Control device, electric power steering device, and drive device

Abstract

The invention provides a control device, an electric power steering device, and a drive device. The control device has a model tracking control unit. The model tracking control unit is configured to constrain the transfer function of the control object to the 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 more. The lower limit value of the band in which the complementary sensitivity gain is 1 is higher than a first resonance frequency which is the resonance frequency of the 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 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 0.5 or more and less than 1.

Description

Technical Field

[0001] The invention relates to a control device, an electric power steering device and a driving device. Background Art

[0002] An electric power steering system mounted on a vehicle is known (for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-183046

[0004] The electric power steering system as described above is configured as a dual inertia system in which a steering wheel and a steering mechanism are connected via a torsion bar as a spring element. A control target configured by such a dual inertia system has a problem that it is difficult to control compared to a single inertia system. Summary of the invention

[0005] In view of the above circumstances, one of the objects of the present invention is to provide a control device capable of improving the controllability of a control object configured as a dual inertia system, an electric power steering device having such a control device, and a drive device having such a control device.

[0006] One embodiment of the present invention is a control device that controls at least a portion of a steering mechanism mounted on a vehicle including a motor as a control object, the steering mechanism having an input shaft connected to a steering wheel steered by a steersman; an output shaft connected to the input shaft via a torsion bar; and the motor connected to the output shaft. The control device has a model tracking control unit that generates a correction torque for correcting an input torque input to the control object based on an output of the control object and a nominal model based on the structure of the control object. The model tracking control unit is configured to constrain a transfer function of the control object to a transfer function of the nominal model in a frequency band in which a gain in a gain characteristic of a complementary sensitivity function with respect to a modeled error between the control object and the nominal model, that is, a complementary sensitivity gain, is approximately 1. The steady-state gain of the complementary sensitivity function is greater than 0.1. The 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 yaw rate of the vehicle. A second resonance frequency as a resonance frequency of the steering mechanism is higher than the first resonance frequency and lower than a lower limit of a frequency band in which the complementary sensitivity gain is 1. The complementary sensitivity gain at the second resonance frequency is higher than the complementary sensitivity gain at the first resonance frequency and is 0.5 or more and less than 1.

[0007] One embodiment of the present invention is a control device that controls a control object including a motor in a drive device that rotates a drive shaft connected to a tire of a vehicle. The control device has a model tracking control unit that generates a correction torque for correcting an input torque input to the control object based on an output of the control object and a nominal model based on the structure of the control object. The model tracking control unit is configured to constrain a transfer function of the control object to a transfer function of the nominal model in a frequency band where a gain in a gain characteristic of a complementary sensitivity function relative to a modeled error between the control object and the nominal model, i.e., a complementary sensitivity gain, is approximately 1. The steady-state gain of the complementary sensitivity function is greater than 0.1. The lower limit value of the frequency band where 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 tire, the drive shaft, and the drive device 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. The complementary sensitivity gain at the second resonance frequency is higher than the complementary sensitivity gain at the first resonance frequency, and is greater than or equal to 0.5 and less than 1.

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

[0009] The driving device of the present invention includes the above-mentioned control device, the motor, and a gear mechanism connected to the motor.

[0010] According to one aspect of the present invention, in an electric power steering device and a drive device, controllability of a control object configured as a dual inertia system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 FIG. 1 is a diagram schematically showing an electric power steering device according to an embodiment.

[0012] Figure 2 This is a block diagram showing the structure of a control device according to one embodiment.

[0013] Figure 3 This is a functional block diagram showing the functions of a processor in a control device according to one embodiment.

[0014] Figure 4 This is a graph showing an example of the relationship between the steering angle and the assist torque.

[0015] Figure 5 1 is a functional block diagram showing the functions of a vehicle stabilization compensating unit according to one embodiment.

[0016] Figure 6Graphs showing, by way of example, the gain characteristic of the complementary sensitivity function and the gain characteristic of the inverse of the modeling error between the transfer function of the controlled object and the transfer function of the nominal model.

[0017] Figure 7 This is a graph showing an example of the relationship between the steering angle and the self-aligning torque.

[0018] Figure 8 This is a graph showing an example of the measurement results of the steering angle and the rotation angular velocity when the model following control is not applied.

[0019] Fig. 9 This is a graph showing an example of the measurement results of the steering angle and the rotation angular velocity when the model following control is applied.

[0020] Fig.10 This is a diagram showing a simplified model of an electric power steering device according to one embodiment.

[0021] Fig.11 This is a diagram schematically showing a driving device according to one embodiment.

[0022] Description of symbols

[0023] 20: shaft; 60, 543: motor; 64, 100: control device; 70: gear mechanism; 73: drive shaft; 74A, 74B, 529A, 529B: tire; 220: basic auxiliary control unit; 230: model tracking control unit; 521: steering wheel; 524a: input shaft; 524b: output shaft; 530: steering mechanism; 546: torsion bar; 560: control object; 1000: electric power steering device; 2000: drive device; 3000: drive mechanism; f st : The second resonance frequency; f yaw : first resonance frequency; GT: complementary sensitivity gain; K tor : spring constant; m: ratio; T(s): complementary sensitivity function; T(0): steady-state gain; T ass : Assist torque; T f : Correction torque; T h : Steering torque (torsion bar torque); T r : Input torque; T SAT : Automatic self-centering torque; θ s : steering angle. DETAILED DESCRIPTION

[0024] <Embodiment of the electric power steering device>

[0025] Figure 1 The electric power steering device 1000 of the present embodiment shown in FIG. Figure 1As shown, the electric power steering device 1000 includes a steering mechanism 530 and a control device 100. The steering mechanism 530 includes a steering mechanism portion 520 and an assist mechanism portion 540. The electric power steering device 1000 controls the assist mechanism portion 540 by the control device 100, thereby generating an assist torque that assists the steering torque T generated in the steering mechanism portion 520 when the driver of the vehicle steers the steering wheel 521. h This assist torque reduces the operational burden on the driver when the driver operates the steering wheel 521. The driver of the vehicle is a steerer who steers the steering wheel 521 of the vehicle.

[0026] The steering mechanism 520 includes a steering wheel 521, a steering shaft 522, universal joints 523A and 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 and 552B, tie rods 527A and 527B, knuckles 528A and 528B, and left and right tires 529A and 529B. That is, the steering mechanism 530 includes a steering wheel 521, a steering shaft 522, universal joints 523A and 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 and 552B, tie rods 527A and 527B, knuckles 528A and 528B, and left and right tires 529A and 529B.

[0027] The steering shaft 522 is a shaft extending from the steering wheel 521 for steering by the helmsman. One end of the input shaft 524a is connected to the end of the steering shaft 522 on the side opposite to the side connected to the steering wheel 521 via the universal couplings 523A and 523B. Thus, the steering wheel 521 is connected to the input shaft 524a via the universal couplings 523A and 523B and the steering shaft 522. The output shaft 524b is connected to the input shaft 524a via the torsion bar 546 described later. In more detail, 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 the rack and pinion mechanism 525.

[0028] The input shaft 524a and the output shaft 524b are coaxially arranged. 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 twist.

[0029] The auxiliary mechanism unit 540 includes a steering torque sensor 541, a steering angle sensor 542, a motor 543, a speed reduction mechanism 544, an inverter 545, and a torsion bar 546. That is, the steering mechanism 530 includes a steering torque sensor 541, a steering angle sensor 542, a motor 543, a speed reduction mechanism 544, an inverter 545, and a torsion bar 546. The torsion bar 546 connects the input shaft 524a and the output shaft 524b. The torsion bar 546 is coaxially arranged with the input shaft 524a and the output shaft 524b. In the following description, an imaginary 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 be twisted around the rotation axis R.

[0030] The steering torque sensor 541 detects the amount of torsion of the torsion bar 546 around the rotation axis R to detect the steering torque T in the steering mechanism 520. h . Steering torque T h is the torsion bar torque generated in the torsion bar 546, and is the torsion moment about the rotation axis R. The steering angle sensor 542 can detect the rotation angle θ of the input shaft 524a about the rotation axis R. a The rotation angle θ of the input shaft 524a is a 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 , which can detect the steering angle θ of the steering wheel 521 h The rotation angle θ of the output shaft 524b can be detected by the steering torque sensor 541 and the steering angle sensor 542. b The rotation angle θ of the output shaft 524b b is the steering angle θ s .

[0031] The inverter 545 converts the DC power into three-phase AC power of simulated sinusoidal waves of U phase, V phase and W phase according to the motor drive signal input from the control device 100, and supplies it to the motor 543. The motor 543 is connected to the output shaft 524b via the 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: Interior Permanent Magnet Synchronous Motor), a surface mounted permanent magnet synchronous motor (SPMSM: Surface mounted Permanent Magnet Synchronous Motor) or a switched reluctance motor (SRM: Switched Reluctance Motor). The motor 543 generates a steering torque T by supplying three-phase AC power from the inverter 545.h The motor 543 transmits the generated assist torque to the output shaft 524 b via the speed reduction mechanism 544 .

[0032] The control device 100 controls at least a portion of the steering mechanism 530 mounted on the vehicle, which includes the motor 543, as a control object 560. In the present embodiment, the control object 560 includes a steering mechanism 520, a torsion bar 546, a motor 543, and a speed reduction mechanism 544. The control object 560 includes an input shaft 524a and an output shaft 524b that can rotate relative to each other via the torsion bar 546, so the motion of the control object 560 cannot be described only by a simple motion equation of a single inertial system. The control object 560 changes between a single inertial system and a dual inertial system according to the strength with which the steersman holds the steering wheel 521. The harder the steersman holds the steering wheel 521, the closer the control object 560 is to a single inertial system. The weaker the steersman holds the steering wheel 521, the closer the control object 560 is to a dual inertial system. In this way, the control object 560 is composed of a dual inertial system.

[0033] The control device 100 is electrically connected to the inverter 545. The control device 100 generates a motor drive signal based on the detection signals detected by the steering torque sensor 541, the steering angle sensor 542, and the vehicle speed sensor 300 mounted on the vehicle, and outputs it to the inverter 545. The control device 100 controls the rotation of the motor 543 via the inverter 545, thereby controlling the control object 560. In more detail, the control device 100 controls the switching action of multiple switching elements possessed by the inverter 545. Specifically, the control device 100 generates a control signal for controlling the switching action of each switching element and outputs it to the inverter 545. Each switching element is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-EffectTransistor). In the following description, the control signal for controlling the switching action of each switching element is referred to as a "gate control signal".

