Motor control device

Abstract

This motor control device comprises: a manual steering command value calculation unit that calculates a manual steering command value by using a torsion bar torque; an integrated angle command value calculation unit that calculates an integrated angle command value by adding a manual steering command value to an automatic steering command value for operation assistance; and a control unit that drives and controls an electric motor on the basis of the integrated angle command value. In an operation assistance mode, the manual steering command value calculation unit is configured to calculate the manual steering command value by using a motion equation of a steering device reference model. The manual steering command value calculation unit calculates the manual steering command value by using, as a virtual spring reaction force in the motion equation, a virtual spring reaction force obtained by adding a virtual spring reaction force according to the automatic steering command value to a virtual spring reaction force according to the manual steering command value.

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] When the driving mode is a manual driving mode, the electric motor is controlled by the first control, whereas when the driving mode is a driving assistance mode in which driving assistance such as lane centering assist (LCA) control is being performed, the electric motor is controlled by the second control.

[0004] International Publication No. 2023 / 286169

[0005] In the first control described in Patent Document 1, when the driver steers the steering wheel, the self-aligning torque attempts to return the steering angle to near zero degrees, which corresponds to the neutral position of the output shaft. On the other hand, in the second control, when the driver's steering intervention causes the vehicle to deviate from the target driving line, the system attempts to return the vehicle to the target driving line by using a driving assistance force according to the automatic steering command value. Because this driving assistance force is greater than or equal to the self-aligning torque, the steering angle passes zero degrees and attempts to return in the opposite direction.

[0006] Such a driving assist force may adversely affect the driver's steering feel, particularly when the vehicle is traveling straight ahead.

[0007] An object of the present disclosure is to provide a motor control device that can improve the steering feel of the driver in a driving assistance mode.

[0008] 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, as a virtual spring reaction force in the equation of motion, a virtual spring reaction force obtained by adding a virtual spring reaction force corresponding to the manual steering command value to a virtual spring reaction force corresponding to the automatic steering command value.

[0009] This configuration makes it possible to improve the steering feel for the driver in the driving assistance mode.

[0010] 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.

[0011] 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 ａｓFIG. 4 is a schematic diagram showing an example of a reference EPS model. FIG. 5 is a block diagram showing the configuration of a manual steering command value calculation unit. FIG. 6 is a block diagram showing the configuration of an angle control unit. FIG. 7 is a schematic diagram showing an example of the configuration of a physical model of an electric power steering system. FIG. 8 is a block diagram showing the configuration of a disturbance torque estimator. FIG. 9 is a schematic diagram showing the configuration of a torque control unit. FIG. 10 is a flowchart showing the procedure of weight setting processing by the weight setting unit. FIG. 11 is a block diagram showing a modified example of the manual steering command value calculation unit. FIG. 12 is a block diagram showing a modified example of the motor control ECU. FIG. 13 is a flowchart showing the procedure of weight setting processing by the weight setting unit of FIG. 12.

[0012] [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, as a virtual spring reaction force in the equation of motion, a virtual spring reaction force obtained by adding a virtual spring reaction force corresponding to the manual steering command value to a virtual spring reaction force corresponding to the automatic steering command value.

[0013] This configuration makes it possible to improve the steering feel for the driver in the driving assistance mode.

[0014] In one embodiment of the present disclosure, when calculating the manual steering command value, the manual steering command value calculation unit uses, as the virtual damper reaction force in the equation of motion, a virtual damper reaction force obtained by adding a virtual damper reaction force corresponding to the differential value of the manual steering command value to a virtual damper reaction force corresponding to the differential value of the automatic steering command value.

[0015] In one embodiment of the present disclosure, the manual steering command value calculation unit performs weighting processing on a virtual spring reaction force corresponding to the automatic steering command value using the torsion bar torque or surrounding environment information.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] In the following description, the reduction ratio (gear ratio) of the reducer 19 is represented by N. The reduction ratio N is expressed as 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

[0026] 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.

[0027] 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.

[0028] 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 T ｆ etc. are included.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] In this embodiment, the host ECU 201 controls the automatic steering command value θ ａｄ In this embodiment, the automatic steering control is, for example, a control for making the vehicle travel along a target travel line (target trajectory). ａｄ is the target value of the steering angle for automatically driving the vehicle along the target driving line.

