Control device, control system, electric power steering device, and vehicle

Abstract

In the present invention, with respect to an input signal including at least one of a first control signal output from a first controller and a second control signal output from a second controller, at least one of the gain and the phase is adjusted to output a filtered signal in a frequency band including a frequency that can be oscillated when a composite signal obtained by synthesizing the first control signal and the second control signal is used as a command value of an output torque, whether or not both the first controller and the second controller function is determined on the basis of at least one of the traveling state of the vehicle, the steering state, and the execution state of automatic steering control, either the filtered signal or the input signal is determined as a switched output signal, and the command value of the output torque is determined on the basis of at least the switched output signal.

Description

Control device, control system, electric power steering device and vehicle

[0001] The present disclosure relates to a control device, a control system, an electric power steering device, and a vehicle.

[0002] An electric power steering device controls a motor to output an output torque corresponding to the steering torque applied to the steering wheel by the driver. The output torque is also called an assist torque or steering assist force. In controlling the motor, the electric power steering device determines a command value for the output torque so that it is approximately proportional to the steering torque. The electric power steering device reduces the driver's steering amount by increasing the torque proportional gain. The torque proportional gain corresponds to the ratio of the output torque to the steering torque. Generally, the greater the torque proportional gain, the more likely vibrations occur in the control system. In electric power steering devices, the command value for the output torque is sometimes determined as a composite value obtained by combining the base torque, which is a command value based on base control, and the compensation torque, which is a command value based on compensation control. Base control is a control method aimed at suppressing vibrations in the control system. Compensation control is a control method aimed at improving steering feel and coordinating with autonomous driving.

[0003] For example, the control device of an electric power steering device described in Patent Document 1 has a derivation unit that derives a command value including a vibration suppression component from the steering torque, an extraction unit that extracts a command value corresponding to the vibration suppression component from the derived command value, an adjustment unit that adjusts the derived command value depending on the operating state of the function of the second control unit, and a synthesis unit that generates a first command value by synthesizing the extracted command value with the adjusted command value.

[0004] Patent No. 7060182

[0005] In recent years, requirements for steering feel have become more diverse. Furthermore, the configuration of control devices has tended to become more complex, such as through coordination between base control and automatic driving functions. When multiple controllers are operated in combination, even under conditions where each controller operates without problems individually, the controllers may interfere with each other, resulting in unstable control. In response to this issue, the electric power steering device described in Patent Document 1 adjusts the blending ratio of command values ​​for base control and automatic driving control according to operating conditions. However, in some frequency bands, the base control command value is output at a predetermined ratio rather than the adjusted ratio, and the automatic driving control command value is output at the adjusted ratio. Therefore, the vibration suppression effect of the base control is not reduced even under operating conditions where the ratio of automatic driving control is high. On the other hand, in those frequency bands, some components of the command value from the base control are effective regardless of the operating conditions, leaving the possibility of control instability due to interference between the base control and automatic driving control. Furthermore, adjusting the command values ​​may prevent the expected effects of each control from being achieved.

[0006] A first aspect of the present disclosure has been made to solve the above-described problems, and is a control device that controls an output torque of a motor based on a running state or a steering state of a vehicle, the control device comprising: a first controller that outputs a first control signal in response to the steering state; a second controller that outputs a second control signal; a frequency characteristic adjuster that adjusts at least one of gain and phase in a frequency band that includes a frequency that can oscillate when a combined signal obtained by combining the first control signal and the second control signal is used as the command value for the output torque, for an input signal that includes at least one of the first control signal and the second control signal, and outputs a filtered signal; and an output torque setter that sets either the filtered signal or the input signal as a switched output signal depending on whether both the first controller and the second controller are functioning, and sets the command value for the output torque based on at least the switched output signal, wherein the output torque setter sets the switched output signal based on at least one of the running state of the vehicle, the steering state, and an execution state of automatic steering control.

[0007] A second aspect of the present disclosure may be a control system including the detector that detects the running state or steering state of the vehicle and the control device.

[0008] A third aspect of the present disclosure may be a control system including an automatic driving system having an automatic steering control function and the above-described control device.

[0009] A fourth aspect of the present disclosure may be an electric power steering device including the motor and the control device.

[0010] A fifth aspect of the present disclosure may be a vehicle including the electric power steering device described above.

[0011] According to the present disclosure, the performance of the first controller and the second controller can be further enhanced, and vibrations due to interference between the first control signal and the second control signal can be suppressed.

