Motor control device

Abstract

To provide a motor control device that becomes able to precisely determine whether it is in a grasped state or in a hands-free state in a drive assist mode.SOLUTION: A manual steering command value generating unit is configured to generate a manual steering command value by using steering torque, a spring constant and viscosity damping coefficient for generating road surface loading torque, and includes a road surface loading characteristic changing unit that increases, in a drive assist mode, when a determination result by a hands on / off determining unit such that it is in a hands-free state continues for a predetermined time or longer, a value of at least either one of the spring constant and the viscosity damping coefficient.SELECTED DRAWING: Figure 2

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] Patent Document 1 discloses the following driving assistance technology. That is, a steering control unit calculates an X coordinate xc of a target passing point at the gaze-ahead distance and an X coordinate xe of an estimated passing point. The steering control unit then adds a calculation term obtained by multiplying the deviation (xc-xe) of these X coordinates xc, xe by a first control gain Gl to a calculation term obtained by multiplying the yaw angle θca by a second control gain Gy to calculate a motor control amount (torque command value) Tc. The first and second control gains Gl, Gy are set to larger values ​​the longer the hands-off time is, and when a hands-off state is not detected, the lower the level of wakefulness or the higher the level of absentmindedness is, the smaller the values ​​are set. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-57037 Summary of the Invention [Problem to be solved by the invention]

[0004] A prerequisite for driving assistance functions equivalent to Level 2 is that the driver must be holding the steering wheel. Therefore, in driving assistance mode, if the result of the determination that the driver has their hands off the steering wheel continues for a predetermined period of time or more, a warning is output, and if the hands-off state continues even after the warning, the driving assistance mode is canceled.

[0005] For this reason, in the driving assistance mode, it is necessary to accurately determine whether the vehicle is in a gripped state or a hands-off state. However, if the determination of whether the vehicle is in a gripped state or a hands-off state is based on the steering torque (torsion bar torque) detected by a torque sensor, in situations where the driver torque input is small, such as when driving in a straight line, there is a risk that the vehicle may be erroneously determined to be in a hands-off state even though the driver is gripping the vehicle.

[0006] An object of one embodiment of the present invention is to provide a motor control device that can accurately determine whether the hand is in a gripped state or a hands-free state in a driving assistance mode. [Means for solving the problem]

[0007] One embodiment of the present invention provides a motor control device including: a torque detection unit for detecting steering torque; a manual steering command value generation unit for generating a manual steering command value using the steering torque; an integrated angle command value calculation unit for calculating 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 for controlling the angle of an electric motor for steering angle control based on the integrated angle command value; and a hands-on / off determination unit for determining whether the driver is in a gripped state where the driver is gripping the steering wheel or in a hands-off state where the driver is not gripping the steering wheel, wherein the manual steering command value generation unit is configured to generate the manual steering command value using the steering torque and a spring constant and a viscous damping coefficient for generating a road load torque, and further including a road load characteristic change unit that changes the value of at least one of the spring constant and the viscous damping coefficient when the hands-on / off determination unit determines that the driver is in a hands-off state for a predetermined period of time or more in the driving assistance mode.

[0008] With this configuration, it becomes possible to accurately determine whether the device is in a gripped state or a hands-off state in the driving assistance mode.

[0009] One embodiment of the present invention is a motor control device that includes a torque detection unit for detecting steering torque, a steering angle detection unit for detecting an actual steering angle, an automatic steering control unit that sets an automatic steering control amount based on an automatic steering command value given in a driving assistance mode, an assist control unit that sets an assist control amount using the steering torque, an integrated control amount calculation unit that calculates an integrated control amount by adding the automatic steering control amount and the assist control amount, and a control unit that controls an electric motor for steering angle control based on the integrated control amount, and includes a hands-on / off determination unit that determines whether the driver is in a gripped state where the driver is gripping the steering wheel or in a hands-off state where the driver is not gripping the steering wheel, and a hands-on / off determination unit that calculates an actual manual steering angle, which is a steering angle for manual steering based on the steering torque and the assist control amount. and an actual automatic steering angle calculation unit that calculates an actual automatic steering angle, which is the steering angle for automatic steering based on the automatic steering control amount, by subtracting the actual manual steering angle from the actual steering angle, wherein the automatic steering control unit sets the automatic steering control amount using the automatic steering angle command value and the actual automatic steering angle, and the actual manual steering angle calculation unit is configured to calculate the actual manual steering angle using the steering torque, the assist control amount, and a spring constant and viscous damping coefficient for generating a road load torque, and the motor control device further includes a road load characteristic change unit that changes the value of at least one of the spring constant and the viscous damping coefficient when the hands-on / off determination unit determines that the vehicle is in a hands-off state for a predetermined period of time or more in the driving assistance mode.

