Motor control device

Abstract

This motor control device includes: a manual steering command value generation unit that generates a manual steering command value; an integrated angle command value calculation unit that adds the manual steering command value to an automatic steering command value applied when in a driving assistance mode and calculates an integrated angle command value; and a control unit that uses the integrated angle command value as a basis to perform angle control of an electric motor for steering control. The manual steering command value generation unit is configured so as to generate the manual steering command value on the basis of an equation of motion including road surface reaction force characteristic coefficients, and said manual steering command value generation unit additionally includes a road surface reaction force characteristic changing unit that changes at least one road surface reaction force characteristic coefficient among the road surface reaction force characteristic coefficients included in the equation of motion on the basis of vehicle environment information which is information relating to the travel environment of a vehicle.

Description

[Technical Field]

[0001] The present invention relates to a motor control device that controls an electric motor for steering angle control. [Background technology]

[0002] The following Patent Document 1 discloses a motor control device that includes a manual steering command value calculation unit that calculates a manual steering command value using steering torque, 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 control unit that controls the angle of an electric motor based on the integrated angle command value.

[0003] The manual steering command value calculation unit in Patent Document 1 calculates the manual steering command value using a reference EPS model. Specifically, the manual steering command value calculation unit calculates the manual steering command value based on an equation of motion that includes, as coefficients, a spring constant and a viscous damping coefficient for applying a virtual reaction force. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-194059 Summary of the Invention [Problem to be solved by the invention]

[0005] Even with the motor control device described in Patent Document 1, there is a risk that a collision or lane departure accident may occur due to an erroneous operation by the driver when the driver intervenes in steering during driving assistance.

[0006] An object of one embodiment of the present invention is to provide a motor control device that can reduce the risk of an accident or the like occurring due to a driver's incorrect operation or the like when the driver intervenes in steering during driving assistance. [Means for solving the problem]

[0007] One embodiment of the present invention includes a manual steering command value generation unit that generates a manual steering 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 given in a driving assistance mode, and a control unit that controls the angle of an electric motor for steering angle control based on the integrated angle command value, wherein the manual steering command value generation unit is configured to generate the manual steering command value based on an equation of motion that includes a road surface reaction force characteristic coefficient, and further includes a road surface reaction force characteristic change unit that changes the value of at least one of the road surface reaction force characteristic coefficients included in the equation of motion based on vehicle environment information that is information about the vehicle's driving environment.

[0008] With this configuration, it is possible to reduce the risk of an accident occurring due to an incorrect operation by the driver when the driver intervenes in steering during driving assistance.

[0009] The above and other objects, features and advantages of the present invention will become apparent from the following description of the embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 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] FIG. 2 is a block diagram illustrating the electrical configuration of the motor control ECU. [Figure 3] FIG. 3 is a block diagram showing the configuration of the manual steering command value generating unit. [Figure 4] FIG. 4 is a graph showing an example of setting the assist torque command value T* m,ad relative to the steering torque Ttb. [Figure 5] FIG. 5 is a schematic diagram showing an example of a reference EPS model used in the command value setting unit. [Figure 6] FIG. 6 is a block diagram showing the configuration of the angle control unit. [Figure 7]FIG. 7 is a schematic diagram showing an example of the configuration of a physical model of an electric power steering system. [Figure 8] FIG. 8 is a block diagram showing the configuration of the disturbance torque estimating unit. [Figure 9] FIG. 9 is a schematic diagram showing the configuration of the torque control unit. [Figure 10] FIG. 10 is a flowchart showing the procedure of the road surface reaction force characteristic setting process performed by the road surface reaction force characteristic setting unit. [Figure 11] Figure 11 is a graph showing an example of the characteristics of k·θ* c,md versus θ* c,md when k is set to kL and kL is set to k1, k2, or k0, and an example of the characteristics of k·θ* c,md versus θ* c,md when k is set to kR and kR is set to k1, k2, or k0. [Figure 12] Figure 12 is a graph showing an example of the characteristics of c·dθ*c,md / dt versus dθ*c,md / dt when cL is set as c and cL is set as c1, c2 or c0, and an example of the characteristics of c·dθ*c,md / dt versus dθ*c,md / dt when cR is set as c and cR is set as c1, c2 or c0. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Description of the embodiment of the present invention] One embodiment of the present invention includes a manual steering command value generation unit that generates a manual steering 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 given in a driving assistance mode, and a control unit that controls the angle of an electric motor for steering angle control based on the integrated angle command value, wherein the manual steering command value generation unit is configured to generate the manual steering command value based on an equation of motion that includes a road surface reaction force characteristic coefficient, and further includes a road surface reaction force characteristic change unit that changes the value of at least one of the road surface reaction force characteristic coefficients included in the equation of motion based on vehicle environment information that is information about the vehicle's driving environment.