[0012] 1 is a diagram illustrating an example of a hardware configuration of an electric power steering device according to embodiment 1. FIG. 2 is a block diagram illustrating a first example of a configuration of a control device according to embodiment 1. FIG. 3 is a Bode plot illustrating a first example of transfer characteristics of a first controller and a second controller. FIG. 4 is a Bode plot illustrating a first example of open-loop characteristics of the control device. FIG. 5 is a Bode plot illustrating a transfer characteristic of a frequency characteristic adjuster according to embodiment 1. FIG. 6 is a Bode plot illustrating an open-loop characteristic of the control device according to embodiment 1. FIG. 7 is a block diagram illustrating a second example of a configuration of a control device according to embodiment 1. FIG. 8 is a block diagram illustrating a third example of a configuration of a control device according to embodiment 1. FIG. 9 is a block diagram illustrating an example of a configuration of a control device according to embodiment 2. FIG. 10 is a Bode plot illustrating a second example of transfer characteristics of a first controller and a second controller. FIG. 11 is a Bode plot illustrating a second example of open-loop characteristics of the control device. FIG. 12 is a Bode plot illustrating a transfer characteristic of a frequency characteristic adjuster according to embodiment 2. FIG. 13 is a block diagram illustrating an example of a configuration of a control device according to embodiment 3. FIG. 14 is a diagram illustrating an example of switching control of a filtered signal according to embodiment 4. FIG. 15 is a diagram illustrating an example of a system configuration according to an embodiment of the present disclosure.

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Elements common to or corresponding to each other in the drawings are denoted by the same reference numerals, and the description thereof will be incorporated unless otherwise specified. <Embodiment 1> FIG. 1 is a configuration diagram showing an example of the hardware configuration of an electric power steering device S1 according to Embodiment 1 of the present disclosure. The electric power steering device S1 includes a motor 1, a control device 2, a torque sensor 22, a motor rotation angle sensor 23, a steering wheel 51, a steering shaft 53, a rack and pinion gear 54, wheels 55, a tie rod 56, and a knuckle arm 57. The example of the hardware configuration illustrated in FIG. 1 is an example of a typical hardware configuration of the electric power steering device S1. An electric power steering device S1 having such a configuration can be mass-produced and installed in a vehicle.

[0014] The steering wheel 51 is a member that can be operated by the driver of the vehicle V1 ( FIG. 16 ) to apply a steering angle to the wheels 55. The steering wheel 51 rotates around the axial direction of a steering shaft 53 connected to the center of the steering wheel 51 in response to steering wheel operation. The steering shaft 53 includes an input shaft 53a and an output shaft 53b. The input shaft 53a is connected to the center of the steering wheel 51. The output shaft 53b is connected to the side of a rack and pinion gear 54. The input shaft 53a and the output shaft 53b are interconnected using a torsion bar (not shown). The torsion bar is disposed within the torque sensor 22 and passes through the steering shaft 53 in the axial direction. The torsion bar generates a twist in response to the steering torque applied to the steering wheel 51 by steering the steering wheel. The torque sensor 22 detects the steering torque acting on the steering shaft 53 based on the direction and amount of twist generated by steering the steering wheel.

[0015] The rack and pinion gear 54 is installed in the center of the tie rod 56 and changes the direction of the axle in response to the rotation of the steering shaft 53. Wheels 55 are attached to both ends of the tie rod 56 via knuckle arms 57. The wheels 55 are steered in response to the rotation of the steering shaft 53. In this application, the set of the steering wheel 51, steering shaft 53, and torsion bar may be referred to as the "steering" or "steering mechanism."

[0016] Next, the operation of the electric power steering device S1 will be described. Steering torque applied to the steering wheel 51 by steering operation is transmitted to a rack (not shown) provided in the rack-and-pinion gear 54 via the input shaft 53a, the torsion bar in the torque sensor 22, and the output shaft 53b. The rack is connected via knuckle arms 57 provided at both ends of a tie rod 56. Therefore, when steering torque is transmitted to the rack by steering operation, the rack pushes the wheels 55 on one side via the knuckle arm 57 provided at one end of the tie rod 56, and pulls the wheels 55 on the opposite side via the knuckle arm 57 provided at the other end of the tie rod 56. A steering angle is applied to each wheel 55. The vehicle V1 (FIG. 16) turns as the direction of the wheels 55 changes.

[0017] On the other hand, the output torque generated by the motor 1 is transmitted to the steering shaft 53 as a steering assist force, and is combined with the steering torque applied during steering to assist the rotation of the steering shaft 53. The motor 1 consumes power supplied from the control device 2 to rotate the rotary shaft. This rotation generates output torque. The motor 1 may be, for example, either an AC motor or a DC motor. The AC motor may be any type, such as a permanent magnet synchronous motor or an induction motor.