[0034] The control device 100 controls the steering torque T hThe torque command value is generated by, for example, controlling the torque of the motor 543 and the rotation speed of the motor 543 by vector control. Vector control is a method of decomposing the current flowing in the motor 543 into a current component that contributes to the generation of torque and a current component that contributes to the generation of magnetic flux, and independently controlling each current component that is perpendicular to each other. The control device 100 is not limited to vector control, and other closed-loop controls can be performed. The rotation speed of the motor 543 is represented by, for example, the rotation speed of the rotor in 1 minute [rpm (revolutions per minute: revolutions / minute)], or the rotation speed of the rotor in 1 second [rps (revolutions per second: revolutions / second)].

[0035] Alternatively, the steering torque T may be directly input from the steering torque sensor 541 to the control device 100. h The control device 100 may calculate the steering torque T according to the output value of the steering torque sensor 541. h The steering angle θ of the steering wheel 521 may also be directly input to the control device 100 from the steering angle sensor 542. h The control device 100 may calculate the steering angle θ based on the output value of the steering angle sensor 542. h The value of .

[0036] In addition, 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 the electric power steering device 1000. In addition, the control device 100 can be manufactured and sold independently of the motor 543 as a control device for controlling the electric power steering device 1000.

[0037] Figure 2 A typical example of the structure of the control device 100 in this embodiment is shown. 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 implemented as a printed wiring board (PCB: Printed Circuit Board) on which these electronic components are mounted.

[0038] The vehicle speed sensor 300, the steering torque sensor 541, and the steering angle sensor 542 mounted on the vehicle are connected to the processor 200 in a manner that allows communication with the processor 200. The vehicle speed is sent from the vehicle speed sensor 300 to the processor 200. The steering torque T is sent from the steering torque sensor 541 to the processor 200. h The steering angle θ is sent from the steering angle sensor 542 to the processor 200. h .

[0039] The processor 200 is a semiconductor integrated circuit, also known as a central processing unit (CPU) or a microprocessor. The processor 200 sequentially executes a computer program stored in the ROM 116 and contains a set of instructions for controlling the motor drive, thereby realizing the desired processing. In addition to or instead of the processor 200, the control device 100 may include an FPGA (Field Programmable Gate Array) equipped with a CPU, a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an ASSP (Application Specific Standard Product), or a combination of two or more circuits selected from these circuits. The processor 200 sets a current command value based on an actual current value and the rotation angle of the rotor of the motor 543, generates a PWM (Pulse Width Modulation) signal, and outputs the PWM signal to the drive circuit 115.

[0040] 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 part of the control device 100. The DC voltage generated in the power supply circuit 111 is, for example, 3V or 5V.

[0041] 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 rotary transformer, a Hall element such as a Hall IC, or an MR sensor having a magnetoresistive element. The processor 200 may detect the rotation angle of the rotor of the motor 543 based on the angle sensor 112. m The angular velocity ω [rad / s] of the motor 543 is calculated. In addition, the control device 100 may include a velocity sensor capable of detecting the rotational angular velocity of the motor 543 and an acceleration sensor capable of detecting the rotational angular acceleration of the motor 543 instead of the angle sensor 112 .

[0042] The motor current value detected by the 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 the "actual current value". The input circuit 113 converts the level of the input actual current value into the input level of the processor 200 as needed, 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.

[0043] The communication I / F 114 is, for example, an input / output interface for transmitting and receiving data in accordance with a vehicle-mounted CAN (Controller Area Network).

[0044] Typically, the drive circuit 115 is a gate driver or a pre-driver. The drive circuit 115 generates a gate control signal according to the PWM signal, and provides the gate control signal to the gates of the plurality of switching elements of the inverter 545. For example, when the motor 543 as the drive object is a motor that can be driven at a low voltage, the drive circuit 115 as a gate driver may not be necessary. In this case, the function of the gate driver in the drive circuit 115 can be installed in the processor 200.

[0045] 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. As a writable memory, for example, a PROM (Programmable Read Only Memory) is cited. As a rewritable memory, for example, a flash memory and an EEPROM (Electrically Erasable Programmable Read Only Memory) are cited. The ROM 116 stores a control program including an instruction group for causing the processor 200 to control the motor drive. For example, the control program stored in the ROM 116 is temporarily expanded to a RAM (not shown) during booting.

[0046] Figure 3 An example of the functional blocks of the processor 200 of this embodiment is shown. The processor 200 as a computer sequentially executes the processing or tasks required for controlling the motor 543 using each functional block. Figure 3 Each functional block of the processor 200 shown can be installed in the processor 200 as software such as firmware, can be installed in the processor 200 as hardware, or can be installed 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 units of software modules and stored in the ROM 116. However, when using FPGA or the like, all or part of these functional blocks can be installed as a hardware accelerator. In addition, the control method of the control device 100 in this embodiment can be implemented by installing it in a computer and causing the computer to perform the desired action.

[0047] 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 tracking control unit 230, a state feedback unit 280, and a subtractor SU2. That is, the control device 100 has a reaction force control unit 210, a model tracking control unit 230, a state feedback unit 280, subtractors SU1, SU2, and an adder AD1. In other words, the processor 200 of the control device 100 is installed with functions corresponding to the reaction force control unit 210, the model tracking control unit 230, the state feedback unit 280, the subtractors SU1, SU2, and the adder AD1.

[0048] The steering angle θ detected by the steering angle sensor 542 is input to the subtractor SU1. h Subtractor SU1 is used to calculate the steering angle θ h Subtract the steering angle θ detected by the steering torque sensor 541 and the steering angle sensor 542 s , and output to the torque conversion unit 211.

[0049] 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, and outputs a steering torque T h The gain in the torque converter 211 is equal to the spring constant K of the torsion bar 546 tor . Steering angle θ h With steering angle θ s The difference is multiplied by the spring constant K of the torsion bar 546 tor The value obtained is the torsion bar torque, that is, the steering torque T h . Steering torque T h The result is input to the adder AD1 and the reaction force control unit 210 .

[0050] The reaction force control unit 210 controls the steering angle θ according to the h and steering angle θ s The input torque T is generated to be input to the control object 560. r . Input torque T r is the target torque of the motor 543 and is the torque command value. The reaction force control unit 210 generates the input torque T r The torque of the motor 543 is controlled, thereby controlling the reaction force transmitted from the steering wheel 521 to the steersman.

[0051] The reaction force control unit 210 includes a differentiator 212, a basic assist control unit 220, a vehicle stabilization compensator 240, and an adder AD2. That is, the control device 100 includes a differentiator 212, a basic assist control unit 220, a vehicle stabilization compensator 240, and an adder AD2.

[0052] The basic assist control unit 220 receives the steering torque T output from the torque conversion unit 211. h The basic assist control unit 220 generates a torque bar torque in the torsion bar 546, that is, a steering torque T h The self-aligning torque T is generated on the tires 529A and 529B of the vehicle. SAT The auxiliary torque T that compensates at least part of ass In this embodiment, the basic assist control unit 220 sets the steering torque T h Multiply by the auxiliary gain K ass The output auxiliary torque T ass . Figure 4 The steering torque T h With assist torque T ass An example of a relationship between Figure 4 In the curve diagram, the horizontal axis is the steering torque T h , the vertical axis is the assist torque T ass , assist torque T ass Relative to steering torque T h The slope is the auxiliary gain K ass . Steering torque T h , auxiliary torque T ass and auxiliary gain K ass Meet dT ass / dT h =K ass Such as Figure 4 As shown, the assist torque T ass For example, with the steering torque T h As it gets bigger, it gets bigger exponentially. Figure 3 As shown, the assist torque T output from the basic assist control unit 220 ass It is input to adder AD2.

[0053] The steering angle θ is input to the vehicle stabilization compensation unit 240. s and the steering angle θ is calculated by differentiator 212 s The steering angular velocity ω calculated by differentiation s .like Figure 5 As shown, the vehicle stabilization compensating unit 240 includes an active return control unit 241 , a return speed control unit 242 , a damping control unit 243 , and an adder AD5 .

[0054] The active return control unit 241 controls the angle of the steering wheel 521, that is, the steering angle θ h The active return control part automatically returns to a predetermined reference angle. The predetermined reference angle is the steering angle θ at which the steering wheel 521 becomes the center position. hThe steering angle θ is input to the active return control unit 241. s The active return control unit 241 is based on the steering angle θ s , output torque T for active return control AC .

[0055] The return speed control unit 242 is a part that performs return speed control. The return speed control is to adjust the angle of the steering wheel 521, that is, the steering angle θ, by active return control. h Steering angle θ when returning to the specified reference angle h The speed, that is, the steering angular velocity ω h The return speed control is, for example, to prevent the steering wheel 521 from returning too fast due to active return control, and the steering angle θ h The steering angle θ is input to the return speed control unit 242. s and the steering angular velocity ω s The return speed control unit 242 is based on the steering angle θ s and the steering angular velocity ω s , output torque T for return speed control RS . Return velocity control is also called convergence control.

[0056] In this embodiment, the control of returning the angle of the steering wheel 521 to a predetermined reference angle is performed through the active return control and the return speed control. That is, in this embodiment, the control device 100 can perform the control of returning the angle of the steering wheel 521 to a predetermined reference angle through the active return control unit 241 and the return speed control unit 242. For example, when the vehicle is traveling at a high speed, the self-aligning torque T generated by the tires 529A and 529B is SAT becomes larger, so the angle of the steering wheel 521 is easily increased by the self-aligning torque T SAT Therefore, when the vehicle is traveling at a high speed, the control amount of the active return control becomes smaller than when the vehicle is traveling at a low speed. SAT This refers to the torque that acts in the direction in which the steering wheel 521 returns due to the elasticity of the tires 529A and 529B that are twisted when the steering wheel 521 is turned.

