Control device, electric power steering apparatus, and drive apparatus

Abstract

To provide: a control device capable of improving controllability of a control target configured as a two-inertial system; an electric power steering apparatus including the control device; and a drive apparatus including the control device.SOLUTION: A control device includes a model following control section. The model following control section is configured such that a transfer function of a control target is restricted to a transfer function of a nominal model in a frequency band where a complementary sensitivity gain is approximately 1. The complementary sensitivity gain is a gain in a gain characteristic of a complementary sensitivity function with respect to a modeling error between the control target and the nominal model. A steady gain of the complementary sensitivity function is 0.1 or greater. A lower limit value of a frequency band where the complementary sensitivity gain is 1 is higher than a first resonance frequency that is a resonance frequency of a yaw rate of a vehicle. A second resonance frequency that is a resonance frequency of a steering mechanism is higher than the first resonance frequency and lower than the lower limit value of the frequency band where the complementary sensitivity gain is 1.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a control device, an electric power steering device, and a drive device. [Background technology]

[0002] 2. Description of the Related Art An electric power steering system mounted on a vehicle is known (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-183046 A Summary of the Invention [Problem to be solved by the invention]

[0004] The electric power steering system described above is configured as a two-inertia system in which the steering wheel and the steering mechanism are connected via a torsion bar, which is a spring element. A controlled object configured as such a two-inertia system has the problem that it is more difficult to control than a one-inertia system.

[0005] In view of the above circumstances, one object of the present invention is to provide a control device that can improve the controllability of a control object configured as a two-inertia system, an electric power steering device equipped with such a control device, and a drive device equipped with such a control device. [Means for solving the problem]

[0006] One embodiment of the control device of the present invention is a control device that controls, as a controlled object, a part of a steering mechanism mounted on a vehicle, the steering mechanism having an input shaft connected to a steering wheel operated by a driver, an output shaft connected to the input shaft via a torsion bar, and a motor connected to the output shaft, at least the part including the motor. The control device includes a model following control unit that generates a correction torque for correcting an input torque input to the controlled object based on an output of the controlled object and a nominal model based on a configuration of the controlled object. The model following control unit is configured such that a transfer function of the controlled object is constrained to a transfer function of the nominal model in a frequency band in which a complementary sensitivity gain, which is a gain in a gain characteristic of a complementary sensitivity function with respect to a modeling error between the controlled object and the nominal model, is approximately 1. The steady-state gain of the complementary sensitivity function is 0.1 or more. The lower limit of the frequency band in which the complementary sensitivity gain is 1 is higher than a first resonance frequency, which is a resonance frequency of a yaw rate of the vehicle. A second resonant frequency, which is a resonant frequency of the steering mechanism, is higher than the first resonant frequency and is lower than a lower limit value of a frequency band in which the complementary sensitivity gain is 1. The complementary sensitivity gain at the second resonant frequency is higher than the complementary sensitivity gain at the first resonant frequency, is equal to or greater than 0.5, and is less than 1.

[0007] One embodiment of the control device of the present invention is a control device that controls a controlled object including a motor in a drive device that rotates a drive shaft to which tires of a vehicle are connected. The control device includes a model following control unit that generates a correction torque for correcting an input torque input to the controlled object based on an output of the controlled object and a nominal model based on a configuration of the controlled object. The model following control unit is configured such that a transfer function of the controlled object is constrained to a transfer function of the nominal model in a frequency band in which a complementary sensitivity gain, which is a gain in a gain characteristic of a complementary sensitivity function with respect to a modeling error between the controlled object and the nominal model, is approximately 1. The steady-state gain of the complementary sensitivity function is 0.1 or more. A lower limit value of the frequency band in which the complementary sensitivity gain is 1 is higher than a first resonance frequency that is a resonance frequency of the drive device. A second resonance frequency that is a resonance frequency of a drive mechanism including the tires, the drive shaft, and the drive device is higher than the first resonance frequency and lower than a lower limit value of a frequency band in which the complementary sensitivity gain is 1. The complementary sensitivity gain at the second resonant frequency is higher than the complementary sensitivity gain at the first resonant frequency, and is greater than or equal to 0.5 and less than 1.

[0008] An electric power steering device of the present invention includes the above-mentioned control device and the steering mechanism.

[0009] A drive device of the present invention includes the above control device, the motor, and a gear mechanism connected to the motor. Effect of the Invention

[0010] According to one aspect of the present invention, in an electric power steering device and a drive device, it is possible to improve the controllability of a controlled object configured as a two-inertia system. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an electric power steering device according to an embodiment. [Diagram 2]FIG. 2 is a block diagram illustrating a configuration of the control device according to an embodiment. [Diagram 3] FIG. 3 is a functional block diagram illustrating functions of a processor in the control device according to one embodiment. [Figure 4] FIG. 4 is a graph showing an example of the relationship between the steering angle and the assist torque. [Diagram 5] FIG. 5 is a functional block diagram illustrating functions of the vehicle stabilization compensation unit according to one embodiment. [Figure 6] FIG. 6 is a graph illustrating the gain characteristic of the complementary sensitivity function and the gain characteristic of the reciprocal of the modeling error between the transfer function of the controlled object and the transfer function of the nominal model. [Figure 7] FIG. 7 is a graph showing an example of the relationship between the steering angle and the self-aligning torque. [Figure 8] FIG. 8 is a graph showing an example of the measurement results of the steering angle and the rotational angular velocity when the model following control is not applied. [Figure 9] FIG. 9 is a graph showing an example of the measurement results of the steering angle and the rotational angular velocity when the model following control is applied. [Figure 10] FIG. 10 is a diagram showing a simplified model of the electric power steering device of one embodiment. [Figure 11] FIG. 11 is a diagram illustrating a schematic diagram of a drive device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <Electric power steering device> An electric power steering device 1000 of this embodiment shown in Fig. 1 is mounted on a vehicle. As shown in Fig. 1, the electric power steering device 1000 includes a steering mechanism 530 and a control device 100. The steering mechanism 530 includes a steering mechanism section 520 and an auxiliary mechanism section 540. The electric power steering device 1000 controls the auxiliary mechanism section 540 by the control device 100, thereby controlling the steering torque T generated in the steering mechanism section 520 when a driver of the vehicle steers a steering wheel 521. h The assist torque is generated to assist the steering wheel 521. The assist torque reduces the burden on the driver when the driver operates the steering wheel 521. The driver of the vehicle is a person who steers the steering wheel 521 of the vehicle.

[0013] The steering mechanism 520 has a handle 521, a steering shaft 522, universal joints 523A, 523B, an input shaft 524a, an output shaft 524b, a rack and pinion mechanism 525, a rack shaft 526, left and right ball joints 552A, 552B, tie rods 527A, 527B, knuckles 528A, 528B, and left and right tires 529A, 529B. That is, the steering mechanism 530 has a handle 521, a steering shaft 522, universal joints 523A, 523B, an input shaft 524a, an output shaft 524b, a rack and pinion mechanism 525, a rack shaft 526, left and right ball joints 552A, 552B, tie rods 527A, 527B, knuckles 528A, 528B, and left and right tires 529A, 529B.

[0014] The steering shaft 522 is a shaft extending from the handle 521 steered by the driver. One end of the input shaft 524a is connected to the end of the steering shaft 522 opposite to the end connected to the handle 521 via universal joints 523A and 523B. Thus, the handle 521 is connected to the input shaft 524a via the universal joints 523A and 523B and the steering shaft 522. The output shaft 524b is connected to the input shaft 524a via a torsion bar 546 described later. More specifically, one end of the output shaft 524b is connected to the other end of the input shaft 524a via the torsion bar 546. The other end of the output shaft 524b is connected to the rack shaft 526 via a rack and pinion mechanism 525.

[0015] The input shaft 524a and the output shaft 524b are arranged coaxially. The input shaft 524a and the output shaft 524b are rotatable around the same central axis. The input shaft 524a and the output shaft 524b are rotatable relative to each other within a range in which a torsion bar 546 (described later) can be twisted.

[0016] The auxiliary mechanism 540 has a steering torque sensor 541, a steering angle sensor 542, a motor 543, a reduction gear mechanism 544, an inverter 545, and a torsion bar 546. That is, the steering mechanism 530 has the steering torque sensor 541, the steering angle sensor 542, the motor 543, the reduction gear mechanism 544, the inverter 545, and the torsion bar 546. The torsion bar 546 connects the input shaft 524a and the output shaft 524b. The torsion bar 546 is disposed coaxially with the input shaft 524a and the output shaft 524b. In the following description, a virtual axis passing through the common central axis of the input shaft 524a, the output shaft 524b, and the torsion bar 546 is referred to as a rotation axis R. The torsion bar 546 can twist around the rotation axis R.

[0017] The steering torque sensor 541 detects the amount of twist of the torsion bar 546 around the rotation axis R, thereby detecting the steering torque T hDetects the steering torque T h is a torsion bar torque generated in the torsion bar 546, and is a torsional moment about the rotation axis R. The steering angle sensor 542 detects a rotation angle θ of the input shaft 524a about the rotation axis R. a The rotation angle θ of the input shaft 524a can be detected. a is the steering angle θ of the steering wheel 521. h That is, the steering angle sensor 542 detects the rotation angle θ of the input shaft 524a. a By detecting the steering angle θ of the steering wheel 521, h Based on the steering torque sensor 541 and the steering angle sensor 542, the rotation angle θ of the output shaft 524b can be detected. b The rotation angle θ of the output shaft 524b can be detected. b is the steering angle θ s It is.

[0018] The inverter 545 converts DC power into three-phase AC power, which is a pseudo-sine wave of U-phase, V-phase, and W-phase, in accordance with a motor drive signal input from the control device 100, and supplies the power to the motor 543. The motor 543 is connected to the output shaft 524b via a reduction gear mechanism 544. The three-phase AC power is supplied to the motor 543 from the inverter 545. The motor 543 is, for example, an interior permanent magnet synchronous motor (IPMSM), a surface mounted permanent magnet synchronous motor (SPMSM), a switched reluctance motor (SRM), or the like. The motor 543 generates a steering torque T by receiving the three-phase AC power from the inverter 545. h The motor 543 transmits the generated auxiliary torque to the output shaft 524b via the reduction gear mechanism 544.