[0018] When the steering wheel 51 is steered by operating the handle as described above, a steering torque is applied to the torsion bar. The torsion bar generates a twist proportional to the steering torque applied to it. The torque sensor 22 detects the rotation angle generated by the twist as a torsion angle and converts the detected torsion angle into steering torque. The torque sensor 22 outputs a steering torque signal indicating the converted steering torque to the control device 2. The motor rotation angle sensor 23 is installed on the rotating shaft of the motor 1 and detects the rotation angle of the rotating shaft as the motor rotation angle. The motor rotation angle sensor 23 outputs a motor rotation angle signal indicating the detected motor rotation angle to the control device 2.

[0019] Next, a configuration example of the control device 2 will be described. Fig. 2 is a block diagram showing a functional configuration example of the control device according to this embodiment. The control device 2 includes a first controller 3, a second controller 4, a frequency characteristic adjuster 5, an output torque setter 9, a current controller 6, a drive circuit 7, and a current detector 8.

[0020] The first controller 3 refers to the steering torque as the steering state of the steering mechanism and generates a first control signal indicating a torque command value for assisting steering. The first controller 3 executes so-called base control. In the following description, the torque command value determined by the first controller 3 may be referred to as the "base torque." The first controller 3 alone can stably control the output torque of the motor 1. The first controller 3 determines the base torque so that it increases monotonically as the steering torque increases. The steering torque is transmitted by a steering torque signal input from the torque sensor 22. The first controller 3 outputs the generated first control signal to the frequency characteristic adjuster 5 and the output torque setter 9.

[0021] The second controller 4 references the steering torque and other reference information as the steering state and generates a second control signal indicating a torque command value for compensating for the steering state or driving state of the vehicle. That is, the second controller 4 performs so-called compensation control. In the following description, the torque command value determined by the second controller 4 may be referred to as "compensation torque." The second controller 4 performs, for example, friction compensation control. The friction compensation control is compensation control aimed at suppressing deterioration of steering feel due to friction elements generated in the steering mechanism. The second controller 4 references the vehicle speed as reference information indicating the vehicle's driving state and determines whether the vehicle speed exceeds a predetermined driving determination threshold. The vehicle speed is notified by a speedometer provided in the vehicle. When the second controller 4 determines that the vehicle speed exceeds the driving determination threshold, it determines a compensation torque based on fluctuations in the steering torque and generates a second control signal indicating the determined compensation torque. The driving determination threshold is a threshold for determining whether the vehicle is driving based on whether the vehicle speed is higher or lower.

[0022] The second controller 4 determines the compensation torque so that, for example, the gain increases as the steering speed increases and gradually approaches a maximum value. The maximum value may be constant regardless of the vehicle speed, or may vary depending on the vehicle speed. The second controller 4 may determine the compensation torque so that, for example, the gain monotonically decreases as the vehicle speed increases until it reaches a predetermined critical value above the travel determination threshold, and the compensation torque monotonically increases as the vehicle speed exceeds the critical value. The second controller 4 outputs the generated second control signal to the output torque setter 9. Note that, if the second controller 4 determines that the vehicle speed is less than the travel determination threshold, the second controller 4 does not generate the second control signal. In this case, the second controller 4 does not output the second control signal.

[0023] The frequency characteristic adjuster 5 adjusts the frequency characteristic of the base torque indicated in the first control signal input from the first controller 3, and outputs a filtered signal indicating the adjusted base torque to the output torque setter 9. The frequency characteristic adjuster 5 adjusts one or both of the gain and phase acting on the base torque so as to prevent oscillation in a frequency band including a frequency at which oscillation occurs when the sum obtained by adding the base torque indicated in the first control signal and the compensation torque indicated in the second control signal is set as the output torque command value. The interference between the base torque indicated in the first control signal and the compensation torque indicated in the second control signal and an example configuration of the frequency characteristic adjuster 5 will be described later.

[0024] The output torque setter 9 includes a switch 9s and an adder 9a. The switch 9s determines whether the conditions for operating the second controller 4 are met based on reference information input thereto. Depending on whether the conditions for functioning the second controller 4 are met, the switch 9s outputs either the filtered signal input from the frequency characteristic adjuster 5 or the first control signal input from the first controller 3 as a switched output signal to the adder 9a. In the above example, the vehicle speed is referenced as reference information, and whether the second controller 4 operates is determined based on whether the vehicle speed exceeds the travel determination threshold. Under conditions for functioning of the second controller 4, the filtered signal is output to the adder 9a. This avoids or suppresses oscillation due to interference with the compensation torque. Under conditions for not functioning of the second controller 4, the first control signal is output to the adder 9a. As a result, under conditions for no interference with the compensation torque, the control function of the first controller 3 is utilized.