[0010] With this configuration, it becomes possible to accurately determine whether the device is in a gripped state or a hands-off state in the driving assistance mode. [Brief explanation of the drawings]

[0011] [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 spring constant setting process performed by the road surface load characteristic setting unit. [Figure 11] FIG. 11 is a block diagram for explaining the electrical configuration of a modified example of the motor control ECU. [Figure 12] FIG. 12 is a block diagram showing the configuration of the automatic steering control unit. [Figure 13] FIG. 13 is a schematic diagram showing an example of the configuration of a physical model of an electric power steering system. [Figure 14] FIG. 14 is a block diagram showing the configuration of the disturbance torque estimating section. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Description of the embodiment of the present invention] One embodiment of the present invention provides a motor control device including: a torque detection unit for detecting steering torque; a manual steering command value generation unit for generating a manual steering command value using the steering torque; an integrated angle command value calculation unit for calculating 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 for controlling the angle of an electric motor for steering angle control based on the integrated angle command value; and a hands-on / off determination unit for determining whether the driver is in a gripped state where the driver is gripping the steering wheel or in a hands-off state where the driver is not gripping the steering wheel, wherein the manual steering command value generation unit is configured to generate the manual steering command value using the steering torque and a spring constant and a viscous damping coefficient for generating a road load torque, and further including a road load characteristic change unit that changes the value of at least one of the spring constant and the viscous damping coefficient when the hands-on / off determination unit determines that the driver is in a hands-off state for a predetermined period of time or more in the driving assistance mode.

[0013] With this configuration, it becomes possible to accurately determine whether the device is in a gripped state or a hands-off state in the driving assistance mode.

[0014] One embodiment of the present invention is a motor control device that includes a torque detection unit for detecting steering torque, a steering angle detection unit for detecting an actual steering angle, an automatic steering control unit that sets an automatic steering control amount based on an automatic steering command value given in a driving assistance mode, an assist control unit that sets an assist control amount using the steering torque, an integrated control amount calculation unit that calculates an integrated control amount by adding the automatic steering control amount and the assist control amount, and a control unit that controls an electric motor for steering angle control based on the integrated control amount, and includes a hands-on / off determination unit that determines whether the driver is in a gripped state where the driver is gripping the steering wheel or in a hands-off state where the driver is not gripping the steering wheel, and a hands-on / off determination unit that calculates an actual manual steering angle, which is a steering angle for manual steering based on the steering torque and the assist control amount. and an actual automatic steering angle calculation unit that calculates an actual automatic steering angle, which is the steering angle for automatic steering based on the automatic steering control amount, by subtracting the actual manual steering angle from the actual steering angle, wherein the automatic steering control unit sets the automatic steering control amount using the automatic steering angle command value and the actual automatic steering angle, and the actual manual steering angle calculation unit is configured to calculate the actual manual steering angle using the steering torque, the assist control amount, and a spring constant and viscous damping coefficient for generating a road load torque, and the motor control device further includes a road load characteristic change unit that changes the value of at least one of the spring constant and the viscous damping coefficient when the hands-on / off determination unit determines that the vehicle is in a hands-off state for a predetermined period of time or more in the driving assistance mode.

[0015] With this configuration, it becomes possible to accurately determine whether the device is in a gripped state or a hands-off state in the driving assistance mode.

[0016] In one embodiment of the present invention, if the spring constant and the viscous damping coefficient whose value is changed by the road load characteristic change unit is defined as a road load variable, when, in the driving assistance mode, the hands-on / off determination unit determines that the vehicle is in a hands-off state for a predetermined period of time, the road load characteristic change unit gradually increases the value of the road load variable from that point onwards as long as the hands-off state determination result continues, and when the road load variable reaches a predetermined upper limit value, the road load variable is maintained at the upper limit value.

[0017] In one embodiment of the present invention, in the driving assistance mode, when the hands-on / off determination unit has determined that the vehicle is in a hands-off state for a predetermined period of time or more and then changes its determination result to a gripped state, the road load characteristic change unit gradually decreases the value of the road load variable from that point onwards as long as the determination result of the gripped state continues, and when the road load variable reaches a predetermined lower limit value, maintains the road load variable at the lower limit value.

[0018] 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.

[0019] [1] Overview of electric power steering system 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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:

[0027] 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.

[0028] 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.

[0029] 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 load torque (road reaction torque) T rl , friction torque T f etc. are included.

[0030] 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.

[0031] Road load 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.

[0032] 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.

[0033] 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 driving assistance 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.

[0034] 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 with respect to the target driving line, and the yaw deviation of the vehicle with respect to the target driving line. * c,ad Since the process of setting the automatic steering command value θ is well known, a detailed description thereof will be omitted here. * c,ad Set to zero.

[0035] The host ECU 201 also outputs a mode signal S indicating whether the driving mode is the normal mode or the driving assistance mode. mode The mode signal S mode , the automatic steering command value θ set by the host ECU 201 * c,ad and the vehicle speed V 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] [2] Motor control ECU 202 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 units by executing predetermined programs. The plurality of functional processing units include a rotation angle calculation unit 41, a reduction ratio division unit 42, a hands-on / off determination unit 43, a road load characteristic setting unit 44, a manual steering command value generation unit 45, an integrated angle command value calculation unit 46, an angle control unit 47, and a torque control unit 48.

