Motor control device

Abstract

This motor control device comprises: an assist torque command value generation unit which uses a steering torque to generate an assist torque command value; a manual steering command value generation unit which uses the steering torque and the assist torque command value to generate a manual steering command value; an integrated angle command value calculation unit which adds the manual steering command value to an automatic steering command value and calculates an integrated angle command value; and a switching unit which switches, in response to a switching signal, between first control for controlling an electric motor on the basis of the assist torque command value and second control for controlling the electric motor on the basis of the integrated angle command value.

Description

[Technical Field]

[0001] This invention relates to a control device for an electric motor used for steering angle control. [Background technology]

[0002] Patent Document 1 discloses a motor control device that performs angle feedback control of an electric motor based on an integrated angle command value obtained by adding an automatic steering command value to a manual steering command value. Patent Document 1 also discloses a method for calculating the integrated angle command value by adding the automatic steering command value after a first weighting process to the manual steering command value after a second weighting process. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-194059 [Overview of the project] [Problems that the invention aims to solve]

[0004] In the motor control device described in Patent Document 1, the disturbance torque estimation unit (disturbance observer) estimates the disturbance torque, including the road surface load torque, steering angle, etc. The basic torque command value is calculated by performing proportional derivative operations on the deviation between the integrated angle command value and the steering angle estimate value calculated by the disturbance torque estimation unit. The steering torque command value is calculated by subtracting the disturbance torque estimate value calculated by the disturbance torque estimation unit from the basic torque command value. This gives a steering torque command value from which the disturbance torque (road surface load torque) has been removed from the basic torque command value. Then, the motor torque command value is calculated by dividing the steering torque command value by the reduction ratio.

[0005] In the motor control device described in Patent Document 1, disturbance torque (road surface load torque) is removed from the basic torque command value. Instead, the manual steering command value generation unit generates a manual steering command value that takes into account a virtual road surface load. In the motor control device described in Patent Document 1, it is possible to control the electric motor based on the manual steering command value generated by the manual steering command value generation unit. However, since the manual steering command value is generated taking into account a virtual road surface load rather than the actual road surface load, the driver cannot perceive the actual road surface conditions, such as whether the road surface is slippery or not. Therefore, the driver may feel an unnatural sensation when steering.

[0006] The objective of this invention is to provide a motor control device that can control an electric motor based on an integrated angle command value obtained by adding a manual steering command value to an automatic steering command value, and that enables motor control in a way that allows the driver to feel the actual road surface conditions. [Means for solving the problem]

[0007] One embodiment of the present invention provides a motor control device for driving and controlling an electric motor for steering angle control, comprising: an assist torque command value generation unit that generates an assist torque command value using steering torque; a manual steering command value generation unit that generates a manual steering command value using the steering 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 an automatic steering command value; and a switching unit that switches between a first control that controls the electric motor based on the assist torque command value and a second control that controls the electric motor based on the integrated angle command value, based on a switching signal.

[0008] In this configuration, a motor control device capable of controlling an electric motor based on an integrated angle command value obtained by adding a manual steering command value to an automatic steering command value enables motor control that allows the driver to feel the actual road surface conditions.

[0009] The above-mentioned, or further, objectives, features, and effects of the present invention will be made clearer by the following description of embodiments with reference to the accompanying drawings. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram showing the general configuration of an electric power steering system to which a motor control device according to one embodiment of the present invention is applied. [Figure 2] Figure 2 is a block diagram illustrating the electrical configuration of the ECU for motor control. [Figure 3] Figure 3 is a graph showing an example of setting the assist torque command value Tas in relation to the steering torque Td. [Figure 4] Figure 4 is a schematic diagram showing an example of a reference EPS model used in the manual steering command value generation unit. [Figure 5] Figure 5 is a block diagram showing the configuration of the angle control unit. [Figure 6] Figure 6 is a schematic diagram showing an example of the configuration of a physical model of an electric power steering system. [Figure 7] Figure 7 is a block diagram showing the configuration of the disturbance torque estimation unit. [Figure 8] Figure 8 is a schematic diagram showing the configuration of the torque control unit. [Figure 9] Figure 9 is a graph showing an example of the settings for the first weight W1, which is set when each mode setting signal S1, S2, and S3 is input. [Figure 10] Figure 10 is a graph showing an example of the setting of the second weight W2 when each mode setting signal S1, S2, and S3 is input. [Figure 11] Figure 11 is a graph showing an example of the setting of the third weight W3 when each mode setting signal S1, S2, and S3 is input. [Figure 12] Figure 12 is a schematic diagram illustrating an example where the higher-level ECU switches steering modes according to the vehicle's driving conditions. [Figure 13] Figure 13 is a block diagram illustrating a modified example of an ECU for motor control. [Modes for carrying out the invention]

[0011] [Description of Embodiments of the Invention] One embodiment of the present invention provides a motor control device for driving and controlling an electric motor for steering angle control, comprising: an assist torque command value generation unit that generates an assist torque command value using steering torque; a manual steering command value generation unit that generates a manual steering command value using the steering 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 an automatic steering command value; and a switching unit that switches between a first control that controls the electric motor based on the assist torque command value and a second control that controls the electric motor based on the integrated angle command value, based on a switching signal.

[0012] In this configuration, a motor control device capable of controlling an electric motor based on an integrated angle command value obtained by adding a manual steering command value to an automatic steering command value enables motor control that allows the driver to feel the actual road surface load.

[0013] In one embodiment of the present invention, the switching unit includes a first weighting unit that performs a first weighting process on the assist torque command value based on the switching signal, a second weighting unit that performs a second weighting process on the integrated torque command value corresponding to the integrated angle command value based on the switching signal, and a motor torque command value calculation unit that calculates a motor torque command value based on the assist torque command value after the first weighting process and the integrated torque command value after the second weighting process.