[0019] The control device 100 controls at least a part including a motor 543 of a steering mechanism 530 mounted on a vehicle as a controlled object 560. In this embodiment, the controlled object 560 has a steering mechanism section 520, a torsion bar 546, a motor 543, and a reduction mechanism 544. Since the controlled object 560 includes an input shaft 524a and an output shaft 524b that can rotate relatively to each other via the torsion bar 546, the motion of the controlled object 560 cannot be described only by a simple equation of motion of a one-inertia system. The controlled object 560 changes between a one-inertia system and a two-inertia system depending on the strength with which the steerer grips the handle 521. The stronger the steerer grips the handle 521, the closer the controlled object 560 is to a one-inertia system. The weaker the steerer grips the handle 521, the closer the controlled object 560 is to a two-inertia system. In this way, the controlled object 560 is configured as a two-inertia system.

[0020] The control device 100 is electrically connected to the inverter 545. The control device 100 generates a motor drive signal based on detection signals detected by the steering torque sensor 541, the steering angle sensor 542, the vehicle speed sensor 300 mounted on the vehicle, and outputs the generated signal to the inverter 545. The control device 100 controls the rotation of the motor 543 via the inverter 545 to control the controlled object 560. More specifically, the control device 100 controls the switching operations of a plurality of switching elements included in the inverter 545. Specifically, the control device 100 generates a control signal for controlling the switching operations of each switching element and outputs the control signal to the inverter 545. Each switching element is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). In the following description, the control signal for controlling the switching operation of each switching element is called a "gate control signal."

[0021] The control device 100 detects the steering torque T hThe control device 100 generates a torque command value based on the above, and controls the torque and rotation speed of the motor 543 by, for example, vector control. The vector control is a method of decomposing the current flowing through the motor 543 into a current component that contributes to torque generation and a current component that contributes to magnetic flux generation, and independently controlling each of the mutually orthogonal current components. The control device 100 is not limited to vector control, and may perform other closed-loop control. The rotation speed of the motor 543 is expressed, for example, by the number of rotations the rotor rotates in one minute [rpm (revolutions per minute)], the number of rotations the rotor rotates in one second [rps (revolutions per second)], or the like.

[0022] The control device 100 receives the steering torque T directly from the steering torque sensor 541. h Alternatively, the control device 100 may calculate the steering torque T h The control device 100 may directly receive the steering angle θ of the steering wheel 521 from the steering angle sensor 542. h Alternatively, the control device 100 may input the steering angle θ h The value of may be calculated.

[0023] Moreover, the control device 100 and the motor 543 are modularized and manufactured and sold as a motor module. The motor module includes the motor 543 and the control device 100, and is suitable for use in the electric power steering device 1000. Moreover, the control device 100 can be manufactured and sold as a control device for controlling the electric power steering device 1000, independent of the motor 543.

[0024] 2 shows a typical example of the configuration of the control device 100 in this embodiment. The control device 100 includes, for example, a power supply circuit 111, an angle sensor 112, an input circuit 113, a communication I / F 114, a drive circuit 115, a ROM 116, and a processor 200. The control device 100 can be realized as a printed circuit board (PCB) on which these electronic components are mounted.

[0025] A vehicle speed sensor 300, a steering torque sensor 541, and a steering angle sensor 542 mounted on the vehicle are communicatively connected to the processor 200. The vehicle speed is transmitted from the vehicle speed sensor 300 to the processor 200. The steering torque sensor 541 transmits the steering torque T h The processor 200 receives the steering angle θ h is sent.

[0026] The processor 200 is a semiconductor integrated circuit, and is also called a central processing unit (CPU) or a microprocessor. The processor 200 sequentially executes a computer program, which is stored in the ROM 116 and describes a group of instructions for controlling the driving of the motor, to realize a desired process. In addition to the processor 200, or instead of the processor 200, the control device 100 may have a field programmable gate array (FPGA) equipped with a CPU, a graphics processing unit (GPU), an application specific integrated circuit (ASIC), an application specific standard product (ASSP), or a combination of two or more circuits selected from these circuits. The processor 200 sets a current command value according to an actual current value and a rotation angle of the rotor of the motor 543, and generates a pulse width modulation (PWM) signal, and outputs the PWM signal to the drive circuit 115.

[0027] The power supply circuit 111 is connected to an external power supply (not shown). The power supply circuit 111 generates a DC voltage required for each component of the control device 100. The DC voltage generated in the power supply circuit 111 is, for example, 3V or 5V.

[0028] The angle sensor 112 detects the rotation angle of the rotor of the motor 543 and outputs it to the processor 200. The angle sensor 112 may be a resolver, a Hall element such as a Hall IC, or an MR sensor having a magnetic resistance element. The processor 200 can calculate the angular velocity ω [rad / s] of the motor 543 based on the electrical angle θm of the motor 543 obtained based on the angle sensor 112. Note that the control device 100 may include, instead of the angle sensor 112, a speed sensor capable of detecting the rotation angular velocity of the motor 543 and an acceleration sensor capable of detecting the rotation angular acceleration of the motor 543.

[0029] A motor current value detected by a current sensor (not shown) is input to the input circuit 113. In the following description, the motor current value detected by the current sensor (not shown) is referred to as an "actual current value." The input circuit 113 converts the level of the input actual current value to an input level of the processor 200 as necessary, and outputs the actual current value to the processor 200. A typical example of the input circuit 113 is an analog-to-digital conversion circuit.

[0030] The communication I / F 114 is, for example, an input / output interface for transmitting and receiving data in accordance with an in-vehicle control area network (CAN: Controller Area Network).

[0031] The driving circuit 115 is typically a gate driver or a pre-driver. The driving circuit 115 generates a gate control signal according to a PWM signal and provides the gate control signal to the gates of a plurality of switching elements of the inverter 545. For example, when the motor 543 to be driven is a motor that can be driven at a low voltage, the driving circuit 115 as a gate driver may not necessarily be required. In that case, the function of the gate driver in the driving circuit 115 may be implemented in the processor 200.

[0032] The ROM 116 is electrically connected to the processor 200. The ROM 116 is, for example, a writable memory, a rewritable memory, or a read-only memory. An example of the writable memory is a PROM (Programmable Read Only Memory). An example of the rewritable memory is a flash memory and an EEPROM (Electrically Erasable Programmable Read Only Memory). The ROM 116 stores a control program including a group of instructions for causing the processor 200 to control the motor drive. For example, the control program stored in the ROM 116 is temporarily deployed in a RAM (not shown) at boot time.

[0033] FIG. 3 shows an example of the functional blocks of the processor 200 of this embodiment. The processor 200, which is a computer, sequentially executes processes or tasks required for controlling the motor 543 using each functional block. Each functional block of the processor 200 shown in FIG. 3 may be implemented in the processor 200 as software such as firmware, may be implemented in the processor 200 as hardware, or may be implemented in the processor 200 as software and hardware. The processing of each functional block in the processor 200 is typically described in a computer program in software module units and stored in the ROM 116. However, when using an FPGA or the like, all or a part of these functional blocks may be implemented as a hardware accelerator. In addition, the control method of the control device 100 in this embodiment may be implemented by being implemented in a computer and causing the computer to execute a desired operation.

[0034] The processor 200 has a controller 200a, a subtractor SU1, a torque conversion unit 211, and an adder AD1. The controller 200a has a reaction force control unit 210, a model following control unit 230, a state feedback unit 280, and a subtractor SU2. That is, the control device 100 includes the reaction force control unit 210, the model following control unit 230, the state feedback unit 280, the subtractors SU1 and SU2, and the adder AD1. In other words, the processor 200 of the control device 100 is implemented with functions corresponding to the reaction force control unit 210, the model following control unit 230, the state feedback unit 280, the subtractors SU1 and SU2, and the adder AD1.

[0035] The subtractor SU1 receives the steering angle θ detected based on the steering angle sensor 542. h The subtractor SU1 receives the steering angle θ h Based on the steering torque sensor 541 and the steering angle sensor 542, the steering angle θ s The result is output to the torque conversion unit 211.

[0036] The value output from the subtractor SU1 is input to the torque conversion unit 211. The torque conversion unit 211 multiplies the value output from the subtractor SU1 by a gain to obtain the steering torque T h The gain in the torque conversion unit 211 is the spring constant K tor Steering angle θ h and steering angle θ s The difference between the spring constant K of the torsion bar 546 tor The value multiplied by is the torsion bar torque, i.e., the steering torque T h The steering torque T h is input to the adder AD1 and the reaction force control unit 210.

[0037] The reaction force control unit 210 calculates the input torque T r The steering angle θ h and steering angle θ s The input torque T r is the target torque of the motor 543 and is a torque command value. The reaction force control unit 210 calculates the input torque T r By generating this to control the torque of the motor 543, the reaction force transmitted from the steering wheel 521 to the driver is controlled.

[0038] The reaction force control unit 210 has a differentiator 212, a base assist control unit 220, a vehicle stabilization compensation unit 240, and an adder AD2. In other words, the control device 100 includes the differentiator 212, the base assist control unit 220, the vehicle stabilization compensation unit 240, and the adder AD2.

[0039] The base assist control unit 220 receives the steering torque T h The base assist control unit 220 receives the torsion bar torque generated in the torsion bar 546, i.e., the steering torque T h Based on this, the self-aligning torque T generated in the tires 529A, 529B of the vehicle SAT An assist torque T that compensates for at least a part of assIn this embodiment, the base assist control unit 220 generates the steering torque T h Assist Gain K ass Assist torque T ass The steering torque T h and assist torque T ass In the graph of FIG. 4, the horizontal axis represents the steering torque T h and the vertical axis is the assist torque T ass and the steering torque T h Assist torque T ass The slope of the assist gain K ass The steering torque T h and assist torque T ass and assist gain K ass What is dT? ass / dT h =K ass As shown in Fig. 4, the assist torque T ass For example, the steering torque T h As shown in FIG. 3, the assist torque T ass is input to adder AD2.

[0040] The vehicle stabilization compensation unit 240 includes a steering angle θ s and steering angle θ s The steering angular velocity ω s 5, the vehicle stabilization compensation unit 240 has an active return control unit 241, a return speed control unit 242, a damper control unit 243, and an adder AD5.

[0041] The active return control unit 241 is configured to control the angle of the handle 521, i.e., the steering angle θ h This is a part that performs active return control to automatically return the steering wheel 521 to a predetermined reference angle. The predetermined reference angle is the steering angle θ h The active return control unit 241 controls the steering angle θ sThe active return control unit 241 receives the steering angle θ s Based on this, the torque T for active return control is AC Output.