[0035] 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 in this embodiment), and the yaw deviation of the vehicle from the target driving line. ａｄThe process of setting the value is well known, so a detailed description will be omitted here.

[0036] The automatic steering control (driving assistance control) may be, for example, lane centering assist (LCA) control that assists in steering so that the vehicle travels in the center of the driving lane, or lane keeping assist (LKA) control that assists in steering so that the vehicle stays within the driving lane.

[0037] The host ECU 201 also outputs the curvature ρ of the lane on which the vehicle is traveling. If the radius of curvature of the lane on which the vehicle is traveling is represented by r, the curvature ρ is expressed as ρ = 1 / r. The larger the curvature ρ (the smaller the radius of curvature r), the greater the curvature of the curved road. The curvature ρ is an example of "surrounding environment information" in the present disclosure.

[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 Output.

[0039] 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.

[0040] Automatic steering command value θ ａｄ , curvature ρ and steering mode signal S ｍｏｄｅ is given to the motor control ECU 202 via the in-vehicle network. ｔｂ The output signals of the rotation angle sensor 23 are 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.

[0041] FIG. 2 is a block diagram for explaining the electrical configuration of the motor control ECU 202. As shown in FIG.

[0042] 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.

[0043] 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 a predetermined program. The functional processing sections include an assist torque command value setting section 51, a weight 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.

[0044] 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.

[0045] 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

[0046] 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 ｔｂThe 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.

[0047] 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 ａｓ may be set taking into consideration the vehicle speed.

[0048] The weight setting unit 52 calculates the torsion bar torque T detected by the torque sensor 12. ｔｂ and the curvature ρ given by the host ECU 201. The weight setting unit 52 sets a weight W (see FIG. 5) used in the manual steering command value calculation unit 53. Details of the weight setting unit 52 will be described later.

[0049] 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 assist torque command value T set by the assist torque command value setting unit 51. ａｓ and the automatic steering command value θ given by the host ECU 201. ａｄ and the weight W set by the weight setting unit 52 to calculate the manual steering command value θ ｍｄ The manual steering command value calculation unit 53 will be described in detail later.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] The motor torque command value T ｍ，ｃｍｄ is given to the torque control section 59.

[0056] 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.

[0057] The manual steering command value calculation unit 53 will now be described in detail.

[0058] First, the manual steering command value θ generated by the manual steering command value generating unit described in Patent Document 1 (WO 2023 / 286169)ｍｄ This section explains how to set this up.

[0059] 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. 4 is an example of the "reference model of the steering device" of the present disclosure.

[0060] 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. 4, 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.

[0061] 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 ) is expressed by the following equation (1).

[0062]

[0063] 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.

[0064] The equation of motion of the reference EPS model is expressed by the following equation (2).

[0065]

[0066] In formula (2), J ｍｄ ・d ２ θ ｃｏｌ / dt ２ is the moment of inertia acting on the lower column.

[0067] 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.

[0068] 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

[0069] 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.

[0070] FIG. 5 is a block diagram showing the configuration of the manual steering command value calculation unit 53.

[0071] 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. ｍｄis the spring constant of the virtual spring. The viscous damping coefficient c of the virtual damper ｍｄ and the spring constant k of the virtual spring ｍｄ is obtained in advance through experiments, analysis, etc.

[0072] The manual steering command value calculation unit 53 includes a reduction ratio multiplication unit 101, an addition / subtraction unit 102, an inertia division unit 103, a first integration unit 104, a second integration unit 105, a first virtual damper reaction force calculation unit 106, a differentiation unit 107, a second virtual damper reaction force calculation unit 108, a first weight multiplication unit 109, a first addition unit 110, a first virtual spring reaction force calculation unit 111, a second virtual spring reaction force calculation unit 112, a second weight multiplication unit 113, and a second addition unit 114.

[0073] The reduction ratio multiplication unit 101 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 Convert to.

[0074] The addition / subtraction unit 102 receives the torsion bar torque T ｔｂ and the assist torque command value N·T for the output shaft 9. ａｓ and the virtual damper reaction force (c ｍｄ ・dθ ｍｄ / dt+W・c ｍｄ ・dθ ａｄ / dt) and the virtual spring reaction force (k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ ) and enter.