[0014] In one embodiment of the present invention, the switching unit is configured to switch between the first control, the second control, and the third control which controls the electric motor based on the automatic steering command value, based on the switching signal.

[0015] In one embodiment of the present invention, the switching unit includes a first weighting unit that performs a first weighting process on the assist torque command value based on the switching signal, a second weighting unit that performs a second weighting process on the integrated torque command value corresponding to the integrated angle command value based on the switching signal, a third weighting unit that performs a third weighting process on the manual steering command value based on the switching signal, and a motor torque command value calculation unit that calculates a motor torque command value based on the assist torque command value after the first weighting process and the integrated torque command value after the second weighting process, wherein the integrated angle command value calculation unit is configured to calculate the integrated angle command value by adding the manual steering command value after the third weighting process to the automatic steering command value.

[0016] In one embodiment of the present invention, the switching unit includes an addition unit for calculating a motor torque command value by adding the assist torque command value generated by the assist torque command value generation unit and an integrated torque command value corresponding to the integrated angle command value calculated by the integrated angle command value calculation unit; a first switch provided between the assist torque command value generation unit and the addition unit, which is turned on and off based on the switching signal; and a second switch provided between the integrated angle command value calculation unit and the addition unit, which is turned on and off based on the switching signal.

[0017] In one embodiment of the present invention, the switching unit includes an addition unit for calculating a motor torque command value by adding the assist torque command value generated by the assist torque command value generation unit and an integrated torque command value corresponding to the integrated angle command value calculated by the integrated angle command value calculation unit; a first switch provided between the assist torque command value generation unit and the addition unit, which is turned on and off based on the switching signal; a second switch provided between the integrated angle command value calculation unit and the addition unit, which is turned on and off based on the switching signal; and a third switch provided between the manual steering command value generation unit and the integrated angle command value calculation unit, which is turned on and off based on the switching signal.

[0018] In one embodiment of the present invention, the control unit for performing the second control includes an angle control unit that performs angle control based on the integrated angle command value, the angle control unit includes a basic torque command value calculation unit that calculates a basic torque command value based on the integrated angle command value, a disturbance torque estimation unit that estimates disturbance torques other than the motor torque of the electric motor that act on the object driven by the electric motor, and a disturbance torque compensation unit that corrects the basic torque command value with the disturbance torque.

[0019] In one embodiment of the present invention, the disturbance torque estimation unit is configured to estimate the disturbance torque and the rotation angle of the driven object using the motor torque command value and the rotation angle of the electric motor, and the basic torque command value calculation unit includes an angle deviation calculation unit that calculates an angle deviation which is the difference between the integrated angle command value and the rotation angle of the driven object, and a feedback calculation unit that calculates the basic torque command value by performing a predetermined feedback calculation on the angle deviation.

[0020] In one embodiment of the present invention, the manual steering command value generation unit is configured to generate the manual steering command value using the assist torque command value, the steering torque, and a spring constant and viscous damping coefficient for generating the road surface load torque.

[0021] [Detailed description of embodiments of the present invention] Hereinafter, embodiments of this invention will be described in detail with reference to the accompanying drawings.

[0022] Figure 1 is a schematic diagram showing the general configuration of an electric power steering system to which a motor control device according to one embodiment of the present invention is applied.

[0023] The electric power steering system 1 comprises a steering wheel (handle) 2 as a steering member for steering the vehicle, a steering mechanism 4 that steers the steering wheels 3 in conjunction with the rotation of the steering wheel 2, and a steering assist mechanism 5 for assisting the driver's steering. The steering wheel 2 and the steering mechanism 4 are mechanically connected via a steering shaft 6 and an intermediate shaft 7.

[0024] 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 to each other via a torsion bar 10 so as to be rotatable relative to each other.

[0025] A torque sensor 12 is positioned near the torsion bar 10. The torque sensor 12 measures the steering torque (torsion bar torque) T applied to the steering wheel 2 based on the relative rotational displacement of the input shaft 8 and the output shaft 9. d The steering torque T detected by the torque sensor 12 is detected. In this embodiment, the steering torque T is detected by the torque sensor 12. d For example, the torque for steering to the left is detected as a positive value, and the torque for steering to the right is detected as a negative value, and the larger the absolute value, the greater the steering torque T. d Assume that the size of will increase.

[0026] The steering mechanism 4 consists of a rack and pinion mechanism including a pinion shaft 13 and a rack shaft 14 as the steering axis. Each end of the rack shaft 14 is connected to a steering wheel 3 via tie rods 15 and knuckle arms (not shown). The pinion shaft 13 is connected to an 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.

[0027] The rack shaft 14 extends linearly along the left-right direction of the vehicle. A rack 17 that meshes with a pinion 16 is formed in the axial middle portion of the rack shaft 14. The pinion 16 and 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 steering wheels 3 can be steered.

[0028] 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. This causes the steering wheel 3 to turn.

[0029] The steering assist mechanism 5 includes an electric motor 18 for generating steering assist force (assist torque) and a reduction gear 19 for amplifying the output torque of the electric motor 18 and transmitting it to the steering mechanism 4. The reduction gear 19 consists of a worm gear mechanism including a worm gear 20 and a worm wheel 21 that meshes with the worm gear 20. The reduction gear 19 is housed in a gear housing 22 which serves as a transmission mechanism housing.

[0030] In the following, the reduction ratio (gear ratio) of the reducer 19 may be represented by N. The reduction ratio N is 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 given value. wg The ratio (θ) wg / θ ww ) is defined as.

[0031] The worm gear 20 is rotationally driven by the electric motor 18. The worm wheel 21 is also integrally rotatably connected to the output shaft 9.