[0057] The damping control unit 243 is a part that performs damping control to apply brakes to the movement of the steering wheel 521 according to the speed at which the steering wheel 521 is steered. s and the steering angular velocity ω s is input to the damping control unit 243. The damping control unit 243 adjusts the steering angle θ according to the steering angle θ. s and the steering angular velocity ω s, output torque T for damping control DM .

[0058] The adder AD5 adds the torque T output from the active return control unit 241 AC , the torque T output from the return speed control unit 242 RS and the torque T output from the damping control unit 243 DM Add and output compensation torque T c . Compensation torque T c is the output of the vehicle stabilization compensation unit 240. Figure 3 As shown, the compensation torque T c It is input to adder AD2.

[0059] Alternatively, the steering angle θ can be replaced by s and the steering angular velocity ω s The steering angle θ is input to the vehicle stabilization compensation unit 240. h and steering angular velocity ω h In this case, the active return control unit 241 controls the steering angle θ h , output torque T for active return control AC The return speed control unit 242 is based on the steering angle θ h and steering angular velocity ω h , output torque T for return speed control RS The damping control unit 243 is based on the steering angle θ h and steering angular velocity ω h , output torque T for damping control DM .

[0060] Adder AD2 converts the auxiliary torque T ass and compensation torque T c The input torque T is added to the control object 560 and outputted. r . Input torque T r It is input to the subtractor SU2.

[0061] The model following control unit 230 generates a response to the input torque T according to the output of the controlled object 560 and a nominal model based on the structure of the controlled object 560. r Correction torque T for correction f In this embodiment, the correction torque T f is fed back to the input torque T rThe nominal model is an internal model of the model used to constrain the control object 560 when controlling the control object 560. The nominal model will be described in detail later. The model tracking control unit 230 is a model tracking controller configured to perform model tracking control. The specific structure of the model tracking control unit 230 will be described in detail later.

[0062] Subtractor SU2 is used to calculate the input torque T r The correction torque T outputted from the model following control unit 230 is subtracted. f The output from the subtractor SU2 is input to the adder AD3 and the model tracking control unit 230. The adder AD3 outputs a value obtained by adding the output from the state feedback unit 280 and the output from the subtractor SU2 to the adder AD1. The adder AD1 adds the steering torque T to the output from the adder AD3. h and disturbance torque T d The obtained value is output to the control object 560.

[0063] Disturbance torque T d The difference between the actual output torque of the motor 543 and the ideal output torque of the motor 543. d The disturbance torque Td includes the disturbance torque applied to the control object 560 from the outside. The disturbance torque Td includes, for example, the excess torque generated by the friction and vibration caused by the mechanical elements such as the motor 543 and the speed reduction mechanism 544, the torque fluctuation generated in the motor 543, the self-aligning torque T SAT And the interference torque that may be generated when driving on unpaved loose roads or gravel roads, etc.

[0064] In this embodiment, the model following control unit 230 controls the steering angle θ according to the steering angle θ. s The correction torque T is generated f , and fed back to the input torque T r The model tracking control unit 230 includes an inverse nominal model 231, a first filter 232a, a second filter 232b, an auxiliary adjustment unit 270, subtractors SU3, SU4, and an adder AD4. In the present 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, greater than 2 Hz and less than 10 Hz. In the present embodiment, the first cutoff frequency Cf1 is greater than 5 Hz and less than 10 Hz.

[0065] In the present embodiment, the second filter 232b is a low-pass filter. The second filter 232b has a second cut-off frequency Cf2 higher than the first cut-off frequency Cf1. The second cut-off frequency Cf2 is, for example, above 3 Hz and below 50 Hz. However, the upper limit of the second cut-off frequency Cf2 can be set to a range of about 140 Hz and below 200 Hz. The number of times of the second filter 232b is more than 3 times. The second filter 232b can also be composed of a plurality of low-pass filters, for example. The first filter 232a and the second filter 232b are connected in series.

[0066] The model tracking control unit 230 is configured to constrain the transfer function P(s) of the controlled object 560 to the transfer function P(s) of the nominal model in a frequency band where the gain in the gain characteristic of the complementary sensitivity function T(s) for the modeling error between the controlled object 560 and the nominal model, that is, the complementary sensitivity gain GT, is approximately 1. n (s). Regarding "the complementary sensitivity gain GT is approximately 1", in addition to the case where the complementary sensitivity gain GT is 1, for example, the case where the complementary sensitivity gain GT is greater than 0.8 and less than 1.2 is also included. This numerical range is, for example, a range in which the gain of the actual interference suppression characteristic can be adjusted to 1 based on the positive efficiency and reverse efficiency of the worm gear when the reduction mechanism 544 connected to the motor 543 has a worm gear. Since the efficiency of the worm gear is about 0.8, the gain needs to be adjusted by ±0.2 relative to the target value 1.

[0067] The complementary sensitivity function T(s) is the complementary sensitivity function of the inner loop formed by the model tracking control unit 230. Figure 6 , the complementary sensitivity gain GT in the complementary sensitivity function T(s) is shown. The complementary sensitivity gain GT is the gain of the complementary sensitivity function T(s) as a transfer function, and is the absolute value of the complementary sensitivity function T(s). Figure 6 As shown, in the frequency band where the frequency f is above the first cutoff frequency Cf1 and below the second cutoff frequency Cf2, the gain of the complementary sensitivity function T(s) is 0 dB, that is, the complementary sensitivity gain GT in the transfer function is 1. That is, the first cutoff frequency Cf1 is the lower limit value of the frequency band where the complementary sensitivity gain GT is 1. The second cutoff frequency Cf2 is the upper limit value of the frequency band where the complementary sensitivity gain GT is 1. In addition, in this specification, "the transfer function of the controlled object is constrained to be the transfer function of the nominal model" means that, for example, when observing 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.

[0068] The transfer function P(s) of the controlled object 560 is a plant characteristic for performing model following control. The transfer function P(s) of the controlled object 560 is represented by the following equation (1), for example.

[0069]

[0070] Here, s is the Laplace transform, J is a parameter representing the inertia moment of the steering mechanism 520, and B is a parameter representing the viscous friction coefficient of the steering mechanism 520. SAT Is the automatic return torque gain. Automatic return torque gain K SAT is the self-aligning torque T generated by the tires 529A and 529B of the vehicle. SAT Relative to the steering angle θ s The slope of . Figure 7 The self-aligning torque T SAT With steering angle θ s An example of a relationship between Figure 7 In the curve diagram, the horizontal axis is the steering angle θ s , the vertical axis is the self-aligning torque T SAT , automatic return torque T SAT Relative to the steering angle θ s The slope is the automatic return torque gain K SAT . Steering angle θ s , Automatic return torque T SAT And the automatic return torque gain K SAT Meet dT SAT / dθ s =K SAT Such as Figure 7 As shown, for example, at a steering angle θ s Before the steering angle θ s The larger the self-aligning torque T SAT The larger the steering angle θ is, the s When the steering angle θ is larger than a certain value, s The larger the self-aligning torque T SAT The smaller.

[0071] The inverse nominal model 231 is an inverse model of a prescribed nominal model for constraining the controlled object 560. The transfer function P of the nominal model n (s) is represented by the following equation (2), for example. The transfer function P of the inverse nominal model 231 is n -1 (s) is represented by, for example, the following formula (3).

[0072]

[0073] In equations (2) and (3), s is the Laplace transform, J n is the parameter representing the inertia moment of the nominal model, B nis a parameter representing the viscous friction coefficient of the nominal model. In addition, the transfer function P of the nominal model 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.

[0074] like Figure 3 As shown, the output of the control object 560 is input to the inverse nominal model 231. Specifically, the steering angle θ is input to the inverse nominal model 231. s The inverse nominal model 231 is based on the above equation (3) and the input steering angle θ s To output torque T p That is, the model following control unit 230 calculates the torque T according to the output of the controlled object 560 using the nominal model. p When the output value of the nominal model becomes the same as the output value of the controlled object 560, the torque T p Equal to the value of the torque input to the nominal model.

[0075] The subtractor SU3 subtracts the output of the subtractor SU2 from the output of the inverse nominal model 231 to generate a differential torque T a That is, the subtractor SU3 subtracts the torque T p Subtract the feedback correction torque T f Then the state compensation value V described later is fed back s The previous input torque T r The differential torque T a . Differential torque T a For example, the disturbance torque T d The differential torque T output from the subtractor SU3 is a After being input to the second filter 232b and subjected to low-pass filtering, it is input to the first filter 232a and subjected to high-pass filtering. The differential torque T after being subjected to filtering by the first filter 232a and the second filter 232b is a The differential torque T after filtering in the first filter 232a and the second filter 232b is input to the adder AD4. a The frequency components lower than the first cutoff frequency Cf1 and the frequency components higher than the second cutoff frequency Cf2 are removed. That is, the differential torque T after filtering by the first filter 232a and the second filter 232b is a The frequency component T is above the first cutoff frequency Cf1 and below the second cutoff frequency Cf2. aM .

[0076] The auxiliary adjustment unit 270 generates a compensation value for friction and disturbance, and adjusts the differential torque T a In this embodiment, the auxiliary adjustment unit 270 adjusts the differential torque T a The frequency component T aM The auxiliary adjustment unit 270 is connected in parallel with the first filter 232a. The auxiliary adjustment unit 270 includes a friction compensation value calculation unit 250, a disturbance compensation value calculation unit 260, and a subtractor SU4.

[0077] 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 obtained from the differential torque T a The output value from the first filter 232a is obtained by removing the frequency components higher than the second cutoff frequency Cf2. a The value obtained by removing the frequency components higher than the second cut-off frequency Cf2 and the frequency components lower than the first cut-off frequency Cf1. Therefore, the value output from the subtractor SU4 becomes the differential torque T a The frequency component T lower than the first cutoff frequency Cf1 aL The output of the subtractor SU4 is input to the friction compensation value calculation unit 250 and the disturbance compensation value calculation unit 260. The frequency component T aL It includes friction force, self-aligning torque, disturbance torque caused by looseness of the controlled object 560 , and torque fluctuation generated in the controlled object 560 .