[0075] The addition / subtraction unit 102 calculates the torsion bar torque T ｔｂ Assist torque command value N·T for output shaft 9 ａｓ and calculate the virtual damper reaction force (c ｍｄ ・dθ ｍｄ / dt+W・c ｍｄ ・dθ ａｄ / dt) and virtual spring reaction force (k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θａｄ ) on the left side of the 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 -(k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ )-(c ｍｄ ・dθ ｍｄ / dt+W・c ｍｄ ・dθ ａｄ / dt) is calculated.

[0076] The inertia division unit 103 divides the moment of inertia J calculated by the addition / subtraction unit 102. 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.

[0077] The first integration unit 104 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.

[0078] The second integration unit 105 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.

[0079] The first virtual damper reaction force calculation unit 106 calculates the manual steering command value θ ｍｄThe first derivative dθ ｍｄ / dt, viscous damping coefficient c ｍｄ By multiplying by ｍｄ ・dθ ｍｄ / dt is calculated.

[0080] The differentiation unit 107 calculates the automatic steering command value θ ａｄ The second virtual damper reaction force calculation unit 108 differentiates the automatic steering command value θ calculated by the differentiation unit 107. ａｄ The differential value dθ ａｄ / dt, viscous damping coefficient c ｍｄ By multiplying this, the second virtual damper reaction force c ｍｄ ・dθ ａｄ / dt is calculated.

[0081] The first weight multiplier 109 calculates the second virtual damper reaction force c ｍｄ ・dθ ａｄ / dt is multiplied by a weight W (0≦W≦1) set by the weight setting unit 52 .

[0082] The first adder 110 calculates the first virtual damper reaction force c ｍｄ ・dθ ｍｄ / dt, the second virtual damper reaction force W c after multiplication by the weight ｍｄ ・dθ ａｄ By adding / dt, the virtual damper reaction force (c ｍｄ ・dθ ｍｄ / dt+W・c ｍｄ ・dθ ａｄ / dt) is calculated. ｍｄ ・dθ ｍｄ / dt+W・c ｍｄ ・dθ ａｄ / dt) is fed back to the adding / subtracting unit 102.

[0083] The first virtual spring reaction force calculation unit 111 calculates the manual steering command value θ ｍｄ , spring constant k ｍｄ By multiplying the first virtual spring reaction force k ｍｄ ・θ ｍｄ Calculate the following.

[0084] The second virtual spring reaction force calculation unit 112 calculates the automatic steering command value θ ａｄ , spring constant kｍｄ By multiplying by , the second virtual spring reaction force k ｍｄ ・θ ａｄ Calculate the following.

[0085] The second weight multiplication unit 113 calculates the second virtual spring reaction force k ｍｄ ・θ ａｄ is multiplied by a weight W (0≦W≦1) set by the weight setting unit 52 .

[0086] The second adder 114 calculates the first virtual spring reaction force k ｍｄ ・θ ｍｄ , the second virtual spring reaction force W·k after weight multiplication ｍｄ ・θ ａｄ By adding ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ ) is calculated. ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ ) is fed back to the addition / subtraction section 102.

[0087] That is, the manual steering command value calculation unit 53 calculates the manual steering command value θ based on the equation of motion of the following equation (3). ｍｄ Calculate the following.

[0088]

[0089] In formula (3), (k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ ) is the virtual spring reaction force. ｍｄ ・dθ ｍｄ / dt+c ｍｄ ・dθ ａｄ / dt) is the virtual damper reaction force.

[0090] That is, the manual steering command value calculation unit 53 calculates the virtual spring reaction force k ｍｄ ・θ ｃｏｌ and virtual damper reaction force c ｍｄ ・dθ ｃｏｌ / dt, respectively, (k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ) and (c ｍｄ ・dθ ｍｄ / dt+W・c ｍｄ ・dθ ａｄ / dt) to obtain the manual steering command value θ ｍｄ Calculate the following.

[0091] The manual steering command value calculation unit 53 has such a configuration, and therefore can adjust the ability of the vehicle to follow the target driving line by changing the weight W. The reason for this will be described later.

[0092] FIG. 6 is a block diagram showing the configuration of the angle control unit 55.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] In this embodiment, the actual steering angle θ ｃis 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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 ｃｍｄｌBy differentiating twice, the target angular acceleration d ２ θ ｃｍｄｌ / dt ２ Calculate the following.

[0101] 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 ２ The inertia J can be calculated from, for example, a physical model (see FIG. 7) 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.