[0042] The return speed control section 242 is a section that performs return speed control. The return speed control is performed by controlling the angle of the handle 521, i.e., the steering angle θ h The steering angle θ when the steering angle returns to a predetermined reference angle h The speed of the steering wheel, i.e., the steering angular velocity ω h The return speed control is a control to adjust the steering angle θ h The return speed control section 242 controls the steering angle θ s and steering angular velocity ω s The return speed control section 242 receives the steering angle θ s and steering angular velocity ω s Based on this, the torque T for controlling the return speed is RS The return speed control is also called convergence control.

[0043] In this embodiment, the control for returning the angle of the steering wheel 521 to a predetermined reference angle is executed by the active return control and the return speed control. That is, in this embodiment, the control device 100 can execute the control for returning the angle of the steering wheel 521 to a predetermined reference angle by the active return control section 241 and the return speed control section 242. For example, when the traveling speed of the vehicle is high, the self-aligning torque T generated in the tires 529A, 529B SAT As a result, the self-aligning torque T SAT Therefore, when the vehicle is traveling at a high speed, the control amount by the active return control is smaller than when the vehicle is traveling at a low speed. SATmeans a torque acting in the direction in which the steering wheel 521 returns due to the elasticity of the tires 529A, 529B which are twisted when the steering wheel 521 is turned.

[0044] The damper control section 243 is a section that performs damper control to brake the movement of the steering wheel 521 in accordance with the speed at which the steering wheel 521 is steered. The damper control section 243 is configured to control a steering angle θ s and steering angular velocity ω s The damper control unit 243 receives the steering angle θ s and steering angular velocity ω s Based on this, the torque T for damper control is calculated. DM Output.

[0045] The adder AD5 calculates the torque T AC and the torque T output from the return speed control section 242. RS and the torque T output from the damper control unit 243. DM Adding and gives the compensation torque T c The compensation torque T c is the output of the vehicle stabilization compensation unit 240. As shown in FIG. c is input to adder AD2.

[0046] The vehicle stabilization compensation unit 240 also detects the steering angle θ s and steering angular velocity ω s Instead of the steering angle θ h and steering angular velocity ω h In this case, the active return control unit 241 may input the steering angle θ h Based on this, the torque T for active return control is AC The return speed control unit 242 outputs the steering angle θ h and steering angular velocity ω h Based on this, the torque T for controlling the return speed is RS The damper control unit 243 outputs the steering angle θ h and steering angular velocity ω h Based on this, the torque T for damper control is calculated.DM Output.

[0047] The adder AD2 calculates the assist torque T ass and compensation torque T c The input torque T r The input torque T r is input to the subtractor SU2.

[0048] The model following control unit 230 calculates the input torque T r Correction torque T f is generated based on the output of the controlled object 560 and a nominal model based on the configuration of the controlled object 560. In this embodiment, the correction torque T f is the input torque T r The nominal model is an internal model used as a model for constraining the control target 560 when controlling the control target 560. The nominal model will be described in detail later. The model following control unit 230 is a model following controller configured to perform model following control. The specific configuration of the model following control unit 230 will be described in detail later.

[0049] The subtractor SU2 subtracts the input torque T r The correction torque T output from the model following control unit 230 is f The output from the subtractor SU2 is input to the adder AD3 and the model following control unit 230. The adder AD3 adds the output from the subtractor SU2 and the output from the state feedback unit 280, and outputs the result to the adder AD1. The adder AD1 adds the steering torque T h and disturbance torque T d The sum of these is output to the control object 560.

[0050] Disturbance torque T d is the difference between the ideal output torque of the motor 543 and the actual output torque of the motor 543. dincludes a disturbance torque applied from outside to the controlled object 560. d is, for example, an excess torque caused by friction and rattle due to mechanical elements such as the motor 543 and the reduction gear mechanism 544, a torque ripple caused in the motor 543, and a self-aligning torque T SAT , and disturbance torque that may occur when traveling on an unpaved bumpy road or a gravel road.

[0051] In this embodiment, the model following control unit 230 controls the steering angle θ s Based on the correction torque T f and generates an input torque T r The model following control unit 230 includes an inverse nominal model 231, a first filter 232a, a second filter 232b, an assist adjustment unit 270, subtractors SU3 and SU4, and an adder AD4. In this embodiment, the first filter 232a is a high-pass filter. The first filter 232a has a first cutoff frequency Cf1. The first cutoff frequency Cf1 is, for example, 2 Hz or more and 10 Hz or less. In this embodiment, the first cutoff frequency Cf1 is higher than 5 Hz and lower than 10 Hz.

[0052] In this embodiment, the second filter 232b is a low-pass filter. The second filter 232b has a second cutoff frequency Cf2 higher than the first cutoff frequency Cf1. The second cutoff frequency Cf2 is, for example, 3 Hz or more and 50 Hz or less. However, the upper limit of the second cutoff frequency Cf2 can be set in a range of about 140 Hz or more and 200 Hz or less. The order of the second filter 232b is third order or more. The second filter 232b may be composed of, for example, a plurality of low-pass filters. The first filter 232a and the second filter 232b are coupled in series.

[0053] The model following control unit 230 calculates whether the transfer function P(s) of the control target 560 is equal to or smaller than the transfer function P(s) of the nominal model in a frequency band where the complementary sensitivity gain GT, which is the gain in the gain characteristic of the complementary sensitivity function T(s) with respect to the modeling error between the control target 560 and the nominal model, is approximately 1. n (s). "The complementary sensitivity gain GT is approximately 1" includes, in addition to the case where the complementary sensitivity gain GT is 1, for example, the case where the complementary sensitivity gain GT is 0.8 or more and 1.2 or less. For example, when the reduction gear 544 connected to the motor 543 has a worm gear, this numerical range is a range in which the substantial gain of the disturbance suppression characteristic can be adjusted to 1, taking into consideration the forward efficiency and reverse efficiency of the worm gear. Since the efficiency of the worm gear is about 0.8, it is necessary to adjust the gain to ±0.2 with respect to the target value of 1.

[0054] The complementary sensitivity function T(s) is a complementary sensitivity function of an inner loop configured by the model following control unit 230. FIG. 6 shows a complementary sensitivity gain GT in the complementary sensitivity function T(s). The complementary sensitivity gain GT is a gain of the complementary sensitivity function T(s) as a transfer function, and is an absolute value of the complementary sensitivity function T(s). As shown in FIG. 6, the complementary sensitivity function T(s) has a gain of 0 dB, that is, a complementary sensitivity gain GT in the transfer function is 1 in a frequency band in which the frequency f is equal to or higher than the first cutoff frequency Cf1 and equal to or lower than the second cutoff frequency Cf2. In other words, the first cutoff frequency Cf1 is the lower limit of the frequency band in which the complementary sensitivity gain GT is 1. The second cutoff frequency Cf2 is the upper limit of the frequency band in which the complementary sensitivity gain GT is 1. In this specification, "the transfer function of the controlled object is constrained to the transfer function of the nominal model" means that, for example, when looking at the input / output relationship, the controlled object is controlled so that the transfer function of the controlled object appears to be the transfer function of the nominal model.

[0055] The transfer function P(s) of the controlled object 560 is a plant characteristic for which model following control is performed. The transfer function P(s) of the controlled object 560 is expressed by, for example, the following equation (1).

[0056]

number

[0057] The inverse nominal model 231 is an inverse model of a predetermined nominal model used to constrain the controlled object 560. The transfer function P n (s) is expressed, for example, by the following equation (2). The transfer function Pn -1 (s) is expressed, for example, by the following formula (3).

[0058]

number

[0059]

number

[0060] In equations (2) and (3), s is the Laplace transformer, and J n is a parameter that represents the moment of inertia of the nominal model, and B n is a parameter that represents the viscous friction coefficient of the nominal model. Note that the transfer function P n (s) and the transfer function P of the inverse nominal model 231 n -1 (s) is not limited to the examples shown in formulas (2) and (3), and is not particularly limited.

[0061] 3, the output of a control target 560 is input to the inverse nominal model 231. Specifically, the inverse nominal model 231 is s The inverse nominal model 231 is based on the above equation (3) and the input steering angle θ s Based on the torque T p That is, the model following control unit 230 calculates the torque T p Calculate the torque T p is equal to the value of the torque input to the nominal model when the output value of the nominal model is the same as the output value of the controlled object 560.

[0062] The subtractor SU3 subtracts the output of the subtractor SU2 from the output of the inverse nominal model 231 to obtain a differential torque T a That is, the subtractor SU3 generates the correction torque T fAfter being fed back, the state compensation value V s The input torque T before being fed back r , and torque T p Subtract the differential torque T from a Generates a differential torque T a For example, the disturbance torque T d The differential torque T output from the subtractor SU3 is a is input to the second filter 232b and subjected to low-pass filtering, and then input to the first filter 232a and subjected to high-pass filtering. The differential torque Ta filtered by the first filter 232a and the second filter 232b is input to an adder AD4. The differential torque T a In other words, the differential torque T filtered by the first filter 232a and the second filter 232b is in a state where frequency components lower than the first cutoff frequency Cf1 and frequency components higher than the second cutoff frequency Cf2 are removed. a is the frequency component T that is equal to or greater than the first cutoff frequency Cf1 and equal to or less than the second cutoff frequency Cf2. aM It is.

[0063] The assist adjustment unit 270 generates a compensation value for friction and disturbances to adjust the differential torque T a In this embodiment, the assist adjustment unit 270 adjusts the differential torque T a Among the frequency components T aM The assist adjustment section 270 is connected in parallel to the first filter 232a. The assist adjustment section 270 has a friction compensation value calculation section 250, a disturbance compensation value calculation section 260, and a subtractor SU4.

[0064] The subtractor SU4 subtracts the output value from the first filter 232a from the output value from the second filter 232b. Here, the output value from the second filter 232b is the differential torque T aThe output value from the first filter 232a is a value obtained by removing frequency components higher than the second cutoff frequency Cf2 from the differential torque T a The value output from the subtractor SU4 is the torque difference T a The frequency component T aL The output of the subtractor SU4 is input to a friction compensation value calculation unit 250 and a disturbance compensation value calculation unit 260. aL includes friction force, self-aligning torque, disturbance torque caused by backlash of the controlled object 560, and torque ripple generated in the controlled object 560.

