Control device, motor device, electric power steering device, control method, and program

Abstract

In electric power steering systems, the magnitude of vibration torque transmitted to the driver is suppressed. [Solution] The control device comprises an assist control unit that generates an input torque input to the controlled object based on the torsion bar torque, a model following control unit that generates a correction torque to correct the input torque based on a nominal model, a vibration torque generation unit that generates vibration torque, and a gain adjustment unit that adjusts the vibration torque gain applied to the vibration torque. The vibration torque multiplied by the vibration torque gain is added to the input torque. The model following control unit is configured such that the transfer function of the controlled object is constrained to the transfer function of the nominal model, calculates an estimated value of the self-aligning torque applied to the controlled object, and generates a correction torque based on the estimated value. The gain adjustment unit increases the vibration torque gain as the estimated value increases.

Description

[Technical Field]

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

[0002] An electric power steering system installed in a vehicle is known (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-183046 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Vehicles equipped with the electric power steering system described above may also be equipped with a Lane Departure Warning System (LDWS) that warns the driver if the vehicle is in danger of deviating from its lane. In this case, the electric power steering system may generate vibration torque based on a command signal from the Lane Departure Warning System and warn the driver by vibrating the steering wheel. However, the greater the torque assisted by the electric power steering system, the less this vibration torque is reflected in the steering torque. Therefore, there was a problem in that the magnitude of the vibration torque transmitted to the driver changed depending on the vehicle's driving conditions. Consequently, there were problems such as the driver having difficulty accurately perceiving the warning provided by the vibration torque.

[0005] In view of the above circumstances, one of the objectives of the present invention is to provide a control device, a motor device, an electric power steering device, a control method, and a program that can suppress changes in the magnitude of vibration torque transmitted to the helmsman. [Means for solving the problem]

[0006] One aspect of the control device of the present invention is a control device for controlling a portion of an electric power steering system mounted on a vehicle, which has an input shaft to which a steering wheel operated by an helmsman is connected, an output shaft connected to the input shaft via a torsion bar, and a motor connected to the output shaft, the portion including the motor being controlled, the control device comprising: an assist control unit that generates an input torque input to the control device based on the torsion bar torque generated in the torsion bar; a model following control unit that generates a correction torque to correct the input torque based on a nominal model based on the configuration of the control device; a vibration torque generation unit that generates a vibration torque based on a command signal from the vehicle; and a gain adjustment unit that adjusts the vibration torque gain applied to the vibration torque. The vibration torque multiplied by the vibration torque gain is added to the input torque. The model following control unit is configured such that the transfer function of the control device is constrained to the transfer function of the nominal model in a frequency band where the complementary sensitivity gain, which is the gain in the gain characteristics of the complementary sensitivity function for the modeling error between the control device and the nominal model, is approximately 1. The system calculates an estimated value of the self-aligning torque applied to the controlled object and generates the correction torque based on the estimated value. The gain adjustment unit increases the vibration torque gain as the estimated value increases.

[0007] One embodiment of the motor device of the present invention comprises the control device described above and the motor.

[0008] One embodiment of the electric power steering device of the present invention comprises the above-described motor device and a steering mechanism having the input shaft, the output shaft, and the torsion bar.

[0009] One aspect of the control method of the present invention is a control method for controlling a portion of an electric power steering device mounted on a vehicle, which has an input shaft to which a steering wheel operated by a driver is connected, an output shaft connected to the input shaft via a torsion bar, and a motor connected to the output shaft, the portion including the motor being controlled, the method comprising: generating an input torque input to the control object based on a torsion bar torque generated in the torsion bar; performing model-following control to generate a correction torque to correct the input torque based on a nominal model based on the configuration of the control object; generating a vibration torque based on a command signal from the vehicle; adjusting a vibration torque gain applied to the vibration torque; adding the vibration torque multiplied by the vibration torque gain to the input torque; and constraining the transfer function of the control object to the transfer function of the nominal model by the model-following control in a frequency band where the complementary sensitivity gain, which is the gain in the gain characteristics of the complementary sensitivity function for the modeling error between the control object and the nominal model, is approximately 1. The model following control includes calculating an estimated value of the self-aligning torque applied to the controlled object, and generating the correction torque based on the estimated value. Adjusting the vibration torque gain includes increasing the vibration torque gain as the estimated value increases.

[0010] One aspect of the program of the present invention involves causing a computer to execute the above-described control method. [Effects of the Invention]

[0011] According to one aspect of the present invention, in an electric power steering system, it is possible to suppress changes in the magnitude of vibration torque transmitted to the driver. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic diagram showing an electric power steering system according to one embodiment. [Figure 2]Figure 2 is a block diagram showing the configuration of a control device according to one embodiment. [Figure 3] Figure 3 is a functional block diagram showing the functions of the processor in a control device according to one embodiment. [Figure 4] Figure 4 is a graph showing an example of the relationship between steering angle and base assist torque. [Figure 5] Figure 5 is a block diagram showing a part of the model-following control unit in a control device according to one embodiment. [Figure 6] Figure 6 is a graph illustrating the gain characteristics of the complementary sensitivity function in one embodiment, and the gain characteristics of the reciprocal of the modeling error between the transfer function of the controlled object and the transfer function of the nominal model. [Figure 7] Figure 7 is a graph showing an example of the relationship between steering angle and self-aligning torque. [Figure 8] Figure 8 is a block diagram showing a gain adjustment unit in one embodiment. [Figure 9] Figure 9 is a graph showing an example of gain information in one embodiment. [Modes for carrying out the invention]

[0013] The electric power steering system 1000 of this embodiment, shown in Figure 1, is mounted on a vehicle. As shown in Figure 1, the electric power steering system 1000 comprises a steering mechanism 530 and a control device 100. The steering mechanism 530 has a steering mechanism section 520 and an auxiliary mechanism section 540. The electric power steering system 1000 controls the auxiliary mechanism section 540 by the control device 100, thereby generating a steering torque T in the steering mechanism section 520 when the driver operating the vehicle steers the steering wheel 521. h It generates an auxiliary torque to assist the driver. This auxiliary torque reduces the burden on the driver when operating the steering wheel 521. The driver of the vehicle is the helmsman who steers the vehicle's steering wheel 521.

[0014] The steering mechanism 520 includes a steering wheel 521, a steering shaft 522, universal joints 523A, 523B, an input shaft 524a, an output shaft 524b, a rack and pinion mechanism 525, a rack shaft 526, left and right ball joints 552A, 552B, tie rods 527A, 527B, knuckles 528A, 528B, and left and right tires 529A, 529B. In other words, the steering mechanism 530 includes a steering wheel 521, a steering shaft 522, universal joints 523A, 523B, an input shaft 524a, an output shaft 524b, a rack and pinion mechanism 525, a rack shaft 526, left and right ball joints 552A, 552B, tie rods 527A, 527B, knuckles 528A, 528B, and left and right tires 529A, 529B.

[0015] The steering shaft 522 is a shaft that extends from the steering wheel 521, which is operated by the driver. One end of the input shaft 524a is connected to the end of the steering shaft 522 opposite to the side connected to the steering wheel 521, via universal joints 523A and 523B. Thus, the steering wheel 521 is connected to the input shaft 524a via the universal joints 523A and 523B and the steering shaft 522. The output shaft 524b is connected to the input shaft 524a via a torsion bar 546, which will be described later. More specifically, one end of the output shaft 524b is connected to the other end of the input shaft 524a via the torsion bar 546. The other end of the output shaft 524b is connected to the rack shaft 526 via a rack and pinion mechanism 525.

[0016] The input shaft 524a and the output shaft 524b are arranged coaxially. The input shaft 524a and the output shaft 524b are rotatable around the same central axis. The input shaft 524a and the output shaft 524b are rotatable relative to each other within the range in which the torsion bar 546, described later, can twist.

[0017] The auxiliary mechanism unit 540 includes a steering torque sensor 541, a steering angle sensor 542, a motor 543, a 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 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 arranged coaxially with the input shaft 524a and the output shaft 524b. In the following description, a virtual axis passing through the common central axis of the input shaft 524a, the output shaft 524b, and the torsion bar 546 is referred to as a rotation axis R. The torsion bar 546 can be twisted around the rotation axis R.

[0018] The steering torque sensor 541 detects the steering torque T in the steering mechanism unit 520 by detecting the amount of twist around the rotation axis R of the torsion bar 546. h to detect. The steering torque T h is the torsion bar torque generated in the torsion bar 546 and is the torsional moment around the rotation axis R. The steering angle sensor 542 can detect the rotation angle θ around the rotation axis R of the input shaft 524a. a The rotation angle θ of the input shaft 524a a is equal to the steering angle θ of the steering wheel 521. h That is, the steering angle sensor 542 can detect the steering angle θ of the steering wheel 521 by detecting the rotation angle θ of the input shaft 524a. a Based on the steering torque sensor 541 and the steering angle sensor 542, it is possible to detect the rotation angle θ of the output shaft 524b. h The rotation angle θ of the output shaft 524b b is the steering angle θ. b s s s

[0019] The inverter 545 converts DC power, which is a pseudo-sine wave of U-phase, V-phase, and W-phase, into three-phase AC power 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 mechanism 544. The motor 543 is supplied with three-phase AC power from the inverter 545. The motor 543 is, for example, an Interior Permanent Magnet Synchronous Motor (IPMSM), a Surface Mounted Permanent Magnet Synchronous Motor (SPMSM), or a Switched Reluctance Motor (SRM). The motor 543, supplied with three-phase AC power from the inverter 545, provides steering torque T h It generates an auxiliary torque corresponding to the current. The motor 543 transmits the generated auxiliary torque to the output shaft 524b via the reduction mechanism 544.