[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] The hands-on / off determination unit 43 determines whether the driver is in a gripping state (hands-on) where the driver is gripping the steering wheel 2, or in a hands-off state (hands-off) where the driver is not gripping the steering wheel 2. The hands-on / off determination unit 43 determines, for example, the steering torque T tb and the actual steering angle θ c,int or rotor rotation angle θ m,intThe hands-on / off determination unit 43 may estimate the driver torque, which is the torque applied to the steering wheel 2 by the driver, based on the estimated value, and determine the state as being gripped if the driver torque is equal to or greater than a predetermined threshold, and determine the state as being hands-off if the driver torque remains below the threshold for a predetermined period of time or longer. In this case, the state is determined as being gripped after the driver torque changes from a state equal to or greater than the threshold to a state below the threshold until the state as being hands-off is determined. As such a hands-on / off determination unit 43, for example, a "steering wheel operation state determination unit" described in Japanese Patent Application Laid-Open No. 2017-114324, Japanese Patent Application Laid-Open No. 2018-165156, Japanese Patent Application Laid-Open No. 2020-142703, Japanese Patent Application Laid-Open No. 2020-59361, Japanese Patent Application Laid-Open No. 2020-59362, etc. may be used.

[0041] The hands-on / off determination unit 43 determines, for example, the steering torque T tb is equal to or greater than a predetermined threshold, it is determined that the vehicle is in a gripping state, and the steering torque T tb The steering torque T may be determined to be in a hands-off state when the steering torque T is less than the threshold value for a predetermined period of time. tb After the value of the threshold value changes from a value equal to or greater than the threshold value to a value less than the threshold value, the state is determined to be the grip state until the state is determined to be the no-hand state.

[0042] The road load characteristic setting unit 44 sets the spring constant k and the viscous damping coefficient c used by the manual steering command value generating unit 45 based on the hands-on / off determination result of the hands-on / off determining unit 43 in the driving assistance mode.

[0043] When the driver operates the steering wheel 2, the manual steering command value generating unit 45 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 45 is provided to set the steering torque T detected by the torque sensor 12 based on the vehicle speed V. tb Using the manual steering command value θ * c,md The operation of the manual steering command value generating unit 45 will be described in detail later.

[0044] The integrated angle command value calculation unit 46 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.

[0045] The angle control unit 47 calculates the integrated angle command value θ * c,int Based on this, the motor torque command value T * m,int The torque control unit 48 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 47 and the torque control unit 48 controls 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 47 approaches the rotational axis 48. The operations of the angle control unit 47 and the torque control unit 48 will be described in detail later.

[0046] FIG. 3 is a block diagram showing the configuration of the manual steering command value generating unit 45.

[0047] The manual steering command value generating unit 45 includes an assist torque command value setting unit 51 and a command value setting unit 52.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 tbis the steering torque. This reference EPS model is tb and the assist torque command value T * m,md The torque N·T acting on the output shaft 9 from the electric motor 18 is * m,md and road load torque T rl The rotation angle θ of the lower column when c This is a model for generating (estimating) the road load torque T rl is expressed by the following equation (1) using the spring constant k and the viscous damping coefficient c.

[0054] T rl =-k θ c -c(dθ c / dt) …(1) The spring constant k and the viscous damping coefficient c are set by the road load characteristic setting unit 44. The operation of the road load characteristic setting unit 44 will be described in detail later.

[0055] The equation of motion of the reference EPS model is expressed by the following equation (2).

[0056] J c ·d 2 θ c / dt 2 =T tb +N·T * m,md -k θ c -c(dθ c / dt) …(2) The command value setting unit 52 is T tb The steering torque T detected by the torque sensor 12 is tb Substituting, 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.

[0057] FIG. 6 is a block diagram showing the configuration of angle control unit 47.

[0058] The angle control unit 47 calculates the integrated angle command value θ * c,int Based on the motor torque command value T * m,int The angle control unit 47 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.

[0059] 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 )

[0060] 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.

[0061] The feedback control unit 62 calculates the actual steering angle θ calculated by the reduction ratio division unit 42. 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,intfand the actual steering angle θ calculated by the reduction ratio division unit 42 (see FIG. 2). 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.

[0062] 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.

[0063] 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 differentiating twice, the target angular acceleration d 2 θ * c,intf / dt 2 Calculate the following.

[0064] 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 / dt2 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.

[0065] 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.

[0066] 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 a steering torque command value T * c,int (=N·T * m,int ) and the actual steering angle θ, which is the plant output c,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.

[0067] 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.

[0068] The disturbance torque compensator 66 calculates the basic torque command value (T fb,int +T ff,int ) to the estimated disturbance torque ^T lcBy 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.

[0069] 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 provided to torque control section 48 (see FIG. 2).

[0070] 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.

[0071] 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 load torque T rl is given.

[0072] 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.

[0073] 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).

[0074]

number

[0075] The state equation for the physical model 101 in FIG. 7 is expressed by the following equation (4).

[0076]

number

[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]

number

[0080] From the extended state equation of the above formula (5), a disturbance observer (extended state observer) expressed by the following formula (7) is constructed.

[0081]

number

[0082]

number

[0083] The disturbance torque estimation unit 64 calculates the state variable vector ^x based on the equation (7). e Calculate the following.

[0084] FIG. 8 is a block diagram showing the configuration of the disturbance torque estimating unit 64.

[0085] 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.

[0086] The steering 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.

[0087] 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.

[0088] 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.

[0089] 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).

[0090] The input matrix multiplication unit 85 multiplies the input vector u1 output from the input vector input unit 81 by the input matrix B eThe second adder 87 multiplies the output (Be·u1) of the input matrix multiplier 85 by the output (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 ^θ c,int and the estimated angular velocity d^θ c,int Calculates / dt.

[0091] 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).