[0078] The friction compensation value calculation unit 250 calculates the friction compensation value according to the differential torque T a The friction compensation value V for compensating at least a part of the friction force generated in the control object 560 is calculated. f As described above, the value input to the friction compensation value calculation unit 250 from the subtractor SU4 becomes the differential torque T a The frequency component T lower than the first cutoff frequency Cf1 aL Therefore, in the present embodiment, the friction compensation value calculation unit 250 calculates the friction compensation value according to the differential torque T a The friction compensation value V is calculated by using the frequency component lower than the first cut-off frequency Cf1 in f .

[0079] The friction compensation value calculation unit 250 includes a limiter 252 and a gain adjuster 253. The limiter 252 limits the output value from the subtractor SU4. When the input value exceeds the upper or lower threshold, the limiter 252 limits 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 aThe frequency components lower than the first cut-off frequency Cf1 in the friction compensation value V are calculated by applying the limiter 252 and the gain K1. f The threshold value of the limiter 252 and the value of the gain K1 are predetermined to be what values ​​according to, for example, the friction force actually generated in the control object 560 .

[0080] The friction compensation value V output from the friction compensation value calculation unit 250 is f is the differential torque T a The frequency component T aL Generally, since the control object 560 requires moderate friction, the friction compensation value calculation unit 250 calculates a value smaller than the friction force actually generated in the control object 560 as the friction compensation value V f Thus, it is possible to achieve high-precision friction compensation while maintaining a moderate friction force on the control object 560. f The objects of friction compensation are, for example, the friction of the motor 543, the friction of the speed reduction mechanism 544, and the left-right difference in friction of the speed reduction mechanism 544.

[0081] Here, the differential torque T a The frequency component T aL In addition to the friction component, the self-aligning torque generated in the control object 560, the disturbance torque caused by looseness generated in the control object 560, and the torque fluctuation generated in the control object 560 are also included. Therefore, when the frequency component T is adjusted by the limiter 252 and the gain adjuster 253, aL The friction compensation value V obtained by processing f The compensation value also includes a compensation value for compensating for at least a portion of the self-aligning torque generated in the control object 560, the disturbance torque caused by looseness generated in the control object 560, and the torque fluctuation generated in the control object 560.

[0082] A vehicle equipped with the electric power steering device 1000 can travel in a driving mode having an automatic driving mode and a manual driving mode. In this case, the gain K1 of the gain adjuster 253 can also 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. Preferably, the gain K1 in the automatic driving mode is greater than the gain K1 set in the manual driving mode. Thus, the optimal friction compensation can be applied to the automatic driving mode that further requires friction reduction.

[0083] The disturbance compensation value calculation unit 260 calculates a disturbance compensation value V for compensating at least a portion of the self-aligning torque generated in the controlled object 560. d In this embodiment, the interference compensation value Vd The compensation value includes a compensation value for compensating at least a part of the friction force generated in the controlled object 560, the disturbance torque caused by looseness generated in the controlled object 560, and the torque fluctuation generated in the controlled object 560. The disturbance compensation value calculation unit 260 calculates the torque T output from the inverse nominal model 231. p With input torque T r The differential torque T a To calculate the interference compensation value V d That is, the disturbance compensation value calculation unit 260 calculates the difference torque T a To calculate the interference compensation value V d , the differential torque T a is the torque T calculated from the output of the control object 560 using the nominal model. p With input torque T r As described above, the value from the subtractor SU4 input to the disturbance compensation value calculation unit 260 becomes the differential torque T a Therefore, in this embodiment, the disturbance compensation value calculation unit 260 calculates the frequency components lower than the first cut-off frequency Cf1 according to the differential torque T a The interference compensation value V is calculated by using the frequency components lower than the first cut-off frequency Cf1 in d .

[0084] The disturbance compensation value calculation unit 260 includes a limiter 262 and a gain adjuster 263. The limiter 262 imposes a limit on the output value from the subtractor SU4. When the input value exceeds the upper or lower threshold, the limiter 262 limits 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. The transfer function P(s) of the control object 560 is constrained to be the transfer function P of the nominal model. n Under the condition of (s), the maximum value of the gain K2 of the gain adjuster 263 is determined. The value of the gain K2 is, for example, different from the value of the gain K1. The value of the gain K2 is, for example, about 0.1 or more and 0.8 or less. The gain K2 of the gain adjuster 263 may also be switched according to the driving mode of the vehicle.

[0085] Interference compensation value V d is the differential torque T a The frequency component T aL The disturbance compensation value calculation unit 260 calculates, for example, a value corresponding to the self-aligning torque T actually generated in the control object 560. SAT The value of about half of V is used as the interference compensation value d The actual self-aligning torque T generated in the control object 560SAT For example, the value of the threshold value of the limiter 262 and the gain K2 of the disturbance compensation value calculation unit 260 is adjusted to the self-aligning torque T calculated in advance. SAT The disturbance compensation value V is calculated as a value of about 0.1 times or more and about 0.8 times or less of the magnitude of d The disturbance compensation value V calculated in the disturbance compensation value calculation unit 260 is d is the friction compensation value V calculated in the friction compensation value calculation unit 250. f Different values.

[0086] Here, the differential torque T a The frequency component T aL In addition to the automatic return torque T SAT In addition, the friction force generated in the control object 560, the disturbance torque caused by the looseness generated in the control object 560, and the torque fluctuation generated in the control object 560 are also included. Therefore, when the frequency component T is adjusted by the limiter 262 and the gain adjuster 263, aL The interference compensation value V obtained by processing d The compensation value for compensating for at least a portion of the friction force generated in the controlled object 560 , the disturbance torque caused by looseness generated in the controlled object 560 , and the torque fluctuation generated in the controlled object 560 is also included.

[0087] In order to adjust the correction torque T used in the model following control in the model following control unit 230 f The friction compensation and disturbance compensation applied in the auxiliary adjustment unit 270 need to pay attention to the stability condition of the model tracking control. This condition is a condition that the gain in the gain characteristic of the transfer function of the auxiliary adjustment unit 270, which is constrained to take into account the stability characteristics, 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, a subtractor SU4 is set in the front stage of the limiter 252 and 262 to apply a subtraction process so that the values ​​of the gains K1 and K2 in the gain adjusters 253 and 263 are a maximum of 1, and the gain in the gain characteristic under this condition is 1. In other words, the auxiliary adjustment unit 270 acts as a low-pass filter having a transfer function of 1-Q1(s). Q1(s) is the transfer function of the first filter 232a as a high-pass filter. The auxiliary adjustment unit 270 performs low-pass filtering processing with a transfer function of 1-Q1(s) on the torque output from the second filter 232b, and adjusts and outputs the processed values ​​in the friction compensation value calculation unit 250 and the disturbance compensation value calculation unit 260, respectively.

[0088] The adder AD4 adds the output value from the auxiliary adjustment unit 270 and the output value from the first filter 232a. That is, the adder AD4 adds the friction compensation value V f and the interference compensation value V d With frequency component T aM The frequency component T is output from adder AD4. aM , Friction compensation value V f And the interference compensation value V d The correction torque T calculated by adding f The correction torque T output from adder AD4 f The input torque T r Thus, in the present embodiment, the model following control unit 230 removes the frequency components lower than the first cutoff frequency Cf1 through the first filter 232a as a high-pass filter, and generates the differential torque T a , that is, the frequency component T aM Add friction compensation value V f and the interference compensation value V d The correction torque T is generated f .

[0089] The state feedback unit 280 generates an input torque T according to the output of the control object 560. r Feedback state compensation value V s , so that the apparent transfer function of the controlled object 560 is close to the transfer function P of the nominal model n (s). The apparent transfer function of the controlled object 560 is, for example, a transfer function of a portion located inside the feedback loop created by the model tracking control unit 230 when the portion is regarded as a single portion. Specifically, in the present embodiment, the apparent transfer function of the controlled object 560 refers to a transfer function of the entire portion from the subtractor SU2 to the output of the controlled object 560, and is a transfer function of a portion that combines the state feedback unit 280 and the controlled object 560. In the present embodiment, the state feedback unit 280 is used to correct the torque T f The input torque T after correction and before input to the control object 560 r Feedback state compensation value V s .

[0090] State compensation value V s The state compensation value V includes a compensation value for compensating 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 friction force generated in the controlled object 560. More specifically, the state compensation value V sThe state compensation value V includes a compensation value for compensating at least a part of the inertial force generated by the motor 543, the viscous force generated by the motor 543, and the friction force generated by the motor 543. In this embodiment, the state compensation value V s These are compensation values ​​respectively including the inertial force generated in the motor 543 , the viscous force generated in the motor 543 , and the friction force generated in the motor 543 .

[0091] The state feedback unit 280 includes an inertia compensator 281, a viscosity compensator 282, and a friction compensator 283. The inertia compensator 281 adjusts the state of the vehicle according to the steering angle θ. s , calculates a compensation value for compensating at least a portion of the inertial force generated by the motor 543. The viscosity compensator 282 is adjusted according to the steering angle θ s , calculates a compensation value for compensating at least a portion of the viscous force generated by the motor 543. The friction compensator 283 is configured according to the steering angle θ. s , calculates a compensation value for compensating at least a portion of the friction force generated by the motor 543. In this embodiment, the state compensation value V s 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 the adder AD3 and added to the correction torque T f Corrected input torque T r Add.

[0092] Next, the control performed by the model tracking control unit 230 will be described in further detail. The model tracking control unit 230 uses the inverse model of the nominal model as an internal model, that is, the inverse nominal model 231 to control the control object 560. In this embodiment, the feedback loop created by the model tracking control unit 230 can compensate for torque fluctuations and the like depending on the angular velocity ω of the motor 543.

[0093] The model tracking control unit 230 is similar in structure to the existing disturbance inference device (disturbance observer), but the expected functions and effects are different. The existing disturbance inference device infers the disturbance torque by setting the inverse plant model as an internal model to a model close to the control object 560, and reduces the influence of the disturbance by adding or subtracting the disturbance torque in advance.