[0012] With this configuration, it is possible to reduce the risk of an accident occurring due to an incorrect operation by the driver when the driver intervenes in steering during driving assistance.

[0013] In one embodiment of the present invention, the road surface reaction force characteristic coefficient includes a spring constant and a viscous damping coefficient, and the road surface reaction force characteristic change unit is configured to change the value of at least one of the spring constant and the viscous damping coefficient in accordance with the steering intervention direction or the steering direction based on the vehicle environment information.

[0014] In one embodiment of the present invention, the road reaction force characteristic change unit is configured to increase the value of at least one of the road reaction force characteristic coefficients included in the equation of motion in relation to a steering intervention direction or a steering direction in which the host vehicle approaches another vehicle or an obstacle.

[0015] In one embodiment of the present invention, the road reaction force characteristic change unit is configured to reduce the value of at least one of the road reaction force characteristic coefficients included in the equation of motion in relation to a steering intervention direction or a steering direction in which the host vehicle moves away from another vehicle or an obstacle.

[0016] Detailed Description of the Embodiments of the Invention Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] FIG. 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.

[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 steering torque (torsion bar 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 steering torque T tb For example, the torque for steering left is detected as a positive value, and the torque for steering right is detected as a negative value. The larger the absolute value of the torque, the greater the steering 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 middle of the rack shaft 14 in the axial direction. 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. In the following, the reduction ratio (gear ratio) of the reducer 19 may be represented by N. The reduction ratio N is determined by the rotation angle θ of the worm wheel 21. ww The rotation angle θ of the worm gear 20 relative to wg The ratio θ wg / θ ww is defined as:

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

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

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

[0028] Steering 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 (driver torque) and the force generated by steering inertia.

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

[0030] The vehicle is equipped with a CCD (Charge Coupled Device) camera 25 that photographs 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, a map information memory 28 that stores map information, and a vehicle speed sensor 29 for detecting vehicle speed V.

[0031] The CCD camera 25, GPS 26, radar 27, map information memory 28, and vehicle speed sensor 29 are connected to a host ECU (Electronic Control Unit) 201 for performing automatic driving control. Based on the information obtained by the CCD camera 25, GPS 26, radar 27, and vehicle speed sensor 29 and 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.

[0032] In this embodiment, there are two driving modes: a normal mode and a driving assistance mode. In the driving assistance mode, the host ECU 201 controls the automatic steering command value θ * c,ad In this embodiment, the driving assistance is a lane centering assist (LCA) for maintaining the vehicle position in the center of the lane. * c,ad is the target value of the steering angle for driving the vehicle along the center of the lane. * c,ad is set based on, for example, the vehicle speed, the lateral deviation of the vehicle with respect to the target driving line, and the yaw deviation of the vehicle with respect to the target driving line. * c,ad The process of setting the value is well known, so a detailed description will be omitted here.

[0033] The automatic steering control (driving assistance control) may be, for example, lane keeping assist (LKA) control for keeping the vehicle within the lane. In the normal mode, the host ECU 201 controls the automatic steering command value θ * c,ad Set to zero.

[0034] Furthermore, in the driving assistance mode, the host ECU 201 generates and outputs left / right direction reaction force control information according to vehicle environment information, which is information about the vehicle's driving environment, based on map information and information obtained from the CCD camera 25, GPS 26, radar 27, and vehicle speed sensor 29. In this embodiment, the left / right direction reaction force control information includes four types of variables kLP, kRP, cLP, and cRP. These variables kLP, kRP, cLP, and cRP will be described in detail later.

[0035] The host ECU 201 also outputs a mode signal S indicating whether the driving mode is the normal mode or the automatic driving mode. mode The mode signal S mode , automatic steering command value θ * c,adThe vehicle speed V and the left and right direction reaction force control information kLP, kRP, cLP, and cRP are provided to the motor control ECU 202 via the in-vehicle network. tb The output signal of the rotation angle sensor 23 is input to the motor control ECU 202. The motor control ECU 202 controls the electric motor 18 based on these input signals and information provided by the host ECU 201.

[0036] FIG. 2 is a block diagram for explaining the electrical configuration of motor control ECU 202. As shown in FIG.