[0065] The friction compensation value calculation unit 250 calculates a friction compensation value V f The differential torque T a As described above, the value from the subtractor SU4 input to the friction compensation value calculation unit 250 is calculated based on the differential torque T a The frequency component T aL Therefore, in this embodiment, the friction compensation value calculation unit 250 calculates the differential torque T a Based on the frequency component lower than the first cutoff frequency Cf1, the friction compensation value V f Calculate.

[0066] The friction compensation value calculation unit 250 has a limiter 252 and a gain adjuster 253. The limiter 252 limits the output value from the subtractor SU4. When the input value exceeds an upper or lower threshold, the limiter 252 clips the input value to the upper or lower threshold. The gain adjuster 253 multiplies the output value from the limiter 252 by a gain K1. The friction compensation value calculation unit 250 calculates the differential torque T a The friction compensation value V fThe threshold value of the limiter 252 and the value of the gain K1 are determined in advance based on the frictional force actually generated in the control target 560, for example.

[0067] The friction compensation value V output from the friction compensation value calculation unit 250 f is the differential torque T a Frequency component T aL Generally, since a moderate amount of friction is required for the controlled object 560, the friction compensation value calculation unit 250 sets a value smaller than the friction force actually generated in the controlled object 560 as the friction compensation value V f This makes it possible to realize highly accurate friction compensation while leaving an appropriate friction force on the control target 560. f The targets of friction compensation by this include, for example, friction of the motor 543, friction of the reduction mechanism 544, and a difference between the left and right friction of the reduction mechanism 544.

[0068] Here, the differential torque T a Frequency component T aL In addition to the friction force component, the frequency component T aL The friction compensation value V obtained by processing the above with the limiter 252 and the gain adjuster 253 is f Also included in the compensation value is a compensation value for compensating for at least a part of the self-aligning torque occurring in the controlled object 560, the disturbance torque caused by backlash occurring in the controlled object 560, and the torque ripple occurring in the controlled object 560.

[0069] A vehicle equipped with the electric power steering device 1000 can travel according to a driving mode having an automatic driving mode and a manual driving mode. In this case, the gain K1 of the gain adjuster 253 may be switched according to the driving mode. The greater the gain K1 of the gain adjuster 253, the greater the degree of reduction in friction. It is preferable that the gain K1 in the automatic driving mode is greater than the gain K1 set in the manual driving mode. This makes it possible to apply optimal friction compensation to the automatic driving mode, which requires greater reduction in friction.

[0070] The disturbance compensation value calculation unit 260 calculates a disturbance compensation value V d In this embodiment, the disturbance compensation value V d includes a compensation value for compensating for at least a part of the frictional force occurring in the controlled object 560, the disturbance torque caused by the backlash occurring in the controlled object 560, and the torque ripple occurring in the controlled object 560. The disturbance compensation value calculation unit 260 calculates the torque T p and input torque T r The differential torque T a Based on the disturbance compensation value V d That is, the disturbance compensation value calculation unit 260 calculates the torque T p and input torque T r The differential torque T a Based on the disturbance compensation value V d As described above, the value from the subtractor SU4 input to the disturbance compensation value calculation unit 260 is the differential torque T a 1. In this embodiment, the torque difference T a Based on the frequency components lower than the first cutoff frequency Cf1, the disturbance compensation value V d Calculate.

[0071] The disturbance compensation value calculation unit 260 has a limiter 262 and a gain adjuster 263. The limiter 262 limits the output value from the subtractor SU4. When the input value exceeds the upper or lower threshold, the limiter 262 clips the input value to the upper or lower threshold. The threshold of the limiter 262 is different from the threshold of the limiter 252, for example. The gain adjuster 263 multiplies the output value from the limiter 262 by a gain K2. When the transfer function P(s) of the controlled object 560 is the transfer function P of the nominal model, n The maximum value of the gain K2 of the gain adjuster 263 is determined under the condition bound by (s). The value of the gain K2 is different from the value of the gain K1, for example. The value of the gain K2 is, for example, not less than 0.1 and not more than 0.8. The gain K2 of the gain adjuster 263 may be switched depending on the running mode of the vehicle.

[0072] Disturbance compensation value V d is the differential torque T a Frequency component T aL The external disturbance compensation value calculation unit 260 calculates, for example, a value that compensates for at least a part of the self-aligning torque component T SAT The disturbance compensation value V is about half of the value d The self-aligning torque T actually generated in the control object 560 is calculated as follows: SAT is experimentally obtained in advance for each frequency. The threshold value of the limiter 262 of the external disturbance compensation value calculation unit 260 and the value of the gain K2 are determined based on the self-aligning torque T SAT The disturbance compensation value V is set to a value between 0.1 and 0.8 times the magnitude of d The disturbance compensation value V calculated by the disturbance compensation value calculation unit 260 is adjusted to a value calculated by the disturbance compensation value V d is the friction compensation value V calculated by the friction compensation value calculation unit 250. f is a different value.

[0073] Here, the differential torque T a Frequency component T aL The self-aligning torque T SATIn addition, the frequency component T aL The disturbance compensation value V obtained by processing the above by the limiter 262 and the gain adjuster 263 is d Also included in the compensation value is a compensation value for compensating for at least a part of the frictional force occurring in the controlled object 560, the disturbance torque caused by backlash occurring in the controlled object 560, and the torque ripple occurring in the controlled object 560.

[0074] The correction torque T used for the model following control in the model following control unit 230 f In order to apply friction compensation and disturbance compensation performed in the assist adjustment unit 270 to the above, it is necessary to pay attention to the stability conditions of the model following control. This condition is that the gain in the gain characteristic of the transfer function of the assist adjustment unit 270, which is constrained to a characteristic considering stability, does not exceed 1 according to the small gain theorem described later. This is derived from the design conditions of the second filter 232b. In this embodiment, the values ​​of the gains K1 and K2 in the gain adjusters 253 and 263 are set to a maximum of 1, and a subtractor SU4 is provided in front of the limiters 252 and 262 to apply subtraction processing so that the gain in the gain characteristic becomes 1 under this condition. In other words, the assist adjustment unit 270 behaves as a low-pass filter having a transfer function of 1-Q1(s). Q1(s) is the transfer function of the first filter 232a, which is a high-pass filter. The assist adjustment unit 270 performs low-pass filter processing having a transfer function of 1-Q1(s) on the torque output from the second filter 232b, and adjusts and outputs the processed value in each of the friction compensation value calculation unit 250 and the disturbance compensation value calculation unit 260.

[0075] The adder AD4 adds the output value from the assist adjustment unit 270 to the output value from the first filter 232a. aM Friction compensation value V f and disturbance compensation value V d The adder AD4 outputs the frequency component T aMand the friction compensation value V f and disturbance compensation value V d The correction torque T is calculated by adding f The correction torque T output from the adder AD4 f is the input of the controlled object 560, i.e., the input torque T r In this manner, in this embodiment, the model following control unit 230 outputs the differential torque T a , i.e., frequency component T aM For the friction compensation value V f and disturbance compensation value V d Adding this, we get the correction torque T f Generate.

[0076] The state feedback unit 280 calculates the apparent transfer function of the controlled object 560 based on the output of the controlled object 560 as a transfer function P n To get closer to (s), the state compensation value V s Input torque T r The apparent transfer function of the controlled object 560 is, for example, the transfer function of one part when the part located inside the feedback loop created by the model following control unit 230 is regarded as one part. Specifically, in this embodiment, the apparent transfer function of the controlled object 560 is the transfer function of the entire part between the subtractor SU2 and the output of the controlled object 560, and is the transfer function of the part combining the state feedback unit 280 and the controlled object 560. In this embodiment, the state feedback unit 280 calculates the correction torque T f After being corrected by and before being input to the control object 560, the input torque T r For the state compensation value V s Provide feedback.

[0077] State compensation value V sincludes a compensation value for compensating for at least a part of the inertial force generated in the controlled object 560, the viscous force generated in the controlled object 560, and the frictional force generated in the controlled object 560. More specifically, the state compensation value V s includes a compensation value that compensates for at least a part of the inertial force generated in the motor 543, the viscous force generated in the motor 543, and the frictional force generated in the motor 543. In this embodiment, the state compensation value V s is a compensation value including the inertial force generated in the motor 543, the viscous force generated in the motor 543, and the frictional force generated in the motor 543.

[0078] The state feedback unit 280 includes an inertia compensator 281, a viscosity compensator 282, and a friction compensator 283. The inertia compensator 281 calculates a steering angle θ s The viscous compensator 282 calculates a compensation value for compensating for at least a part of the inertial force generated in the motor 543 based on the steering angle θ s The friction compensator 283 calculates a compensation value for compensating for at least a part of the viscous force generated in the motor 543 based on the steering angle θ s Based on this, a compensation value for compensating for at least a part of the frictional force generated in the motor 543 is calculated. In this embodiment, the state compensation value V s is composed of a compensation value calculated by an inertia compensator 281, a compensation value calculated by a viscosity compensator 282, and a compensation value calculated by a friction compensator 283. The compensation value calculated by the inertia compensator 281, the compensation value calculated by the viscosity compensator 282, and the compensation value calculated by the friction compensator 283 are output to an adder AD3, and a correction torque T f The input torque T after correction by r is added to.

[0079] Next, the control by the model following control unit 230 will be described in more detail. The model following control unit 230 controls the controlled object 560 using an inverse model of the nominal model held as an internal model, that is, an inverse nominal model 231. In this embodiment, the feedback loop created by the model following control unit 230 makes it possible to compensate for torque ripples that depend on the angular velocity ω of the motor 543.

[0080] The model following control unit 230 is similar in configuration to a conventional disturbance estimator (disturbance observer), but has different intended actions and effects. A conventional disturbance estimator estimates disturbance torque by making an inverse plant model, which is an internal model, a model close to the control target 560, and reduces the influence of disturbance by adjusting the disturbance torque in advance.

[0081] In the control by the model following control unit 230 according to the present embodiment, the transfer function P(s) of the controlled object 560 is adjusted to the transfer function P n The effect of being constrained to (s) is utilized. For example, if a nominal model is defined so that there is no torque ripple, the transfer function P(s) of the controlled object 560 is constrained to a characteristic without torque ripple by the model following control, and as a result, it is possible to reduce the torque ripple by applying torque ripple compensation. In addition, by making the nominal model a low inertia model and constraining the controlled object 560 with the nominal model, the controlled object 560 can be treated as a low inertia model. In addition, by making the nominal model a low viscosity model and constraining the controlled object 560 with the nominal model, the controlled object 560 can be treated as a low viscosity model. By executing the model following control by the model following control unit 230, in addition to the compensation for the torque ripple of the motor 543, for example, loss torque compensation or motor inertia compensation is performed. In the above-mentioned equations (2) and (3), J n and B. n By appropriately setting, it is possible to impart a desired frequency characteristic to the transfer function P(s) of the controlled object 560.