[0032] When the worm gear 20 is rotationally driven by the electric motor 18, the worm wheel 21 is rotationally driven, motor torque is applied to the steering shaft 6, and the steering shaft 6 (output shaft 9) rotates. Then, the rotation of the steering shaft 6 is transmitted to the pinion shaft 13 via the intermediate shaft 7. The rotation of the pinion shaft 13 is converted into the axial movement of the rack shaft 14. Thereby, the steered wheels 3 are steered. That is, by rotationally driving the worm gear 20 by the electric motor 18, it becomes possible to assist steering by the electric motor 18 and to steer the steered wheels 3. 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.

[0033] As the torque applied to the output shaft 9 (an example of the drive target of the electric motor 18), there are the motor torque by the electric motor 18 and the disturbance torque T other than the motor torque. lc And there is a disturbance torque T other than the motor torque. lc The disturbance torque T other than the motor torque d includes the steering torque T, rl the road surface load torque (road surface reaction torque) T, f the frictional torque T, and the like.

[0034] The steering torque T d is the torque applied to the output shaft 9 from the steering wheel 2 side due to the force applied to the steering wheel 2 by the driver, the force generated by the steering inertia, and the like.

[0035] The road surface load torque T rl is the torque applied to the output shaft 9 from the steered wheel 3 side via the rack shaft 14 due to the self-aligning torque generated in the tire, the force generated by the suspension and the tire wheel alignment, the frictional force of the rack and pinion mechanism, and the like.

[0036] The vehicle is equipped with a CCD (Charge Coupled Device) camera 25 that photographs the road ahead in the direction of travel, a GPS (Global Positioning System) 26 for detecting the vehicle's position, a radar 27 for detecting road shape and obstacles, and a map information memory 28 that stores map information. The vehicle is also equipped with three mode switches 31, 32, and 33 for manually switching steering modes.

[0037] As will be described later, steering modes include manual steering mode, where steering is performed by manual driving; automatic steering mode, where steering is performed by automatic driving; and cooperative steering mode, where steering is possible based on both manual and automatic driving. More specific definitions of these steering modes will be described later.

[0038] The CCD camera 25, GPS 26, radar 27, and map information memory 28 are connected to a higher-level ECU (Electronic Control Unit) 201 for performing driver assistance control and autonomous driving control. Based on the information obtained from the CCD camera 25, GPS 26, and radar 27, as well as map information, the higher-level ECU 201 performs surrounding environment recognition, vehicle position estimation, route planning, etc., and determines control target values ​​for steering and drive actuators.

[0039] In this embodiment, the higher-level ECU 201 sets the automatic steering command value θ for automatic steering. adac Set the following. In this embodiment, the automatic steering control is, for example, a control to drive the vehicle along a target trajectory. Automatic steering command value θ adac This is the target value of the steering angle for automatically driving the vehicle along a target trajectory. Such an automatic steering command value θ adac The process for setting this is well known, so a detailed explanation will be omitted here. Note that the automatic steering control (driving assistance control) may be, for example, lane keeping assist (LKA) control to keep the vehicle within its lane.

[0040] Furthermore, the higher-level ECU 201 generates mode setting signals S1, S2, and S3 in response to the operation of mode switches 31, 32, and 33. Specifically, when the first mode switch 31 is turned on by the driver, the higher-level ECU 201 outputs a manual steering setting signal S1 to set the steering mode to manual steering mode. When the second mode switch 32 is turned on by the driver, the higher-level ECU 201 outputs an automatic steering mode setting signal S2 to set the steering mode to automatic steering mode. When the third mode switch 33 is turned on by the driver, the higher-level ECU 201 outputs a cooperative steering mode setting signal S3 to set the steering mode to cooperative steering mode. Mode setting signals S1, S2, and S3 are examples of "switching signals" in the present invention.

[0041] The automatic steering command value θ is set by the higher-level ECU201. adac The mode setting signals S1, S2, and S3 are provided to the motor control ECU 202 via the in-vehicle network. The steering torque T detected by the torque sensor 12 d The output signal from 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 higher-level ECU 201.

[0042] Figure 2 is a block diagram illustrating the electrical configuration of the ECU202 for motor control.

[0043] The motor control ECU 202 includes a microcomputer 50, a drive circuit (inverter circuit) 41 controlled by the microcomputer 50 that supplies power to the electric motor 18, and a current detection circuit 42 for detecting the current (hereinafter referred to as "motor current I") flowing through the electric motor 18.

[0044] The microcomputer 50 is equipped with a CPU and memory (ROM, RAM, non-volatile memory, etc.) and functions as multiple function processing units by executing a predetermined program. These multiple function processing units include an assist torque command value setting unit 51, a manual steering command value generation unit 52, an integrated angle command value calculation unit 53, an angle control unit 54, a torque control unit (current control unit) 55, a first weighting unit 56, a second weighting unit 57, a third weighting unit 58, and an addition unit 59. In this embodiment, the first weighting unit 56, the second weighting unit 57, and the addition unit 59 are examples of "switching units" in the present invention. The addition unit 59 is an example of a "motor torque command value calculation unit" in the present invention.

[0045] The assist torque command value setting unit 51 sets the assist torque command value T, which is the target value of the assist torque required for manual operation. as The assist torque command value setting unit 51 sets the steering torque T detected by the torque sensor 12. d Based on this, the assist torque command value T as Set the steering torque T. d Assist torque command value T as An example of the settings is shown in Figure 3.

[0046] Assist torque command value T as This value is positive when the electric motor 18 should generate steering assist force for leftward steering, and negative when the electric motor 18 should generate steering assist force for rightward steering. Assist Torque Command Value T as is steering torque T d For positive values ​​of T, it takes a positive value, and the steering torque T d For negative values, it takes the negative value. And the assist torque command value T as is steering torque T d The larger the absolute value of [the variable], the more it is set to increase its absolute value.

[0047] The assist torque command value setting unit 51 sets the steering torque T d By multiplying by a preset constant, the assist torque command value T is calculated. as You may perform the calculation.