[0037] The motor control ECU 202 includes a microcomputer 40, a drive circuit (inverter circuit) 31 controlled by the microcomputer 40 to supply power to the electric motor 18, and a current flowing through the electric motor 18 (hereinafter referred to as the "motor current I m,int The device is provided with a current detection circuit 32 for detecting the current.

[0038] The microcomputer 40 includes a CPU and memory (ROM, RAM, non-volatile memory, etc.), and functions as a plurality of functional processing sections by executing predetermined programs. The plurality of functional processing sections include a rotation angle calculation section 41, a reduction ratio division section 42, a road surface reaction force characteristic setting section 43, a manual steering command value generation section 44, an integrated angle command value calculation section 45, an angle control section 46, and a torque control section 47.

[0039] The rotation angle calculation unit 41 calculates the rotor rotation angle θ of the electric motor 18 based on the output signal of the rotation angle sensor 23. m,int The reduction ratio division unit 42 calculates the rotor rotation angle θ m,int By dividing by the reduction ratio N, the rotor rotation angle θ m,int The rotation angle (actual steering angle) of the output shaft 9 is θ c,int Convert to.

[0040] In the driving assistance mode, the road surface reaction force characteristic setting unit 43 sets the spring constant k and the viscous damping coefficient c used by the manual steering command value generating unit 44 based on the left / right direction reaction force control information kLP, kRP, cLP, cRP, etc. provided by the higher-level ECU 201. The operation of the road surface reaction force characteristic setting unit 43 will be described in detail later.

[0041] When the driver operates the steering wheel 2, the manual steering command value generating unit 44 generates a steering angle according to the steering wheel operation as a manual steering command value θ * c,md The manual steering command value generating unit 44 is provided to set the vehicle speed V and the steering torque T detected by the torque sensor 12 as tb Using the manual steering command value θ * c,md The operation of the manual steering command value generating unit 44 will be described in detail later.

[0042] The integrated angle command value calculation unit 45 calculates the automatic steering command value θθ set by the host ECU 201. * c,ad Manual steering command value θ * c,md The integrated angle command value θ * c,int Calculate the following.

[0043] The angle control unit 46 calculates the integrated angle command value θ * c,int Based on this, the motor torque command value T * m,int The torque control unit 47 calculates the motor torque of the electric motor 18 in accordance with the motor torque command value T * m,int In other words, the control unit consisting of the angle control unit 46 and the torque control unit 47 drives the drive circuit 31 so that the actual steering angle θ c,int (rotation angle θ of output shaft 9 c,int ) is the integrated angle command value θ * c,int The drive circuit 31 is controlled so that the angle of the rotational axis 46 approaches the rotational axis 47. The operations of the angle control unit 46 and the torque control unit 47 will be described in detail later.

[0044] FIG. 3 is a block diagram showing the configuration of the manual steering command value generating unit 44.

[0045] The manual steering command value generating unit 44 includes an assist torque command value setting unit 51 and a command value setting unit 52.

[0046] The assist torque command value setting unit 51 sets the assist torque command value T * m,md The assist torque command value setting unit 51 sets the vehicle speed V and the steering torque T detected by the torque sensor 12. tb Based on this, the assist torque command value T * m,md Set the steering torque T tb Assist torque command value T * m,md An example of the configuration is shown in Figure 4.

[0047] Assist torque command value T * m,md is set to a positive value when the electric motor 18 is to generate a steering assist force for steering to the left, and is set to a negative value when the electric motor 18 is to generate a steering assist force for steering to the right. * m,md is the steering torque T tb The steering torque T tb The assist torque command value T * m,md is the steering torque T tb The larger the absolute value of the assist torque command value T * m,md is set so that the absolute value thereof decreases as the vehicle speed V increases.

[0048] The assist torque command value setting unit 51 is configured to set the steering torque T tb is multiplied by a preset constant to obtain the assist torque command value T* m,md may be calculated.

[0049] In this embodiment, the command value setting unit 52 uses the reference EPS model to calculate the manual steering command value θ * c.md Set.

[0050] FIG. 5 is a schematic diagram showing an example of a reference EPS model used in the command value setting unit 52. As shown in FIG.

[0051] 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 FIG. 5, J c is the inertia of the lower column, and θ c is the rotation angle of the lower column, and T tb is the steering torque. This reference EPS model is tb and the assist torque command value T * m,md The output shaft torque command value N·T acting on the output shaft 9 from the electric motor 18 based on * m,md and road reaction torque T rl The rotation angle θ of the lower column when c This is a model for generating (estimating) the road reaction torque T rl is expressed by the following equation (1) using the spring constant k and the viscous damping coefficient c.