[0092]

number

[0093] 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.

[0094] 9 is a block diagram showing the electrical configuration of torque control unit 48. 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] Next, the operation of the road surface load characteristic setting unit 44 will be described in detail. In the driving assistance mode, the road surface load characteristic setting unit 44 performs a spring constant setting process for setting the spring constant k and a viscous damping coefficient setting process for setting the viscous damping coefficient c. These processes will be described below.

[0099] Fig. 10 is a flowchart showing the steps of the spring constant setting process performed by the road surface load characteristic setting unit 44. The spring constant setting process shown in Fig. 10 is started every time the driving assistance mode is started, and is repeatedly performed at predetermined calculation intervals until the driving assistance mode is canceled.

[0100] In the following, ΔT is the time (sampling time) corresponding to one calculation period. off is the duration of the release state. k min is the preset minimum spring constant. The normal value of the spring constant k is the minimum spring constant k min It is set as k max is the maximum spring constant that has been set in advance. decrease is the spring constant decrease amount in one calculation cycle that is set in advance. increase is the spring constant increase amount in one calculation cycle that is preset. The initial value of k is k min T off The initial value of is 0.

[0101] The road surface load characteristic setting unit 44 determines whether the result of the determination by the hands-on / off determination unit 43 is a hands-off state (step S1).

[0102] If the result of the determination by the hands-on / off determination unit 43 is the gripped state (step S1: NO), the road surface load characteristic setting unit 44 determines the duration T off is set to zero (step S2). Then, the road load characteristic setting unit 44 determines whether the spring constant k is equal to the minimum spring constant k min It is determined whether it is greater than (step S3).

[0103] The spring constant k is the minimum value k min If it is greater than (step S3: YES), the road surface load characteristic setting unit 44 calculates the spring constant reduction amount k from the spring constant k. decrease The value obtained by subtracting k from the spring constant k is set as the spring constant k (step S4). decrease The value obtained by subtracting is the minimum spring constant k minIf the spring constant is smaller than the minimum spring constant k min is set as the spring constant k. Then, the road surface load characteristic setting unit 44 ends the processing in the current calculation cycle.

[0104] In step S3, the spring constant k is set to the minimum spring constant k min If it is determined that the spring constant is equal to or smaller than the minimum spring constant k (step S3: NO), the road load characteristic setting unit 44 sets the minimum spring constant k min is set as the spring constant k (step S5). Then, the road surface load characteristic setting unit 44 ends the processing in the current calculation cycle.

[0105] In step S1, when the hands-on / off determining unit 55 determines that the hands are not in the hands-off state (step S1: YES), the road load characteristic setting unit 44 determines the duration T off The value obtained by adding ΔT to off (Step S6). In other words, the duration of the hands-off state T off will be updated.

[0106] Next, the road load characteristic setting unit 44 sets the duration T off is a given time T LCA (Step S7) off is a given time T LCA If it is less than or equal to T off ≦T LCA If so (step S7: NO), the road surface load characteristic setting unit 44 proceeds to step S3.

[0107] In step S7, the duration T off is a given time T LCA If it is determined to be longer than T off >T LCA If it is determined that the spring constant k is equal to or greater than the maximum spring constant k (step S7: YES), the road surface load characteristic setting unit 44 max (Step S8) It is determined whether the spring constant k is smaller than the maximum spring constant k maxIf it is smaller than k (step S8: YES), the road surface load characteristic setting unit 44 adds the spring constant k to the spring constant increment k increase The value obtained by adding the above is set as the spring constant k (step S9). increase The value obtained by adding the above is the maximum spring constant k max If the spring constant is larger than the maximum spring constant k max is set as the spring constant k. Then, the road surface load characteristic setting unit 44 ends the processing in the current calculation cycle.

[0108] In step S8, the spring constant k is set to the maximum spring constant k max If it is determined that the spring constant is equal to or greater than the maximum spring constant k (step S8: NO), the road load characteristic setting unit 44 calculates the maximum spring constant k max is set as the spring constant k (step S10: NO), and the gain setting unit 73 ends the processing in the current calculation cycle.

[0109] The viscous damping coefficient setting process is the same as the spring constant setting process in Fig. 10. However, in the viscous damping coefficient setting process, the spring constant k and the minimum spring constant k in Fig. 10 are min , maximum spring constant k max , spring constant reduction amount k decrease and spring constant increase k increase are the viscous damping coefficient c and the minimum viscous damping coefficient c, respectively. min , the maximum value of the viscous damping coefficient c max , viscous damping coefficient reduction amount c decrease and the viscous damping coefficient increase c increase can be replaced by

[0110] When the driving mode is the normal mode, the road load characteristic setting unit 44 sets the minimum spring constant k min is set as the spring constant k, and the minimum viscous damping coefficient c min is set as the viscous damping coefficient c. In other words, in normal mode, the spring constant k and the viscous damping coefficient c are not changed.

[0111] In the above-described embodiment, when the hands-on / off determination unit 55 determines that the vehicle is in a hands-off state for a predetermined period of time or longer in the driving assistance mode, the road load characteristics (spring constant k and viscous damping coefficient c) used by the command value setting unit 52 are increased. When the road load characteristics k and c are increased, the manual steering command value θ * c,md As a result, the amount of rotation of the output shaft 9 based on the driver torque becomes smaller, so that the torsion bar 10 is more likely to twist even with a relatively small rotation of the steering wheel 2 operated by the driver. tb and driver torque increases, which increases the accuracy of the hands-on / off determination by the hands-on / off determination unit 55. This makes it possible to prevent or suppress erroneous determination that the driver is in a hands-off state despite gripping the steering wheel 2 in situations where there is little driver torque input, such as when driving in a straight line.

