Therefore, in the LCA mode, the manual steering command value calculation unit 53C calculates the manual steering command value θ based on the equation of motion of the following equation (24): ｍｄ Calculate the following.

[0302]

[0303] In formula (24), (J ｍｄ ・d ２ θ ｍｄ / dt ２ +J ｍｄ ・d ２ θ ａｄ / dt ２ ) is the moment of inertia. ｍｄ ・dθ ｍｄ / dt+c ｍｄ ・dθ ａｄ / dt) is the virtual damper reaction force. (k ｍｄ ・θ ｍｄ +k ｍｄ ・θ ａｄ +T ｔｂ，ｄ＿ＬＣＡ (e ｌ )) is the virtual spring reaction force.

[0304] That is, in the LCA mode, the manual steering command value calculation unit 53C calculates the N·T in the equation of motion of the above-mentioned formula (2). ｍ (= N.T. ａｓ ) is set to 0, and the moment of inertia J ｍｄ ・d ２ θ ｍｄ / dt ２ , virtual damper reaction force c ｍｄ ・θ ｃｏｌ and virtual spring reaction force k ｍｄ ・θ ｃｏｌ As such, (J ｍｄ ・d ２ θ ｍｄ / dt ２ +J ｍｄ ・d ２ θ ａｄ / dt ２ ), (c ｍｄ ・dθ ｍｄ / dt+c ｍｄ ・dθ ａｄ / dt) and (k ｍｄ ・θ ｍｄ +k ｍｄ ・θ ａｄ +T ｔｂ，ｄ＿ＬＣＡ (e ｌ )) to obtain the manual steering command value θ ｍｄ Calculate the following.

[0305] In the LKA mode, the addition result Z of the second adder 110 is expressed as {c ｍｄ · (dθ ｍｄ / dt+dθ ａｄ / dt) + T ｔｂ，ｄ＿ＬＫＡ (e ｌ )}. Therefore, the calculation result of the addition / subtraction unit 101 is {T ｔｂ -J ｍｄ ・d ２ θ ａｄ / dt ２ -c ｍｄ ・dθ ｍｄ / dt-c ｍｄ ・dθ ａｄ / dt-T ｔｂ，ｄ＿ＬＫＡ (e ｌ )}.

[0306] Therefore, in the LKA mode, the manual steering command value calculation unit 53C calculates the manual steering command θ based on the equation of motion of the following equation (25), which is the same as the above equation (19). ｍｄ Calculate the following.

[0307]

[0308] In formula (25), (J ｍｄ ・d ２ θ ｍｄ / dt ２ +J ｍｄ ・d ２ θ ａｄ / dt ２ ) is the moment of inertia. ｍｄ ・dθ ｍｄ / dt+c ｍｄ ・dθ ａｄ / dt) is the virtual damper reaction force. ｔｂ，ｄ＿ＬＫＡ (e ｌ ) is the target virtual spring reaction force for the LKA.

[0309] That is, in the LKA mode, the manual steering command value calculation unit 53C calculates the N·T in the equation of motion of the above-mentioned formula (2). ｍ (= N.T. ａｓ ) is set to 0, and the moment of inertia J ｍｄ ・d ２ θ ｃｏｌ / dt ２ , virtual damper reaction force c ｍｄ ・dθｃｏｌ / dt and virtual spring reaction force k ｍｄ ・θ ｃｏｌ As such, (J ｍｄ ・d ２ θ ｍｄ / dt ２ +J ｍｄ ・d ２ θ ａｄ / dt ２ ), (c ｍｄ ・dθ ｍｄ / dt+c ｍｄ ・dθ ａｄ / dt) and T ｔｂ，ｄ＿ＬＫＡ (e ｌ ) to obtain the manual steering command value θ ｍｄ Calculate the following.

[0310] The manual steering command value calculation unit 53C calculates the assist torque command value T ａｓ By multiplying this by the reduction ratio N, we get N・T ａｓ Calculate the obtained N.T. ａｓ In this case, the addition / subtraction unit 101 calculates the torsion bar torque T ｔｂ N.T. ａｓ and the automatic steering command value θ ａｄ Moment of inertia J ｍｄ ・ ２ θ ａｄ / dt ２ and subtract Z.

[0311] In this case, in the LCA mode, the manual steering command value calculation unit 53C adds N·T to the right side of the following equation (24). ａｓ Based on the equation of motion to which is added, the manual steering command value θ ｍｄ In addition, in the LKA mode, the manual steering command value calculation unit 53C calculates N·T on the right side of the following equation (25). ａｓ Based on the equation of motion to which is added, the manual steering command value θ ｍｄ The following calculation is performed.

[0312] The third modification has the same effect as the second modification. Furthermore, the third modification has the effect of reducing the driver's discomfort not only in the LKA mode but also in the LCA mode. This point will be explained below.

[0313] In the third modification, the manual steering command value θ ｍｄ The equation of motion (24) for calculating the above equation is expressed as a virtual damper reaction force, and the manual steering command value θ ｍｄ Virtual damper reaction force c ｍｄ ・dθ ｍｄ / dt plus the automatic steering command value θ ａｄ Virtual damper reaction force c ｍｄ ・dθ ａｄ / dt included.

[0314] In addition, this equation of motion (24) uses the manual steering command value θ as the moment of inertia. ｍｄ Moment of inertia J ｍｄ ・d ２ θ ｍｄ / dt ２ In addition to the automatic steering command value θ ａｄ Moment of inertia J ｍｄ ・d ２ θ ａｄ / dt ２ Includes.

[0315] Furthermore, the equation of motion (24) is expressed as a virtual spring reaction force, i.e., the manual steering command value θ ｍｄ Virtual spring reaction force k ｍｄ ・dθ ｍｄ / dt plus the automatic steering command value θ ａｄ Virtual spring reaction force k ｍｄ ・dθ ａｄ / dt included.