[0082] Transfer function P(s) of the controlled object 560 and transfer function P of the nominal model n When a modeling error with respect to (s) is Δ(s), a transfer function P(s) of the controlled object 560 is expressed, for example, by the following equation (4).

[0083]

number

[0084] The gain characteristic of the transfer function P(s) of the controlled object 560 has peaks at, for example, two frequency values. The modeling error Δ(s) appears, for example, near the higher frequency of the two peaks in the gain characteristic of the controlled object 560. Therefore, as shown in FIG. 6, the reciprocal 1 / Δ(s) of the modeling error Δ(s) has a bottom in a relatively high frequency region. In FIG. 6, the modeling error Δ(s) is shown in absolute value. When the modeling error Δ(s) becomes large, the difference between the transfer function P(s) of the controlled object 560 and the transfer function P of the nominal model n As a result, the deviation from the nominal model becomes large, and the control of the control target 560 by the model following control unit 230 using the nominal model becomes unstable. Therefore, in a region where the modeling error Δ(s) is relatively small, the control target 560 can be controlled stably and appropriately by setting the gain of the complementary sensitivity function T(s) to 1 and constraining the control target 560 to the nominal model. The frequency characteristic of the modeling error Δ(s) is expressed by the transfer function P n J in (s) n and B. n The frequency band in which the gain of the complementary sensitivity function T(s) is 1 can be adjusted by adjusting the first cutoff frequency Cf1 and the second cutoff frequency Cf2. This allows the gain of the complementary sensitivity function T(s) to be adjusted to 1 in a frequency band in which the modeling error Δ(s) is small.

[0085] 6, 1 / Δ(s) is relatively high in a frequency band equal to or lower than the second cutoff frequency Cf2, and drops sharply in a frequency band higher than the second cutoff frequency Cf2. The model following control that constrains the control target 560 to the nominal model can be stably performed, for example, in a range in which 1 / Δ(s) is greater than 1, i.e., in a range in which 1 / Δ(s) is greater than 0 dB. Therefore, as shown in FIG. 6, by adjusting 1 / Δ(s) to be greater than 1 in a frequency band in which the gain of the complementary sensitivity function T(s) is 1, when the gain of the complementary sensitivity function T(s) is 1, the control target 560 can be stably and suitably controlled by being constrained to the nominal model.

[0086] For example, in order to broaden the frequency band in which the controlled object 560 can be stably and suitably controlled by constraining it to the nominal model, the second cutoff frequency Cf2 may be increased within a range in which 1 / Δ(s) is not equal to or less than 1, that is, within a frequency band lower than the frequency at which the curve showing 1 / Δ(s) intersects with the horizontal axis in FIG. 6. However, if the second cutoff frequency Cf2 is increased too much, the gain of the complementary sensitivity function T(s) may remain relatively high in a frequency band higher than the second cutoff frequency Cf2, even though 1 / Δ(s) is lowered, which may cause unstable control. In contrast, in this embodiment, the order of the second filter 232b, which is a low-pass filter, is set to third or higher, so that the gain of the complementary sensitivity function T(s) can be sharply reduced in a frequency range higher than the second cutoff frequency Cf2. As a result, even if the second cutoff frequency Cf2 is set relatively high, the gain of the complementary sensitivity function T(s) can be immediately reduced in a frequency band higher than the second cutoff frequency Cf2, thereby preventing the control of the controlled object 560 from becoming unstable.

[0087] The robust stability of model following control section 230 is guaranteed when the small gain theorem shown in the following equation (5) holds between complementary sensitivity function T(s) and modeling error Δ(s).

[0088]

number

[0089] As described above, in order to perform model following control using a nominal model in model following control section 230, it is sufficient that complementary sensitivity gain GT of complementary sensitivity function T(s) is approximately 1, but in consideration of robust stability, it is necessary to satisfy the above formula (5). As can be seen from this, it is not possible to make complementary sensitivity gain GT approximately 1 in all frequency bands and to satisfy formula (5), and therefore suppression of disturbances and the like by model following control section 230 and robust stability are not compatible.

[0090] 6, even in a low-frequency region FA1 in which the frequency f is lower than the first cutoff frequency Cf1, the complementary sensitivity gain GT of the complementary sensitivity function T(s) is smaller than 1. In a region in which the complementary sensitivity gain GT of the complementary sensitivity function T(s) is smaller than 1, the reaction force control unit 210 r As described above, in the high frequency region FA2 where the frequency is higher than the second cutoff frequency Cf2, the complementary sensitivity gain GT of the complementary sensitivity function T(s) is significantly lowered to control the correction torque T f is hardly fed back to the input of the controlled object 560. On the other hand, in the low frequency region FA1, the complementary sensitivity gain GT of the complementary sensitivity function T(s) is set to a certain magnitude, and the correction torque T f is fed back to the input of the controlled object 560. In the low frequency region FA1, the compensation value generated in the above-described assist adjustment unit 270 is fed back to the input of the controlled object 560 in accordance with the complementary sensitivity gain GT of the complementary sensitivity function T(s).

[0091] The control device 100 performs torque control in the reaction force control unit 210 for torque signals with low frequencies lower than the first cutoff frequency Cf1, and performs control so that the angular velocity ω≈0 for disturbances with high frequencies higher than the second cutoff frequency Cf2, thereby realizing stabilization of steering so that the steering wheel 521 is not moved. To achieve this objective, the control device 100 uses the reaction force control unit 210 to lower the high-frequency gain of the torque control, and uses the model following control unit 230 to constrain the transfer function P(s) of the control target 560 to a characteristic that lowers the high-frequency gain. The reason for performing the latter process is to prevent the control target 560 from reacting to a disturbance when the disturbance is input to the control target 560.

[0092] The transfer function of the combined part of the torque conversion unit 211 and the base assist control unit 220 is C2(s), and the disturbance torque T d (s), that is, the correction torque T f If the ratio of these is m, the disturbance torque T d (s) to steering torque T h The transfer characteristics up to (s) are expressed by the following equation (6) using the complementary sensitivity function T(s), and the complementary sensitivity function T(s) is expressed by the following equation (7).

[0093]

number

[0094]

number

[0095] From the above formula (6), it can be seen that if the complementary sensitivity function T(s) is 1, the disturbance is completely suppressed, and if the complementary sensitivity function T(s) is smaller than 1, at least a part of the disturbance is transmitted. Therefore, by dividing the disturbance to be transmitted and the disturbance to be suppressed in the frequency domain and frequency shaping the complementary sensitivity function T(s) accordingly, it is possible to design the disturbance sensitivity for each frequency domain. m in the above formulas (6) and (7) is the disturbance torque T d Correction torque T f The compensation rate is equal to T f =mT d For example, if the ratio m is 0.5, the correction torque T f The disturbance torque T d is compensated for by 50%. In this embodiment, the ratio m is equal to or greater than 0.1 and equal to or less than 0.8.

[0096] When the transfer function P(s) of the controlled object 560 is expressed by the above-mentioned formula (1), C2(s)=K tor +K ass Therefore, the steady-state gain T(0) of the complementary sensitivity function T(s) at s=0 is expressed by the following equation (8) from the above equation (7). tor The steering angle θ s The self-aligning torque T generated in the vehicle tires 529A, 529B with respect to SAT The slope of K SAT The torsion bar torque, i.e., the steering torque T h Assist torque T ass The slope of K ass The steady-state gain is T(0), and the disturbance input to the control target 560, i.e., the disturbance torque T d Correction torque T f When the ratio is m, the following equation (8) holds.

[0097]

number

[0098] In a steady state, such as when the steering wheel 521 is at or near the center position and when the vehicle is traveling at a high speed, the assist gain K ass is close to zero. Also, the spring constant K tor is the self-aligning torque gain K SAT Therefore, in a steady state, such as when the steering wheel 521 is at or near the center position and when the vehicle is traveling at a high speed, the steady gain T(0) is calculated from the above formula (8) as d Correction torque T for (s) f The steady-state gain T(0) of the complementary sensitivity function T(s) expressed by the above formula (8) is 0.1 or more. In this embodiment, the steady-state gain T(0) is 0.3 or more. The steady-state gain T(0) is, for example, 0.5 or less. The steady-state gain T(0) is the minimum value of the complementary sensitivity gain GT in the low-frequency region FA1.

[0099] Conventionally, for example, complementary sensitivity function T(s) in the low-frequency region FA1 had a waveform as shown by the two-dot chain line in Fig. 6. In this embodiment, by performing model following control by the above-mentioned model following control section 230, the steady-state gain T(0) of complementary sensitivity function T(s) can be made as shown in the above formula (8), and complementary sensitivity function T(s) can be shaped into a waveform as shown by the solid line in Fig. 6 with respect to frequency f.

[0100] In this embodiment, the low-frequency portion TFA1, which is a portion of the low-frequency region FA1 in the waveform of the complementary sensitivity gain GT of the complementary sensitivity function T(s) shown in Fig. 6, is generated by the first filter 232a, the vehicle stabilization compensation unit 240, and the adder AD4 in the model following control unit 230. More specifically, the frequency component T aM and the friction compensation value V output from the vehicle stabilization compensation unit 240, which functions as a low-pass filter. f and disturbance compensation value V dThe waveform of the low-frequency portion TFA1 is created by adding together these. The value at which the frequency f in the low-frequency portion TFA1 becomes zero is the value at which s=0 in the complementary sensitivity function T(s), and is the steady-state gain T(0) expressed by the above-mentioned equation (8).

[0101] As shown in FIG. 6, the first cutoff frequency Cf1 is yaw The first resonant frequency f yaw is the resonance frequency of the vehicle yaw rate. In other words, the lower limit of the frequency band in which the complementary sensitivity gain GT is 1 is the first resonance frequency f yaw The yaw rate of a vehicle is a parameter that indicates a change in the yaw angle, which is the yaw angle of the vehicle in the left-right direction. In other words, the yaw rate is the angular velocity of the vehicle when it sways in the left-right direction. The first resonance frequency f yaw is, for example, about 1 Hz or more and 1.5 Hz or less.