[0102] The torque adder 65 calculates the feedback control torque T ｆｂ The feedforward control torque T ｆｆ By adding ｆｂ +T ｆｆ ) is calculated.

[0103] 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.

[0104] 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.

[0105] 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 -^T ｌｃ ) is calculated. As a result, the integrated torque command value T ｃｏ (torque command value for the output shaft 9) is obtained.

[0106] 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).

[0107] 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. 7 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.

[0108] 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.

[0109] 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.

[0110] 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).

[0111]

[0112] 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.

[0113] The state equation for the physical model 300 in FIG. 7 is expressed by the following equation (5).

[0114]

[0115] 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.

[0116] 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).

[0117]

[0118] In the formula (6), x ｅ is the state variable vector of the extended system, and is expressed by the following equation (7).

[0119]

[0120] 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.

[0121] 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.

[0122]

[0123] 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).

[0124]

[0125] In equation (9), ^θ ｃ is θ ｃ is an estimate of ^T ｌｃ is T ｌｃ is an estimate of

[0126] The disturbance torque estimation unit 64 calculates the state variable vector ^x based on the equation (8). ｅ Calculate the following.

[0127] FIG. 8 is a block diagram showing the configuration of the disturbance torque estimating section 64.

[0128] 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.

[0129] The output shaft torque command value N·T calculated by the reduction ratio multiplication unit 68 (see FIG. 6) ｍ，ｃｍｄ is given to the input vector input unit 81. The input vector input unit 81 receives the input vector u １ Output.

[0130] 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.

[0131] 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.

[0132] The first adder 83 calculates the actual steering angle θ calculated by the second reduction ratio divider 70 (see FIG. 6). 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).

[0133] 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.

[0134] Unlike the above-mentioned extended state observer, a general disturbance observer is composed 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 described above. Therefore, the inverse model of the plant is expressed by the following equation (10).

[0135]

[0136] 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.

[0137] The disturbance torque estimating unit 64 may be a general disturbance observer that is configured from an inverse model of the plant and a low-pass filter.

[0138] FIG. 9 is a schematic diagram showing the configuration of the torque control unit 59.

[0139] 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 .

[0140] 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.

[0141] 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.

[0142] 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.

[0143] The weight setting process executed by the weight setting unit 52 will be described below.

[0144] First, the change in the ability of the vehicle to follow the target driving line depending on the magnitude of the weight W of the manual steering command value calculation unit 53 will be described.

[0145] As described above, the manual steering command value calculation unit 53 calculates the virtual spring reaction force k ｍｄ ・θ ｃｏｌ and virtual damper reaction force c ｍｄ ・dθ ｃｏｌ / dt, respectively, (k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ ) and (c ｍｄ ・dθ ｍｄ / dt+W・c ｍｄ ・dθ ａｄ / dt) to obtain the manual steering command value θ ｍｄ is calculated.

[0146] 2 and 6, in the cooperative steering mode, for example, 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 θｃｍｄ Assuming that the system follows the ｍｄ = θ ｃ -θ ａｄ The following relationship holds.

[0147] In this case, the first virtual spring reaction force k in the formula (3) ｍｄ ・θ ｍｄ (Manual steering command value θ ｍｄ The virtual spring reaction force corresponding to the spring force is expressed by the following equation (11).

[0148]

[0149] Similarly, the first virtual damper reaction force c in the above equation (3) ｍｄ ・dθ ｍｄ / dt (manual steering command value θ ｍｄ The virtual damper reaction force corresponding to the damper force is expressed by the following equation (12).

[0150]

[0151] That is, the first virtual spring reaction force k ｍｄ ・θ ｍｄ is the actual steering angle θ ｃ Actual steering angle component k according to ｍｄ ・θ ｃ and the automatic steering command value θ ａｄ Automatic steering component -k according to ｍｄ ・θ ａｄ Similarly, the first virtual damper reaction force c ｍｄ ・dθ ｍｄ / dt is the actual steering angle θ ｃ The actual steering angle component c corresponding 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.

[0152] Assuming that equations (11) and (12) hold, equation (3) can be expressed as equation (13) below.

[0153]

[0154] When W=0, the above-mentioned equation (13) is equivalent to the above-mentioned equation (2). Therefore, in the cooperative steering mode, as in the comparison method, the automatic steering command value θ ａｄ In other words, the vehicle's ability to follow the target driving line is improved.