[0112] [3] Modification of motor control ECU 202 FIG. 11 is a block diagram for explaining the electrical configuration of a modified example of motor control ECU 202. In FIG.

[0113] The motor control ECU 202 includes a microcomputer 40A, a drive circuit (inverter circuit) 31 controlled by the microcomputer 40A 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.

[0114] The microcomputer 40A 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 an assist control section 111, an automatic steering control section 112, an integrated torque calculation section (integrated control amount calculation section) 113, a torque control section (control section) 114, an actual steering angle calculation section 115, a hands-on / off determination section 116, an actual automatic steering angle calculation section 117, and a road load characteristic setting section 118.

[0115] The assist control unit 111 calculates an assist torque command value (assist control amount) T * m,md The assist control unit 11 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 The assist control unit 111 sets the assist torque command value T * m,md Set.

[0116] The automatic steering control unit 112 receives an automatic steering angle command value θ * c,ad and the actual automatic steering angle θ c,ad Using this, the automatic steering torque command value (automatic steering control amount) T required for automatic steering is calculated. * m,ad The automatic steering control unit 112 will be described in detail later.

[0117] The integrated torque calculation unit 113 calculates the assist torque command value T * m,md The automatic steering torque command value T * m,ad By adding these, the integrated torque command value (integrated control amount) T * m,int Calculate the following.

[0118] The torque control unit 114 controls the motor torque of the electric motor 18 to be equal to the integrated torque command value T * m,int The drive circuit 31 is driven so that the torque control section 114 approaches the torque control section 48. The configuration of the torque control section 114 is the same as the configuration of the torque control section 48 shown in Fig. 9, and therefore a description thereof will be omitted.

[0119] The actual steering angle calculation unit 115 calculates the rotation angle θ of the output shaft 9 based on the output signal of the rotation angle sensor 23. c,int Specifically, the actual steering angle calculation unit 115 includes a rotation angle calculation unit 115A and a reduction ratio division unit 115B. The rotation angle calculation unit 115A 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 115B calculates the rotor rotation angle θ calculated by the rotation angle calculation unit 115A. m,int is divided by the reduction ratio N of the reducer 19, the rotor rotation angle θ m,int The rotation angle (actual steering angle) of the output shaft 9 is θ c,int Convert to.

[0120] Actual steering angle θ c,int is the steering torque T tb and the assist torque command value T * m,md The steering angle of the manual steering based on the actual manual steering angle θ c,md ") and the automatic steering torque command value T * m,ad The steering angle for automatic steering based on the actual automatic steering angle θ c,ad ").

[0121] The hands-on / off determination unit 116 determines whether the device is in a gripped state or a hands-off state using a method similar to that used by the hands-on / off determination unit 42 in FIG.

[0122] The actual automatic steering angle calculation unit 117 calculates the actual steering angle θ c,int The actual automatic steering angle θ included in c,ad Specifically, the actual automatic steering angle calculation unit 117 includes an actual manual steering angle calculation unit 117A and a subtraction unit 117B. The actual manual steering angle calculation unit 117A calculates the steering torque Ttb , assist torque command value T * m,md and the actual manual steering angle θ based on the spring constant k and the viscous damping coefficient c set by the road surface load characteristic setting unit 118. c,md The subtraction unit 117B calculates the actual steering angle θ calculated by the actual steering angle calculation unit 115. c,int The actual manual steering angle θ calculated by the actual manual steering angle calculation unit 117A from c,md By subtracting the actual automatic steering angle θ c,ad The actual automatic steering angle θ c,ad is given to the automatic steering control unit 112.

[0123] In this embodiment, the actual manual steering angle calculation unit 117A calculates the actual manual steering angle θ using a reference model (reference EPS model) of the electric power steering system 1. c,md Calculate the following.

[0124] The actual manual steering angle calculation unit 117A calculates the actual manual steering angle θ using, for example, the reference EPS model shown in FIG. 5 described above. c,md Calculate the following.

[0125] Referring to Figure 5, the road load torque T rl is expressed by the above equation (1) using the spring constant k and the viscous damping coefficient c.

[0126] The spring constant k and viscous damping coefficient c are set by road load characteristic setting unit 118. In driving assistance mode, road load characteristic setting unit 118 sets the spring constant k and viscous damping coefficient c based on the hands-on / off determination result of hands-on / off determination unit 116. The method of setting the spring constant k and viscous damping coefficient c by road load characteristic setting unit 118 is the same as the method of setting the spring constant k and viscous damping coefficient c by road load characteristic setting unit 44 in Fig. 2 described above, and therefore description thereof will be omitted.

[0127] The equation of motion of the reference EPS model in Fig. 5 is expressed by the above-mentioned equation (2). The actual manual steering angle calculation unit 116A calculates the rotation angle θ of the lower column by solving the differential equation of equation (2). c Calculate the rotation angle θ c Actual manual steering angle θ c,md Set as.