[0020] The control device 100 controls the portion of the steering mechanism 530 mounted on the vehicle that includes at least the motor 543, as the controlled object 560. In this embodiment, the controlled object 560 includes a steering mechanism 520, a torsion bar 546, a motor 543, and a reduction mechanism 544. Since the controlled object 560 includes an input shaft 524a and an output shaft 524b that can rotate relative to each other via the torsion bar 546, the motion of the controlled object 560 cannot be described by the equations of motion of a simple one-inertial frame alone. The controlled object 560 changes between one-inertial frames and two-inertial frames depending on how hard the driver grips the steering wheel 521. The harder the driver grips the steering wheel 521, the closer the controlled object 560 is to one-inertial frames. The looser the driver grips the steering wheel 521, the closer the controlled object 560 is to two-inertial frames. Thus, the controlled object 560 is composed of two inertial frames.

[0021] The control device 100 is electrically connected to the inverter 545. Based on detection signals detected by the steering torque sensor 541, the steering angle sensor 542, and the vehicle speed sensor 300 mounted on the vehicle, the control device 100 generates a motor drive signal and outputs it to the inverter 545. The control device 100 controls the controlled object 560 by controlling the rotation of the motor 543 via the inverter 545. More specifically, the control device 100 controls the switching operation of multiple switching elements in the inverter 545. Specifically, the control device 100 generates a control signal to control the switching operation of each switching element and outputs it to the inverter 545. Each switching element is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). In the following description, the control signal that controls the switching operation of each switching element will be called a "gate control signal".

[0022] The control device 100 controls the steering torque T h A torque command value is generated based on these factors, and the torque and rotational speed of the motor 543 are controlled, for example, by vector control. Vector control is a method of decomposing the current flowing through the motor 543 into a current component that contributes to torque generation and a current component that contributes to magnetic flux generation, and independently controlling each mutually orthogonal current component. The control device 100 is not limited to vector control and can perform other closed-loop control methods. The rotational speed of the motor 543 is expressed, for example, as the number of revolutions per minute [rpm (revolutions per minute)] or the number of revolutions per second [rps (revolutions per second)].

[0023] Furthermore, the control device 100 receives the steering torque T directly from the steering torque sensor 541. h The value may be input, or the control device 100 may input the steering torque T from the output value of the steering torque sensor 541. h The value of may be calculated. The control device 100 directly receives the steering angle θ of the steering wheel 521 from the steering angle sensor 542. hThe value may be input, or the control device 100 may input the steering angle θ from the output value of the steering angle sensor 542. h You may also calculate the value of .

[0024] In this embodiment, the electric power steering system 1000 includes a motor unit 100a. The motor unit 100a includes a control device 100, a motor 543, and an inverter 545. The motor unit 100a can be manufactured and sold independently of the other parts of the electric power steering system 1000. Furthermore, the control device 100 can be manufactured and sold independently of the other parts of the motor unit 100a as a control device for controlling the electric power steering system 1000.

[0025] Figure 2 shows a typical configuration of the control device 100 in this embodiment. The control device 100 includes, for example, a power supply circuit 111, an angle sensor 112, an input circuit 113, a communication interface 114, a drive circuit 115, a ROM 116, and a processor 200. The control device 100 can be implemented as a printed circuit board (PCB) on which these electronic components are mounted.

[0026] The vehicle speed sensor 300, steering torque sensor 541, and steering angle sensor 542 mounted on the vehicle are connected to the processor 200 so that they can input signals to the processor 200. The vehicle speed is input to the processor 200 from the vehicle speed sensor 300. The steering torque T is input to the processor 200 from the steering torque sensor 541. h The following is input: The processor 200 receives the steering angle θ from the steering angle sensor 542. h The following is entered.

[0027] The processor 200 is a semiconductor integrated circuit, also known as a central processing unit (CPU) or microprocessor. The processor 200 sequentially executes a computer program stored in the ROM 116, which contains instructions for controlling the motor drive, to achieve the desired processing. In addition to the processor 200, or in place of the processor 200, the control device 100 may have 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 according to the actual current value and the rotation angle of the motor 543 rotor, generates a PWM (Pulse Width Modulation) signal, and outputs the PWM signal to the drive circuit 115.

[0028] The power supply circuit 111 is connected to an external power supply (not shown). The power supply circuit 111 generates the DC voltage required for each part of the control device 100. The DC voltage generated by the power supply circuit 111 is, for example, 3V or 5V.

[0029] The angle sensor 112 detects the rotation angle of the motor 543's rotor and outputs it to the processor 200. The angle sensor 112 may be a resolver, a Hall element such as a Hall IC, or an MR sensor having a magnetoresistive element. The processor 200 can calculate the angular velocity ω [rad / s] of the motor 543 based on the electrical angle of the motor 543 obtained from the angle sensor 112. The control device 100 may also be equipped with a speed 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.

[0030] The input circuit 113 receives the motor current value detected by a current sensor (not shown). In the following description, the motor current value detected by the current sensor (not shown) will be referred to as the "actual current value". The input circuit 113 converts the level of the input actual current value to 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.

[0031] Communication I / F114 is an input / output interface for transmitting and receiving data in accordance with, for example, an in-vehicle control area network (CAN: Controller Area Network).

[0032] The drive circuit 115 is typically a gate driver or pre-driver. The drive circuit 115 generates gate control signals according to the PWM signal and applies gate control signals to the gates of the multiple switching elements of the inverter 545. For example, when the motor 543 to be driven is a motor that can be driven at a low voltage, the drive circuit 115 as a gate driver may not be necessary. In that case, the gate driver function of the drive circuit 115 can be implemented in the processor 200.

[0033] ROM116 is electrically connected to processor 200. ROM116 is, for example, writable memory, rewritable memory, or read-only memory. Examples of writable memory include PROM (Programmable Read Only Memory). Examples of rewritable memory include flash memory and EEPROM (Electrically Erasable Programmable Read Only Memory). ROM116 stores a control program containing instructions for processor 200 to control motor drive. For example, the control program stored in ROM116 is temporarily loaded into RAM (not shown) during boot-up.

[0034] Figure 3 shows an example of the functional blocks of the processor 200 in this embodiment. The processor 200, which is a computer, sequentially executes the processing or tasks necessary for controlling the motor 543 using each functional block. Each functional block of the processor 200 shown in Figure 3 may be implemented in the processor 200 as software such as firmware, as hardware, or as both software and hardware. Typically, the processing of each functional block in the processor 200 is described in a computer program in software module units and stored in the ROM 116. However, when using an FPGA or the like, all or part of these functional blocks may be implemented as hardware accelerators. Furthermore, the control method for the controlled object 560 in this embodiment is executed by the processor 200, which is a computer, executing a program stored in the control device 100. In other words, the program of this embodiment stored in the control device 100 causes the processor 200, which is a computer, to execute the control method for the controlled object 560 in this embodiment.

[0035] The processor 200 has a controller 200a. The controller 200a has an assist control unit 210, a model following control unit 230, a state feedback unit 280, a vibration torque generation unit 290, a gain adjustment unit 291, an adder AD4, and a subtractor SU1. In other words, the control device 100 is equipped with an assist control unit 210, a model following control unit 230, a state feedback unit 280, a vibration torque generation unit 290, a gain adjustment unit 291, an adder AD4, and a subtractor SU1. To put it another way, the processor 200 of the control device 100 has functions corresponding to the assist control unit 210, the model following control unit 230, the state feedback unit 280, the vibration torque generation unit 290, the gain adjustment unit 291, the adder AD4, and the subtractor SU1, respectively.

[0036] The assist control unit 210 receives the steering torque T detected by the steering torque sensor 541. hThe input torque T is input to the controlled object 560. The assist control unit 210 receives the input torque T from the controlled object 560. r steering torque T h In other words, it is generated based on the torsion bar torque generated in the torsion bar 546. To put it another way, the control method of the controlled object 560 is the input torque T input to the controlled object 560. r steering torque T h This includes generating based on the input torque T. r This is the target torque of motor 543 and is the torque command value. The assist control unit 210 receives the input torque T r The assist control unit 210 controls the reaction force transmitted to the helmsman from the steering wheel 521 by generating a steering torque T when the steering frequency or steering speed is within a predetermined range. h By applying phase compensation to the input torque T r The steering frequency is the frequency of the steering angle that changes based on the steering wheel 521's operation by the steering wheel operator. The steering speed is the speed of the steering angle that changes based on the steering wheel 521's operation by the steering wheel operator. The assist control unit 210 illustrated in Figure 3 includes a base assist calculation unit 211 and a phase compensator 212.

[0037] The base assist calculation unit 211 calculates the steering torque T h The vehicle speed V is obtained. The vehicle speed V is the speed of the vehicle. The base assist calculation unit 211 calculates the steering torque T h and base assist torque T based on vehicle speed V ass It generates the steering torque T. For example, the base assist calculation unit 211 generates the steering torque T. h Vehicle speed V and base assist torque T ass It has a lookup table (LUT) that defines the relationship with the steering torque T. The base assist calculation unit 211 refers to the lookup table and calculates the steering torque T h And based on the vehicle speed V, the corresponding base assist torque T ass The base assist calculation unit 211 can determine the steering torque T. h Base assist torque T for the amount of variation assThe base assist gain K is determined by the slope defined by the ratio of the change in the amount of change. ass It is possible to make a decision.

[0038] Figure 4 shows the steering torque T. h and base assist torque T ass An example of the relationship is shown. In the graph in Figure 4, the horizontal axis is steering torque T. h The vertical axis represents the base assist torque T. ass This indicates steering torque T h Base assist torque T ass The slope of the base assist gain K ass Steering torque T h and base assist torque T ass and Base Assist Gain K ass That is, dT ass / dT h =K ass The relationship is satisfied. As shown in Figure 4, the base assist torque T ass For example, steering torque T h As the value increases, it increases exponentially.