[0048] The first weighting unit 56 sets the assist torque command value T set by the assist torque command value setting unit 51 in accordance with the input mode setting signal. as The first weighting process is performed on the following. Specifically, when any of the mode setting signals S1, S2, or S3 is input to the first weighting unit 56, it first sets the first weight W1 according to the current steering mode and the input mode setting signal. Next, the first weighting unit 56 sets the assist torque command value T as The first weight W1 is multiplied by the first weighting unit 56. as The assist torque command value T after the first weighting process. as This is given to the addition unit 59.

[0049] The manual steering command value generation unit 52 generates a manual steering command value θ corresponding to the steering angle (more precisely, the rotation angle θ of the output shaft 9) when the driver operates the steering wheel 2. mdac It is provided for setting as follows. The manual steering command value generation unit 52 generates the steering torque T detected by the torque sensor 12. d The assist torque command value T set by the assist torque command value setting unit 51. as The manual steering command value θ is used with mdac This generates the manual steering command value generation unit 52. Details of the manual steering command value generation unit 52 will be described later.

[0050] The third weighting unit 58 generates a manual steering command value θ in accordance with the input mode setting signal, which is generated by the manual steering command value generation unit 52. mdacA third weighting process is performed on the following. Specifically, when any of the mode setting signals S1, S2, or S3 is input to the third weighting unit 58, first it sets the third weight W3 according to the current steering mode and the input mode setting signal. Next, the third weighting unit 58 sets the manual steering command value θ mdac The third weight W3 is multiplied by the third weight W3. Then, the third weighting unit 58 multiplies the value W3·θ mdac The manual steering command value θ after the third weighting process. mdac This is provided to the integrated angle command value calculation unit 53.

[0051] The integrated angle command value calculation unit 53 calculates the automatic steering command value θ set by the higher-level ECU 201. adac The manual steering command value θ after the third weighting process. mdac Add ' to get the integrated angle command value θ sint Perform the calculation.

[0052] The angle control unit 54 controls the integrated angle command value θ. sint Based on this, the integrated angle command value θ sint The corresponding integrated motor torque command value T mint The integrated motor torque command value T is calculated. mint This is an example of the "integrated torque command value" in the present invention. Details of the angle control unit 54 will be described later.

[0053] The second weighting unit 57 adjusts the integrated motor torque command value T according to the input mode setting signal. mint A second weighting process is performed on the second weighting unit 57. Specifically, when any of the mode setting signals S1, S2, or S3 is input, the second weighting unit 57 first sets the second weight W2 according to the current steering mode and the input mode setting signal. Next, the second weighting unit 57 sets the integrated motor torque command value T mint The second weight W2 is multiplied by the second weight W2. Then, the second weighting unit 57 calculates the multiplicative value W2·T. mint The integrated motor torque command value T after the second weighting process. mint This is given to the addition unit 59.

[0054] The addition unit 59 calculates the assist torque command value T after the first weighting process. as 'and the integrated motor torque command value T after the second weighting process. mint By adding ' and , the motor torque command value T for the electric motor 18 is obtained. m Perform the calculation.

[0055] The torque control unit 55 controls the motor torque of the electric motor 18 when it reaches the motor torque command value T. m The drive circuit 41 is driven to approach it.

[0056] In this embodiment, the manual steering command value generation unit 52 uses a reference EPS model to generate the manual steering command value θ mdac Set it.

[0057] Figure 4 is a schematic diagram showing an example of a reference EPS model used in the manual steering command value generation unit 52.

[0058] 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. In Figure 4, J c θ is the inertia of the lower column, c is the rotation angle of the lower column, and T d This is the steering torque. The lower column has a steering torque T. d Torque N·T acting from the electric motor 18 to the output shaft 9 m and road surface load torque T rl The road surface load torque T is given. rl It can be expressed by the following equation (1), using the spring constant k and the viscous damping coefficient c.

[0059] T rl =-k·θ c -c(dθ c / dt) …(1) In this embodiment, predetermined values ​​are set as the spring constant k and the viscous damping coefficient c, which are determined in advance through experiments, analyses, etc.

[0060] The equation of motion of the reference EPS model is represented by the following equation (2).

[0061] J c ·d 2 θ c / dt 2 =T d +N·T m -k·θ c -c(dθ c / dt) …(2) The manual steering command value generation unit 52 substitutes the steering torque T d detected by the torque sensor 12 into T d and substitutes the assist torque command value T m set by the assist torque command value setting unit 51 into N·T as and solves the differential equation of equation (2) to calculate the rotation angle θ c of the lower column. Then, the manual steering command value generation unit 52 generates the obtained rotation angle θ c of the lower column as the manual steering command value θ mdac .

[0062] Figure 5 is a block diagram showing the configuration of the angle control unit 54.

[0063] Based on the integrated angle command value θ sint , the angle control unit 54 calculates the integrated motor torque command value T mint . The angle control unit 54 includes a low-pass filter (LPF) 61, a feedback control unit 62, a feed-forward control unit 63, a disturbance torque estimation unit 64, a torque addition unit 65, a disturbance torque compensation unit 66, a first reduction ratio division unit 67, a reduction ratio multiplication unit 68, a rotation angle calculation unit 69, and a second reduction ratio division unit 70.

[0064] The reduction ratio multiplication unit 68 multiplies the motor torque command value T m calculated by the addition unit 59 (see Figure 2) by the reduction ratio N of the reduction gear 19 to convert the motor torque command value T m into the output shaft torque command value N·T m acting on the output shaft 9 (worm wheel 21).