[0155] On the other hand, when W=1, the above equation (13) becomes the following equation (14).

[0156]

[0157] In other words, when W = 1, the virtual spring reaction force is k ｍｄ ・θ ｃ and the automatic steering command value θ ａｄ Automatic steering component -k according to ｍｄ ・θ ａｄ Similarly, when W = 1, the virtual damper reaction force is c 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 becomes zero. In other words, when W=1, the automatic steering command value θ ａｄ In other words, the vehicle is no longer able to follow the target driving line.

[0158] When W is in the range of 0<W<1, cooperative control is performed in which the vehicle's ability to follow the target driving line is weakened from the basic characteristics where W = 0. In this case, the larger W is, the weaker the vehicle's ability to follow the target driving line becomes.

[0159] 10 is a flowchart showing the procedure of the weight setting process by the weight setting unit 52. The process in FIG. 10 is repeatedly executed at predetermined calculation intervals. It is assumed that the initial value of W is 0.

[0160] The weight setting unit 52 first calculates the torsion bar torque T ｔｂis equal to or less than a predetermined threshold A (A>0) (step S1). The threshold A is a threshold for determining whether the driver is gripping the steering wheel (hands-on state) or not (hands-off state).

[0161] Torsion bar torque T ｔｂ If W is equal to or less than the threshold value A (step S1: YES), the weight setting unit 52 determines that the vehicle is in a hands-off state and sets the weight W to zero (step S2). In other words, when the vehicle is in a hands-off state, W is set so that the vehicle's ability to follow the target driving line is increased. The reason for this is that if the vehicle's ability to follow the target driving line is weakened when the vehicle is in a hands-off state, the vehicle will not be able to follow the target driving line.

[0162] In step S1, the torsion bar torque T ｔｂ is determined to be equal to or less than threshold value A, W may be set to a value equal to or greater than zero that is close to zero. After performing the process of step S2, the weight setting unit 52 ends the process for the current calculation cycle.

[0163] In step S1, a sensor for determining whether or not the driver has made contact may be attached to the steering wheel to determine whether or not the contact pressure or contact time is equal to or less than a predetermined threshold value B (B>0).

[0164] In step S1, the torsion bar torque T ｔｂ If it is determined that the curvature ρ is greater than the threshold A (step S1: NO), the weight setting unit 52 determines that the vehicle is in a hands-on state and determines whether the driving lane is a straight road (step S3). In this embodiment, if the curvature ρ is equal to or less than a predetermined threshold C (C>0), the weight setting unit 52 determines that the driving lane is a straight road, and if the curvature ρ is greater than the threshold C, the weight setting unit 52 determines that the driving lane is a curved road.

[0165] If the driving lane is a straight road (step S3: YES), the weight setting unit 52 sets W to a predetermined value α (0<α<1) within a range greater than 0 and less than 1 (step S4). That is, in this embodiment, the weight setting unit 52 sets a value greater than the weight set in step S2 as α. In this embodiment, α is set to 0.7. This weakens the vehicle's ability to follow the target driving line compared to when W=0. In other words, the manual steering command value θ is calculated by the comparison method. ｍｄ Compared with generating the automatic steering command value θ ａｄ This makes it possible to improve the steering feel of the driver in the driving assistance mode.

[0166] If it is determined in step S3 that the driving lane is a straight road, it is preferable to set W to a predetermined value α (0<α<1) in the range greater than 0 and less than 1, but W may also be set to 1. After performing the process of step S4, the weight setting unit 52 ends the process for the current calculation cycle.

[0167] If it is determined in step S3 that the driving lane is a curved road (step S3: NO), the weight setting unit 52 sets W to zero (step S5). That is, in this embodiment, the weight setting unit 52 sets a weight that is smaller than the weight set in step S4. In other words, when the driving lane is a curved road, W is set so that the vehicle's ability to follow the target driving line is improved. The reason for this is that on a curved road, centrifugal force acting on the vehicle makes it easier for the vehicle to deviate from the target driving line.

[0168] If it is determined in step S3 that the driving lane is a curved road, W may be set to a value equal to or greater than zero but close to zero. Also, if it is determined in step S3 that the driving lane is a curved road, W may be set to a value equal to or greater than the weight set in step S4. After performing the process of step S5, the weight setting unit 52 ends the process for the current calculation cycle.