[0039] In this embodiment, the phase compensator 212 provides a base assist gain K within the range of steering frequencies that can be taken when the helmsman operates the steering wheel 521. ass The steering frequency is adjusted to compensate for the stiffness of the torsion bar 546. The range of possible steering frequencies is, for example, 5 Hz or less. The phase compensator 212 adjusts the steering torque T when the steering frequency is 5 Hz or less. h In other words, a first-order phase compensation may be applied to the torsion bar torque. The first-order phase compensation is represented, for example, by the transfer function of equation (1).

[0040]

number

[0041] In equation (1), s is a Laplace transformer, f1 is the zero frequency [Hz] of the transfer function, and f2 is the pole frequency [Hz] of the transfer function. A graph with gain, or loop gain, on the vertical axis and the logarithm of frequency on the horizontal axis is called a gain diagram. In a gain diagram, the zero point represents the intersection of the gain curve and the horizontal axis representing 0 dB, and the pole represents the maximum point of the gain curve. For example, phase lead compensation can be applied by setting the pole frequency higher than the zero frequency. The larger the distance between the pole frequency and the zero frequency, the greater the phase lead.

[0042] The phase compensator 212 outputs the base assist torque T from the base assist calculation unit 211. ass and base assist gain K ass Based on the input torque T r It generates the following. For example, the phase compensator 212 is a stabilization compensator, and the base assist torque T ass Stability phase compensation can be applied to it. The phase compensator 212 has a base assist gain K ass A transfer function of order second or higher may have a variable frequency response. A transfer function of order second or higher can be expressed using response parameters and damping parameters. A transfer function of order second or higher can be expressed, for example, by equation (2). By making the order of the transfer function second, damping can be introduced into the characteristics of the transfer function. By changing the damping, it becomes possible to adjust the phase characteristics.

[0043]

number

[0044] In equation (2), s is a Laplace transformer, ω1 is the zero frequency of the transfer function, ω2 is the pole frequency of the transfer function, ζ1 is the zero attenuation ratio, and ζ2 is the pole attenuation ratio. The pole frequency ω2 is lower than the zero frequency ω1.

[0045] As shown in Figure 3, the input torque T output from the assist control unit 210r This is input to adder AD4. Adder AD4 receives the input torque T r The vibration torque T, described later, is in relation to this. wa The result is added and output to the subtractor SU1.

[0046] The model following control unit 230 controls the input torque T r Correction torque T to compensate for f This is generated based on a nominal model based on the configuration of the controlled object 560. In this embodiment, the corrected torque T f The input torque T r This is the feedback torque that is fed back to the control target 560. The nominal model is an internal model used as a constraint model for the control target 560 when controlling the control target 560. The nominal model will be described in detail later. The model following control unit 230 is a controller configured to perform model following control. The control method for the control target 560 is the input torque T r Correction torque T to compensate for f This includes performing model-following control, which generates a model based on a nominal model derived from the configuration of the controlled object 560. The specific configuration of the model-following control unit 230 will be described in detail later.

[0047] The subtractor SU1 receives the input torque T output from the adder AD4. r Therefore, the corrected torque T output from the model following control unit 230. f Subtract the value. The output from subtractor SU1 is input to adder AD1 and model following control unit 230. Adder AD1 outputs the value obtained by adding the output from state feedback unit 280 to the output from subtractor SU1 to adder AD2. Adder AD2 adds the disturbance torque T to the output from adder AD1. d The value obtained by adding this value is output to the controlled device 560.

[0048] Disturbance Torque T d This is the difference between the output torque of the ideal motor 543 and the actual output torque of the motor 543. Disturbance torque T dThis includes disturbance torques applied externally to the controlled object 560. Disturbance torque T d This includes, for example, excess torque caused by friction and play resulting from mechanical elements such as the motor 543 and reduction mechanism 544, torque ripple in the motor 543, and self-aligning torque T. SAT , external disturbance torque that may occur when driving on unpaved, bumpy or gravel roads, and steering torque T h This includes, among others.

[0049] In this embodiment, the model following control unit 230 controls the steering angle θ s Based on the corrected torque T f Generates input torque T r The model following control unit 230 includes an inverse nominal model 231, a corrected torque generation unit 233, a second filter 232b, and a subtractor SU2. As shown in Figure 5, the corrected torque generation unit 233 includes an assist adjustment unit 270, a first filter 232a, and an adder AD3. In this embodiment, the first filter 232a is a high-pass filter. The first filter 232a has a first cutoff frequency Cf1. The first cutoff frequency Cf1 is, for example, 2Hz or more and 10Hz or less. In this embodiment, the first cutoff frequency Cf1 is higher than 5Hz and lower than 10Hz.

[0050] In this embodiment, the second filter 232b is a low-pass filter. The second filter 232b has a second cutoff frequency Cf2 that is higher than the first cutoff frequency Cf1. The second cutoff frequency Cf2 is, for example, 3 Hz or more and 50 Hz or less. However, the upper limit of the second cutoff frequency Cf2 may be set to a range of approximately 140 Hz or more and 200 Hz or less. The order of the second filter 232b is third order or higher. The second filter 232b may be composed of, for example, multiple low-pass filters. The first filter 232a and the second filter 232b are connected in series.

[0051] The model-following control unit 230 ensures that in the frequency band where the complementary sensitivity gain GT, which is 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, is approximately 1, the transfer function P(s) of the controlled object 560 is equal to the transfer function P of the nominal model. n It is configured to be constrained to (s). In other words, the control method of this embodiment uses model following control to determine the transfer function P(s) of the controlled object 560 in a frequency band where the complementary sensitivity gain GT is approximately 1, compared to the transfer function P of the nominal model. n This includes being constrained to (s). "The complementary sensitivity gain GT is approximately 1" includes not only the case where the complementary sensitivity gain GT is 1, but also, for example, the case where the complementary sensitivity gain GT is 0.8 or more and 1.2 or less. This numerical range is, for example, the range in which the gain of the effective disturbance suppression characteristic can be adjusted to 1, taking into account the positive and negative 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, it is necessary to adjust the gain by ±0.2 relative to the target value of 1.

[0052] The complementary sensitivity function T(s) is the complementary sensitivity function of the inner loop composed of the model following control unit 230. Figure 6 shows the complementary sensitivity gain GT in the complementary sensitivity function T(s). 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). In the graph of Figure 6, the horizontal axis represents frequency f [Hz], and the vertical axis represents the complementary sensitivity gain GT. As shown in Figure 6, the complementary sensitivity function T(s) has a gain of approximately 0 dB, that is, the complementary sensitivity gain GT in the transfer function is approximately 1, in at least a portion of the frequency band where the frequency f is above the first cutoff frequency Cf1 and below the second cutoff frequency Cf2. In the example in Figure 6, the complementary sensitivity gain GT is 1 in the frequency band where the frequency is above f1a, which is higher than the first cutoff frequency Cf1, and below f2a, which is lower than the second cutoff frequency Cf2. Frequency f1a is lower than frequency f2a. In the frequency band between frequency f1a and frequency f2a, the complementary sensitivity gain GT may be, for example, a value of 0.95 or more and less than 1. The complementary sensitivity gain GT at the first cutoff frequency Cf1 is smaller than the complementary sensitivity gain GT at frequency f1a. The complementary sensitivity gain GT at the second cutoff frequency Cf2 is smaller than the complementary sensitivity gain GT at frequency f2a. In this embodiment, the frequency band in which the complementary sensitivity gain GT is approximately 1 is the frequency band between frequency f1b and frequency f2b. Frequency f1b is higher than the first cutoff frequency Cf1 and lower than frequency f1a. Frequency f2b is lower than the second cutoff frequency Cf2 and higher than frequency f2a. In the frequency band between frequency f1b and frequency f2b, the complementary sensitivity gain GT is, for example, 0.8 or more and less and less than 1. In this specification, "the transfer function of the controlled object is constrained to the transfer function of the nominal model" means, for example, that the controlled object is controlled in such a way that, when looking at the input-output relationship, its transfer function appears to be the transfer function of the nominal model.

[0053] The transfer function P(s) of the controlled object 560 is a plant characteristic on which model-following control is performed. The transfer function P(s) of the controlled object 560 is expressed, for example, by the following equation (3).

[0054] [Number] However, s is a Laplace transform operator, J is a parameter representing the moment of inertia of the steering mechanism unit 520, and B is a parameter representing the viscous friction coefficient of the steering mechanism unit 520. K SAT is the self-aligning torque gain. The self-aligning torque gain K SAT is the slope of the self-aligning torque T s generated in the vehicle tires 529A and 529B with respect to the steering angle θ SAT . In FIG. 7, an example of the relationship between the self-aligning torque T SAT and the steering angle θ s is shown. In the graph of FIG. 7, the horizontal axis represents the steering angle θ s , the vertical axis represents the self-aligning torque T SAT , and the slope of the self-aligning torque T s with respect to the steering angle θ SAT is the self-aligning torque gain K SAT . The steering angle θ s , the self-aligning torque T SAT , and the self-aligning torque gain K SAT satisfy the relationship dT SAT / dθ s = K SAT . As shown in FIG. 7, the self-aligning torque T SAT increases as the steering angle θ s increases up to a certain magnitude, and decreases as the steering angle θ s increases beyond a certain magnitude.

[0055] The inverse nominal model 231 is the inverse model of a predetermined nominal model used to constrain the control object 560. The transfer function P n ​​​​(s) can be expressed, for example, by the following equation (4): Transfer function P of the inverse nominal model 231. n -1 (s) can be expressed, for example, by the following equation (5).