[0065] 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 divides the rotor rotation angle θ calculated by the rotation angle calculation unit 69 by the reduction ratio N to convert the rotor rotation angle θ m into the rotation angle (actual steering angle) θ of the output shaft 9. m

[0066] The low-pass filter 61 performs low-pass filter processing on the integrated angle command value θ sint The integrated angle command value θ after the low-pass filter processing is given to the feedback control unit 62 and the feedforward control unit 63. sin

[0067] The feedback control unit 62 is provided to make the steering angle estimated value ^θ calculated by the disturbance torque estimation unit 64 approach the integrated angle command value θ sin after the low-pass filter processing. 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 the deviation Δθ (= θ sin - ^θ) between the integrated angle command value θ and the steering angle estimated value ^θ. Note that the angle deviation calculation unit 62A may calculate the deviation (θ sin - θ) between the integrated angle command value θ and the actual steering angle θ calculated by the second reduction ratio division unit 70 as the angle deviation Δθ. sin sin

[0068] The PD control unit 62B performs PD calculation (proportional derivative calculation) on the angle deviation Δθ calculated by the angle deviation calculation unit 62A to calculate the feedback control torque T fb The feedback control torque T fb is given to the torque addition unit 65.

[0069] The feedforward control unit 63 is provided to improve the responsiveness of the control by compensating for the response delay caused by the inertia of the electric power steering system 1. 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 the integrated angular command value θ sin By taking the second derivative of this, we obtain the target angular acceleration d 2 θ sin / dt 2 Perform the calculation.

[0070] The inertia multiplication unit 63B calculates the target angular acceleration d calculated by the angular acceleration calculation unit 63A. 2 θ sin / dt 2 By multiplying this by the inertia J of the electric power steering system 1, the feedforward controlled torque T is generated. ff (=J·d 2 θ sin / dt 2 The inertia J is calculated from, for example, the physical model of the electric power steering system 1 described later (see Figure 6). Feedforward controlled torque T ff This value is provided to the torque addition unit 65 as an inertia compensation value.

[0071] The torque addition unit 65 controls the feedback-controlled torque T fb Feedforward controlled torque T ff By adding this, the basic torque command value (T fb +T ff ) is calculated.

[0072] The disturbance torque estimation unit 64 is provided to estimate the nonlinear torque (disturbance torque: torque other than motor torque) that occurs as a disturbance in the plant (the object controlled by the electric motor 18). The disturbance torque estimation unit 64 estimates the output shaft torque command value N·T m Based on the actual steering angle θ, the disturbance torque (disturbance load) T is calculated. lc The steering angle θ and the derivative of the steering angle (angular velocity) dθ / dt are estimated. The disturbance torque T lc The estimated values ​​of the steering angle θ and the derivative of the steering angle (angular velocity) dθ / dt are given by ^T, respectively.lc These are expressed in terms of ^θ and d^θ / dt. Details of the disturbance torque estimation unit 64 will be described later.

[0073] The disturbance torque estimate ^T calculated by the disturbance torque estimation unit 64 lc This value is provided to the disturbance torque compensation unit 66 as a disturbance torque compensation value. The steering angle estimate value^θ calculated by the disturbance torque estimation unit 64 is provided to the angle deviation calculation unit 62A.

[0074] The disturbance torque compensation unit 66 controls the basic torque command value (T fb +T ff ) from the estimated disturbance torque ^T lc By subtracting this, the integrated steering torque command value T sint (=T fb +T ff -^T lc This calculates the integrated steering torque command value T, which is compensated for disturbance torque. sint (The torque command value for output shaft 9) is obtained.

[0075] Integrated steering torque command value T sint This is provided to the first reduction ratio division unit 67. The first reduction ratio division unit 67 receives the integrated steering torque command value T sint By dividing by the reduction ratio N, the integrated motor torque command value T is obtained. mint The integrated motor torque command value T is calculated. mint This is then applied to the second weighting unit 57 (see Figure 2).

[0076] The disturbance torque estimation unit 64 will now be explained in detail. The disturbance torque estimation unit 64 uses, for example, the physical model 101 of the electric power steering system 1 shown in Figure 6 to estimate the disturbance torque T lc It consists of a disturbance observer that estimates the steering angle θ and angular velocity dθ / dt.

[0077] This physical model 101 includes a plant (an example of a motor-driven object) 102 which includes an output shaft 9 and a worm wheel 21 fixed to the output shaft 9. The plant 102 receives steering torque T from a steering wheel 2 via a torsion bar 10. d Along with this, a road surface load torque T is applied from the steering wheel 3 side. rl It is given.

[0078] Furthermore, the plant 102 has an output shaft torque command value N·T via the worm gear 20. m A friction torque T is given, and friction between the worm wheel 21 and the worm gear 20 causes friction torque T. f It is given.

[0079] If the inertia of plant 102 is J, then the equation of motion for the inertia of physical model 101 is expressed by the following equation (3).

[0080]

number

[0081] d 2 θ / dt 2 is the angular acceleration of plant 102. N is the reduction ratio of gearbox 19. T lc This represents disturbance torques other than the motor torque applied to plant 102. In this embodiment, the disturbance torque T lc is steering torque T d and road surface load torque T rl and friction torque T f Although it is shown as the sum of the two, in reality, the disturbance torque T lc This includes torque other than these.

[0082] The equation of state for physical model 101 in Figure 6 is given by equation (4) below.

[0083]

number

[0084] In equation (4) above, x is the state variable vector, u1 is the known input vector, u2 is the unknown input vector, and y is the output vector (measured value). Also in equation (4) above, A is the system matrix, B1 is the first input matrix, B2 is the second input matrix, C is the output matrix, and D is the direct matrix.

[0085] The above state equation is extended to a system that includes the unknown input vector u2 as one of its states. The state equation of the extended system (extended state equation) is expressed by the following equation (5).

[0086]

number

[0087] In equation (5) above, x e This is the state variable vector of the extended system, and is represented by equation (6) below.

[0088]

number

[0089] In the above formula (5), A e This is the system matrix of the extended system, B e is the known input matrix of the extended system, and Ce is the output matrix of the extended system.

[0090] From the extended state equation in equation (5) above, a disturbance observer (extended state observer) represented by the following equation (7) is constructed.

[0091]

number

[0092] In equation (7), ^x e is x e This represents an estimate of . L is the observer gain. ^y represents an estimate of y. ^x e This can be expressed by the following equation (8).