[0128] The automatic steering control unit 112 will be described in detail below.

[0129] FIG. 12 is a block diagram showing the configuration of the automatic steering control unit 112.

[0130] The automatic steering control unit 112 calculates the automatic steering angle command value θ * c,ad and the actual automatic steering angle θ c,ad and the automatic steering torque command value T * m,ad The automatic steering control unit 112 includes a low-pass filter (LPF) 161, a feedback control unit 162, a feedforward control unit 163, a disturbance torque estimation unit 164, a torque addition unit 165, a disturbance torque compensation unit 166, a reduction ratio division unit 167, and a reduction ratio multiplication unit 168.

[0131] The reduction ratio multiplication unit 168 multiplies the automatic steering torque command value T * m,ad is multiplied by the reduction ratio N of the reducer 19 to obtain the automatic steering torque command value T * m,ad is the automatic output shaft torque command value N·T acting on the output shaft 9 (worm wheel 21). * m,ad (=T * c,ad )

[0132] The low-pass filter 161 detects the automatic steering angle command value θ * c,ad The automatic steering angle command value θ after low-pass filtering is * c,adfis given to the feedback control section 162 and the feedforward control section 163.

[0133] The feedback control unit 162 receives the actual automatic steering angle θ calculated by the actual automatic steering angle calculation unit 117 (see FIG. 11). c,ad is the automatic steering angle command value θ after low-pass filtering. * c,adf The feedback control unit 162 includes an angle deviation calculation unit 162A and a PD control unit 162B. The angle deviation calculation unit 162A calculates an automatic steering angle command value θ * c,adf and the actual automatic steering angle θ c,ad Deviation Δθ c,ad (=θ * c,adfd -θ c,ad ) is calculated. The angle deviation calculation unit 162A calculates the automatic steering angle command value θ * c,adf and the actual automatic steering angle estimated value ^θ calculated by the disturbance torque estimation unit 164. c,ad deviation from (θ * c,adfd -^θ c,ad ) and the angle deviation Δθ c,ad It may be calculated as:

[0134] The PD control unit 162B calculates the angle deviation Δθ calculated by the angle deviation calculation unit 162A. c,ad By performing PD calculation (proportional differential calculation) on the feedback control torque T fb,ad Calculate the feedback control torque T fb,ad is given to the torque adder 165.

[0135] The feedforward control unit 163 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 163 includes an angular acceleration calculation unit 163A and an inertia multiplication unit 163B. The angular acceleration calculation unit 163A calculates an automatic steering angle command value θ * c,adf By differentiating twice, the target angular acceleration d 2 θ* c,adf / dt 2 Calculate the following.

[0136] The inertia multiplication unit 163B multiplies the target angular acceleration d calculated by the angular acceleration calculation unit 163A by 2 θ * c,adf / dt 2 is multiplied by the inertia J of the electric power steering system 1 to obtain the feedforward control torque T ff,ad (=J·d 2 θ * c,adf / dt 2 The inertia J can be calculated from, for example, a physical model (see FIG. 13) of the electric power steering system 1, which will be described later. The feedforward control torque T ff,ad is given to the torque adder 165 as an inertia compensation value.

[0137] The torque adder 165 calculates the feedback control torque T fb,ad to the feedforward control torque T ff,ad By adding fb,ad +T ff,ad ) is calculated.

[0138] The disturbance torque estimation unit 164 mainly estimates the disturbance torque T other than the motor torque acting on the object to be driven by the electric motor 18. lc The disturbance torque T for automatic steering included in lc,ad The automatic disturbance torque estimate ^T lc,ad The disturbance torque T for automatic steering is calculated. lc,ad The automatic steering torque command value T * m,ad This refers to torque other than the motor torque that occurs as a disturbance in the driven object (plant) of the electric motor 18 when it is assumed that only automatic steering control based on the above is being performed.

[0139] Automatic steering torque command value T * m,adIf we assume that only automatic steering control based on the above is performed, the target value of the plant is the automatic output shaft torque command value N·T * m,ad (=T * c,ad ) and the plant output is the actual automatic steering angle θ c,ad Therefore, the disturbance torque estimation unit 164 calculates the automatic output shaft torque command value N·T * m,ad (=T * c,ad ) and actual automatic steering angle θ c,ad and based on the automatic disturbance torque T lc,ad and the actual automatic steering angle θ c,ad and the actual automatic steering angle θ c,ad Derivative value (actual automatic angular velocity) dθ c,ad / dt. In the following, T lc,ad , θ c,ad and dθ c,ad / dt estimates, respectively, lc,ad , ^θ c,ad and ^dθ c,ad The disturbance torque estimation unit 164 will be described in detail later.

[0140] The automatic disturbance torque estimated value ^T calculated by the disturbance torque estimation unit 164 lc,ad is given to the disturbance torque compensator 166 as an automatic disturbance torque compensation value.

[0141] The disturbance torque compensator 166 calculates the basic torque command value (T fb,ad +T ff,ad ) to the automatic disturbance torque estimate ^T lc,ad By subtracting the automatic output shaft torque command value T * c,ad (=T fb,ad +T ff,ad -^T lc,ad ) is calculated. This results in the automatic output shaft torque command value T * c,ad (target torque for output shaft 9) is obtained.