[0056]

number

[0057]

number

[0058] In equations (4) and (5), s is the Laplace transformer, and J n is a parameter that represents the moment of inertia of the nominal model, and B n This parameter represents the viscous friction coefficient of the nominal model. The transfer function P of the nominal model is also shown. n (s) and the transfer function P of the inverse nominal model 231 n -1 (s) is not limited to the examples shown in equations (4) and (5), and is not particularly limited.

[0059] As shown in Figure 3, the inverse nominal model 231 receives the output from the controlled device 560. In this embodiment, the steering angle θ is input to the inverse nominal model 231. s This is input. In other words, in this embodiment, the steering angle θ is input to the model following control unit 230 as the output of the controlled object 560. s The following is input. The inverse nominal model 231 is obtained by the above equation (5) and the input steering angle θ. s Torque T based on p It outputs the torque T. In other words, the model-following control unit 230 uses the nominal model based on the output of the controlled object 560 to output the torque T. p Calculate the torque T. p This value is equal to the torque input to the nominal model when the output value of the nominal model is the same as the output value of the controlled device 560.

[0060] The subtractor SU2 subtracts the output from the subtractor SU1 from the output of the inverse nominal model 231 to obtain the differential torque T. a It generates the corrected torque T. f After the feedback is given, the state compensation value V described later is used. s Input torque T before it is fed back r Torque T p Subtracting the difference torque T a This generates the input torque T input to the subtractor SU1 in this embodiment. r This refers to the vibration torque T, which will be discussed later. wa Input torque T after addition r Therefore, in the subtractor SU1, the input torque T r Corrected Torque T f This is subtracted. Therefore, the output from the subtractor SU1 is the vibration torque T, which will be described later. wa This is added, and the corrected torque T f Input torque T after subtraction r In this embodiment, the differential torque T a is the disturbance torque T d This is an estimated value.

[0061] The differential torque T output from subtractor SU2 a This is input to the second filter 232b and undergoes low-pass filtering. The differential torque T output from the second filter 232b. a This is the frequency component T from which frequency components higher than the second cutoff frequency Cf2 have been removed. aML In this embodiment, the frequency component T aML This is the self-aligning torque T applied to the controlled object 560. SAT Estimated value E SAT Thus, in this embodiment, the model following control unit 230 controls the output (torque T) from the inverse nominal model 231. p ) From the vibration torque T described later wa Input torque T after addition r The difference obtained by subtracting (difference torque T) a Estimated value E based on ) SATThis calculates the oscillation torque T from the output of the inverse nominal model 231. In other words, model-following control calculates the oscillation torque T from the output of the inverse nominal model 231. wa Input torque T after addition r The estimated value E is based on the difference obtained by subtracting the difference. SAT This includes calculating [the value].

[0062] In this specification, "Self-aligning torque T SAT Estimated value E SAT " is Self-Aligning Torque T SAT Any value that can be considered an estimate of the self-aligning torque T is sufficient. SAT The self-aligning torque T may also be an estimate of a value that includes disturbances other than those mentioned above. SAT A value that can be considered an estimate of the self-aligning torque T is, for example, the proportion of disturbances in that value. SAT This includes the case where the proportion is the largest. Frequency component T in this embodiment aML Self-aligning torque T SAT Other disturbances include frictional force, disturbance torque caused by play in the controlled object 560, and torque ripple occurring in the controlled object 560.

[0063] The frequency component T output from the second filter 232b aML , that is, the estimated value E SAT The frequency component T is input to the correction torque generation unit 233 and the gain adjustment unit 291. As shown in Figure 5, the frequency component T is input to the correction torque generation unit 233. aML The signal is input to the first filter 232a and subjected to high-pass filtering. The frequency component T after filtering by the first filter 232a aML This is input to adder AD3. The torque input from the first filter 232a to adder AD3 is the difference torque T output from subtractor SU2. aThe signal is filtered by the first filter 232a and the second filter 232b, removing frequency components lower than the first cutoff frequency Cf1 and frequency components higher than the second cutoff frequency Cf2. In other words, the torque input from the first filter 232a to the adder AD3 is the differential torque T output from the subtractor SU2. a Among these, frequency components T with a first cutoff frequency of Cf1 or higher and a second cutoff frequency of Cf2 or lower. aM That is the case.

[0064] The assist adjustment unit 270 generates compensation values ​​for friction and disturbances, and adjusts the differential torque T a Adjusts the differential torque T. In this embodiment, the assist adjustment unit 270 adjusts the differential torque T. a Among them, frequency component T aM The assist adjustment unit 270 is connected in parallel to the first filter 232a. The assist adjustment unit 270 includes a friction compensation value calculation unit 250, a disturbance compensation value calculation unit 260, and a subtractor SU3.

[0065] The subtractor SU3 subtracts the output value from the first filter 232a from the output value from the second filter 232b. Here, the output value from the second filter 232b is the differential torque T. a The value obtained by removing frequency components higher than the second cutoff frequency Cf2, i.e., frequency component T. aML Therefore, the output value from the first filter 232a is the differential torque T. a The value obtained by removing frequency components higher than the second cutoff frequency Cf2 and frequency components lower than the first cutoff frequency Cf1, i.e., frequency component T aM Therefore, the value output from the subtractor SU3 is the differential torque T. a Among these, the frequency component T is lower than the first cutoff frequency Cf1. aL The output of the subtractor SU3 is input to the friction compensation value calculation unit 250 and the disturbance compensation value calculation unit 260. Frequency component T aL This includes frictional force and self-aligning torque T SATThis includes disturbance torque caused by play in the controlled object 560, and torque ripple occurring in the controlled object 560.

[0066] The friction compensation value calculation unit 250 calculates a friction compensation value V that compensates for at least a portion of the friction force generated in the controlled object 560. f The difference torque T a The calculation is based on the following: As described above, the value from the subtractor SU3 input to the friction compensation value calculation unit 250 is the differential torque T a Among these, the frequency component T is lower than the first cutoff frequency Cf1. aL Therefore, in this embodiment, the friction compensation value calculation unit 250 calculates the differential torque T a Based on the component with a frequency lower than the first cutoff frequency Cf1, the friction compensation value V f Calculate.

[0067] 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 SU3. If the input value exceeds an upper or lower threshold, the limiter 252 clips the input value to the upper or lower threshold. The gain adjuster 253 multiplies the output value from the limiter 252 by a gain K1. The friction compensation value calculation unit 250 calculates the differential torque T a For the components with frequencies lower than the first cutoff frequency Cf1, the limiter 252 and the gain K1 are applied to obtain a friction compensation value V. f The threshold value of the limiter 252 and the gain K1 value are predetermined, for example, based on the frictional force actually generated on the controlled object 560.

[0068] Friction compensation value V output from friction compensation value calculation unit 250 f is the differential torque T a The frequency component T aL This value compensates for at least a portion of the frictional force component included in the control object 560. Generally, a moderate amount of friction is required for the control object 560, so the friction compensation value calculation unit 250 sets the friction compensation value V to a value smaller than the frictional force actually generated in the control object 560. fThis is calculated as follows. This makes it possible to achieve highly accurate friction compensation while leaving an appropriate amount of frictional force on the controlled object 560. Friction compensation value V f The friction compensation provided by this system includes, for example, the friction of the motor 543, the friction of the reduction mechanism 544, and the difference in friction between the left and right sides of the reduction mechanism 544.

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

[0070] The disturbance compensation value calculation unit 260 calculates the self-aligning torque T generated in the controlled object 560. SAT Disturbance compensation value V compensates for at least a portion of it. d The disturbance compensation value V is calculated in this embodiment. d This includes a compensation value that compensates for at least a portion of the frictional force generated in the controlled object 560, the disturbance torque caused by the play in the controlled object 560, and the torque ripple 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 and input torque T r The difference is the differential torque T. a Based on this, the disturbance compensation value V d The disturbance compensation value calculation unit 260 calculates the torque T based on the output of the controlled object 560 using a nominal model. p and input torque T r The difference is the differential torque T. a Based on this, the disturbance compensation value V d The differential torque T is calculated. As described above, the value from the subtractor SU3 input to the disturbance compensation value calculation unit 260 is the differential torque T. aAmong these, the frequency component is lower than the first cutoff frequency Cf1. Therefore, in this embodiment, the disturbance compensation value calculation unit 260 calculates the differential torque T a The disturbance compensation value V is based on the component with a frequency lower than the first cutoff frequency Cf1. d Calculate.

[0071] The disturbance compensation value calculation unit 260 includes a limiter 262 and a gain adjuster 263. The limiter 262 limits the output value from the subtractor SU3. If the input value exceeds an upper or lower threshold, the limiter 262 clips the input value to the upper or lower threshold. The threshold of the limiter 262 is different from, for example, the threshold of the limiter 252. The gain adjuster 263 multiplies the output value from the limiter 262 by a gain K2. The transfer function P(s) of the controlled object 560 is the transfer function P of the nominal model. n The maximum value of the gain K2 of the gain adjuster 263 is determined under the constraint of (s). The value of gain K2 is different from, for example, the value of gain K1. The value of gain K2 is, for example, between 0.1 and 0.8. The gain K2 of the gain adjuster 263 may be switched according to the vehicle's driving mode.

[0072] Disturbance compensation value V d is the differential torque T a The frequency component T aL This value compensates for at least a portion of the self-aligning torque component included in the control. The disturbance compensation value calculation unit 260 calculates, for example, the self-aligning torque T that actually occurs in the control target 560. SAT The disturbance compensation value V is approximately half of the value of the disturbance compensation value. d The self-aligning torque T that actually occurs in the controlled object 560 is calculated as follows. SAT For example, the threshold value and gain K2 of the limiter 262 of the disturbance compensation value calculation unit 260 are determined in advance by the self-aligning torque T SAT The disturbance compensation value V is set to a value between 0.1 and 0.8 times the magnitude of the disturbance. d The value is adjusted to the value at which the disturbance compensation value V is calculated in the disturbance compensation value calculation unit 260. dThis is the friction compensation value V calculated in the friction compensation value calculation unit 250. f This is a different value.