[0094] The control performed by the model following control unit 230 in this embodiment uses a feedback loop to constrain the transfer function P(s) of the controlled object 560 to the transfer function P(s) of the nominal model as the internal model. n(s) effect. For example, if the nominal model is defined in such a way that there is no torque fluctuation, the transfer function P(s) of the control object 560 is constrained to a characteristic without torque fluctuation through model tracking control, and as a result, the torque fluctuation can be reduced by applying compensation for the torque fluctuation. In addition, by setting the nominal model to a low-inertia model and using the nominal model to constrain the control object 560, the control object 560 can be treated as a low-inertia model. In addition, by setting the nominal model to a low-viscosity model and using the nominal model to constrain the control object 560, the control object 560 can also be treated as a low-viscosity model. By performing model tracking control by the model tracking control unit 230, in addition to compensating for the torque fluctuation of the motor 543, for example, loss torque compensation or motor inertia compensation is also performed. In the above equations (2) and (3), by appropriately setting J n and B n , it is possible to give the desired frequency characteristics to the transfer function P(s) of the controlled object 560.

[0095] When the transfer function P(s) of the controlled object 560 is compared with the transfer function P(s) of the nominal model n When the modeling error of (s) is Δ(s), the transfer function P(s) of the controlled object 560 is expressed by, for example, the following equation (4).

[0096]

[0097] 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 peak with a higher frequency of the two peaks in the gain characteristic of the controlled object 560. Figure 6 As shown in FIG. 1 , the inverse of the modeling error Δ(s) 1 / Δ(s) has a valley in a relatively high-frequency region. Figure 6 In the example, the modeling error Δ(s) is expressed as an absolute value. If the modeling error Δ(s) increases, the transfer function P(s) of the control object 560 will deviate from the transfer function P(s) of the nominal model. n As the deviation of (s) increases, the control of the controlled object 560 using the nominal model by the model tracking control unit 230 becomes unstable. Therefore, in the region where the modeling error Δ(s) is relatively small, the gain of the complementary sensitivity function T(s) is set to 1, and the controlled object 560 is constrained to the nominal model, thereby enabling the controlled object 560 to be stably and appropriately controlled. The frequency characteristics of the modeling error Δ(s) can be adjusted by adjusting the transfer function P of the nominal model. n J in (s) n and B nThe 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. Thus, the gain of the complementary sensitivity function T(s) can be adjusted to 1 in the frequency band in which the modeling error Δ(s) is small.

[0098] exist Figure 6 In the above example, 1 / Δ(s) is relatively high in the frequency band below the second cutoff frequency Cf2, and decreases sharply in the frequency band higher than the second cutoff frequency Cf2. Model tracking control that constrains the control object 560 to be a nominal model can be stably performed in a range where 1 / Δ(s) is greater than 1, that is, greater than 0 dB. Therefore, Figure 6 As shown, by adjusting in a frequency band where the gain of the complementary sensitivity function T(s) is 1 in a manner such that 1 / Δ(s) is greater than 1, the control object 560 can be constrained to the nominal model and stably and appropriately controlled when the gain of the complementary sensitivity function T(s) is 1.

[0099] For example, in order to expand the frequency band in which the controlled object 560 can be stably and appropriately controlled by constraining it to the nominal model, as long as 1 / Δ(s) does not become less than 1, that is, Figure 6 In the frequency band below the frequency where the curve representing 1 / Δ(s) intersects with the horizontal axis, the second cut-off frequency Cf2 can be increased. However, when the second cut-off frequency Cf2 is too high, in the frequency band higher than the second cut-off frequency Cf2, although 1 / Δ(s) becomes lower, the gain of the complementary sensitivity function T(s) is still relatively high, and the control may become unstable. In contrast, in the present embodiment, since the order of the second filter 232b as a low-pass filter is set to 3 or more, the gain of the complementary sensitivity function T(s) can be sharply reduced in the region where the frequency is higher than the second cut-off frequency Cf2. Thus, even if the second cut-off frequency Cf2 is relatively high, the gain of the complementary sensitivity function T(s) can be immediately reduced in the frequency band higher than the second cut-off frequency Cf2, so that the control of the control object 560 can be suppressed from becoming unstable.

[0100] The robust stability of the model tracking control unit 230 is ensured when the small gain theorem expressed by the following equation (5) holds true between the complementary sensitivity function T(s) and the modeling error Δ(s).

[0101]

[0102] As described above, in order to perform model tracking control using a nominal model in the model tracking control unit 230, the complementary sensitivity gain GT of the complementary sensitivity function T(s) only needs to be approximately 1, but if robust stability is considered, the above-mentioned formula (5) must be satisfied. As can be seen from this, it is impossible to take into account both the complementary sensitivity gain GT being approximately 1 and the formula (5) in all frequency bands, and it is impossible to take into account both the suppression of interference and the like by the model tracking control unit 230 and the robust stability.

[0103] like Figure 6 As shown, in the low frequency region FA1 where the frequency f is lower than the first cutoff frequency Cf1, the complementary sensitivity gain GT of the complementary sensitivity function T(s) is also less than 1. In the region where the complementary sensitivity gain GT of the complementary sensitivity function T(s) is less than 1, the input torque T is controlled by the reaction force control unit 210. r As described above, in the high frequency region FA2, which is an area with a frequency higher than the second cutoff frequency Cf2, the complementary sensitivity gain GT of the complementary sensitivity function T(s) is greatly reduced, and the correction torque T from the model tracking control unit 230 is obtained. f The state in which there is almost no feedback 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 Feedback to the input of the controlled object 560. In the low frequency region FA1, the compensation value generated in the auxiliary adjustment unit 270 is fed back to the input of the controlled object 560 according to the complementary sensitivity gain GT of the complementary sensitivity function T(s).

[0104] The control device 100 performs torque control in the reaction force control unit 210 for a low-frequency torque signal lower than the first cutoff frequency Cf1, and performs control to make the angular velocity ω≈0 for a high-frequency disturbance higher than the second cutoff frequency Cf2, thereby stabilizing the steering in a manner that the steering wheel 521 is not removed. To achieve this purpose, the control device 100 uses the reaction force control unit 210 to reduce the high-frequency gain of the torque control and uses the model tracking control unit 230 to constrain the transfer function P(s) of the control object 560 to a characteristic of decreasing the high-frequency gain. The reason for performing the latter process is to prevent the control object 560 from reacting to the disturbance when the disturbance is input to the control object 560.

[0105] When the transfer function of the combined portion of the torque conversion unit 211 and the basic assist control unit 220 is represented by C2(s), the disturbance torque T as the disturbance sensitivity characteristic is d (s), namely the correction torque T f When the ratio of the disturbance input to the controlled object 560 is m, the disturbance torque Td (s) to steering torque T h The transfer characteristic of (s) is expressed as shown in the following equation (6) using the complementary sensitivity function T(s), and the complementary sensitivity function T(s) is expressed as shown in the following equation (7).

[0106]

[0107] According to the above formula (6), if the complementary sensitivity function T(s) is 1, the interference is completely suppressed, and if the complementary sensitivity function T(s) is less than 1, at least a part of the interference is transmitted. Therefore, by dividing the interference to be transmitted and the interference to be suppressed in the frequency region and performing frequency shaping on the complementary sensitivity function T(s) accordingly, the interference sensitivity design for each frequency region can be performed. m in the above formulas (6) and (7) is related to the correction torque T f Compensation of disturbance torque T d The ratio is equal, T f =mT d For example, if the ratio m is 0.5, then by correcting the torque T f Interference torque T d 50% compensation is performed. In the present embodiment, the ratio m is greater than or equal to 0.1 and less than or equal to 0.8.

[0108] When the transfer function P(s) of the controlled object 560 is expressed by the above-mentioned equation (1), C2(s)=K tor +K ass Therefore, the steady-state gain T(0) of the complementary sensitivity function T(s) when s=0 is expressed as the following equation (8) according to the above equation (7). That is, when the spring constant of the torsion bar 546 is set to K tor , the self-aligning torque T generated by the tires 529A and 529B of the vehicle SAT With respect to the steering angle θ as the rotation angle of the output shaft 524b s The slope of SAT , the auxiliary torque T ass Relative to the torsion bar torque, that is, the steering torque T h The slope of ass , set the steady-state gain to T(0), and the correction torque T f The disturbance input to the controlled object 560, namely, the disturbance torque T d When the ratio is set to m, the following formula (8) holds.

[0109]

[0110] In a stable 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 The spring constant K of the torsion bar 546 is close to zero. tor Sufficiently smaller than the automatic return torque gain K SAT Therefore, in a stable 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-state gain T(0) changes from the above equation (8) to a value close to the correction torque T f With the interference torque T d The value of the ratio m of (s). The steady-state gain T(0) of the complementary sensitivity function T(s) represented by the above equation (8) is greater than or equal to 0.1. In the present embodiment, the steady-state gain T(0) is greater than or equal to 0.3. The steady-state gain T(0) is, for example, less than or equal to 0.5. The steady-state gain T(0) is the minimum value of the complementary sensitivity gain GT in the low-frequency area FA1.

[0111] Conventionally, for example, the complementary sensitivity function T(s) in the low-frequency region FA1 is Figure 6 In this embodiment, by performing the model tracking control based on the above-mentioned model tracking control unit 230, the steady-state gain T(0) of the complementary sensitivity function T(s) can be made as shown in the above-mentioned equation (8), and the complementary sensitivity function T(s) can be shaped with respect to the frequency f as follows: Figure 6 The waveform is as shown by the solid line.

[0112] In this embodiment, Figure 6 The low frequency region FA1 of the waveform of the complementary sensitivity gain GT of the complementary sensitivity function T(s) shown in FIG. 1 is produced by the first filter 232a, the vehicle stabilization compensator 240, and the adder AD4 in the model tracking control unit 230. More specifically, the frequency component T output from the first filter 232a as a high pass filter is converted into aM The friction compensation value V output from the vehicle stabilization compensation unit 240 functioning as a low-pass filter is f And the interference compensation value V d The value at which the frequency f in the low-frequency part TFA1 becomes zero is the value of s=0 in the complementary sensitivity function T(s), which is the steady-state gain T(0) represented by the above equation (8).