[0093]

number

[0094] In equation (8), ^θ is an estimate of θ, and ^T lc is T lc This is an estimated value.

[0095] The disturbance torque estimation unit 64 estimates the state variable vector ^x based on equation (7). e Perform the calculation.

[0096] Figure 7 is a block diagram showing the configuration of the disturbance torque estimation unit 64.

[0097] The disturbance torque estimation unit 64 includes an input vector input unit 81, an output matrix multiplication unit 82, a first adder unit 83, a gain multiplication unit 84, an input matrix multiplication unit 85, a system matrix multiplication unit 86, a second adder unit 87, an integral unit 88, and a state variable vector output unit 89.

[0098] Output shaft torque command value N·T calculated by reduction ratio multiplication unit 68 (see Figure 5) m This is provided to the input vector input unit 81. The input vector input unit 81 outputs the input vector u1.

[0099] The output of the integral unit 88 is the state variable vector ^x e (See equation (8) above) At the start of the operation, the state variable vector ^x e The initial values ​​are given as follows: State variable vector ^x e The initial value of is, for example, 0.

[0100] The system matrix multiplication unit 86 is the state variable vector ^x e System matrix A e Multiply by . Output matrix multiplication unit 82 is the state variable vector ^x e Output matrix C e Multiply by .

[0101] The first adder 83 calculates the output (C) of the output matrix multiplier 82 from the output vector (measured value) y, which is the actual steering angle θ calculated by the second reduction ratio division unit 70 (see Figure 5). e ·^x e ) is subtracted. In other words, the first adder 83 subtracts the output vector y from the output vector estimate ^y (=C e ·^x e The difference (y-^y) between the first adder 83 and the first adder 83 is calculated. The gain multiplier 84 multiplies the output (y-^y) of the first adder 83 by the observer gain L (see equation (7) above).

[0102] The input matrix multiplication unit 85 multiplies the input matrix B by the input vector u1 output from the input vector input unit 81. e The second adder 87 multiplies the output of the input matrix multiplication unit 85 (Be·u1) and the output of the system matrix multiplication unit 86 (A e ·^x e By adding the output of the gain multiplier unit 84 (L(y-^y)) to the derivative of the state variable vector d^x e The integral unit 88 calculates / dt. The integral unit 88 takes the output of the second adder unit 87 (d^x e By integrating ( / dt), the state variable vector ^x e The state variable vector output unit 89 outputs the state variable vector ^x e Based on this, the disturbance torque estimate ^T lc Then, the steering angle estimate ^θ and the angular velocity estimate d^θ / dt are calculated.

[0103] Unlike the extended state observer described above, a typical disturbance observer consists of an inverse model of the plant and a low-pass filter. The equation of motion for the plant is given by equation (3) above. Therefore, the inverse model of the plant is given by equation (9).

[0104]

number

[0105] The input to a typical disturbance observer is J·d 2 θ / dt2 and N·T m Therefore, since the second derivative of the actual steering angle θ is used, it is greatly affected by the noise of the rotation angle sensor 23. In contrast, the extended state observer of the above embodiment estimates the disturbance torque using an integral method, thus reducing the noise effect due to differentiation.

[0106] Alternatively, a general disturbance observer consisting of an inverse model of the plant and a low-pass filter may be used as the disturbance torque estimation unit 64.

[0107] Figure 8 is a schematic diagram showing the configuration of the torque control unit 55.

[0108] The torque control unit 55 (see Figure 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.

[0109] The motor current command value calculation unit 91 calculates the motor torque command value T calculated by the addition unit 59 (see Figure 2). m Torque constant K of electric motor 18 t By dividing by I, the motor current command value I cmd Perform the calculation.

[0110] The current deviation calculation unit 92 calculates the motor current command value I obtained by the motor current command value calculation unit 91. cmd The difference ΔI(=I) between the motor current I detected by the current detection circuit 42 and the motor current I is also detected by the current detection circuit 42. cmd Calculate -I).

[0111] 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 setting the motor current I flowing through the electric motor 18 to the motor current command value I. cmd A drive command value is generated to guide the motor to the desired state. The PWM control unit 94 generates a PWM control signal with a duty cycle corresponding to the drive command value and supplies it to the drive circuit 41. As a result, power corresponding to the drive command value is supplied to the electric motor 18.

[0112] The operation of this embodiment will be described below.

[0113] The automatic steering mode refers to the automatic steering command value θ. adac This refers to a steering mode in which the electric motor 18 is controlled based on the assist torque command value T. as This refers to a steering mode in which the electric motor 18 is controlled based on the automatic steering command value θ. The cooperative steering mode refers to an automatic steering command value θ. adac and manual steering command value θ mdac The integrated angle command value θ takes both of the above into account. sint This refers to a steering mode in which the electric motor 18 is controlled based on [the specified parameters].

[0114] When the steering mode is set to cooperative steering mode, the first weight W1 becomes 0, and the second weight W2 and third weight W3 become 1.0.

[0115] When the steering mode is set to automatic steering mode, the first weight W1 and the third weight W3 become zero, and the second weight W2 becomes 1.0.

[0116] When the steering mode is set to manual steering mode, the first weight W1 becomes 1.0, the second weight W2 becomes zero, and the third weight W3 becomes 0 or 1.0.

[0117] In other words, the motor control ECU 202 allows the driver to switch between steering modes between normal steering mode, automatic steering mode, and manual steering mode by operating mode switches 31, 32, and 33.

[0118] Examples of setting the first weight W1, second weight W2, and third weight W3 in conjunction with the switching of steering modes are shown in Figures 9, 10, and 11, respectively.

[0119] In Figure 9, line L1 shows the state in which the first weight W1 gradually increases from zero to 1.0 from the time of input of each mode setting signal S1, S2, and S3 (time t1) to time t2, when a predetermined time T has elapsed, and line L2 shows the state in which it gradually decreases from 1.0 to zero.