[0052] T rl =-k θ c -c(dθ c / dt) …(1) The equation of motion of the reference EPS model is expressed by the following equation (2).

[0053] J c ·d 2 θ c / dt 2 =T tb +N·T * m,md -k θ c -c(dθc / dt) …(2) The values ​​of the spring constant k and the viscous damping coefficient c, which are coefficients of the equation of motion of Equation (2), are set by the road reaction force characteristic setting unit 43. The spring constant k and the viscous damping coefficient c, which are coefficients of the equation of motion of Equation (2), are an example of the "road reaction force characteristic coefficient" in the present invention.

[0054] The command value setting unit 52 is T tb The steering torque T detected by the torque sensor 12 is tb Substituting N·T * m,md The assist torque command value T set by the assist torque command value setting unit 51 is * m,md By substituting and solving the differential equation (2), the rotation angle θ of the lower column is c Then, the command value setting unit 52 calculates the obtained rotation angle θ of the lower column. c The manual steering command value θ * c,md Set as.

[0055] FIG. 6 is a block diagram showing the configuration of the angle control unit 46.

[0056] The angle control unit 46 calculates the integrated angle command value θ * c,int Based on the motor torque command value T * m,int The angle control unit 46 includes a low-pass filter (LPF) 61, a feedback control unit 62, a feedforward control unit 63, a disturbance torque estimation unit 64, a torque addition unit 65, a disturbance torque compensation unit 66, a reduction ratio division unit 67, and a reduction ratio multiplication unit 68.

[0057] The reduction ratio multiplication unit 68 multiplies the motor torque command value T * m,int is multiplied by the reduction ratio N of the reducer 19 to obtain the motor torque command value T * m,int is the output shaft torque command value T * c,int (=N·T* m,int )

[0058] The low-pass filter 61 calculates the integrated angle command value θ * c,int The integrated angle command value θ after low-pass filtering is * c,intf is provided to the feedback control section 62 and the feedforward control section 63.

[0059] The feedback control unit 62 calculates the actual steering angle θ calculated by the reduction ratio division unit 42 (see FIG. 2). c,int is the integrated angle command value θ after low-pass filtering. * c,intf 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 * c,intf and the actual steering angle θ calculated by the reduction ratio division unit 42. c,int Deviation Δθ c,int (=θ * c,intf -θ c,int ) is calculated. The angle deviation calculation unit 62A calculates the integrated angle command value θ * c,intf and the steering angle estimated value ^θ calculated by the disturbance torque estimator 64. c,int deviation from (θ * c,intf -^θ c,int ) and the angle deviation Δθ c,int It may be calculated as follows.

[0060] The PD control unit 62B calculates the angle deviation Δθ calculated by the angle deviation calculation unit 62A. c,int By performing PD calculation (proportional differential calculation) on the feedback control torque T fb,int Calculate the feedback control torque T fb,int is given to the torque adder 65.

[0061] 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 * c,intf By taking the second derivative, the target angular acceleration d 2 θ * c,intf / dt 2 Calculate the following.

[0062] The inertia multiplication unit 63B multiplies the target angular acceleration d calculated by the angular acceleration calculation unit 63A by 2 θ * c,intf / dt 2 is multiplied by the inertia J of the electric power steering system 1 to obtain the feedforward control torque T ff,int (=J·d 2 θ * c,intf / 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,int is given to the torque adder 65 as an inertia compensation value.

[0063] The torque adder 65 calculates the feedback control torque T fb,int to the feedforward control torque T ff,int By adding fb,int +T ff,int ) is calculated.

[0064] 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 an output shaft torque command value T * c,int (=N·T * m,int ) and the actual steering angle θ, which is the plant outputc,int Based on this, the disturbance torque (disturbance load) T lc , steering angle θ c,int and steering angle differential value (angular velocity) dθ c,int / dt is estimated. lc , steering angle θ c,int and steering angle differential value (angular velocity) dθ c,int / dt estimates, respectively, lc , ^θ c,int and d^θ c,int The disturbance torque estimating section 64 will be described in detail later.

[0065] 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.