[0073] Here, the differential torque T a The frequency component T aL This includes the frictional force generated in the controlled object 560 and the self-aligning torque T generated in the controlled object 560. SAT This includes disturbance torque caused by play in the controlled object 560, and torque ripple occurring in the controlled object 560. Therefore, the frequency component T aL The friction compensation value V obtained by processing with limiter 252 and gain adjuster 253 f This includes disturbances other than friction, namely the self-aligning torque T generated in the controlled object 560. SAT This also includes compensation values ​​that compensate for at least a portion of the disturbance torque caused by play in the controlled object 560, and the torque ripple that occurs in the controlled object 560. Furthermore, the frequency component T aL The disturbance compensation value V obtained by processing with limiter 262 and gain adjuster 263 is obtained. d Self-aligning torque T SAT This also includes compensation values ​​that compensate for other disturbances, namely frictional forces occurring in the controlled object 560, disturbance torques resulting from play in the controlled object 560, and at least a portion of the torque ripple occurring in the controlled object 560.

[0074] Correction torque T used for model following control in the model following control unit 230 fIn order to apply friction compensation and disturbance compensation performed in the assist adjustment unit 270, it is necessary to pay attention to the stability conditions of the model following control. This condition, according to the small gain theorem described later, is that the gain in the gain characteristics of the transfer function of the assist adjustment unit 270, constrained to characteristics that consider stability, does not exceed 1. This is derived from the design conditions of the second filter 232b. In this embodiment, the values ​​of gains K1 and K2 in the gain adjusters 253 and 263 are set to a maximum of 1, and subtraction processing is applied by providing a subtractor SU3 before the limiters 252 and 262 so that the gain in the gain characteristics under these conditions becomes 1. In other words, the assist adjustment unit 270 behaves as a low-pass filter having a transfer function of 1-Q1(s). Q1(s) is the transfer function of the first filter 232a, which is a high-pass filter. The assist adjustment unit 270 applies a low-pass filter process with a transfer function of 1-Q1(s) to the torque output from the second filter 232b, and the friction compensation value calculation unit 250 and the disturbance compensation value calculation unit 260 adjust and output the processed value, respectively.

[0075] The adder AD3 adds the output value from the assist adjustment unit 270 to the output value from the first filter 232a. In other words, the adder AD3 adds the frequency component T aM Friction compensation value V f and disturbance compensation value V d Add and . Adder AD3 outputs the frequency component T aM and friction compensation value V f and disturbance compensation value V d The corrected torque T is calculated by adding these together. f The following is output. Correction torque T is output from adder AD3. f This is the input to the controlled object 560, i.e., the input torque T. r This is fed back to the model following control unit 230. In this embodiment, the model following control unit 230 receives the differential torque T from which frequency components lower than the first cutoff frequency Cf1 have been removed by the first filter 232a, which is a high-pass filter. a , that is, frequency component T aM For this, the friction compensation value V f and disturbance compensation value Vd Adding these together, the corrected torque T f Generates.

[0076] As described above, the model following control unit 230 calculates the estimated value E SAT The difference torque T is a The frequency component T aML Based on the corrected torque T f This generates the estimated value E. In other words, model-following control generates the estimated value E. SAT The difference torque T is a The frequency component T aML Based on this, corrected torque T f This includes generating [something].

[0077] The state feedback unit 280 shown in Figure 3 calculates the apparent transfer function of the controlled object 560 based on the output of the controlled object 560, and calculates the transfer function P of the nominal model. n (s) should be approached, state compensation value V s Input torque T r Feedback is provided to the control target 560. The apparent transfer function of the control target 560 is, for example, the transfer function of a single part when the part located inside the feedback loop created by the model following control unit 230 is considered as a single part. Specifically, in this embodiment, the apparent transfer function of the control target 560 is the transfer function of the entire part from the subtractor SU1 to the output of the control target 560, and is the transfer function of the combined part of the state feedback unit 280 and the control target 560. In this embodiment, the state feedback unit 280 is corrected torque T f The input torque T after correction and before being input to the controlled object 560. r For this, the state compensation value V s Provide feedback.

[0078] State compensation value V s This includes a compensation value that compensates for at least a portion of the inertial force, viscous force, and frictional force acting on the controlled object 560. More specifically, the state compensation value V sThis includes a compensation value that compensates for at least a portion of the inertial force, viscous force, and frictional force generated in the motor 543. In this embodiment, the state compensation value V s This is a compensation value that includes the inertial force, viscous force, and frictional force acting on the motor 543, respectively.

[0079] The state feedback unit 280 includes an inertia compensator 281, a viscosity compensator 282, and a friction compensator 283. The inertia compensator 281 controls the steering angle θ s Based on this, a compensation value is calculated to compensate for at least a portion of the inertial force generated in the motor 543. The viscous compensator 282 controls the steering angle θ s Based on this, a compensation value is calculated to compensate for at least a portion of the viscous force generated in the motor 543. The friction compensator 283 controls the steering angle θ. s Based on this, a compensation value is calculated that compensates for at least a portion of the frictional force generated in the motor 543. In this embodiment, the state compensation value V s This consists of a compensation value calculated by the inertia compensator 281, a compensation value calculated by the viscosity compensator 282, and a compensation value calculated by the friction compensator 283. The compensation value calculated by the inertia compensator 281, the compensation value calculated by the viscosity compensator 282, and the compensation value calculated by the friction compensator 283 are output to the adder AD1, and the corrected torque T f Input torque T after correction r It will be added to.

[0080] The vibration torque generation unit 290 generates vibration torque T based on the command signal CS from the vehicle. w This generates the vibration torque T based on the command signal CS from the vehicle. In other words, the control method for the controlled object 560 is based on the command signal CS from the vehicle. wThis includes generating a command signal CS, which is a signal input to the control device 100 from a Lane Departure Warning System (LDWS) (not shown) mounted on the vehicle. When the Lane Departure Warning System determines that the vehicle is about to deviate from its lane based on an imaging device that images the road surface, it sends a vibration torque T to the vibration torque generation unit 290. w A command signal CS is sent to instruct the generation of the vibration torque T generated by the vibration torque generation unit 290. w This is input to the gain adjustment unit 291.

[0081] Vibration Torque T w It has a predetermined amplitude and a predetermined frequency f w This is a torque that vibrates at a predetermined frequency f. In this embodiment, the predetermined frequency f w The value of is determined within the range of the lower limit f3a and the upper limit f3b shown in Figure 6. The lower limit f3a is, for example, 10 Hz. The upper limit f3b is, for example, 30 Hz. In other words, the given frequency f w For example, the frequency is between 10 Hz and 30 Hz. As shown in Figure 6, the predetermined frequency f w The lower limit f3a and the predetermined frequency f w The upper limit f3b is higher than the first cutoff frequency Cf1 and lower than the second cutoff frequency Cf2. w The lower limit f3a and the predetermined frequency f w The upper limit f3b is higher than frequency f1a and lower than frequency f2a. For example, a given frequency f w The absolute value of the difference between and the first cutoff frequency Cf1 is the predetermined frequency f w The vibration torque T is smaller than the absolute value of the difference between it and the second cutoff frequency Cf2. w frequency f w The complementary sensitivity gain GT in this embodiment is 0.5 or more and 1 or less. In this embodiment, the vibration torque T w frequency f w The complementary sensitivity gain GT in this case is approximately 1. In the example in Figure 6, the vibration torque T w frequency f wThe complementary sensitivity gain GT is 1. The vibration torque T w frequency f w The complementary sensitivity gain GT in this case may be 0.95 or greater and less than 1.

[0082] The gain adjustment unit 291 controls the vibration torque T w The vibration torque gain K applied to it w Adjust the vibration torque T. w The vibration torque gain K applied to it w This includes adjusting the vehicle speed V and the vibration torque T. As shown in Figure 3, the gain adjustment unit 291 controls the vehicle speed V and vibration torque T. w And the estimated value E SAT And is input. As shown in Figure 8, the gain adjustment unit 291 has a gain calculation unit 291a and a multiplier 291b.

[0083] The gain calculation unit 291a receives an estimated value E SAT The vehicle speed V and are input. The gain calculation unit 291a calculates the estimated value E SAT and vibration torque gain K w Based on the gain information GI that shows the relationship, the estimated value E SAT The corresponding vibration torque gain K w The gain adjustment unit 291 calculates the estimated value E based on the gain information GI. SAT The corresponding vibration torque gain K w This calculates the vibration torque gain K. w Adjusting the gain information GI gives an estimated value E SAT The corresponding vibration torque gain K w This includes calculating [the value].

[0084] Figure 9 is a graph showing an example of gain information GI. In Figure 9, the horizontal axis represents the estimated value E. SAT The vertical axis represents the vibration torque gain K. w As shown in Figure 9, the estimated value E shown by the gain information GI of this embodiment SAT and vibration torque gain K w The relationship is the estimated value E SATIn contrast to vibration torque gain K w The relationship is logarithmically proportional. Estimated value E SAT The larger the vibration torque gain K, the greater the vibration torque gain. w This increases. In other words, the gain adjustment unit 291 adjusts the estimated value E SAT The larger the vibration torque gain K, the greater the vibration torque gain. w The vibration torque gain K is increased by the gain adjustment unit 291. In other words, the vibration torque gain K is increased by the gain adjustment unit 291. w Adjusting the estimated value E SAT The larger the vibration torque gain K, the greater the vibration torque gain. w This includes making it larger.