[0169] The operation of this embodiment will be described below with reference to FIG.

[0170] In this embodiment, the manual steering mode is when 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.

[0171] 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.

[0172] In the above embodiment, the integrated angle command value θ ｃｍｄ and 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.

[0173] 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.

[0174] 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.

[0175] 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 ｍｄ ・θ ｃｏｌ and virtual damper reaction force c ｍｄ ・dθ ｃｏｌ / dt, respectively, (k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ ) and (c ｍｄ ・dθ ｍｄ / dt+W・c ｍｄ ・dθ ａｄ / dt) to obtain the manual steering command value θ ｍｄ is calculated.

[0176] This makes it possible to adjust the vehicle's ability to follow the target driving line by changing the weight W. This makes it possible to improve the steering feel for the driver in the driving assistance mode.

[0177] In the above embodiment, the second virtual damper reaction force c ｍｄ ・dθ ａｄ / dt is multiplied by a weight W, and the second virtual spring reaction force k ｍｄ ・θ ａ The weight W multiplied by the second virtual damper reaction force c is the same. ｍｄ ・dθ ａｄ / dt is multiplied by a weight W, and the second virtual spring reaction force k ｍｄ ・θ ａ may be different from the weight W by which it is multiplied.

[0178] In the above embodiment, the virtual spring reaction force k ｍｄ ・θ ｃｏｌ As such, (k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ ) and the virtual damper reaction force c ｍｄ ・dθ ｃｏｌ / dt, and the virtual damper reaction force (c ｍｄ ・dθ ｍｄ / dt+W・c ｍｄ ・dθ ａｄ However, the virtual spring reaction force k in the above formula (2) ｍｄ ・θ ｃｏｌ As such, (k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ ) is used, but the virtual damper reaction force cｍｄ ・dθ ｃｏｌ / dt, c ｍｄ ・dθ ｍｄ / dt may also be used.

[0179] In this case, the manual steering command value calculation unit has a configuration as shown in Fig. 11. In Fig. 11, parts corresponding to those in Fig. 5 are denoted by the same reference numerals as in Fig. 5.

[0180] The manual steering command value calculation unit 53A in Fig. 11 does not include the differentiation unit 107, the second virtual damper reaction force calculation unit 108, the first weight multiplication unit 109, and the first addition unit 110 of the manual steering command value calculation unit 53 in Fig. 5. The first virtual damper reaction force c calculated by the first virtual damper reaction force calculation unit 106 ｍｄ ・dθ ｍｄ / dt is fed back to the adding / subtracting unit 102 as a virtual damper reaction force.

[0181] In this case, 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 (15). ｍｄ Calculate the following.

[0182]

[0183] In equation (15), k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ is the virtual spring reaction force. ｍｄ ・dθ ｍｄ / dt is the virtual damper reaction force.

[0184] That is, the manual steering command value calculation unit 53A calculates the virtual spring reaction force k ｍｄ ・θ ｍｄ and virtual damper reaction force c ｍｄ ・dθ ｃｏｌ / dt, respectively, (k ｍｄ ・θ ｍｄ +W·k ｍｄ ・θ ａｄ ) and c ｍｄ ・dθ ｍｄ / dt, the manual steering command value θ ｍｄ Calculate the following.

[0185] Fig. 12 is a block diagram showing a 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. 2.

[0186] The motor control ECU 202B in FIG. 12 differs from the motor control ECU 202 in FIG. 2 in the following points (1), (2), and (3): (1) The first switch 56, the second switch 57, and the adder 58 in FIG. 2 are not provided. (2) The weight setting unit 52B does not include the torsion bar torque T detected by the torque sensor 12. ｔｂ In addition to the curvature ρ given by the host ECU 201, the steering mode signal S ｍｏｄｅ (3) The operation of the weight setting unit 52B is different from the operation of the weight setting unit 52 in FIG.

[0187] In this modification, the integrated motor torque command value T ｃｏｍ is the motor torque command value T ｍ，ｃｍｄ Therefore, not only when the steering mode is the cooperative steering mode, but also when the steering mode is the manual steering mode, the integrated motor torque command value T ｃｏｍ (Integrated angle command value θ ｃｍｄ ) and the electric motor 18 is controlled based on the automatic steering command value θ ａｄ is set to zero.