[0066] The disturbance torque compensator 66 calculates the basic torque command value (T fb,int +T ff,int ) to the estimated disturbance torque ^T lc By subtracting the output torque command value T * c,int (=T fb,int +T ff,int -^T lc ) is calculated. This results in the output shaft torque command value T * c,int (torque command value for output shaft 9) is obtained.

[0067] Output shaft torque command value T * c,int is given to the reduction ratio division unit 67. The reduction ratio division unit 67 calculates the output shaft torque command value T * c,int By dividing by the reduction ratio N, the motor torque command value T * m,int This motor torque command value T * m,int is given to the torque control section 47 (see FIG. 2).

[0068] The disturbance torque estimation unit 64 will be described in detail. The disturbance torque estimation unit 64 uses, for example, a physical model 101 of the electric power steering system 1 shown in FIG. 7 to estimate the disturbance torque T lc , steering angle θ c,int and angular velocity dθ c,int It consists of a disturbance observer that estimates / dt.

[0069] This physical model 101 includes a plant (an example of a motor-driven object) 102 including an output shaft 9 and a worm wheel 21 fixed to the output shaft 9. The plant 102 receives a steering torque T tb is applied, and a road reaction torque T rl is given.

[0070] Furthermore, the plant 102 receives an output shaft torque command value T * c,int (=N·T * m,int ) is given, and friction torque T f is given.

[0071] When the inertia of the plant 102 is J, the equation of motion for the inertia of the physical model 101 is expressed by the following equation (3).

[0072]

number

[0073] d 2 θ c,int / dt 2 is the angular acceleration of the plant 102. N is the reduction ratio of the reducer 19. T lc represents a disturbance torque other than the motor torque applied to the plant 102. In this embodiment, the disturbance torque T lc is the steering torque T tb and road reaction torque T rl and friction torque T fHowever, in reality, the disturbance torque T lc includes torques other than these.

[0074] The state equation for the physical model 101 in FIG. 7 is expressed by the following equation (4).

[0075]

number

[0076] In the above formula (4), x is a state variable vector, u1 is a known input vector, u2 is an unknown input vector, and y is an output vector (measurement value). In the above formula (4), A is a system matrix, B1 is a first input matrix, B2 is a second input matrix, C is an output matrix, and D is a direct feedthrough matrix.

[0077] The state equation is expanded to a system including the unknown input vector u2 as one of the states. The state equation of the expanded system (expanded state equation) is expressed by the following equation (5).

[0078]

number

[0079] In the formula (5), x e is the state variable vector of the extended system and is expressed by the following equation (6).

[0080]

number

[0081] In the formula (5), 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.

[0082] From the extended state equation of the above formula (5), a disturbance observer (extended state observer) expressed by the following formula (7) is constructed.

[0083]

number

[0084] In equation (7), ^x e 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 (8).

[0085]

number

[0086] In equation (8), ^θ c,int is θ c,int is an estimate of ^T lc is T lc is an estimate of

[0087] The disturbance torque estimation unit 64 calculates the state variable vector ^x based on the equation (7). e Calculate the following.

[0088] FIG. 8 is a block diagram showing the configuration of the disturbance torque estimating unit 64.

[0089] 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.

[0090] The output shaft torque command value T calculated by the reduction ratio multiplication unit 68 (see FIG. 6) * c,int (=N·T * m,int ) is given to the input vector input unit 81. The input vector input unit 81 outputs the input vector u1.

[0091] The output of the integrator 88 is the state variable vector ^x e (See equation (8) above.) At the start of 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.

[0092] The system matrix multiplication unit 86 multiplies the state variable vector ^x e In the 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.

[0093] The first adder 83 calculates the actual steering angle θ calculated by the reduction ratio divider 42 (see FIG. 2). c,int From the output vector (measurement value) y, which is 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 (7) above).

[0094] The input matrix multiplication unit 85 multiplies the input vector u1 output from the input vector input unit 81 by the input matrix B e The second adder 87 multiplies the output (B e u1) 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 (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 ^θc,int and the estimated angular velocity d^θ c,int Calculates / dt.

[0095] Unlike the extended state observer described above, a general disturbance observer consists of an inverse model of the plant and a low-pass filter. The equation of motion of the plant is expressed by equation (3) as described above. Therefore, the inverse model of the plant is expressed by the following equation (9).

[0096]

number

[0097] The input to a typical disturbance observer is J d 2 θ c,int / dt 2 and N.T. * m,int and the actual steering angle θ c,int 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.

[0098] 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.

[0099] 9 is a block diagram showing the electrical configuration of torque control unit 47. Torque control unit 48 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.