[0113] like Figure 6 As shown, the first cut-off frequency Cf1 is higher than the first resonant frequency f yaw High. The first resonance frequency f yawis the resonance frequency of the yaw rate of the vehicle. That is, the lower limit value of the frequency band in which the complementary sensitivity gain GT is 1 is greater than the first resonance frequency f which is the resonance frequency of the yaw rate of the vehicle. yaw The yaw rate of the vehicle is a parameter indicating the change in the yaw angle, which is the deflection angle of the vehicle in the left-right direction. In other words, the yaw rate refers to the angular velocity of the vehicle when it vibrates in the left-right direction. The first resonance frequency f yaw For example, it is about 1 Hz or more and 1.5 Hz or less.

[0114] Figure 6 The second resonant frequency f is shown st is the resonant frequency of the steering mechanism 530. More specifically, the second resonant frequency f st The inertia and self-aligning torque T of the steering mechanism 530 are generated. SAT The resonant frequency of the mode formed by the spring elements. The second resonant frequency f st The first resonance frequency f yaw The second resonance frequency f is higher than the first cutoff frequency Cf1, which is the lower limit of the frequency band in which the complementary sensitivity gain GT is 1. st For example, the second resonance frequency f is about 3 Hz or more and about 5 Hz or less. st The complementary sensitivity gain GT under the first resonance frequency f yaw The complementary sensitivity gain GT is high. The second resonance frequency f st The complementary sensitivity gain GT under the condition of is greater than or equal to 0.5 and less than 1. In this embodiment, the second resonance frequency f st The complementary sensitivity gain GT is above 0.8.

[0115] In this embodiment, Figure 6 The high-frequency region FA2 of the waveform of the complementary sensitivity gain GT of the complementary sensitivity function T(s) shown, that is, the high-frequency portion TFA2 is generated by the second filter 232 b in the model following control unit 230 .

[0116] According to the present embodiment, the control device 100 has a function of generating an input torque T to be input to the controlled object 560 based on the output of the controlled object 560 and a nominal model based on the structure of the controlled object 560. r Correction torque T for correction fThe model tracking control unit 230. The model tracking control unit 230 is configured such that, in a frequency band where the gain of the complementary sensitivity function T(s) with respect to the modeled error Δs between the control object 560 and the nominal model, i.e., the complementary sensitivity gain GT, is approximately 1, the transfer function of the control object 560 is constrained to be the transfer function of the nominal model. The steady-state gain T(0) of the complementary sensitivity function T(s) is greater than 0.1. The lower limit value of the frequency band where the complementary sensitivity gain GT is 1, i.e., the first cutoff frequency Cf1, is lower than the first resonant frequency f which is the resonant frequency of the yaw rate of the vehicle. yaw The second resonance frequency f is the resonance frequency of the steering mechanism 530. st The first resonance frequency f yaw The second resonance frequency f is higher than the lower limit value of the frequency band where the complementary sensitivity gain GT is 1, that is, the first cutoff frequency Cf1. st The complementary sensitivity gain GT under the first resonance frequency f yaw The complementary sensitivity gain GT is high, being greater than 0.5 and less than 1.

[0117] For example, in the existing disturbance inference device, a model close to the control object 560 is provided as an internal model, and the disturbance generated in the control object 560 is compensated. However, it is difficult to have a model that is completely identical to the control object 560 as an internal model, and a modeling error Δ(s) will be generated in any case. Therefore, in order to suppress the control from becoming unstable, in the existing disturbance inference device, 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 existing disturbance inference device, the internal model is simply made close to the actual model of the control object 560, so even if the disturbance applied to the control object 560 from the outside can be inferred, the torque fluctuation generated by the control object 560 itself cannot be removed.

[0118] In contrast, in the present embodiment, the nominal model that the control device 100 has as an internal model is not a model that reproduces the model of the actual controlled object 560, but is set as an ideal model as the controlled object 560, and the complementary sensitivity gain GT of the complementary sensitivity function T(s) is set to approximately 1 in the region where the modeling error Δ(s) is small. Thus, by appropriately setting the nominal model, not only the disturbance applied to the actual controlled object 560 from the outside can be removed, but also the torque fluctuation generated inside the controlled object 560 can be removed. Thus, the disturbance generated by the controlled object 560 being a dual inertia system can be removed, and the controllability of the controlled object 560 configured as a dual inertia system can be improved. In addition, the controlled object 560 can be appropriately controlled by the control device 100, so the steering feeling felt by the helmsman can be improved.

[0119] In addition, in this embodiment, the steady-state gain T(0) of the complementary sensitivity function T(s) is greater than 0.1, so Figure 6 Unlike the conventional situation shown by the two-dot chain line in the middle, the reaction force received from the tires 529A and 529B, that is, the self-aligning torque T can be compensated to some extent by the model following control in the low frequency region FA1. SAT In addition, the complementary sensitivity gain GT is lower than the lower limit of the frequency band of 1, and is higher than the first resonance frequency f yaw High second resonance frequency f st The complementary sensitivity gain GT under the first resonance frequency f yaw Therefore, in the region where the frequency f is relatively high in the low-frequency region FA1, the self-aligning torque T of the tires 529A and 529B can be further compensated. SAT Thus, the reaction force received by the steersman from the steering wheel 521 can be appropriately reduced. In addition, due to the second resonance frequency f st The complementary sensitivity gain GT under the condition of 1 is less than 1, so even in the region where the frequency f is relatively high in the low-frequency region FA1, the self-aligning torque T of the tires 529A and 529B is SAT It is not compensated 100%, and the self-correcting torque T SAT A portion of the torque is transmitted to the steersman. Thus, an appropriate reaction force can be applied to the steersman via the steering wheel 521. In addition, the self-aligning torque T can be compensated by model following control. SAT By applying other controls such as active return control and return speed control (convergence control), the reaction force received by the helmsman from the steering wheel 521 can be more appropriately adjusted. As described above, according to this embodiment, the steering feeling felt by the helmsman can be further improved.

[0120] For example, in order to stabilize the driving of the vehicle without performing model tracking control, it is considered to apply return speed control (convergence control) that applies damping to the steering wheel 521 to a certain extent. However, in this case, since the braking force applied to the steering of the steering wheel 521 acts strongly, the steering feeling felt by the helmsman becomes worse. In contrast, for example, it is also possible to consider applying return speed control only when the helmsman does not operate the steering wheel 521, and not applying return speed control when the helmsman operates the steering wheel 521. However, in this case, the control amount of the return speed control is greatly different when the helmsman operates the steering wheel 521 and when he does not operate it. Therefore, for example, when the helmsman turns the steering wheel 521 back, the control amount of the return speed control changes greatly, causing discomfort to the helmsman.

[0121] In the present embodiment, by adjusting the complementary sensitivity gain GT of the complementary sensitivity function T(s) to the above-mentioned value, the self-aligning torque T , which is the reaction force received from the tires 529A and 529B, can be compensated. SAT Therefore, the vehicle can be stabilized while the return speed control is weakened. Thus, the steering feeling felt by the steersman can be suppressed from being deteriorated while the steersman is suppressed from being uncomfortable.

[0122] In addition, by the active return control and the return speed control, the rotation angular velocity of the steering wheel 521 when the angle of the steering wheel 521 starts to return to the predetermined reference angle, that is, the steering angular velocity ω h The self-aligning torque T transmitted to the steering wheel 521 SAT Therefore, when the model following control is not performed, the self-aligning torque T transmitted to the steering wheel 521 is SAT The steering angular velocity ω when the angle of the steering wheel 521 starts to return to the reference angle h In this case, the steering angular velocity ω from the time when the angle of the steering wheel 521 returns to the reference angle to the time when the angle of the steering wheel 521 returns to the reference angle h The difference in the change of becomes larger, and the movement of the steering wheel 521 when the angle of the steering wheel 521 returns to the reference angle is difficult to become smooth. In addition, when the model tracking control is not performed, since the first resonance frequency f yaw and the second resonance frequency f st The resonance generated in each of them produces beat vibration (beat frequency vibration), and the steering angular velocity ω h The steering wheel 521 changes periodically, and when the angle of the steering wheel 521 returns to the reference angle, a shake occurs in the movement of the steering wheel 521. As a result, the movement of the steering wheel 521 becomes more difficult to be smooth.

[0123] In view of the above problem, in this embodiment, the self-aligning torque T can be compensated by model following control. SAT Therefore, the self-aligning torque T transmitted to the steering wheel 521 can be reduced. SAT This can reduce the steering angular velocity ω when the angle of the steering wheel 521 starts to return to the reference angle. h Thus, the steering angular velocity ω from the time when the angle of the steering wheel 521 returns to the reference angle to the time when the angle of the steering wheel 521 returns to the reference angle can be reduced. h Therefore, it is easy to make the steering wheel 521 move smoothly when the angle of the steering wheel 521 returns to the reference angle. In addition, by making the second resonance frequency f st The complementary sensitivity gain GT is greater than 0.5, and the second resonance frequency f stAutomatic return torque T SAT Therefore, it is possible to suppress the second resonance frequency f st Therefore, the shaking of the steering wheel 521 when the angle of the steering wheel 521 returns to the reference angle can be suppressed, thereby suppressing the rotational angular velocity of the steering wheel 521, that is, the steering angular velocity ω h Therefore, it is easy to make the movement of the steering wheel 521 smoother when the angle of the steering wheel 521 returns to the reference angle. By making the movement of the steering wheel 521 smooth, the movement of the steering wheel 521 when the angle of the steering wheel 521 returns to the reference angle can be given a sense of luxury.

[0124] In addition, if there are irregularities on the road surface on which the vehicle is traveling, the tires 529A and 529B receive forces from the irregularities, and the steerer can easily remove the steering wheel 521. The steering angle θ in this case is h The frequency f is about 5 Hz or more and about 10 Hz or less, which is similar to the second resonance frequency f st is the same as or higher than 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 is relatively large, which is greater than 0.5, at a frequency greater than the second resonance frequency f st At the high first cutoff frequency Cf1, 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 is running on a road with uneven surfaces, the force received by the tires 529A and 529B from the uneven surfaces can be appropriately compensated by the model following control. Therefore, even when the vehicle is running on a road with uneven surfaces, it is possible to prevent the steersman from removing the steering wheel 521. As a result, the steering feeling felt by the steersman can be further improved.