[0085] Gain information GI is the self-aligning torque T SAT and Base Assist Gain K ass It is determined based on the relationship with the gain information GI, which is an estimated value E. SAT Vibration torque gain K w The waveform is self-aligning torque T SAT Base assist gain K ass The waveform will have a similar shape to the self-aligning torque T. SAT and Base Assist Gain K ass The relationship is with self-aligning torque T SAT Base assist gain K ass The relationship is logarithmically proportional. Self-aligning torque T SAT The larger the base assist gain K, the greater the base assist gain. ass It gets bigger.

[0086] In this embodiment, multiple gain information GIs are provided according to the vehicle speed V. Figure 9 illustrates the gain information GI when the vehicle speed V is value V1, the gain information GI when the vehicle speed V is value V2, and the gain information GI when the vehicle speed V is value V3. Value V2 is greater than value V1. Value V3 is greater than value V2. The vibration torque gain K in gain information GI2 when the vehicle speed V is value V2. w The value of is the vibration torque gain K in gain information GI1 when the vehicle speed V is value V1. wIt is smaller than the value of . Vibration torque gain K in gain information GI3 when vehicle speed V is value V3 w The value of is the vibration torque gain K in gain information GI2 when the vehicle speed V is value V2. w It is smaller than the value of . In other words, the larger the vehicle speed V, the greater the vibration torque gain K. w It becomes smaller.

[0087] The gain calculation unit 291a uses the gain information GI corresponding to the vehicle speed V to calculate the vibration torque gain K w The gain calculation unit 291a calculates the value V2 when the vehicle speed V is an estimated value E. SAT is value E SAT1 In this case, the estimated value E in gain information GI2 SAT is value E SAT1 The value K when this is the case w1 The vibration torque gain K w The gain adjustment unit 291 calculates the estimated value E based on the gain information GI corresponding to the current vehicle speed V among multiple gain information GI when the vehicle speeds V are different. SAT The corresponding vibration torque gain K w The vibration torque gain K is calculated in the gain adjustment unit 291. In other words, the vibration torque gain K is calculated in the gain adjustment unit 291. w Adjusting the vehicle speed V is done based on the gain information GI corresponding to the current vehicle speed V among multiple gain information GI when the vehicle speed V is different from each other, and estimates the value E SAT The corresponding vibration torque gain K w This includes calculating the following. In Figure 9, three gain information GIs corresponding to three different vehicle speeds V are shown, but the number of gain information GIs corresponding to different vehicle speeds V may be two or four or more.

[0088] As shown in Figure 8, the vibration torque gain K calculated in the gain calculation unit 291a w In multiplier 291b, the vibration torque T w This is applied to the multiplier 291b, which then outputs the vibration torque gain K. w Vibration torque T when multiplied by wAs such, vibration torque T wa The following is output. As shown in Figure 3, the vibration torque T output from the gain adjustment unit 291 is output. wa This is input to adder AD4. Vibration torque T wa In the adder AD4, the input torque T output from the assist control unit 210 r It is added to the input torque T. r The vibration torque gain K w The applied vibration torque T wa It will be added.

[0089] Next, the control by the model-following control unit 230 will be described in more detail. The model-following control unit 230 controls the controlled object 560 using the inverse model of the nominal model it has as an internal model, i.e., the inverse nominal model 231. In this embodiment, the feedback loop created by the model-following control unit 230 makes it possible to compensate for torque ripple and other factors that depend on the angular velocity ω of the motor 543.

[0090] The model-following control unit 230 is structurally similar to a conventional disturbance estimator (disturbance observer), but its intended function and effect are different. Conventional disturbance estimators estimate disturbance torque by using an inverse plant model, which is an internal model, that closely resembles the controlled object 560, and reduce the effect of disturbances by pre-adding or subtracting the disturbance torque.

[0091] In this embodiment, the control by the model-following control unit 230 is performed by a feedback loop so that the transfer function P(s) of the controlled object 560 is the transfer function P of the nominal model which has an internal model. nThe effect of being constrained by (s) is utilized. For example, if the nominal model is defined so that there is no torque ripple, the transfer function P(s) of the controlled object 560 is constrained to the characteristic of having no torque ripple by model following control, and as a result, torque ripple can be reduced by applying torque ripple compensation. Alternatively, by making the nominal model a low-inertia model and constraining the controlled object 560 with the nominal model, the controlled object 560 can be treated as a low-inertia model. Alternatively, by making the nominal model a low-viscosity model and constraining the controlled object 560 with the nominal model, the controlled object 560 can be treated as a low-viscosity model. By executing model following control by the model following control unit 230, in addition to torque ripple compensation for the motor 543, for example, lost torque compensation or motor inertia compensation is performed. In the above-mentioned equations (4) and (5), J n and B n By appropriately setting this, the desired frequency characteristics can be imparted to the transfer function P(s) of the controlled object 560.

[0092] Transfer function P(s) of the controlled object 560 and the transfer function P of the nominal model n When the modeling error with (s) is Δ(s), the transfer function P(s) of the controlled object 560 can be expressed, for example, by the following equation (6).

[0093]

number

[0094] The gain characteristics of the transfer function P(s) of the controlled object 560 have peaks at, for example, two frequency values. The modeling error Δ(s) appears, for example, near the higher frequency peak of the two peaks in the gain characteristics of the controlled object 560. Therefore, as shown in Figure 6, the reciprocal of the modeling error Δ(s), 1 / Δ(s), has a bottom in the relatively high-frequency region. In Figure 6, the modeling error Δ(s) is shown as an absolute value. As the modeling error Δ(s) increases, the transfer function P(s) of the controlled object 560 and the transfer function P of the nominal model nThe deviation from (s) becomes large, and the control of the controlled object 560 using the nominal model by the model-following 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 approximately 1, and the controlled object 560 is constrained to the nominal model, thereby enabling stable and suitable control of the controlled object 560. Transfer function P of the nominal model n (s) J n and B n By adjusting the modeling error Δ(s), the frequency characteristics of the modeling error Δ(s) are adjusted. By adjusting the first cutoff frequency Cf1 and the second cutoff frequency Cf2, the frequency band in which the gain of the complementary sensitivity function T(s) is approximately 1 is adjusted. This allows the gain of the complementary sensitivity function T(s) to be approximately 1 in the frequency band in which the modeling error Δ(s) is small.

[0095] In Figure 6, 1 / Δ(s) is relatively high in the frequency band below the second cutoff frequency Cf2, and decreases sharply in the frequency band above the second cutoff frequency Cf2. Model-following control, which constrains the controlled object 560 to the nominal model, can be performed stably, for example, in the range where 1 / Δ(s) is greater than 1, i.e., greater than 0 dB. Therefore, as shown in Figure 6, by adjusting 1 / Δ(s) to be greater than 1 in the frequency band where the gain of the complementary sensitivity function T(s) is approximately 1, the controlled object 560 can be stably and suitably controlled by constraining it to the nominal model when the gain of the complementary sensitivity function T(s) is approximately 1.

[0096] For example, in order to broaden the frequency band over which the controlled object 560 can be stably and suitably controlled while constrained to the nominal model, the second cutoff frequency Cf2 should be increased within the range where 1 / Δ(s) is not less than 1, that is, within the frequency band lower than the frequency at which the curve representing 1 / Δ(s) in Figure 6 intersects with the horizontal axis. However, if the second cutoff frequency Cf2 is increased too much, the gain of the complementary sensitivity function T(s) may remain relatively high in the frequency band above the second cutoff frequency Cf2, even though 1 / Δ(s) has decreased, which may lead to unstable control. In contrast, in this embodiment, since the order of the second filter 232b, which is a low-pass filter, is set to the third order or higher, the gain of the complementary sensitivity function T(s) can be sharply reduced in the region where the frequency is higher than the second cutoff frequency Cf2. This allows the gain of the complementary sensitivity function T(s) to be quickly reduced in frequency bands higher than the second cutoff frequency Cf2, even when the second cutoff frequency Cf2 is set relatively high, thereby suppressing instability in the control of the controlled device 560.

[0097] The robust stability of the model-following control unit 230 is guaranteed when the small gain theorem shown in equation (7) below holds between the complementary sensitivity function T(s) and the modeling error Δ(s).

[0098]

number

[0099] As described above, in order to perform model following control using a nominal model in the model following control unit 230, the complementary sensitivity gain GT of the complementary sensitivity function T(s) only needs to be approximately 1. However, considering robust stability, it is necessary to satisfy equation (7) above. As can be understood from this, it is not possible to reconcile making the complementary sensitivity gain GT approximately 1 in all frequency bands with satisfying equation (7), and thus the suppression of disturbances by the model following control unit 230 and robust stability are incompatible.

[0100] As shown in Figure 6, even 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) becomes less than 1. In the region where the complementary sensitivity gain GT of the complementary sensitivity function T(s) becomes less than 1, the assist control unit 210 controls the input torque T r The controlled object 560 is controlled by performing this control. In the high-frequency region FA2, where the frequency is higher than the second cutoff frequency Cf2, the complementary sensitivity gain GT of the complementary sensitivity function T(s) is greatly reduced, and the correction torque T from the model following control unit 230 is reduced. f This results in a state where 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 corrected torque T f This is fed back to the input of the controlled device 560. In the low-frequency region FA1, the compensation value generated in the assist adjustment unit 270 described above is fed back to the input of the controlled device 560 according to the complementary sensitivity gain GT of the complementary sensitivity function T(s). In this embodiment, the value of the complementary sensitivity gain GT in the low-frequency region FA1 is 0.5 or more. In this embodiment, the steady-state gain T(0) of the complementary sensitivity function T(s) is 0.5.

[0101] Input Torque T r Vibration torque T applied wa From steering torque T h The transfer function F(s) up to that point can be expressed, for example, by the following equation (8).