[0100] The motor current command value calculation unit 91 calculates the motor torque command value T * m,int The torque constant K of the electric motor 18 t By dividing by, the motor current command value I * m,int Calculate the following.

[0101] The current deviation calculation unit 92 calculates the motor current command value I obtained by the motor current command value calculation unit 91. * m,int and the motor current I detected by the current detection circuit 32 m,int Deviation ΔI m,int (=I * m,int -I m,int ) is calculated.

[0102] The PI control unit 93 calculates the current deviation ΔI m,int By performing a PI calculation (proportional integral calculation) on m,int The motor current command value I * m,int The PWM control unit 94 generates a PWM control signal with a duty ratio corresponding to the drive command value and supplies it to the drive circuit 31. As a result, power corresponding to the drive command value is supplied to the electric motor 18.

[0103] Next, the operation of the road surface reaction force characteristic setting unit 43 will be described in detail. In the driving assistance mode, the road surface reaction force characteristic setting unit 43 sets the manual steering command value θ * c,md The road surface reaction force characteristic setting process is performed to set the spring constant k and the viscous damping coefficient c used in the calculation of the manual steering command value θ * c,md The calculation is performed by the command value setting unit 52 (see FIG. 3).

[0104] In the following, the steering intervention direction is the automatic steering command value θ * c,ad Manual steering command value θ based on * c,md The direction of θ * c,md The steering intervention direction when θ ≥ 0 is called the left steering intervention direction, and θ * c,md The steering intervention direction when the value is <0 is referred to as the right steering intervention direction.

[0105] The steering direction is determined by the manual steering command value θ * c,md The direction in which dθ is changing. * c,md The steering direction when / dt≧0 is called the left steering direction, and dθ * c,md The steering direction when / dt<0 is called a right steering direction.

[0106] Also, k L ,k R ,c L ,c R is a variable used in the road reaction force characteristic setting process, and is defined as follows:

[0107] k L :Left steering intervention direction (θ * c,md ≧0) k R :Right steering intervention direction (θ * c,md <0) c L : Left steering direction (dθ * c,md / dt≧0) c R : Right steering direction (dθ * c,md / dt<0) Furthermore, k0, k1, and k2 are candidate values ​​for the spring constant k stored in advance in the memory of the motor control ECU 202, and are set to the following values.

[0108] k0: Medium spring constant candidate value k1: Spring constant candidate value smaller than k0 k2: Spring constant candidate value greater than k0 Furthermore, c0, c1, and c2 are candidate values ​​of the viscous damping coefficient c stored in advance in the memory of the motor control ECU 202, and are set to the following values.

[0109] c0: Medium-sized candidate viscous damping coefficient c1: Viscous damping coefficient candidate value smaller than c0 c2: Viscous damping coefficient candidate value greater than c0 The left and right direction reaction force control information kLP, kRP, cLP, and cRP set by the host ECU 201 have the following meanings.

[0110] kLP:k L is a parameter that indicates "small," "medium," or "large" for the

[0111] kRP:k R is a parameter that indicates "small," "medium," or "large" for the

[0112] cLP:c L is a parameter that indicates "small," "medium," or "large" for the

[0113] cRP:c R is a parameter that indicates "small," "medium," or "large" for the

[0114] The host ECU 201 determines the respective values ​​of the reaction force control information kLP, kRP, cLP, and cRP in the left and right directions based on the vehicle environment information, and provides the determined values ​​to the motor control ECU 202 .

[0115] For example, the host ECU 201 may determine the values ​​of kLP, kRP, cLP, and cRP for the purpose of avoiding danger.

[0116] Specifically, when a vehicle is traveling on a road with two or more lanes, the host ECU 201 detects other vehicles in the vicinity and determines the values ​​of kLP, kRP, cLP, and cRP so that the reaction force (both or either k and c) in the direction in which the other vehicle is present (the direction in which the vehicle is approaching the other vehicle) increases.

[0117] For example, if another vehicle is present to the right of the host vehicle, the host ECU 201 sets kLP and cLP to 0, and sets kRP and cRP to 2. In this case, the host ECU 201 may set kLP, cLP, and cRP to 0, and set kRP to 2. In this case, the host ECU 201 may also set kLP, kRP, and cLP to 0, and set cRP to 2. In this case, the host ECU 201 may also set kLP and cLP to 1, and set kRP and cRP to 0.