[0316] As a result, even in the LCA mode, the manual steering command value θ ｍｄ Virtual damper reaction force c ｍｄ ・dθ ｍｄ Similarly, the automatic steering component included in the manual steering command value θ ｍｄ Moment of inertia J ｍｄ ・d ２ θ ｍｄ / dt２ Furthermore, the automatic steering component included in the manual steering command value θ ｍｄ Virtual spring reaction force k ｍｄ ・dθ ｍｄ Therefore, in the third modified example, the sense of discomfort felt by the driver can be reduced in the LKA mode and the LCA mode.

[0317] Although the embodiments and modifications of the present disclosure have been described above, the present disclosure can also be embodied in other forms.

[0318] In the above-described embodiment, the spring constant k in the above-described equations (11), (18), and (24) ｍｄ However, the spring constant k in the above equations (11), (18), and (21) is ｍｄ is the disturbance torque estimated value ^T calculated by the disturbance torque estimating unit 64 (see FIG. 7). ｌｃ and the actual steering angle θ calculated by the second reduction ratio division unit 70. ｃ and may be calculated based on the following equation (26).

[0319]

[0320] In the above-described embodiment, the viscous damping coefficient c ｍｄ is obtained in advance through experiments, analysis, etc.

[0321] However, the viscous damping coefficient c in the above equations (3), (11), (12), (18), (19), (24), and (25) ｍｄ is the disturbance torque estimated value ^T calculated by the disturbance torque estimator 64 ｌｃ and the actual steering angle θ calculated by the second reduction ratio division unit 70. ｃ and may be calculated based on the following equation (27).

[0322]

[0323] In the above embodiment, the angle control unit 55 (see FIG. 7) includes the feedforward control unit 63, but the feedforward control unit 63 may be omitted. In this case, the feedback control torque T ｆｂ is the basic target torque.

[0324] In addition, although the above-described embodiment shows an example in which the present disclosure is applied to motor control of a column-type EPS, the present disclosure can also be applied to motor control of EPS other than column-type EPS. Furthermore, the present disclosure can also be applied to control of an electric motor for steering angle control in a steer-by-wire system.

[0325] Although the embodiments of the present disclosure have been described in detail, these are merely specific examples used to clarify the technical content of the present disclosure, and the present disclosure should not be construed as being limited to these specific examples, and the scope of the present disclosure is limited only by the appended claims.

[0326] REFERENCE SIGNS LIST 1... electric power steering device, 3... steered wheels, 4... steering mechanism, 18... electric motor, 51... assist torque command value setting section, 52... target virtual spring reaction force setting section, 52A... LKA target virtual spring reaction force / weight setting section, 52B... LCA target virtual spring reaction force setting section, 53, 53A, 53B, 53C... manual steering command value calculation section, 54... integrated angle command value calculation section, 55... angle control section, 56, 56A... subtraction section, 56... first switch, 57... second switch, 58... addition section, 59... torque control section, 201... host ECU, 202, 202A, 202B, 202C... motor control ECU

Claims

1. A motor control device for driving and controlling the electric motor of a steering system, A manual steering command value calculation unit that calculates manual steering command values ​​using torsion bar torque, An integrated angle command value calculation unit calculates an integrated angle command value by adding the manual steering command value to the automatic steering command value for driver assistance, Includes a control unit that drives and controls the electric motor based on the integrated angle command value, In the driving assistance mode, the manual steering command value calculation unit is configured to calculate the manual steering command value using the equations of motion of the reference model of the steering device. The aforementioned equation of motion includes the moment of inertia acting on the steering device, the torsion bar torque, the torque applied to the steering device by the electric motor, and the road surface reaction torque. The aforementioned road surface reaction torque includes a virtual spring reaction force, which is a spring component, and a virtual damper reaction force, which is a damper component. The motor control device calculates the manual steering command value using, at least under predetermined conditions, a target virtual spring reaction force that does not depend on the manual steering command value, and which corresponds to the lateral position of the vehicle's reference position relative to the driving lane, as the virtual spring reaction force in the equation of motion.

2. The motor control device according to claim 1, wherein when the driving assistance mode is a lane-keeping assist mode that assists in steering the vehicle to maintain within the driving lane, the manual steering command value calculation unit calculates the manual steering command value using a target virtual spring reaction force that does not depend on the manual steering command value and corresponds to the lateral position of the vehicle's reference position relative to the driving lane as the virtual spring reaction force in the equation of motion.

3. The aforementioned driving assistance modes include the lane-keeping assist mode and a driving mode separate from the lane-keeping assist mode. The motor control device according to claim 2, wherein when transitioning from an operating mode other than the lane-keeping assist mode to the lane-keeping assist mode, the target virtual spring reaction force is set to match the virtual spring reaction force immediately before transitioning from the other operating mode to the lane-keeping assist mode.

4. The aforementioned alternative driving mode is a lane-centering assist mode, which assists in steering the vehicle so that it travels in the center of the driving lane. When the vehicle reference position is within a predetermined distance from the center of the driving lane, the driving mode is set to the lane centering assist mode. When the vehicle reference position is outside the range of a predetermined distance from the center of the driving lane, the driving mode is set to the lane-keeping assist mode. In the lane centering assist mode, the manual steering command value calculation unit calculates the manual steering command value using the virtual spring reaction force, which is set using the spring constant of the virtual spring, as the virtual spring reaction force in the equation of motion. The motor control device according to claim 3, wherein when transitioning from the lane centering assist mode to the lane keeping assist mode, the target virtual spring reaction force at the time of the transition is set to match the virtual spring reaction force immediately before the transition.