[0102] The second resonant frequency f st is the resonance frequency of the steering mechanism 530. More specifically, the second resonance frequency fst is a function of the inertia of the entire steering mechanism 530 and the self-aligning torque T SAT The second resonant frequency f is the resonant frequency of the mode formed by the spring element that generates the second resonant frequency f st is the first resonant frequency f yaw The second resonance frequency fst is higher than the lower limit of the frequency band where the complementary sensitivity gain GT is 1, that is, lower than the first cutoff frequency Cf1. The second resonance frequency fst is, for example, about 3 Hz or more and 5 Hz or less. st The complementary sensitivity gain GT at the first resonant frequency f yaw The complementary sensitivity gain GT at the second resonant frequency f st The complementary sensitivity gain GT at the second resonant frequency f st The complementary sensitivity gain GT in is 0.8 or more.

[0103] In this embodiment, the high frequency portion TFA2, which is a portion of the high frequency region FA2 in the waveform of the complementary sensitivity gain GT of the complementary sensitivity function T(s) shown in FIG.

[0104] According to this embodiment, the control device 100 calculates the input torque T r Correction torque T f The control system further includes a model following control unit 230 that generates a transfer function of the controlled object 560 based on the output of the controlled object 560 and a nominal model based on the configuration of the controlled object 560. The model following control unit 230 is configured so that the transfer function of the controlled object 560 is constrained to the transfer function of the nominal model in a frequency band where a complementary sensitivity gain GT, which is a gain in the gain characteristic of the complementary sensitivity function T(s) with respect to the modeling error Δs between the controlled object 560 and the nominal model, is approximately 1. The steady-state gain T(0) of the complementary sensitivity function T(s) is 0.1 or more. The lower limit of the frequency band where the complementary sensitivity gain GT is 1, i.e., a first cutoff frequency Cf1, is set to a first resonant frequency f yaw The second resonance frequency f st is the first resonant frequency f yaw The second resonance frequency f is higher than the lower limit of the frequency band in which the complementary sensitivity gain GT is 1, that is, the first cutoff frequency Cf1. st The complementary sensitivity gain GT at the first resonant frequency f yaw is higher than the complementary sensitivity gain GT at

[0105] For example, a conventional disturbance estimator has a model close to the controlled object 560 as an internal model, and compensates for disturbances occurring in the controlled object 560. However, it is difficult to have a model that is completely the same as the controlled object 560 as an internal model, and modeling error Δ(s) inevitably occurs. Therefore, in the conventional disturbance estimator, in order to suppress control instability, the gain in the gain characteristic of the complementary sensitivity function T(s) is set to a value smaller than 1 in all frequency bands. In addition, in the conventional disturbance estimator, since the internal model is always close to the actual model of the controlled object 560, it is possible to estimate disturbances applied from the outside to the controlled object 560, but it is not possible to remove torque ripples occurring in the controlled object 560 itself.

[0106] In contrast, in this embodiment, the nominal model held by the control device 100 as an internal model is set as an ideal model for the control object 560, rather than a model that attempts to reproduce the model of the actual control object 560, and the complementary sensitivity gain GT of the complementary sensitivity function T(s) is set to approximately 1 in a region where the modeling error Δ(s) is small. As a result, by appropriately setting the nominal model, not only the disturbance applied from the outside to the actual control object 560, but also the torque ripple generated internally in the control object 560 can be removed. As a result, the disturbance generated due to the control object 560 being a two-inertia system can also be removed, and the controllability of the control object 560 configured as a two-inertia system can be improved. In addition, since the control device 100 can appropriately control the control object 560, the steering feeling felt by the steering operator can be improved.

[0107] In addition, in this embodiment, the steady-state gain T(0) of the complementary sensitivity function T(s) is 0.1 or more. Therefore, unlike the conventional case shown by the two-dot chain line in FIG. 6, even in the low-frequency region FA1, the reaction force received from the tires 529A and 529B, i.e., the self-aligning torque T SAT can be compensated for to some extent by model following control. Also, the first resonance frequency f is lower than the lower limit of the frequency band in which the complementary sensitivity gain GT is 1. yawThe second resonant frequency f st The complementary sensitivity gain GT at the first resonant frequency f yaw Therefore, in the low-frequency region FA1 where the frequency f is relatively high, the self-aligning torque T SAT As a result, the reaction force that the steering wheel 521 receives from the steering wheel 521 can be reduced. st Since the complementary sensitivity gain GT in is less than 1, the self-aligning torque T SAT However, the self-aligning torque T SAT A part of the torque is transmitted to the steerer. This allows an appropriate reaction force to be applied to the steerer via the steering wheel 521. In addition, the self-aligning torque T SAT While compensating for disturbances such as the above, other controls such as active return control and return speed control (convergence control) can be applied, and the reaction force received by the steering wheel 521 by the steering wheel 521 can be more suitably adjusted. As described above, according to this embodiment, the steering feel felt by the steering wheel 521 can be further improved.

[0108] For example, when model following control is not performed, it is conceivable to apply a return speed control (convergence control) that provides damping to the steering wheel 521 to some extent in order to stabilize the running of the vehicle. However, in this case, a force that applies a brake to the steering of the steering wheel 521 acts strongly, and the steering feeling felt by the steerer becomes worse. In response to this, for example, it is conceivable to apply the return speed control only when the steerer is not operating the steering wheel 521, and not to apply the return speed control when the steerer is operating the steering wheel 521. However, in this case, the control amount of the return speed control is significantly different between when the steerer is operating the steering wheel 521 and when he is not operating it. Therefore, for example, when the steerer turns the steering wheel 521, the control amount of the return speed control changes significantly, causing the steerer to feel uncomfortable.

[0109] In this embodiment, the complementary sensitivity gain GT of the complementary sensitivity function T(s) is adjusted to the value described above, so that the self-aligning torque T SAT Since it is possible to compensate for a part of the above, it is possible to stabilize the running of the vehicle while weakening the return speed control. This makes it possible to suppress a feeling of discomfort felt by the steerer and to suppress a deterioration in the steering feel felt by the steerer.

[0110] In addition, the rotational angular velocity of the steering wheel 521 when the angle of the steering wheel 521 starts to return to the predetermined reference angle by the active return control and the return speed control, that is, the steering angular velocity ω h is the self-aligning torque T transmitted to the handle 521. SAT Therefore, when model following control is not performed, the self-aligning torque T SAT becomes larger, and the steering angle velocity ω h In this case, the steering angular velocity ω from when the angle of the steering wheel 521 starts to return to the reference angle until the angle of the steering wheel 521 finishes returning to the reference angle is h The difference in the change in the first resonance frequency f becomes large, and the movement of the handle 521 when the angle of the handle 521 returns to the reference angle becomes difficult to be smooth. yaw and the second resonant frequency f st The resonance between the steering angle velocity ω h changes periodically, causing rattling in the movement of handle 521 when the angle of handle 521 returns to the reference angle. This makes it even more difficult to make the movement of handle 521 smooth.

[0111] In response to the above problem, in this embodiment, the self-aligning torque T SAT Since it is possible to compensate for a part of the self-aligning torque TSAT This allows the steering angular velocity ω h This allows the steering angular velocity ω from when the angle of the steering wheel 521 starts to return to the reference angle until the angle of the steering wheel 521 finishes returning to the reference angle to be reduced. h Therefore, it is easy to make the movement of the handle 521 smooth when the angle of the handle 521 returns to the reference angle. st By setting the complementary sensitivity gain GT at 0.5 or more, the second resonant frequency f st At self-aligning torque T SAT Therefore, the second resonant frequency f st Therefore, it is possible to suppress the occurrence of rattling in the movement of the steering wheel 521 when the angle of the steering wheel 521 returns to the reference angle, and the rotational angular velocity of the steering wheel 521, i.e., the steering angular velocity ω h This can suppress the occurrence of unevenness in the angle of handle 521. This makes it easier to make the movement of handle 521 smoother when the angle of handle 521 returns to the reference angle. By making the movement of handle 521 smoother, it is possible to impart a sense of luxury to the movement of handle 521 when the angle of handle 521 returns to the reference angle.

[0112] In addition, if the road surface on which the vehicle is traveling is uneven, the tires 529A, 529B receive force from the unevenness, and the driver is likely to lose control of the steering wheel 521. h The frequency f is about 5 Hz or more and 10 Hz or less, and the second resonance frequency f st Approximately the same as the second resonance frequency f st As described above, in the model following control of this embodiment, the second resonance frequency f st The complementary sensitivity gain GT at the second resonant frequency f stAt a first cutoff frequency Cf1 higher than , the complementary sensitivity gain GT is 1. Therefore, by adjusting the complementary sensitivity function T(s) to the above-mentioned numerical range, when the vehicle runs on an uneven road surface, it becomes possible to suitably compensate by model following control for the force that the tires 529A, 529B receive from the unevenness. Therefore, even when the vehicle runs on an uneven road surface, it is possible to suppress the steering wheel 521 from being taken away by the helmsman. This can further improve the steering feel that the helmsman feels.

[0113] Furthermore, the road surface on which the vehicle runs may have a slight incline to improve drainage, etc. In this case, to drive the vehicle straight, the helmsman must turn the steering wheel 521 slightly. Therefore, if model following control is not performed, a strain may be placed on the helmsman's arms. In contrast, in this embodiment, the steady-state gain T(0) is 0.1 or more, so that even in the low-frequency region FA1 where the steering wheel 521 is not operated or is operated only slightly, the self-aligning torque T received from the tires 529A, 529B by the model following control is reduced. SAT This can compensate to some extent. Even if the steering wheel 521 is turned slightly when trying to drive the vehicle straight on a road with a slight incline, the reaction force that the steering wheel 521 receives from the steering wheel 521 can be reduced. This can reduce the strain on the steering wheel's arms.

[0114] According to the present embodiment, the control device 100 calculates the torsion bar torque generated in the torsion bar 546, i.e., the steering torque T h Based on this, the self-aligning torque T generated in the tires 529A, 529B of the vehicle SAT An assist torque T that compensates for at least a part of ass The base assist control unit 220 generates the spring constant of the torsion bar 546. tor and the steering angle θ s The self-aligning torque T generated in the vehicle tires 529A, 529B with respect to SATLet the slope be K SAT and the torsional bar torque, i.e., the steering torque T h and the assist torque T ass with respect to have a slope of K ass Let the self-aligning torque be T SAT Let the assist torque be T ass Let the steady-state gain be T(0), and T ass =mT SAT (where 0 < m < 1) holds, the above-described equation (9) holds. When the steady-state gain T(0) is represented by equation (9), the complementary sensitivity gain GT in the low-frequency region FA1 can be suitably increased as described above. Thereby, the above-described effects can be obtained more, and the steering feeling felt by the driver can be improved more. In order to more suitably obtain the above-described effects, m is preferably 0.1 or more and 0.8 or less, and more preferably 0.3 or more and 0.8 or less.