[0118] In addition, the host ECU 201 detects obstacles such as walls, pedestrians, bicycles, etc. while the vehicle is traveling, and determines the values ​​of kLP, kRP, cLP, and cRP so that the reaction force (both or either k and c) increases in the direction in which there is a high possibility of colliding with them (the direction in which the vehicle approaches them).

[0119] In addition, when a vehicle is traveling around a curve, steering to the outside of the curve has less margin before the vehicle deviates from its lane compared to steering to the inside of the curve, so the values ​​of kLP, kRP, cLP, and cRP are determined so that the reaction force (both or either k and c) toward the outside of the curve increases.

[0120] The host ECU 201 may determine the values ​​of kLP, kRP, cLP, and cRP for the purpose of, for example, driving instruction.

[0121] Specifically, when the vehicle is traveling on a curve such as a mountain road in the driving assistance mode, the host ECU 201 determines the values ​​of kLP, kRP, cLP, and cRP so as to reduce the reaction force (both or either one of k and c) in the steering direction that results in small lateral acceleration and comfortable vehicle behavior. Alternatively, the host ECU 201 determines the values ​​of kLP, kRP, cLP, and cRP so as to increase the reaction force (both or either one of k and c) in the steering direction that results in uncomfortable vehicle behavior.

[0122] Fig. 10 is a flowchart showing the procedure of the road surface reaction force characteristic setting process performed by the road surface reaction force characteristic setting unit 43. The road surface reaction force characteristic setting process shown in Fig. 10 is started every time the driving assistance mode is started, and is repeatedly executed at predetermined calculation intervals until the driving assistance mode is cancelled.

[0123] First, the road surface reaction force characteristic setting unit 43 obtains kLP, kRP, cLP, and cRP provided from the host ECU 201 (step S1).

[0124] Next, the road surface reaction force characteristic setting unit 43 calculates k L , k according to kLP (kLP) Set k R k according to kRP (kRP) Set c L c according to cLP (cLP) Set c R , c according to cRP (cRP) (Step S2). For example, if kLP=0, then k L If k0 is set to kLP=1, then k L If k1 is set to kLP=2, then k L k2 is set to

[0125] Next, the road surface reaction force characteristic setting unit 43 calculates θ * c,md The previous value of (θ * c,md(n-1) ) is equal to or greater than 0 (step S3).

[0126] θ* c,md(n-1) If .gtoreq.0 (step S3: YES), the road surface reaction force characteristic setting unit 43 sets the current .theta. * c,md The spring constant k used in calculating is the k set in step S2. L (=k1, k2 or k3) (step S4). Then, the road surface reaction force characteristic setting unit 43 proceeds to step S6.

[0127] In step S3, θ * c,md(n-1) If it is determined that the value is less than 0 (step S3: NO), the road surface reaction force characteristic setting unit 43 sets the current θ * c,md The spring constant k used in calculating is the k set in step S2. R (=k1, k2 or k3) (step S5). Then, the road surface reaction force characteristic setting unit 43 proceeds to step S6.

[0128] In step S6, dθ * c,md Previous value of / dt (dθ * c,md / dt) (n-1) Determine whether is greater than or equal to 0.

[0129] (dθ * c,md / dt) (n-1) If .gtoreq.0 (step S6: YES), the road surface reaction force characteristic setting unit 43 sets the current .theta. * c,md The viscous damping coefficient c used in calculating L (=c1, c2 or c3) is set (step S7). Then, the road surface reaction force characteristic setting unit 43 ends the processing for the current calculation cycle.

[0130] In step S6, (dθ * c,md / dt) (n-1) If it is determined that the value is less than 0 (step S6: NO), the road surface reaction force characteristic setting unit 43 sets the current θ *c,md The viscous damping coefficient c used in calculating R (=c1, c2 or c3) is set (step S8). Then, the road surface reaction force characteristic setting unit 43 ends the processing for the current calculation cycle.

[0131] In addition, this time θ * c,md The spring constant k used when calculating the new value (target value k target ), it takes about 0.5 to 1 second to change from the previous k to the target value k target Gradually approach the target value k target In this case, the k before the change may be changed to the target value k after multiple calculation cycles. target Similarly, this θ * c,md The viscous damping coefficient c used when calculating the new value (target value c target When the value of c is changed, it takes about 0.5 to 1 second to change from the previous value c to the target value c target Gradually approach the target value c target In this case, the c before the change may be changed to the target value c after multiple calculation cycles. target can be switched to.