[0102]

number

[0103] To address the above problem, according to this embodiment, the control device 100 of the electric power steering device 1000 controls the input torque T r Correction torque T to compensate for f A model-following control unit 230 generates vibration torque T based on a nominal model based on the configuration of the controlled object 560, and a vibration torque T based on a command signal CS from the vehicle. w A vibration torque generating unit 290 that generates vibration torque T w The vibration torque gain K applied to it w It includes a gain adjustment unit 291 for adjusting the input torque T. r The vibration torque gain K w The applied vibration torque T wa The self-aligning torque T applied to the controlled object 560 is added. The model following control unit 230 controls the self-aligning torque T applied to the controlled object 560. SAT Estimated value ESAT The model following control unit 230 calculates the estimated value E. SAT Based on the corrected torque T f The gain adjustment unit 291 generates the estimated value E SAT The larger the vibration torque gain K, the greater the vibration torque gain. w To increase the input torque T. In other words, the control method for controlling the controlled object 560 is to increase the input torque T. r Correction torque T to compensate for f This involves performing model-following control, which generates the vibration torque T based on a nominal model based on the configuration of the controlled object 560, and based on the command signal CS from the vehicle. w To generate vibration torque T w The vibration torque gain K applied to it w Adjusting the input torque T r The vibration torque gain K w The applied vibration torque T wa The addition of the self-aligning torque T applied to the controlled object 560 is included. SAT Estimated value E SAT To calculate the estimated value E SAT Based on the corrected torque T f This includes generating and generating vibration torque gain K. w Adjusting the estimated value E SAT The larger the vibration torque gain K, the greater the vibration torque gain. w This includes making it larger.

[0104] Therefore, self-aligning torque T SAT Estimated value E SAT The larger the vibration torque T, the greater the vibration torque T. wa This allows for a significant increase in self-aligning torque T. SAT The base assist gain K increases ass As it increases, the vibration torque T wa This allows for a larger base assist gain K. ass The vibration torque T increases wa From steering torque T hEven if the gain of the transfer function F(s) up to this point decreases, the steering torque T h The vibration torque T that appears wa This suppresses changes in size. Therefore, the self-aligning torque T SAT Even if the vibration torque T changes, the vibration torque T transmitted to the helmsman remains unchanged. wa This suppresses changes in the magnitude of the vibration torque T. This means that no matter how the driver steers the vehicle when it is about to deviate from its lane, the vibration torque T transmitted to the driver is suppressed. wa This suppresses changes in the magnitude of the vibration torque T. wa This makes it easier to accurately grasp the information transmitted. Furthermore, because the controlled object 560 can be constrained to the nominal model by model following control, the base assist gain K in the assist control unit 210 is increased compared to the case without model following control. ass This allows for an overall reduction in the gain of the transfer function F(s), thereby suppressing the decrease in vibration torque T transmitted to the helmsman. w The reduction in vibration torque T transmitted to the helmsman is suppressed. wa frequency f w This frequency range is considered to have little effect on the steering of the vehicle performed by the driver. In this frequency range, disturbances are compensated for by model following control. Therefore, by executing model following control, disturbances having frequencies in this frequency range are compensated for, and the vibration torque T wa frequency f w This suppresses the transmission of disturbances with a frequency of similar magnitude to the helmsman to the steering wheel. As a result, the vibration torque T transmitted to the steering wheel is reduced. wa This can suppress interference from external disturbances. Therefore, the vibration torque T wa This makes it easier for the steering wheel operator to understand the steering behavior. Furthermore, when performing model-following control, it is necessary to estimate disturbances. Therefore, the self-aligning torque T is calculated using the estimated disturbances in model-following control. SAT Estimated value E SAT By obtaining the base assist gain K assThere is no need to separately obtain the value, and it is possible to suppress an increase in the computational load of the control device 100.

[0105] According to the present embodiment, the model following control unit 230 has an inverse nominal model 231 which is an inverse model of the nominal model and to which the output from the control target 560 is input, and the vibration torque T from the output of the inverse nominal model 231 wa is added, and then the input torque T r is subtracted, that is, the difference, namely the differential torque T a is used to calculate the estimated value E SAT of the self-aligning torque T SAT In other words, the model following control calculates the estimated value E wa based on the difference obtained by subtracting the vibration torque T r added to the input torque T SAT after being added. Therefore, based on the difference between the input and output of the control target 560, the estimated value E SAT of the self-aligning torque T SAT can be generated. As a result, the model following control unit 230 can accurately calculate the estimated value E SAT of the self-aligning torque T SAT Therefore, it is possible to more easily and accurately change the vibration torque gain K SAT in accordance with the change in the self-aligning torque T w Therefore, it is possible to further suppress a change in the magnitude of the vibration torque T wa transmitted to the driver.

[0106] According to the present embodiment, the gain adjustment unit 291 calculates the vibration torque gain K SAT corresponding to the estimated value E w based on the gain information GI indicating the relationship between the estimated value E SAT and the vibration torque gain K w In other words, adjusting the vibration torque gain K w is based on the gain information GI indicating the relationship between the estimated value E SAT and the vibration torque gain K w and is based on the estimated value ESAT The corresponding vibration torque gain K w This includes calculating the vibration torque gain K based on the gain information GI. w It can be easily calculated. In addition, the estimated value E shown by the gain information GI can be easily calculated. SAT and vibration torque gain K w The relationship is with the self-aligning torque T SAT and Base Assist Gain K ass By establishing a relationship similar to that of the previous relationship, the vibration torque gain K w Base assist gain K ass It can be changed in the same way that the vibration torque T changes. wa The size of the base assist gain K ass It can be precisely adjusted in response to changes in the vibration torque T transmitted to the helmsman. wa This can further suppress changes in size.

[0107] According to this embodiment, the gain adjustment unit 291 estimates a value E based on the gain information GI corresponding to the current vehicle speed among a plurality of gain information GIs when the vehicle speeds are different from each other. SAT The corresponding vibration torque gain K w This calculates the vibration torque gain K. w Adjusting this involves estimating the value E based on the gain information GI corresponding to the current vehicle speed among multiple gain information GIs when the vehicle speeds are different from each other. SAT The corresponding vibration torque gain K w This includes calculating the base assist gain K which changes in accordance with the change in vehicle speed V. ass In accordance with the vibration torque gain K w This allows the vibration torque T to be changed. wa The size of the base assist gain K ass It can be changed with greater precision in response to the changes in the vibration torque T transmitted to the helmsman. wa This can further suppress changes in size.

[0108] According to this embodiment, the estimated value E indicated by the gain information GI SAT and the vibration torque gain K w have a relationship such that the vibration torque gain K SAT is in a logarithmic proportional relationship with respect to the estimated value E w . By using such gain information GI as the gain information GI, the relationship between the estimated value E SAT indicated by the gain information GI and the vibration torque gain K w is made easier to be the same as the relationship between the self-aligning torque T SAT and the base assist gain K ass . As a result, by using the gain information GI, the vibration torque gain K ass can be calculated more accurately in accordance with the change in the base assist gain K w . Therefore, it is possible to further suppress the change in the magnitude of the vibration torque T wa transmitted to the driver.

[0109] According to this embodiment, the complementary sensitivity gain GT at the frequency f wa of the vibration torque T w is 0.5 or more and 1 or less. Therefore, at the frequency f wa of the vibration torque T w , more than half of the disturbance can be compensated by the model following control. As a result, a disturbance having the frequency f w can be compensated to a certain extent or more by the model following control, and it is possible to suitably suppress the vibration torque T wa transmitted to the driver from being inhibited by a disturbance having the frequency f w . In this embodiment, the complementary sensitivity gain GT at the frequency f wa of the vibration torque T w is approximately 1. Therefore, at the frequency f wa of the vibration torque T w , all or almost all of the disturbance can be compensated by the model following control. As a result, it is possible to more suitably suppress the vibration torque T wa transmitted to the driver from being inhibited by a disturbance having the frequency f w .

[0110] At least some of the functions of each component of the control device 100 described above may be implemented by hardware including circuit sections such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit), or by the cooperation of software and hardware. The storage unit that stores the program causing the processor 200 of the control device 100, which is a computer, to execute the control method described above, is implemented by a storage medium such as RAM (Random Access Memory), ROM (Read Only Memory), HDD (hard disk drive), and flash memory. The storage unit is not particularly limited as long as it can store the program causing the computer to execute the control method described above, and may be a microcomputer or a disk medium such as a CD-ROM. The storage unit may be provided separately from the control device 100. In this case, the control device 100 may communicate with the storage unit by wired communication or wireless communication and execute the program stored in the storage unit.

[0111] The present invention is not limited to the embodiments described above, and other configurations and methods may be adopted within the scope of the technical idea of ​​the present invention. The model following control unit may calculate the estimated value of the self-aligning torque in any way. The gain adjustment unit may change the vibration torque gain with respect to the estimated value of the self-aligning torque in any way, provided that the vibration torque gain increases as the estimated value of the self-aligning torque increases. The estimated value of the self-aligning torque may be input to the gain adjustment unit after being filtered. The vibration torque gain adjusted by the gain adjustment unit may be applied to the vibration torque generated in the vibration torque generation unit after being filtered.