[0115] Also, according to the present embodiment, the control device 100 can execute control to return the angle of the steering wheel 521 to a predetermined reference angle, i.e., active return control and return speed control. As described above, while using model following control, by adjusting the complementary sensitivity gain GT of the complementary sensitivity function T(s), it is possible to smoothly move the steering wheel 521 when the angle of the steering wheel 521 returns to the reference angle while suppressing a decrease in the steering feeling felt by the driver. Therefore, the effect obtained by adjusting the complementary sensitivity gain GT of the complementary sensitivity function T(s) within the numerical range as described above is more usefully obtained when the control to return the angle of the steering wheel 521 to the reference angle is performed.

[0116] Also, according to the present embodiment, the steady-state gain T(0) is 0.3 or more, and the complementary sensitivity gain GT at the second resonance frequency f st is 0.8 or more. Therefore, the complementary sensitivity gain GT in the low-frequency region FA1 can be suitably increased. Thereby, the above-described effects can be obtained more usefully, and the steering feeling felt by the driver can be improved more suitably.

[0117] Furthermore, according to this embodiment, the lower limit of the frequency band where the complementary sensitivity gain GT is 1, i.e., the first cutoff frequency Cf1, is lower than 10 Hz. Therefore, the complementary sensitivity gain GT can be set to 1 or a value close to 1 in the range of 5 Hz or more and 10 Hz or less, which is likely to be the frequency f when the tires 529A, 529B receive force from unevenness in the road surface. This makes it possible to more suitably prevent the driver from losing control of the steering wheel 521 when the vehicle is traveling on an uneven road surface.

[0118] Moreover, according to this embodiment, the complementary sensitivity function T(s) is a function including a transfer function of a low-pass filter and a transfer function of a high-pass filter. In this embodiment, the transfer function of the low-pass filter includes the transfer function of the second filter 232b and the transfer function of the assist adjustment unit 270 functioning as a low-pass filter. The transfer function of the high-pass filter includes the transfer function of the first filter 232a. Therefore, the complementary sensitivity gain GT of the complementary sensitivity function T(s) can be suitably adjusted to the above-mentioned numerical range in each frequency domain.

[0119] The present inventors have confirmed the effect of applying the model following control by the control device 100 of the above-described embodiment by performing an actual vehicle measurement. In the actual vehicle measurement, the steering angle θ of the steering wheel 521 when the angle of the steering wheel 521 returns to a predetermined reference angle h and steering angular velocity ω h For each of the above, a comparison was made between the case where model following control was not applied and the case where model following control was applied.

[0120] Fig. 8 shows the steering angle θ h [deg] and steering angular velocity ω h The measurement results of steering angle θ [deg / s] when model following control is applied are shown in Fig. 9. h [deg] and steering angular velocity ω h 8 and 9, the horizontal axis represents time, and the vertical axis represents the steering angle θ h and steering angular velocity ω hThe magnitude of each parameter of the steering angular velocity ω h The steering angle θ represents the speed in the direction in which the angle of the steering wheel 521 returns to the predetermined reference angle as a negative value. h is shown by a dashed line, and the steering angular velocity ω h is shown by a solid line.

[0121] As shown in FIG. 8, when the model following control is not applied, when the angle of the steering wheel 521 starts to return to a predetermined reference angle, the steering angular velocity ω h The absolute value of becomes larger, and the steering angular velocity ω h While the steering angle of the steering wheel 521 periodically changes, the steering angle of the steering wheel 521 returns to the reference angle. h If the angle changes, the movement of the handle 521 will appear jerky. Note that the predetermined reference angle is 0° in Figures 8 and 9.

[0122] On the other hand, as shown in FIG. 9, when model following control is applied, when the angle of the steering wheel 521 starts to return to a predetermined reference angle, the steering angular velocity ω h It can be seen that the absolute value of is smaller than that in FIG. 8. Specifically, when the angle of the steering wheel 521 starts to return to the reference angle, the steering angular velocity ω h The absolute value of is ω2, but the steering angular velocity ω h The absolute value of is ω1 which is smaller than ω2. Also, the steering angular velocity ω h Although the absolute value of fluctuates slightly, the amplitude is the same as that of the steering angular velocity ω h is sufficiently smaller than . Therefore, when the angle of the handle 521 returns to the reference angle, the movement of the handle 521 is prevented from appearing jerky. As a result, it was confirmed that by performing model following control as in the above-described embodiment, the movement of the handle 521 can be made smooth when the angle of the handle 521 returns to the predetermined reference angle.

[0123] The electric power steering device 1000 can also be expressed as a simplified model as shown in Fig. 10. In Fig. 10, a model of a controlled object 560 of the electric power steering device 1000 is regarded as a one-inertia system. A steered side mechanism 570 shown in Fig. 10 is a portion of the steering mechanism 520 from the output shaft 524b to the tires 529A, 529B. When the electric power steering device 1000 is regarded as a one-inertia system model as shown in Fig. 10, a transfer function P(s) of the controlled object 560 is expressed, for example, by the following equation (10).

[0124]

number

[0125] The transfer function P(s) of the controlled object 560, i.e., the plant characteristic in the model following control, is not limited to the above example and may be expressed in any manner. The transfer function P(s) of the controlled object 560 may be expressed as a two-inertia system or may be expressed by an equation derived by a high-order approximation.

[0126] Furthermore, in this embodiment, the low-frequency portion TFA1, which is a portion of the low-frequency region FA1 of the waveform of the complementary sensitivity gain GT of the complementary sensitivity function T(s), may be created by a phase-lead compensator. Specifically, the first filter 232a may be the phase-lead compensator. In this case, the complementary sensitivity function T(s) is a function including the transfer function of the second filter 232b as a low-pass filter and the transfer function of the phase-lead compensator. Even in this case, the complementary sensitivity gain GT of the complementary sensitivity function T(s) can be suitably adjusted to the above-mentioned numerical range, and the waveform of the complementary sensitivity gain GT as shown in FIG. 6 can be realized.

[0127] <Embodiments of the driving device> The control device 100 described in the above-mentioned embodiment of the electric power steering can also be applied to a drive device 2000 shown in Fig. 11. The drive device 2000 shown in Fig. 11 is a drive device that is mounted on a vehicle and rotates a drive shaft 73 of the vehicle. The vehicle on which the drive device 2000 is mounted is a vehicle that uses a motor as a power source, such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHV), or an electric vehicle (EV).

[0128] FIG. 11 shows an XYZ coordinate system as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Z axis direction is the up-down direction. The side where the Z axis arrow points (+Z side) is the upper side, and the opposite side to the side where the Z axis arrow points (-Z side) is the lower side. The X axis direction is a direction perpendicular to the Z axis direction, and is the front-rear direction of the vehicle on which the drive unit 2000 is mounted. In the following embodiments, the side where the X axis arrow points (+X side) is the front side of the vehicle, and the opposite side to the side where the X axis arrow points (-X side) is the rear side of the vehicle. The Y axis direction is a direction perpendicular to both the X axis direction and the Z axis direction, and is the left-right direction of the vehicle, that is, the vehicle width direction. In this embodiment, the side where the Y axis arrow points (+Y side) is the left side of the vehicle, and the opposite side to the side where the Y axis arrow points (-Y side) is the right side of the vehicle.

[0129] The positional relationship in the front-rear direction is not limited to that in this embodiment, and the +X side may be the rear side of the vehicle, and the -X side may be the front side of the vehicle. In this case, the +Y side is the right side of the vehicle, and the -Y side is the left side of the vehicle. In this specification, the "parallel direction" includes a substantially parallel direction, and the "orthogonal direction" includes a substantially orthogonal direction.

[0130] The central axis J shown in FIG. 11 is a virtual axis extending in a direction intersecting the up-down direction. More specifically, the central axis J extends in the Y-axis direction perpendicular to the up-down direction, that is, in the left-right direction of the vehicle. In the following description, unless otherwise specified, the direction parallel to the central axis J is simply called the "axial direction", the radial direction centered on the central axis J is simply called the "radial direction", and the circumferential direction centered on the central axis J is simply called the "circumferential direction". In the following description, the left side (+Y side) in the axial direction is called the "one axial side", and the right side (-Y side) in the axial direction is called the "other axial side". The up-down direction is, for example, a vertical direction, and the front-rear direction and the left-right direction (axial direction) are, for example, horizontal directions perpendicular to the vertical direction.

[0131] 11, the drive device 2000 includes a motor 60, a gear mechanism 70 connected to the motor 60, a housing 80 that accommodates the motor 60 and the gear mechanism 70, and a control device 64 that controls the motor 60. The housing 80 accommodates the motor 60 and the gear mechanism 70. The housing 80 has a motor housing 81 that accommodates the motor 60, and a gear housing 82 that accommodates the gear mechanism 70. In this embodiment, oil O is accommodated inside the motor housing 81 and inside the gear housing 82.

[0132] The motor 60 includes a rotor 10 that can rotate about a central axis J, and a stator 61 that faces the rotor 10 with a gap therebetween. In this embodiment, the stator 61 is located radially outside the rotor 10. The stator 61 has a stator core 62 and a plurality of coils 63 attached to the stator core 62. The rotor 10 has a shaft 20 and a rotor core 30 fixed to the outer circumferential surface of the shaft 20. Although not shown, a magnet is held in the rotor core 30. The shaft 20 extends in the axial direction with the central axis J as the center. The left end (+Y side) of the shaft 20 protrudes into the gear housing 82. The left end of the shaft 20 is connected to the gear mechanism 70.

[0133] The gear mechanism 70 transmits the rotation of the motor 60 to a drive shaft 73 of the vehicle. The gear mechanism 70 has a reduction gear 71 connected to the shaft 20 of the motor 60, and a differential gear 72 connected to the reduction gear 71. A drive shaft 73 extending in the axial direction (Y-axis direction) is connected to the differential gear 72. A pair of drive shafts 73 are provided. A pair of tires 74A, 74B are respectively connected to the pair of drive shafts 73.