[0132] Figure 11 shows the relationship between k and k L is set and k L θ when set to k1, k2 or k0 * c,md k θ for * c,md An example of the properties of k and k R is set and k R θ when set to k1, k2 or k0 * c,md k θ for * c,md 10 is a graph showing an example of the characteristics of

[0133] Figure 12 shows the c L is set and c Ldθ when set to c1, c2 or c0 md c dθ for / dt * c,md An example of the characteristics of / dt and c as c R is set and c R dθ when set to c1, c2 or c0 md c dθ for / dt * c,md 10 is a graph showing an example of a characteristic of / dt.

[0134] When the driving mode is the normal mode, the road surface reaction force characteristic setting unit 43 sets the spring constant k and the viscous damping coefficient c to k0 and c0, respectively. In other words, in the normal mode, the spring constant k and the viscous damping coefficient c are not changed.

[0135] In the driving assistance mode, the road surface reaction force characteristic setting unit 43 may change both the spring constant k and the viscous damping coefficient c, or may change either one of the spring constant k and the viscous damping coefficient c. In other words, in the driving assistance mode, the road surface reaction force characteristic setting unit 43 may change at least one of the spring constant k and the viscous damping coefficient c.

[0136] In the above embodiment, k L ,k R There are three candidate values ​​k0, k1, and k2. L ,k R As the candidate values ​​of c, two types of candidate values ​​may be prepared, or four types of candidate values ​​may be prepared. L ,c R There are three candidate values ​​c0, c1, and c2 available. L ,c R As the candidate values ​​of k, two types of candidate values ​​may be prepared, or four types of candidate values ​​may be prepared. L ,k R ,c L ,c R The types of values ​​that the left and right direction reaction force control information kLP, kRP, cLP, and cRP take also change depending on the types of candidate values.

[0137] In the above-described embodiment, the host ECU 201 determines the respective values ​​of left / right direction reaction force control information kLP, kRP, cLP, and cRP based on the vehicle environment information and provides the determined values ​​to the motor control ECU 202. In the driving assistance mode, the road surface reaction force characteristic setting unit 43 can change at least one value of the spring constant k and the viscous damping coefficient c based on the left / right direction reaction force control information kLP, kRP, cLP, and cRP provided by the host ECU 201 and both or either of the steering intervention direction and the steering direction. This makes it possible to reduce the risk of an accident or the like occurring due to a driver's incorrect operation or the like when the driver intervenes in steering during driving assistance.

[0138] In the above embodiment, an example was shown in which the present invention is applied to motor control of a column-type EPS, but the present invention can also be applied to motor control of EPS other than column types.

[0139] Although the embodiments of the present invention have been described in detail, these are merely examples used to clarify the technical contents of the present invention, and the present invention should not be construed as being limited to these examples, and the scope of the present invention is limited only by the appended claims. [Explanation of symbols]

[0140] 1... electric power steering device, 3... steered wheels, 4... steering mechanism, 18... electric motor, 43... road surface reaction force characteristic setting unit, 44... manual steering command value generation unit, 45... integrated angle command value calculation unit, 46... angle control unit, 47... torque control unit, 51... assist torque command value setting unit, 52... command value setting unit, 201... host ECU, 202... motor control ECU

Claims

1. a manual steering command value generating unit that generates a manual steering 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 given in a driving assistance mode; a control unit that controls the angle of an electric motor for steering angle control based on the integrated angle command value, the manual steering command value generation unit is configured to generate the manual steering command value based on a motion equation including a road surface reaction force characteristic coefficient, a road reaction force characteristic changing unit that changes a value of at least one of the road reaction force characteristic coefficients included in the equation of motion based on vehicle environment information that is information about a vehicle running environment, the road reaction force characteristic coefficient includes a spring constant and a viscous damping coefficient, the road surface reaction force characteristic changing unit is configured to change the value of at least one of the spring constant and the viscous damping coefficient in accordance with the steering intervention direction or the steering direction based on the vehicle environment information.

2. 2. The motor control device according to claim 1, wherein the road reaction force characteristic change unit is configured to increase a value of at least one of the road reaction force characteristic coefficients included in the equation of motion with respect to a steering intervention direction or a steering direction in which the host vehicle approaches another vehicle or an obstacle.

3. 2. The motor control device according to claim 1, wherein the road reaction force characteristic change unit is configured to decrease a value of at least one of the road reaction force characteristic coefficients included in the equation of motion with respect to a steering intervention direction or a steering direction in which the host vehicle moves away from another vehicle or an obstacle.

4. (delete)

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