[0112] Furthermore, this technology can be configured as follows: [1] A control device for controlling the portion of an electric power steering system mounted on a vehicle, which includes an input shaft to which a steering wheel operated by a driver is connected, an output shaft connected to the input shaft via a torsion bar, and a motor connected to the output shaft, the control device comprising: an assist control unit that generates an input torque input to the control device based on the torsion bar torque generated in the torsion bar; a model following control unit that generates a correction torque to correct the input torque based on a nominal model based on the configuration of the control device; a vibration torque generation unit that generates a vibration torque based on a command signal from the vehicle; and a control device applied to the vibration torque A control device comprising: a gain adjustment unit for adjusting the vibration torque gain, wherein the vibration torque multiplied by the vibration torque gain is added to the input torque, the model following control unit is configured such that the transfer function of the controlled object is constrained to the transfer function of the nominal model in a frequency band where the complementary sensitivity gain, which is the gain in the gain characteristic of the complementary sensitivity function for the modeling error between the controlled object and the nominal model, is approximately 1, calculates an estimated value of the self-aligning torque applied to the controlled object, and generates the correction torque based on the estimated value, and the gain adjustment unit increases the vibration torque gain as the estimated value increases. [2] The control device according to [1], wherein the model following control unit has an inverse nominal model which is the inverse model of the nominal model and to which the output from the controlled object is input, and calculates the estimated value based on the difference obtained by subtracting the input torque after the vibration torque has been added from the output from the inverse nominal model. [3] The control device according to [1] or [2], wherein the gain adjustment unit calculates the vibration torque gain corresponding to the estimated value based on gain information showing the relationship between the estimated value and the vibration torque gain. [4] The control device according to [3], wherein the gain adjustment unit calculates the vibration torque gain corresponding to the estimated value based on the gain information corresponding to the current vehicle speed from among a plurality of gain pieces of information when the vehicle speeds are different from each other. [5] The control device according to [3] or [4], wherein the relationship between the estimated value indicated by the gain information and the vibration torque gain is logarithmically proportional to the estimated value. [6] The control device according to any one of [1] to [5], wherein the complementary sensitivity gain at the frequency of the vibration torque is 0.5 or more and 1 or less. [7] The control device according to [6], wherein the complementary sensitivity gain at the frequency of the vibration torque is approximately 1. A motor device comprising a control device described in any one of items [1] to [7] [8] and the motor. An electric power steering device comprising the motor device described in [9] [8] and a steering mechanism having the input shaft, the output shaft, and the torsion bar.

[10] A control method for controlling the portion of an electric power steering system mounted on a vehicle, which includes an input shaft to which a steering wheel operated by a driver is connected, an output shaft connected to the input shaft via a torsion bar, and a motor connected to the output shaft, the control method comprising: generating an input torque input to the control object based on the torsion bar torque generated in the torsion bar; performing model following control to generate a correction torque to correct the input torque based on a nominal model based on the configuration of the control object; generating a vibration torque based on a command signal from the vehicle; adjusting the vibration torque gain applied to the vibration torque; and the input A control method comprising: adding the vibration torque multiplied by the vibration torque gain to the force torque; and constraining the transfer function of the controlled object to the transfer function of the nominal model by model following control in a frequency band where the complementary sensitivity gain, which is the gain in the gain characteristic of the complementary sensitivity function for the modeling error between the controlled object and the nominal model, is approximately 1; the model following control comprises: calculating an estimated value of the self-aligning torque applied to the controlled object; and generating the correction torque based on the estimated value; and adjusting the vibration torque gain comprises increasing the vibration torque gain as the estimated value increases.

[11] The control method according to

[10] , wherein the model following control is an inverse model of the nominal model, and the output from the controlled object is input to an inverse nominal model, and the estimated value is calculated based on the difference obtained by subtracting the input torque after the vibration torque has been added to the output from the inverse nominal model.

[12] The control method according to

[10] or

[11] , wherein adjusting the vibration torque gain includes calculating the vibration torque gain corresponding to the estimated value based on gain information showing the relationship between the estimated value and the vibration torque gain.

[13] The control method according to

[12] , wherein adjusting the vibration torque gain includes calculating the vibration torque gain corresponding to the estimated value based on the gain information corresponding to the current vehicle speed among a plurality of gain pieces of information for which the vehicle speeds are different from each other.

[14] The control method according to

[12] or

[13] , wherein the relationship between the estimated value indicated by the gain information and the vibration torque gain is such that the vibration torque gain is logarithmically proportional to the estimated value.

[15] The control method according to any one of

[10] to

[14] , wherein the complementary sensitivity gain at the frequency of the vibration torque is 0.5 or more and 1 or less.

[16] The control method according to

[15] , wherein the complementary sensitivity gain at the frequency of the vibration torque is approximately 1.

[17] A program that causes a computer to execute one of the control methods described in any one of the items

[10] through

[16] .

[0113] The configurations and methods described herein can be combined as appropriate, within the bounds of non-inconsistency. [Explanation of Symbols]

[0114] 100...Control device, 100a...Motor device, 210...Assist control unit, 230...Model following control unit, 231...Inverse nominal model, 290...Vibration torque generation unit, 291...Gain adjustment unit, 521...Steering wheel, 524a...Input shaft, 524b...Output shaft, 530...Steering mechanism, 543...Motor, 546...Torsion bar, 560...Controlled object, 1000...Electric power steering device, CS...Command signal, E SAT ...Estimated value, GI, GI1, GI2, GI3...Gain information, GT...Complementary sensitivity gain, K w ...vibration torque gain, T(s)... complementary sensitivity function, T f ...correction torque, T h ...Steering torque (torsion bar torque), T r ...input torque, T SAT ...Self-aligning torque, T w ,Twa ...vibration torque

Claims

1. A control device for controlling the portion of an electric power steering system mounted on a vehicle, which includes an input shaft to which a steering wheel operated by the driver is connected, an output shaft connected to the input shaft via a torsion bar, and a motor connected to the output shaft, wherein the control device controls the portion including the motor, An assist control unit that generates an input torque to the controlled object based on the torsion bar torque generated in the torsion bar, A model-following control unit generates a correction torque for correcting the input torque based on a nominal model based on the configuration of the controlled object, A vibration torque generation unit that generates vibration torque based on a command signal from the vehicle, A gain adjustment unit for adjusting the vibration torque gain applied to the aforementioned vibration torque, Equipped with, The vibration torque, multiplied by the vibration torque gain, is added to the input torque. The aforementioned model following control unit is: In a frequency band where the complementary sensitivity gain, which is the gain in the gain characteristic of the complementary sensitivity function with respect to the modeling error between the controlled object and the nominal model, is approximately 1, the transfer function of the controlled object is configured to be constrained to the transfer function of the nominal model. The estimated value of the self-aligning torque applied to the controlled object is calculated, and, Based on the estimated value, the corrected torque is generated. The gain adjustment unit is a control device that increases the vibration torque gain as the estimated value increases.

2. The control device according to claim 1, wherein the model following control unit has an inverse nominal model which is the inverse model of the nominal model and to which the output from the controlled object is input, and calculates the estimated value based on the difference obtained by subtracting the input torque after the vibration torque has been added from the output from the inverse nominal model.

3. The control device according to claim 1, wherein the gain adjustment unit calculates the vibration torque gain corresponding to the estimated value based on gain information showing the relationship between the estimated value and the vibration torque gain.

4. The control device according to claim 3, wherein the gain adjustment unit calculates the vibration torque gain corresponding to the estimated value based on the gain information corresponding to the current vehicle speed from among a plurality of gain pieces of information when the vehicle speeds are different from each other.

5. The control device according to claim 3, wherein the relationship between the estimated value indicated by the gain information and the vibration torque gain is such that the vibration torque gain is logarithmically proportional to the estimated value.

6. The control device according to claim 1, wherein the complementary sensitivity gain at the frequency of the vibration torque is 0.5 or more and 1 or less.

7. The control device according to claim 6, wherein the complementary sensitivity gain at the frequency of the vibration torque is approximately 1.

8. A control device according to any one of claims 1 to 7, The motor and, A motor device equipped with the following features.

9. The motor device according to claim 8, A steering mechanism having the input shaft, the output shaft, and the torsion bar, An electric power steering system equipped with this system.

10. A control method for controlling the portion of an electric power steering system mounted on a vehicle, which includes an input shaft to which a steering wheel operated by the driver is connected, an output shaft connected to the input shaft via a torsion bar, and a motor connected to the output shaft, wherein the control method controls the portion including the motor, The input torque input to the controlled object is generated based on the torsion bar torque generated in the torsion bar, This involves performing model-following control to generate a correction torque for correcting the input torque based on a nominal model based on the configuration of the controlled object, To generate vibration torque based on the command signal from the aforementioned vehicle, Adjusting the vibration torque gain applied to the aforementioned vibration torque, The input torque is increased by the vibration torque multiplied by the vibration torque gain, The model-following control constrains the transfer function of the controlled object to the transfer function of the nominal model in a frequency band where the complementary sensitivity gain, which is the gain in the gain characteristic of the complementary sensitivity function with respect to the modeling error between the controlled object and the nominal model, is approximately 1. Includes, The aforementioned model following control is, To calculate an estimated value of the self-aligning torque applied to the controlled object, The corrected torque is generated based on the estimated value, Includes, A control method that includes adjusting the vibration torque gain by increasing the vibration torque gain as the estimated value increases.

11. The control method according to claim 10, wherein the model following control includes calculating the estimated value based on the difference obtained by subtracting the input torque after the vibration torque has been added from the output of an inverse nominal model, which is an inverse model of the nominal model and to which the output from the controlled object is input.

12. The control method according to claim 10, wherein adjusting the vibration torque gain includes calculating the vibration torque gain corresponding to the estimated value based on gain information showing the relationship between the estimated value and the vibration torque gain.

13. The control method according to claim 12, wherein adjusting the vibration torque gain includes calculating the vibration torque gain corresponding to the estimated value based on the gain information corresponding to the current vehicle speed among a plurality of gain pieces of information when the vehicle speeds are different from each other.

14. The control method according to claim 12, wherein the relationship between the estimated value indicated by the gain information and the vibration torque gain is such that the vibration torque gain is logarithmically proportional to the estimated value.

15. The control method according to claim 10, wherein the complementary sensitivity gain at the frequency of the vibration torque is 0.5 or more and 1 or less.

16. The control method according to claim 15, wherein the complementary sensitivity gain at the frequency of the vibration torque is approximately 1.

17. A program that causes a computer to execute the control method described in any one of claims 10 to 16.

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