[0142] Automatic output shaft torque command value T *c,ad is given to the reduction ratio division unit 167. The reduction ratio division unit 167 calculates the automatic output shaft torque command value T * c,ad By dividing by the reduction ratio N, the automatic steering torque command value T * m,ad (target torque for the electric motor 18). * m,ad is given to the integrated torque calculation unit 113 (see FIG. 11).

[0143] The disturbance torque estimation unit 164 will be described in detail. The disturbance torque estimation unit 164 uses, for example, a physical model 101A of the electric power steering system 1 shown in FIG. 13 to calculate an automatic disturbance torque estimation value ^T lc,ad , actual automatic steering angle estimate ^θ c,ad and actual automatic angular velocity estimate ^dθ c,ad The automatic steering torque command value T * m,ad This shows a physical model assuming that only automatic steering control based on

[0144] This physical model 101A includes a plant (an example of a motor-driven object) 102A including an output shaft 9 and a worm wheel 21 fixed to the output shaft 9. The plant 102A includes a steering torque (torsion bar torque) T tb is applied, and a road load torque T rl,ad Furthermore, the plant 102A receives an automatic output shaft torque command value N·T from the motor via the worm gear 20. * m,ad is given, and friction torque T f,ad is given.

[0145] When the inertia of the plant 102A is J, the equation of motion for the inertia of the physical model 101A is expressed by the following equation (10).

[0146]

number

[0147] The state equation for the physical model 101A in FIG. 13 is expressed by the following equation (11).

[0148]

number

[0149] 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 (12).

[0150]

number

[0151]

number

[0152] From the extended state equation of the above-mentioned equation (12), a disturbance observer (extended state observer) expressed by the following equation (14) is constructed.

[0153]

number

[0154]

number

[0155] The disturbance torque estimation unit 164 calculates the state variable vector ^x based on the equation (14). e Calculate the following.

[0156] FIG. 14 is a block diagram showing the configuration of the disturbance torque estimation unit 164.

[0157] The disturbance torque estimation unit 164 includes an input vector input unit 181, an output matrix multiplication unit 182, a first addition unit 183, a gain multiplication unit 184, an input matrix multiplication unit 185, a system matrix multiplication unit 186, a second addition unit 187, an integration unit 188, and a state variable vector output unit 189.

[0158] The automatic output shaft torque command value N·T calculated by the reduction ratio multiplication unit 168 (see FIG. 12) * m,ad (=T * c,ad ) is given to the input vector input unit 181. The input vector input unit 181 outputs the input vector u1.

[0159] The output of the integrator 188 is the state variable vector ^x e (See the above equation (15)). At the start of the calculation, the state variable vector ^x e The initial value is given as the state variable vector ^x e The initial value of is, for example, 0.

[0160] The system matrix multiplication unit 186 multiplies the state variable vector ^x e In the system matrix A e The output matrix multiplication unit 182 multiplies the state variable vector ^x e into the output matrix C e Multiply by.

[0161] The first adder 183 calculates the actual automatic steering angle θ c,ad From the output vector y, which is e ^x e ) is subtracted from the output vector y. That is, the first adder 183 subtracts the output vector estimate ^y(=C e ^x e ) and calculates the difference (y-^y). The gain multiplication unit 184 multiplies the output (y-^y) of the first addition unit 183 by the observer gain L (see the above equation (14)).

[0162] The input matrix multiplication unit 185 multiplies the input vector u1 output from the input vector input unit 181 by the input matrix B e The second adder 187 multiplies the output (B e u1) and the output of the system matrix multiplication unit 186 (A e ^x e ) and the output (L(y-^y)) of the gain multiplication unit 184, the differential value d^x of the state variable vector is obtained. eThe integrator 188 calculates the output (d^x e / dt), the state variable vector ^x e The state variable vector output unit 189 calculates the state variable vector ^x e Based on this, the automatic disturbance torque estimate ^T lc,ad , actual automatic steering angle estimate ^θ c,ad and actual automatic angular velocity estimate d^θ c,ad Calculates / dt.

[0163] Instead of the above-mentioned extended state observer, a disturbance observer consisting of an inverse model of the plant and a low-pass filter may be used. In this case, the equation of motion of the plant is expressed by Equation (10) as described above.

[0164] Therefore, the inverse model of the plant is given by the following equation (16).

[0165]

number

[0166] In this modification, the feedback control torque T fb,ad The automatic steering torque command value T is calculated based on the * m,ad and the assist torque command value T * m,md The integrated torque command value T * m,int Therefore, in the driving assistance mode, the electric motor 18 is driven based on the automatic steering torque command value T* m,ad The output shaft 9 is rotated based on the torque, and the steering torque T tb and the assist torque command value T * m,md The output shaft 9 is rotated based on the

[0167] In the driving assistance mode, when the hands-on / off determination unit 116 determines that the vehicle is in a hands-off state for a predetermined period of time or more, the road load characteristics (spring constant k and viscous damping coefficient c) used in the actual manual steering angle calculation unit 117A are increased. When the road load characteristics k and c are increased, the actual manual steering angle θ c,md , that is, the absolute value of the angle at which the driver is allowed to steer in response to driving assistance, becomes smaller than normal.

[0168] As a result, the actual automatic steering angle θ used for feedback control c,ad The value of becomes larger than normal, and the feedback control torque T fb,ad , automatic steering torque command value T * m,ad are transmitted in order and reflected in the torque command value of the motor.