[0188] 13 is a flowchart showing the procedure of the weight setting process by the weight setting unit 52 B. In FIG. 13, steps corresponding to those in FIG. 10 are denoted by the same step numbers as in FIG.

[0189] 13 is repeatedly executed at predetermined calculation intervals. The initial value of W is assumed to be 0.

[0190] The weight setting unit 52B first calculates the steering mode signal S ｍｏｄｅ Based on this, it is determined whether the steering mode is the manual steering mode (step S11).

[0191] If the steering mode is the manual steering mode (step S11: YES), the weight setting unit 52B sets the weight W to 1 (step S12). In other words, when the steering mode is the manual steering mode, there is no need to make the vehicle follow the target driving line, so W is set so that the vehicle's ability to follow the target driving line is low. After performing the processing of step S12, the weight setting unit 52B ends the processing for the current calculation cycle.

[0192] In step S11, when it is determined that the steering mode is the cooperative steering mode (step S11: NO), the weight setting unit 52B proceeds to step S1. Then, the weight setting unit 52B performs the processes from step S1 onward described with reference to FIG.

[0193] Although the embodiments and modifications of the present disclosure have been described above, the present disclosure can also be embodied in other forms.

[0194] In the above-described embodiment and modified example, the weight setting unit 52, 52B is configured to set the torsion bar torque T ｔｂ The weight W is set based on the curvature (an example of the surrounding environment information) ρ. However, the weight setting units 52 and 52B do not set the torsion bar torque T ｔｂ The weight W may be set based only on the curvature ρ (an example of the surrounding environment information) or the weight W may be set based only on the curvature ρ (an example of the surrounding environment information). ｔｂ and curvature ρ, at least the torsion bar torque T ｔｂ It is preferable to set the weights based on the following:

[0195] Torsion bar torque T ｔｂ 10 and 13, steps S3 and S5 are omitted. ｔｂ If it is determined that the weight is greater than A, the weight setting units 52 and 52B proceed to step S4.

[0196] When the weight W is set based only on the curvature ρ, steps S1 and S2 are omitted in Fig. 10 and Fig. 13. That is, in Fig. 10, the weight setting unit 52 first performs the process of step S3. In Fig. 13, if it is determined in step S11 that the steering mode is the cooperative steering mode, the weight setting unit 52B proceeds to step S3.

[0197] In the above embodiment, the spring constant k in the above equations (3) and (15) ｍｄ However, the spring constant k in the above equations (3) and (15) is ｍｄ is the disturbance torque estimated value ^T calculated by the disturbance torque estimating unit 64 (see FIG. 6). 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 (16).

[0198]

[0199] In the above-described embodiment, the viscous damping coefficient c ｍｄ is obtained in advance through experiments, analysis, etc.

[0200] However, the viscous damping coefficient c in the above equations (3) and (15) 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 (17):

[0201]

[0202] In the above embodiment, the angle control unit 55 (see FIG. 6) 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.

[0203] 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.

[0204] 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.

[0205] This application corresponds to Patent Application No. 2023-098544 filed with the Japan Patent Office on June 15, 2023, the entire disclosures of which are incorporated herein by reference.

[0206] 1... electric power steering device, 3... steered wheels, 4... steering mechanism, 18... electric motor, 51... assist torque command value setting section, 52, 52B... weight setting section, 53, 53A... manual steering command value calculation section, 54... integrated angle command value calculation section, 55... angle control section, 56... first switch, 57... second switch, 58... addition section, 59... torque control section, 201... host ECU, 202, 202A... motor control ECU

Claims

1. A motor control device for controlling the drive of an electric motor of a steering device, comprising: 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 drives and 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 using, as a virtual spring reaction force in the equation of motion, a virtual spring reaction force obtained by adding a virtual spring reaction force corresponding to the manual steering command value to a virtual spring reaction force corresponding to the automatic steering command value.

2. A motor control device as described in claim 1, wherein when calculating the manual steering command value, the manual steering command value calculation unit uses a virtual damper reaction force in the equation of motion that is a virtual damper reaction force obtained by adding a virtual damper reaction force corresponding to the differential value of the automatic steering command value to a virtual damper reaction force corresponding to the differential value of the manual steering command value.

3. The motor control device according to claim 1, wherein the manual steering command value calculation unit performs weighting processing on a virtual spring reaction force corresponding to the automatic steering command value using the torsion bar torque or surrounding environment information.