[0134] When the rotation of the rotor 10 in the motor 60 is transmitted to the differential gear 72 via the reduction gear 71, a pair of drive shafts 73 connected to the differential gear 72 rotate. In this manner, the driving device 2000 rotates the drive shafts 73 to which the vehicle tires 74A, 74B are connected. The rotation of the pair of drive shafts 73 rotates the pair of tires 74A, 74B, causing the vehicle to run.

[0135] In this embodiment, the control target of the control device 64 includes the motor 60. The control device 64 controls the drive device 2000 by supplying power to the motor 60. The control device 64 also controls the pair of drive shafts 73 connected to the drive device 2000 and the pair of tires 74A, 74B connected to the pair of drive shafts 73 by driving the drive device 2000. In this embodiment, the control target of the control device 64 is a drive mechanism 3000 including the tires 74A, 74B, the drive shaft 73, and the drive device 2000.

[0136] The drive unit 2000 is configured as a two-inertia system similar to the electric power steering device 1000 described above. The electric power steering device 1000 described above is configured as a two-inertia system in which the steering wheel 521 and the motor 543 are connected via the torsion bar 546, which is a spring element. The drive unit 2000 of this embodiment is configured as a two-inertia system in which the tires 74A, 74B and the motor 60 are connected via the drive shaft 73, which can be regarded as a spring element. Since it is configured as a two-inertia system, the drive unit 2000 also has a problem derived from a two-inertia system, such as the drive shaft 73 being twisted when the torque of the motor 60 is increased, and the acceleration of the tires 74A, 74B vibrating when the twist is eliminated by the rotation of the tires 74A, 74B. The problem can be solved by configuring the control device 64 of this embodiment in the same way as the control device 100 in the electric power steering device 1000 described above and performing model following control. Moreover, by adjusting the complementary sensitivity gain GT of the complementary sensitivity function T(s) in the same manner as in the above-described control device 100, the drive device 2000 can also obtain the same effects as those described in the embodiment of the above-described electric power steering device 1000.

[0137] As an example, in the control device 64, the steering angle θ h is replaced with the rotation angle of the tires 74A, 74B around the axis of the drive shaft 73, and the steering angle θ s with the rotation angle about the central axis J of the shaft 20, and perform control similar to that of the control device 100. The rotation angle of the tires 74A, 74B about the axis of the drive shaft 73 may be detected by an angle sensor (not shown) or a rotation speed sensor (not shown).

[0138] In this embodiment, the first resonance frequency is the resonance frequency of the drive device 2000, and the lower limit of the frequency band in which the complementary sensitivity gain GT of the complementary sensitivity function T(s) is 1 is higher than the first resonance frequency. In this embodiment, the second resonance frequency is the resonance frequency of the drive mechanism 3000 including the tires 74A, 74B, the drive shaft 73, and the drive device 2000. The second resonance frequency is higher than the first resonance frequency of this embodiment described above, and is lower than the lower limit of the frequency band in which the complementary sensitivity gain GT is 1. In this embodiment, the complementary sensitivity gain GT at the second resonance frequency is also higher than the complementary sensitivity gain GT at the first resonance frequency, is 0.5 or more, and is less than 1. The complementary sensitivity gain GT of the complementary sensitivity function T(s) and the steady-state gain T(0) of the complementary sensitivity function T(s) can be set in the same manner as in the embodiment of the electric power steering device 1000 described above.

[0139] The present invention is not limited to the above-described embodiment, and other configurations and methods may be adopted within the scope of the technical concept of the present invention. The object controlled by the control device is not particularly limited as long as it includes a motor. In the above-described embodiment, the control device 100 controls the steering angle θ h and steering angle θ s In the above embodiment, the control device 100 performs control using the steering torque T h and steering angle θ s In this case, the value input to the controller 200a is the steering angle θ h Instead of steering torque T h The output from the control object 560 is the steering angle θ s Instead of the steering angle θ s The control device 100 may use any other parameters to perform the control as in the above-described embodiment.

[0140] The present technology can be configured as follows. (1) A control device for controlling a steering mechanism mounted on a vehicle, the steering mechanism having an input shaft connected to a steering wheel steered by a driver, an output shaft connected to the input shaft via a torsion bar, and a motor connected to the output shaft, at least a portion including the motor as a controlled object, the control device comprising a model following control unit that generates a correction torque for correcting an input torque input to the controlled object based on an output of the controlled object and a nominal model based on a configuration of the controlled object, the model following control unit generating a complementary sensitivity gain, which is a gain in a gain characteristic of a complementary sensitivity function for a modeling error between the controlled object and the nominal model, of approximately 1. a steady-state gain of the complementary sensitivity function is 0.1 or more, a lower limit of the frequency band in which the complementary sensitivity gain is 1 is higher than a first resonance frequency which is a resonance frequency of a yaw rate of the vehicle, a second resonance frequency which is a resonance frequency of the steering mechanism is higher than the first resonance frequency and is lower than a lower limit of the frequency band in which the complementary sensitivity gain is 1, and the complementary sensitivity gain at the second resonance frequency is higher than the complementary sensitivity gain at the first resonance frequency, is 0.5 or more and is less than 1. (2) A base assist control unit is provided that generates an assist torque that compensates for at least a part of the self-aligning torque generated in the tire of the vehicle based on a torsion bar torque generated in the torsion bar, and the spring constant of the torsion bar is set to K tor The gradient of the self-aligning torque generated in the tires of the vehicle relative to the steering angle, which is the rotation angle of the output shaft, is K SAT The gradient of the assist torque relative to the torsion bar torque is K ass , the steady-state gain is T(0), and a ratio of the correction torque to a disturbance input to the controlled object is m, the following formula is established.

number

[0141] The configurations and methods described in this specification can be combined as appropriate within the scope of not being mutually inconsistent. [Explanation of symbols]

[0142] 20...shaft, 60, 543...motor, 64, 100...control device, 70...gear mechanism, 73...drive shaft, 74A, 74B, 529A, 529B...tire, 220...base assist control unit, 230...model following control unit, 521...steering wheel, 524a...input shaft, 524b...output shaft, 530...steering mechanism, 546...torsion bar, 560...control target, 1000...electric power steering device, 2000...drive device, 3000...drive mechanism, f st …Second resonant frequency, f yaw …first resonance frequency, GT…complementary sensitivity gain, K tor …Spring constant, m…Ratio, T(s)…Complementary sensitivity function, T(0)…Stationary gain, T ass … Assist torque, T f …corrected torque, T h …Steering torque (torsion bar torque), T r …input torque, T SAT …Self-aligning torque, θ s …Steering angle

Claims

1. A control device for controlling a steering mechanism mounted on a vehicle, the steering mechanism having an input shaft connected to a steering wheel operated by a driver, an output shaft connected to the input shaft via a torsion bar, and a motor connected to the output shaft, the control device controlling at least a portion including the motor as a controlled object, a model following control unit that generates a correction torque for correcting an input torque input to the controlled object based on an output of the controlled object and a nominal model based on a configuration of the controlled object, the model following control unit is configured such that a transfer function of the control object is constrained to a transfer function of the nominal model in a frequency band in which a complementary sensitivity gain, which is a gain in a gain characteristic of a complementary sensitivity function with respect to a modeling error between the control object and the nominal model, is approximately 1; the steady-state gain of the complementary sensitivity function is 0.1 or greater; a lower limit value of a frequency band in which the complementary sensitivity gain is 1 is higher than a first resonance frequency which is a resonance frequency of a yaw rate of the vehicle; a second resonance frequency which is a resonance frequency of the steering mechanism is higher than the first resonance frequency and is lower than a lower limit value of a frequency band in which the complementary sensitivity gain is 1; The complementary sensitivity gain at the second resonant frequency is higher than the complementary sensitivity gain at the first resonant frequency, and is greater than or equal to 0.5 and less than 1.

2. a base assist control unit that generates an assist torque that compensates for at least a part of a self-aligning torque generated in a tire of the vehicle based on a torsion bar torque generated in the torsion bar, The spring constant of the torsion bar is K ｔｏｒ The gradient of the self-aligning torque generated in the tire of the vehicle relative to the steering angle, which is the rotation angle of the output shaft, is K ＳＡＴ The gradient of the assist torque with respect to the torsion bar torque is K ａｓｓ 2. The control device according to claim 1, wherein the following formula is established when x = 1 , the steady-state gain is T(0), and a ratio of the correction torque to the disturbance input to the controlled object is m. [0010]

3. The control device according to claim 1 , further comprising a control unit that is operable to return the angle of the steering wheel to a predetermined reference angle.

4. A control device for controlling a controlled object including a motor in a drive device that rotates a drive shaft to which tires of a vehicle are connected, a model following control unit that generates a correction torque for correcting an input torque input to the controlled object based on an output of the controlled object and a nominal model based on a configuration of the controlled object, the model following control unit is configured such that a transfer function of the control object is constrained to a transfer function of the nominal model in a frequency band in which a complementary sensitivity gain, which is a gain in a gain characteristic of a complementary sensitivity function with respect to a modeling error between the control object and the nominal model, is approximately 1; the steady-state gain of the complementary sensitivity function is 0.1 or greater; a lower limit value of a frequency band in which the complementary sensitivity gain is 1 is higher than a first resonant frequency that is a resonant frequency of the drive device, a second resonance frequency, which is a resonance frequency of a drive mechanism including the tire, the drive shaft, and the drive device, is higher than the first resonance frequency and is lower than a lower limit value of a frequency band in which the complementary sensitivity gain is 1; The complementary sensitivity gain at the second resonant frequency is higher than the complementary sensitivity gain at the first resonant frequency, and is greater than or equal to 0.5 and less than 1.

5. The steady-state gain is 0.3 or more, The control device according to claim 1 , wherein the complementary sensitivity gain at the second resonant frequency is greater than or equal to 0.

8.

6. The control device according to claim 1 , wherein a lower limit of a frequency band in which the complementary sensitivity gain is 1 is lower than 10 Hz.

7. The control device according to claim 1 , wherein the complementary sensitivity function is a function including a transfer function of a low-pass filter and a transfer function of a phase lead compensator.

8. The control device according to claim 1 , wherein the complementary sensitivity function is a function including a transfer function of a low-pass filter and a transfer function of a high-pass filter.

9. A control device according to any one of claims 1 to 3; The steering mechanism; An electric power steering device comprising:

10. A control device according to claim 4; The motor; A gear mechanism connected to the motor; A drive device comprising:

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