[0169] As a result, the amount of rotation of the output shaft 9 based on the driver torque is reduced, similar to the embodiment of FIG. 2. This makes it difficult for the rotation of the steering wheel 2 to be transmitted, making it easier for the torsion bar 10 to twist. This reduces the steering torque T tb and driver torque increases, which increases the accuracy of the hands-on / off determination by the hands-on / off determination unit 116. This makes it possible to prevent or suppress erroneous determination that the driver is in a hands-off state despite gripping the steering wheel 2 in situations where there is little driver torque input, such as when driving in a straight line.

[0170] In the normal mode, the assist torque command value T * m,md is the integrated torque command value T* m,int Therefore, in the normal mode, the assist torque command value T * m,md The drive circuit 31 is driven based only on the signal.

[0171] In the above-described embodiment, in the driving assistance mode, the road surface load characteristic setting unit 44, 118 changes both the spring coefficient k and the viscous damping coefficient c based on the hands-on / off determination result, but it is also possible to change only one of the spring coefficient k and the viscous damping coefficient c.

[0172] 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.

[0173] 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]

[0174] 1...electric power steering device, 3...steered wheels, 4...steering mechanism, 18...electric motor, 43...hands on / off determination unit, 44...road surface load characteristic setting unit, 45...manual steering command value generation unit, 46...integrated angle command value calculation unit, 47...angle control unit, 48...torque control unit, 51...assist torque command value setting unit, 52...command value setting unit, 111...assist control unit, 112...automatic steering control unit, 113...integrated torque calculation unit (integrated control amount calculation unit), 114...torque control unit (control unit), 115...actual steering angle calculation unit, 116...hands on / off determination unit, 117...actual automatic steering angle calculation unit 117A...actual manual steering angle calculation unit, 117B...subtraction unit, 118...road surface load characteristic setting unit, 201...host ECU 201, 202...motor control ECU

Claims

1. a torque detection unit for detecting a steering torque; a manual steering command value generating unit that generates a manual steering command value using the steering torque; an integrated angle command value calculation unit that calculates an integrated angle command value by adding the manual steering command value to an automatic steering command value 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; a hands-on / off determination unit that determines whether the driver is in a gripped state where the driver is gripping the steering wheel or in a hands-off state where the driver is not gripping the steering wheel, the manual steering command value generation unit is configured to generate the manual steering command value by using the steering torque, and a spring constant and a viscous damping coefficient for generating a road surface load torque, The motor control device further includes a road surface load characteristic change unit that increases the value of at least one of the spring constant and the viscous damping coefficient when, in the driving assistance mode, the hands-on / off determination unit determines that the vehicle is in a hands-off state for a predetermined period of time or more.

2. A motor control device including: a torque detection unit for detecting steering torque; a steering angle detection unit for detecting an actual steering angle; an automatic steering control unit for setting an automatic steering control amount based on an automatic steering command value given in a driving assistance mode; an assist control unit for setting an assist control amount using the steering torque; an integrated control amount calculation unit for calculating an integrated control amount by adding the automatic steering control amount and the assist control amount; and a control unit for controlling an electric motor for steering angle control based on the integrated control amount, a hands-on / off determination unit that determines whether the driver is in a gripped state where the driver is gripping the steering wheel or in a hands-off state where the driver is not gripping the steering wheel; an actual manual steering angle calculation unit that calculates an actual manual steering angle, which is a steering angle for manual steering based on the steering torque and the assist control amount; an actual automatic steering angle calculation unit that calculates an actual automatic steering angle, which is a steering angle for automatic steering based on the automatic steering control amount, by subtracting the actual manual steering angle from the actual steering angle, the automatic steering control unit sets the automatic steering control amount using the automatic steering command value and the actual automatic steering angle, the actual manual steering angle calculation unit is configured to calculate the actual manual steering angle by using the steering torque, the assist control amount, and a spring constant and a viscous damping coefficient for generating a road surface load torque, The motor control device further includes a road surface load characteristic change unit that increases the value of at least one of the spring constant and the viscous damping coefficient when, in the driving assistance mode, the hands-on / off determination unit determines that the vehicle is in a hands-off state for a predetermined period of time or more.

3. If the spring constant and the viscous damping coefficient, the values ​​of which are changed by the road load characteristic changing unit, are defined as road load variables, then 3. The motor control device according to claim 1, wherein, when the hands-on / off determination unit determines that the vehicle is in a hands-off state for a predetermined period of time in the driving assistance mode, the road load characteristic change unit gradually increases the value of the road load variable from that point on while the hands-on / off determination unit determines that the vehicle is in a hands-off state, and when the road load variable reaches a predetermined upper limit value, the road load characteristic change unit maintains the value of the road load variable at the upper limit value.

4. 4. The motor control device according to claim 3, wherein, in the driving assistance mode, when the hands-on / off determination unit determines that the vehicle is in a hands-off state for a predetermined period of time or more and then changes the determination result by the hands-on / off determination unit to a gripped state, the road load characteristic change unit gradually decreases the value of the road load variable from that point onwards while the determination result that the vehicle is in a gripped state continues, and when the road load variable reaches a predetermined lower limit value, the road load variable is maintained at the lower limit value.

Images