[0125] In addition, the road surface on which the vehicle is traveling may have a slight inclination in order to facilitate drainage, etc. In this case, if the vehicle is to be driven straight, the steersman needs to slightly rotate the steering wheel 521. Therefore, when the model tracking control is not performed, a burden may be imposed on the steersman's arm. In contrast, in the present embodiment, since the steady-state gain T(0) is greater than 0.1, even in the low-frequency region FA1 where the steering wheel 521 is not operated or is rarely operated, the self-aligning torque T received from the tires 529A and 529B can be compensated to some extent by the model tracking control. SATThus, when the vehicle is driven straight on a road surface with a slight inclination, even if the steering wheel 521 is slightly rotated, the reaction force received by the steersman from the steering wheel 521 can be reduced. Therefore, the burden on the steersman's arms can be suppressed.

[0126] According to the present embodiment, the control device 100 includes a basic assist control unit 220 that controls the steering torque T according to the torsion bar torque generated in the torsion bar 546. h , generating a self-aligning torque T generated on the tires 529A and 529B of the vehicle SAT The auxiliary torque T that compensates at least part of ass . When the spring constant of the torsion bar 546 is set to K tor , the self-aligning torque T generated by the tires 529A and 529B of the vehicle SAT With respect to the steering angle θ as the rotation angle of the output shaft 524b s The slope of SAT , the auxiliary torque T ass Relative to the torsion bar torque, that is, the steering torque T h The slope of ass , set the self-aligning torque to T SAT , the assist torque is set to T ass , set the steady-state gain to T(0), and T ass =mT SAT (where 0<m<1) holds, the above formula (9) holds. By expressing the steady-state gain T(0) by formula (9), the complementary sensitivity gain GT in the low-frequency region FA1 can be appropriately and significantly adjusted as described above. As a result, the above effect can be further obtained, and the steering feeling felt by the helmsman can be further improved. In order to more appropriately obtain the above effect, m is preferably greater than 0.1 and less than 0.8, and more preferably greater than 0.3 and less than 0.8.

[0127] In addition, according to the present embodiment, the control device 100 can perform control to return the angle of the steering wheel 521 to a predetermined reference angle, that is, active return control and return speed control. As described above, by adjusting the complementary sensitivity gain GT of the complementary sensitivity function T(s) while using the model following control, the movement of the steering wheel 521 when the angle of the steering wheel 521 returns to the reference angle can be smoothed while suppressing the reduction in the steering feeling felt by the helmsman. Therefore, the effect obtained by adjusting the complementary sensitivity gain GT of the complementary sensitivity function T(s) within the above-mentioned numerical range can be more effectively obtained when the angle of the steering wheel 521 is controlled to return to the reference angle.

[0128] According to the present embodiment, the steady-state gain T(0) is equal to or greater than 0.3, and the second resonance frequency f st The complementary sensitivity gain GT in the low frequency region FA1 is 0.8 or more. Therefore, the complementary sensitivity gain GT in the low frequency region FA1 can be appropriately increased. Thus, the above-mentioned effect can be obtained more effectively, and the steering feeling felt by the helmsman can be improved more appropriately.

[0129] In addition, according to the present embodiment, the lower limit value of the frequency band in which the complementary sensitivity gain GT is 1, that is, 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 the frequency f at which the tires 529A and 529B are likely to receive force from the unevenness of the road surface. As a result, when the vehicle is running on an uneven road surface, it is possible to more appropriately prevent the steersman from removing the steering wheel 521.

[0130] In addition, according to the present embodiment, the complementary sensitivity function T(s) is a function including the transfer function of the low-pass filter and the transfer function of the high-pass filter. In the present embodiment, the transfer function of the low-pass filter includes the transfer function of the second filter 232b and the transfer function of the auxiliary adjustment unit 270 that functions 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 appropriately adjusted to the above-mentioned numerical range in each frequency region.

[0131] The inventors of the present invention have confirmed the effect of applying the model following control of the control device 100 of the above embodiment by performing actual vehicle measurements. In the actual vehicle measurements, the steering angle θ of the steering wheel 521 when the angle of the steering wheel 521 returns to a predetermined reference angle is h and steering angular velocity ω h , respectively comparing the case where model tracking control is not applied and the case where model tracking control is applied.

[0132] Figure 8 The steering angle θ when model following control is not applied is shown. h [deg] and steering angular velocity ω h The measurement results of [deg / s]. Fig. 9 The steering angle θ when the model following control is applied is shown in FIG. h [deg] and steering angular velocity ω h The measurement results of [deg / s]. Figure 8 and Fig. 9 In each graph of h and steering angular velocity ω h The size of each parameter. Figure 8 and Fig. 9 In each graph of h , with a negative value representing the speed at which the angle of the steering wheel 521 returns to the direction of the specified reference angle. Figure 8 and Fig. 9 In each of the graphs, the single-point dashed line represents the steering angle θ h , the solid line represents the steering angular velocity ω h .

[0133] like Figure 8 As shown, when the model following control is not applied, when the angle of the steering wheel 521 starts to return to the predetermined reference angle, the steering angular velocity ω h The absolute value of becomes larger, at the steering angular velocity ω h The angle of the steering wheel 521 returns to the reference angle while periodically changing with a relatively large amplitude. h In the case of changes, the movement of the steering wheel 521 appears to be shaking. Figure 8 and Fig. 9 The reference angle is specified as 0°.

[0134] On the other hand, Fig. 9 As shown, when the model following control is applied, it is confirmed that when the angle of the steering wheel 521 starts to return to the predetermined reference angle, the steering angular velocity ω h The absolute value ratio Figure 8 Specifically, when the angle of the steering wheel 521 begins to return to the reference angle, Figure 8 The steering angular velocity ω h The absolute value of becomes ω2, but Fig. 9 The steering angular velocity ω h The absolute value of becomes ω1 which is smaller than ω2. In addition, although Fig. 9 The steering angular velocity ω h There is some fluctuation in the absolute value of Figure 8 The steering angular velocity ω h Therefore, when the angle of the steering wheel 521 returns to the reference angle, the movement of the steering wheel 521 can be suppressed from appearing to be shaking. Thus, it is confirmed that by performing model tracking control as in the above-mentioned embodiment, the movement of the steering wheel 521 can be smooth when the angle of the steering wheel 521 returns to the specified reference angle.

[0135] In addition, the electric power steering device 1000 is also represented as Fig.10 A simplified model as shown in Fig.10 In FIG. 1 , the model of the control object 560 of the electric power steering device 1000 is understood as a single inertia system. Fig.10 The steering mechanism 570 shown is the portion of the steering mechanism 520 extending from the output shaft 524b to the tires 529A and 529B. Fig.10 In the case of a single inertial system model as shown, the transfer function P(s) of the controlled object 560 is represented by the following equation (9), for example.

[0136]

[0137] Where s is the Laplace transform, J h is a parameter representing the inertia moment of the steering wheel 521, J STG is a parameter representing the inertia moment of the steering mechanism unit 570, and B STG It is a parameter indicating the viscous friction coefficient of the steering-side mechanism unit 570 .

[0138] The transfer function P(s) of the controlled object 560, i.e., the plant characteristics in the model following control, is not limited to the above example, and can be expressed arbitrarily. The transfer function P(s) of the controlled object 560 can be expressed as a dual inertia system or by an equation derived by a high-order approximation.

[0139] In addition, in the present embodiment, the low-frequency region FA1 of the waveform of the complementary sensitivity gain GT of the complementary sensitivity function T(s), i.e., the low-frequency portion TFA1, may also be produced by a phase lead compensator. Specifically, the first filter 232a may be a 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 appropriately adjusted to the above-mentioned numerical range, which can achieve Figure 6 The waveform of the complementary sensitivity gain GT is as shown.

[0140] <Embodiment of driving device>

[0141] The control device 100 described in the above-mentioned embodiment of the electric power steering device can also be applied to Fig.11 The drive device 2000 is shown. Fig.11 The drive device 2000 shown is a drive device mounted on a vehicle and rotates a drive shaft 73 of the vehicle. The vehicle equipped with the drive device 2000 is a vehicle using 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).

[0142] exist Fig.11, an XYZ coordinate system is shown as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Z-axis direction is the up-down direction. The side to which the arrow of the Z-axis points (+Z side) is the upper side, and the side opposite to which the arrow of the Z-axis points (-Z side) is the lower side. The X-axis direction is a direction perpendicular to the Z-axis direction, and is the front-to-back direction of the vehicle equipped with the drive device 2000. In the following embodiments, the side to which the arrow of the X-axis points (+X side) is the front side of the vehicle, and the side opposite to which the arrow of the X-axis 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, i.e., the vehicle width direction. In the present embodiment, the side to which the arrow of the Y-axis points (+Y side) is the left side of the vehicle, and the side opposite to which the arrow of the Y-axis points (-Y side) is the right side of the vehicle.

[0143] In addition, the positional relationship in the front-rear direction is not limited to that in the present 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 addition, in this specification, "parallel direction" also includes substantially parallel direction, and "vertical direction" also includes substantially vertical direction.

[0144] Fig.11 The center axis J shown is an imaginary axis extending in a direction intersecting the up-down direction. In more detail, the center axis J extends in the Y-axis direction perpendicular to the up-down direction, that is, the left-right direction of the vehicle. In the following description, unless otherwise specified, the direction parallel to the center axis J is referred to as "axial", the radial direction centered on the center axis J is referred to as "radial", and the circumferential direction centered on the center axis J is referred to as "circumferential". In the following description, the left side (+Y side) in the axial direction is referred to as "one axial side", and the right side (-Y side) in the axial direction is referred to as "the other axial side". The up-down direction is, for example, the vertical direction, and the front-back direction and the left-right direction (axial direction) are, for example, horizontal directions perpendicular to the vertical direction.

[0145] like Fig.11 As shown, 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 includes a motor housing 81 that accommodates the motor 60 and a gear housing 82 that accommodates the gear mechanism 70. In the present embodiment, oil O is accommodated inside the motor housing 81 and inside the gear housing 82.