[0120] In Figure 10, line L3 shows the state in which the second weight W2 gradually increases from zero to 1.0 from time t1 to time t2, and line L4 shows the state in which it gradually decreases from 1.0 to zero.

[0121] In Figure 11, line L5 shows the state in which the third weight W3 gradually increases from zero to 1.0 from time t1 to time t2, and line L6 shows the state in which it gradually decreases from 1.0 to zero.

[0122] This results in the assist torque command value T after the first weighting process. as ', Integrated motor torque command value T after second weighting process mint 'and the manual steering command value θ after the third weighting process mdac Since the absolute values ​​of each of the ' values ​​are gradually increased or decreased, the switching between steering modes is smooth.

[0123] The time T required to switch the first weight W1, second weight W2, and third weight W3 between zero and 1.0 is set to a predetermined value determined in advance through experiments, analyses, etc. ad The time T required to switch between zero and 1.0 may be set differently for the second weight W2 and the third weight W3. Furthermore, the first weight W1, second weight W2, and third weight W3 may be set to increase or decrease non-linearly rather than linearly.

[0124] In this embodiment, any operation of mode switches 31, 32, and 33 that does not involve a change in steering mode will be invalidated. Furthermore, in this embodiment, any operation of mode switches 31, 32, and 33 before a predetermined time T has elapsed since the operation of each mode switch 31, 32, and 33 will be invalidated.

[0125] While the steering mode is switched by mode switches 31, 32, and 33, the higher-level ECU 201 may also switch the steering mode according to the ON / OFF signals of the driver assistance function or automatic driving function, obstacles, driver status, driver operations such as accelerator and brake, and the vehicle's driving status. In this case, the higher-level ECU 201 generates a mode setting signal according to the ON / OFF signals of the driver assistance function or automatic driving function, obstacles, driver status, driver operations such as accelerator and brake, and the vehicle's driving status, and provides it to the motor control ECU 202. In this case, the mode setting signal generated by the higher-level ECU 201 according to the ON / OFF signals of the driver assistance function or automatic driving function, obstacles, driver status, driver operations such as accelerator and brake, and the vehicle's driving status is an example of a "switching signal" in the present invention.

[0126] For example, when lane-keeping assist control is performed to keep the vehicle within its lane, the higher-level ECU 201 may automatically switch steering modes as follows:

[0127] In Figure 12, in a plan view, lane L L ,L R Center line L S If a predetermined position of length at the center of the width of the vehicle 300 (hereinafter referred to as the "reference position") exists within a first region E1 with width α (where α > 0) centered on the vehicle, the higher-level ECU 201 sets the steering mode to manual steering mode.

[0128] In a plan view, lane L L ,L R Center line L S If the reference position of the vehicle 300 is located within a third region E3 that is outside the first region but within a second region E2 with a width β (where β > α) centered on the reference position, the higher-level ECU 201 sets the steering mode to cooperative steering mode.

[0129] Then, in a plan view, if the reference position of the vehicle 300 is outside the second region E2, the higher-level ECU 201 sets the steering mode to automatic steering mode.

[0130] In the above-described embodiment, the integrated angle command value θ sint A coordinated steering mode that can control the electric motor 18 based on the assist torque command value T as A manual steering mode that can control the electric motor 18 based on the automatic steering command value θ adac Based on this, it becomes possible to switch between an automatic steering mode that controls the electric motor 18 and an automatic steering mode.

[0131] In other words, the integrated angle command value θ sint In an electric power steering system 1 that can control the electric motor 18 based on the assist torque command value T as Based on this, the electric motor 18 can be controlled.

[0132] In the above-described embodiment, when in manual steering mode, the assist torque command value T as Because the electric motor 18 is controlled based on this, the driver can receive the actual road surface load torque (road surface reaction torque). This allows the driver to feel the actual road surface conditions, such as whether the road surface is slippery or not, thus reducing the likelihood of the driver feeling any discomfort in steering.

[0133] Furthermore, in the above-described embodiment, the integrated angle command value θ sint Based on the basic torque command value (T fb +T ff The disturbance torque estimate ^T is calculated by the disturbance torque estimation unit 64. lc The basic torque command value (T fb +T ff Since this is compensated for, the influence of disturbance torque on angle control performance can be suppressed. This makes it possible to achieve high-precision angle control.

[0134] Figure 13 is a block diagram illustrating a modified example of the motor control ECU 202. In Figure 13, parts corresponding to the parts in Figure 2 are denoted by the same reference numerals as the parts in Figure 2.

[0135] In this motor control ECU 202, the first weighting unit 56, second weighting unit 57, and third weighting unit 58 in Figure 2 are replaced by a first switch 156, a second switch 157, and a third switch 158.

[0136] When the steering mode is set to cooperative steering mode, the first switch 156 is turned off, and the second switch 157 and the third switch 158 are turned on.

[0137] When the steering mode is set to automatic steering mode, the first switch 156 and the third switch 158 are turned off, and the second switch 157 is turned on.

[0138] When the steering mode is set to manual steering mode, the first switch 156 is turned on, the second switch 157 is turned off, and the third switch 158 is either turned off or on.

[0139] The first switch 156, the second switch 156, and the adding unit 59 are examples of the "switching unit" in the present invention. Furthermore, the first switch 156, the second switch 157, the third switch 158, and the adding unit 59 are examples of the "switching unit" in the present invention. The adding unit 59 is an example of the "adding unit" in the present invention.

[0140] While embodiments and variations of the present invention have been described above, the present invention can be implemented in yet other forms.

[0141] In the above-described embodiment, the spring constant k in equation (2) is determined in advance by experiment, analysis, etc. However, the spring constant k in equation (2) is the disturbance torque estimate value^T calculated by the disturbance torque estimation unit 64 (see Figure 5). lcThe actual steering angle θ calculated by the second reduction ratio division unit 70 may be used to perform the calculation based on the following equation (10).

[0142] k = ^T lc / θ …(10) Furthermore, in the above-described embodiment, the viscous damping coefficient c in equation (2) is determined in advance by experimentation, analysis, etc.

[0143] However, the viscous damping coefficient c in equation (2) is the disturbance torque estimate value ^T calculated by the disturbance torque estimation unit 64. lc The actual steering angle θ calculated by the second reduction ratio division unit 70 may be used to perform the calculation based on the following equation (11).

[0144] c=^T lc / (dθ / dt) …(11) Furthermore, in the above-described embodiment, the angle control unit 54 (see Figure 5) includes a feedforward control unit 63, but the feedforward control unit 63 may be omitted. In this case, the feedback control torque T calculated by the feedback control unit 62 fb This will be the basic target torque.

[0145] Furthermore, in the above-described embodiment, a first weighting unit 56, a second weighting unit 57, and a third weighting unit 58 are provided, but the third weighting unit 58 may be omitted. In this case, there will be two steering modes: manual steering mode and coordinated steering mode.

[0146] Similarly, in the modified example described above, a first switch 156, a second switch 157, and a third switch 158 are provided, but the third switch 158 may be omitted. In this case, there are two steering modes: manual steering mode and coordinated steering mode.

[0147] Furthermore, although the above-described embodiment showed an example of applying this invention to the motor control of a column-type EPS, this invention can also be applied to the motor control of EPS systems other than the column type. In addition, this invention can also be applied to the control of an electric motor for steering angle control in a steer-by-wire system.

[0148] Although embodiments of the present invention have been described in detail, these are merely specific examples used to clarify the technical content of the present invention, and the present invention should not be interpreted as being limited to these specific examples. The scope of the present invention is limited only by the appended claims. [Explanation of symbols]

[0149] 1...Electric power steering system, 3...Steering wheel, 4...Steering mechanism, 18...Electric motor, 51...Assist torque command value setting unit, 52...Manual steering command value generation unit, 53...Integrated angle command value calculation unit, 54...Angle control unit, 55...Torque control unit, 56...First weighting unit, 57...Second weighting unit, 58...Third weighting unit, 59...Addition unit, 61...Low-pass filter (LPF), 62...Feedback control unit, 63...Feedforward control unit, 64...Disturbance torque estimation unit, 65...Torque addition unit, 66...Disturbance torque compensation unit, 156...First switch, 157...Second switch, 158...Third switch

Claims

1. A motor control device for driving and controlling an electric motor for steering angle control, An assist torque command value generation unit that generates an assist torque command value using steering torque, A manual steering command value generation unit generates a manual steering command value using the steering torque and the assist torque command value, 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, A switching unit that switches between the assist torque command value and the integrated torque command value corresponding to the integrated angle command value based on a switching signal and outputs them as a motor torque command value, A motor control device including a torque control unit that drives and controls the electric motor based on the motor torque command value.

2. The aforementioned switching unit is A first weighting unit performs a first weighting process on the assist torque command value based on the switching signal, A second weighting unit performs a second weighting process on the integrated torque command value corresponding to the integrated angle command value based on the switching signal, The motor control device according to claim 1, further comprising a motor torque command value calculation unit that calculates the motor torque command value based on the assist torque command value after the first weighting process and the integrated torque command value after the second weighting process.

3. The motor control device according to claim 1, wherein the switching unit is configured to switch between a first control that controls the electric motor using the assist torque command value as the motor torque command value, a second control that controls the electric motor using the integrated torque command value as the motor torque command value, and a third control that controls the electric motor using the torque command value corresponding to the automatic steering command value as the motor torque command value, based on the switching signal.

4. The aforementioned switching unit is A first weighting unit performs a first weighting process on the assist torque command value based on the switching signal, A second weighting unit performs a second weighting process on the integrated torque command value corresponding to the integrated angle command value based on the switching signal, A third weighting unit performs a third weighting process on the manual steering command value based on the switching signal, The system includes a motor torque command value calculation unit that calculates the motor torque command value based on the assist torque command value after the first weighting process and the integrated torque command value after the second weighting process, The motor control device according to claim 3, wherein the integrated angle command value calculation unit is configured to calculate the integrated angle command value by adding the manual steering command value after the third weighting process to the automatic steering command value.

5. The aforementioned switching unit is An addition unit for calculating the motor torque command value by adding the assist torque command value generated by the assist torque command value generation unit and the integrated torque command value corresponding to the integrated angle command value calculated by the integrated angle command value calculation unit, A first switch is provided between the assist torque command value generation unit and the addition unit, and is turned on or off based on the switching signal, The motor control device according to claim 1, further comprising a second switch provided between the integrated angle command value calculation unit and the addition unit, which is turned on or off based on the switching signal.

6. The aforementioned switching unit is The assist torque command value generated by the assist torque command value generation unit and the integrated torque command corresponding to the integrated angle command value calculated by the integrated angle command value calculation unit An addition unit for calculating the motor torque command value by adding the value, A first switch is provided between the assist torque command value generation unit and the addition unit, and is turned on or off based on the switching signal, A second switch is provided between the integrated angle command value calculation unit and the addition unit, and is turned on or off based on the switching signal, The motor control device according to claim 3, further comprising a third switch provided between the manual steering command value generation unit and the integrated angle command value calculation unit, which is turned on or off based on the switching signal.

7. The control unit for controlling the electric motor using the integrated torque command value as the motor torque command value includes an angle control unit that performs angle control based on the integrated angle command value. The angle control unit is A basic torque command value calculation unit calculates a basic torque command value based on the integrated angle command value, A disturbance torque estimation unit estimates disturbance torques other than the motor torque of the electric motor that act on the object driven by the electric motor, The motor control device according to claim 1, further comprising a disturbance torque compensation unit that corrects the basic torque command value by the disturbance torque.

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