[0146] The motor 60 has a rotor 10 that can rotate around a central axis J and a stator 61 that is opposite to the rotor 10 with a gap therebetween. In the present 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 mounted on the stator core 62. The rotor 10 has a shaft 20 and a rotor core 30 fixed to the outer peripheral surface of the shaft 20. Although not shown in the figure, a magnet is retained in the rotor core 30. The shaft 20 extends axially around the central axis J. The end of the left side (+Y side) of the shaft 20 protrudes into the gear housing 82. The end of the left side of the shaft 20 is connected to the gear mechanism 70.

[0147] The gear mechanism 70 transmits the rotation of the motor 60 to the drive shaft 73 of the vehicle. The gear mechanism 70 includes a reduction gear 71 connected to the shaft 20 of the motor 60 and a differential device 72 connected to the reduction gear 71. A drive shaft 73 extending in the axial direction (Y-axis direction) is connected to the differential device 72. A pair of drive shafts 73 are provided. A pair of tires 74A and 74B are connected to the pair of drive shafts 73, respectively.

[0148] When the rotation of the rotor 10 in the motor 60 is transmitted to the differential device 72 via the speed reduction device 71, the pair of drive shafts 73 connected to the differential device 72 rotates. In this way, the drive device 2000 rotates the drive shafts 73 connected to the tires 74A and 74B of the vehicle. The pair of tires 74A and 74B rotate when the pair of drive shafts 73 rotates, so that the vehicle travels.

[0149] In the present embodiment, the control object controlled by 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 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 the present embodiment, the control object of the control device 64 is the drive mechanism 3000 including the tires 74A, 74B, the drive shaft 73, and the drive device 2000.

[0150] The drive device 2000 is configured as a dual inertia system in the same manner as the above-mentioned electric power steering device 1000. The above-mentioned electric power steering device 1000 is configured as a dual inertia system in which the steering wheel 521 and the motor 543 are connected via a torsion bar 546 as a spring element. The drive device 2000 of this embodiment is configured as a dual inertia system in which the tires 74A, 74B and the motor 60 are connected via a drive shaft 73 regarded as a spring element. Since it is configured as a dual inertia system, in the drive device 2000, when the torque of the motor 60 is increased, the drive shaft 73 is twisted. When the twisting is eliminated by the rotation of the tires 74A, 74B, acceleration vibration of the tires 74A, 74B and other issues originating from the dual inertia system are generated. This issue can be solved by configuring the control device 64 of this embodiment in the same manner as the control device 100 in the above-mentioned electric power steering device 1000 and performing model tracking control. Further, similarly to the above-described control device 100 , by adjusting the complementary sensitivity gain GT of the complementary sensitivity function T(s), the same effects as those described in the above-described embodiment of the electric power steering device 1000 can be obtained in the drive device 2000 .

[0151] As an example, it is considered that the control device 64 sets the steering angle θ in the embodiment of the electric power steering device 1000 to h is replaced by the rotation angle of the tires 74A, 74B around the axis of the drive shaft 73, and the steering angle θ s The same control as that of the control device 100 is performed by replacing the rotation angle of the shaft 20 about the central axis J. The rotation angle of the tires 74A and 74B about the axis of the drive shaft 73 may be detected by an unillustrated angle sensor or a unillustrated rotation speed sensor.

[0152] In the present embodiment, the first resonant frequency is the resonant frequency of the drive device 2000, and the lower limit value 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 resonant frequency. In the present embodiment, the second resonant frequency is the resonant frequency of the drive mechanism 3000 including the tires 74A, 74B, the drive shaft 73, and the drive device 2000. The second resonant frequency is higher than the first resonant frequency of the present embodiment described above and lower than the lower limit value of the frequency band in which the complementary sensitivity gain GT is 1. In the present embodiment, the complementary sensitivity gain GT at the second resonant frequency is higher than the complementary sensitivity gain GT at the first resonant frequency, and is greater than 0.5 and 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 the same as those in the above-mentioned embodiment of the electric power steering device 1000.

[0153] The present invention is not limited to the above-mentioned embodiment, and other structures and other methods can also be adopted within the scope of the technical concept of the present invention. The control object controlled by the control device is not particularly limited as long as it includes a motor. In the above-mentioned embodiment, the control device 100 uses the steering angle θ h and steering angle θ s The control device 100 may also use the steering torque T h and steering angle θ s In this case, the value input to the controller 200a replaces the steering angle θ h The steering torque T h , the output from the control object 560 replaces the steering angle θ s The steering angle θ s The control device 100 may also use any other parameters to perform control as in the above-mentioned embodiment.

[0154] In addition, the present technology can adopt the following structures.

[0155] (1) A control device that controls at least a portion of a steering mechanism mounted on a vehicle that includes a motor as a control object, the steering mechanism comprising: an input shaft connected to a steering wheel steered by a steersman; an output shaft connected to the input shaft via a torsion bar; and the motor connected to the output shaft, wherein the control device comprises a model tracking control unit that generates a correction torque for correcting an input torque input to the control object based on an output of the control object and a nominal model based on the structure of the control object, the model tracking control unit being configured to: The gain in the gain characteristic of the complementary sensitivity function, i.e., in a frequency band where the complementary sensitivity gain is approximately 1, the transfer function of the controlled object is constrained to the transfer function of the nominal model, the steady-state gain of the complementary sensitivity function is greater than 0.1, the lower limit value of the frequency band where the complementary sensitivity gain is 1 is higher than a first resonant frequency which is a resonant frequency of the yaw rate of the vehicle, the second resonant frequency which is a resonant frequency of the steering mechanism is higher than the first resonant frequency and lower than the lower limit value of the frequency band where the complementary sensitivity gain is 1, and 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 0.5 and less than 1.

[0156] (2) A control device according to (1), wherein the control device comprises a basic assist control unit, the basic assist control unit generating an assist torque for compensating at least a portion of the self-aligning torque generated by the tires of the vehicle based on the torsion bar torque generated by the torsion bar, and setting the spring constant of the torsion bar to K tor , the slope of the self-aligning torque generated by the tire of the vehicle with respect to the steering angle as the rotation angle of the output shaft is set to K SAT , the slope of the auxiliary torque relative to the torsion bar torque is set to K ass , when the steady-state gain is set to T(0) and the ratio of the correction torque to the disturbance input to the control object is set to m, the following equation holds:

[0157]

[0158] (3) The control device according to (1) or (2), wherein the control device is capable of executing control to return the angle of the steering wheel to a predetermined reference angle.

[0159] (4) A control device that controls a control object including a motor in a drive device that rotates a drive shaft connected to a tire of a vehicle, wherein the control device has a model tracking control unit that generates a correction torque for correcting an input torque input to the control object based on an output of the control object and a nominal model based on the structure of the control object, wherein the model tracking control unit is configured to: in a frequency band where the gain in a gain characteristic of a complementary sensitivity function of a modeled error between the control object and the nominal model, i.e., a complementary sensitivity gain, is approximately 1, The transfer function constraint of the controlled object is the transfer function of the nominal model, the steady-state gain of the complementary sensitivity function is greater than 0.1, the lower limit value of the frequency band in which the complementary sensitivity gain is 1 is higher than the first resonance frequency which is the resonance frequency of the drive device, the second resonance frequency which is the resonance frequency of the drive mechanism including the tire, the drive shaft and the drive device is higher than the first resonance frequency and lower than the lower limit value 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, and is greater than 0.5 and less than 1.

[0160] (5) The control device according to any one of (1) to (4), wherein the steady-state gain is greater than or equal to 0.3, and the complementary sensitivity gain at the second resonant frequency is greater than or equal to 0.8.

[0161] (6) The control device according to any one of (1) to (5), wherein a lower limit value of a frequency band in which the complementary sensitivity gain is 1 is lower than 10 Hz.

[0162] (7) The control device according to any one of (1) to (6), 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.

[0163] (8) The control device according to any one of (1) to (7), 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.

[0164] (9) An electric power steering device comprising: the control device described in any one of (1) to (3); and the steering mechanism.

[0165] (10) A driving device comprising: the control device described in (4); the motor; and a gear mechanism connected to the motor.

[0166] The structures and methods described above in this specification can be appropriately combined within a range that does not contradict each other.

Claims

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

2. The control device according to claim 1, wherein: The control device includes a basic assist control unit that generates an assist torque for compensating for at least a portion of a self-aligning torque generated by a tire of the vehicle based on a torsion bar torque generated by the torsion bar. When the spring constant of the torsion bar is set to K tor , the slope of the self-aligning torque generated by the tire of the vehicle with respect to the steering angle as the rotation angle of the output shaft is set to K SAT , the slope of the auxiliary torque relative to the torsion bar torque is set to K ass , when the steady-state gain is set to T(0) and the ratio of the correction torque to the disturbance input to the control object is set to m, the following equation holds:

3. The control device according to claim 1, wherein: The control device can execute control to return the angle of the steering wheel to a predetermined reference angle.

4. A control device for controlling a control object including a motor in a drive device for rotating a drive shaft connected to a tire of a vehicle, wherein: The control device includes a model following control unit that generates a correction torque for correcting an input torque input to the control object based on an output of the control object and a nominal model based on a structure of the control object. The model tracking control unit is configured to constrain the transfer function of the controlled object to the transfer function of the nominal model in a frequency band where a gain in a gain characteristic of a complementary sensitivity function with respect to a modeled error between the controlled object and the nominal model, that is, a complementary sensitivity gain, is approximately 1. The steady-state gain of the complementary sensitivity function is greater than 0.1, The lower limit value of the frequency band in which the complementary sensitivity gain is 1 is higher than the first resonance frequency which is the resonance frequency of the driving 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 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 resonance frequency is higher than the complementary sensitivity gain at the first resonance frequency, and is greater than or equal to 0.5 and less than 1.

5. The control device according to any one of claims 1 to 4, wherein: The steady-state gain is greater than 0.3, The complementary sensitivity gain at the second resonance frequency is greater than or equal to 0.

8.

6. The control device according to any one of claims 1 to 4, wherein: The lower limit value of the frequency band in which the complementary sensitivity gain is 1 is lower than 10 Hz.

7. The control device according to any one of claims 1 to 4, 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 any one of claims 1 to 4, 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. An electric power steering device, comprising: The control device according to any one of claims 1 to 3; and The steering mechanism.

10. A driving device, comprising: The control device according to claim 4; the motor; and A gear mechanism is connected with the motor.

Images