[0025] The adder 9a determines, as the output torque command value, the sum obtained by adding the value of the post-switching output signal input from the switch 9s and the compensation torque value indicated in the second control signal input from the second controller 4. The adder 9a outputs an output signal indicating the determined output torque command value to the current controller 6.

[0026] The current controller 6 receives an output signal from the output torque setter 9 and a current detection signal from the current detector 8. The current controller 6 controls the current detection value indicated by the current detection signal so as to approximate as closely as possible a target current value corresponding to the output torque command value indicated by the output signal. The current controller 6 outputs an output command signal indicating a current value corresponding to the output torque command value to the drive circuit 7. The current controller 6 generates, for example, a PWM (Pulse Width Modulation) signal as the output command signal. The PWM signal represents a rectangular wave in which a period in which the voltage value is a high voltage value (H: High) and a period in which the voltage value is a low voltage value (L: Low) are repeated at regular intervals. The high voltage value corresponds to a voltage value significantly higher than a reference potential. The low voltage value corresponds to a voltage value that is not significantly different from the reference potential. The current controller 6 determines a duty ratio of the PWM signal so that the duty ratio is proportional to the output torque command value. The duty ratio corresponds to the ratio of the period in which the voltage value is a high voltage value per period.

[0027] The drive circuit 7 supplies the motor 1 with power instructed by the output command signal input from the current controller 6. The motor 1 generates an output torque corresponding to the power supplied from the drive circuit 7. When the output command signal is a PWM signal, the drive circuit 7 supplies AC power from a power source having a period and power instructed by the PWM signal. The drive circuit 7 includes, for example, an H-bridge circuit, an inverter circuit, or the like. According to the PWM signal, a voltage whose voltage value becomes a high voltage value at regular intervals is applied to the motor 1. The current detector 8 detects the current supplied from the drive circuit 7 to the motor 1. The current detector 8 outputs a current detection signal indicating the detected current value to the current controller 6.

[0028] Next, the control characteristics of the control device 2 illustrated in FIG. 2 will be described. FIG. 3 is a Bode diagram illustrating the transfer function of the first controller 3 and the transfer function of the second controller 4. FIG. 4 is a Bode diagram illustrating the open-loop characteristics of the control device 2. In FIGS. 3 and 4, the term "base control" refers to the first controller 3 or its control, and the term "compensation control" refers to the second controller 4 or its control. That is, the solid line indicates the open-loop characteristics of the control device 2 that applies the first controller 3 and obtains the base torque indicated in the first control signal as the command value for the output torque. The dashed line indicates the open-loop characteristics of the control device 2 that applies both the first controller 3 and the second controller 4 and obtains the sum of the base torque indicated in the first control signal and the compensation torque indicated in the second control signal as the command value for the output torque. The former is derived from the transfer function of the first controller 3 illustrated in FIG. 3. The latter is derived from the transfer function of the first controller 3 and the transfer function of the second controller 4 illustrated in FIG. 3. 3 and 4, the vertical axis in the upper row indicates gain, the vertical axis in the lower row indicates phase, and the horizontal axis in both the upper and lower rows indicates frequency.

[0029] According to FIG. 4 , when the first controller 3 is applied but the second controller 4 is not, the gain at the phase crossover frequency is approximately −3 dB, below 0 dB, and the phase lag at the gain crossover frequency is approximately 150 degrees, below 180 degrees. This indicates that both the gain margin and the phase margin are secured, resulting in a stable state and no instability in the open-loop characteristics. On the other hand, when both the first controller 3 and the second controller 4 are applied, the gain at the phase crossover frequency is approximately 2 dB, above 0 dB, and the phase lag at the gain crossover frequency is approximately 190 degrees, above 180 degrees. This indicates that neither the stability margin nor the phase margin is secured, resulting in instability in the open-loop characteristics. In this case, there is a possibility that the output torque will oscillate at the phase crossover frequency and the gain crossover frequency. Despite the application of the second controller 4, the generated vibrations may actually degrade the steering feel for the driver.

[0030] Generally, open-loop characteristics become unstable when the gain at the phase crossover frequency is 0 dB or greater or the phase lag at the gain crossover frequency is 180 degrees or greater. In the example of FIG. 4 , when both the first controller 3 and the second controller 4 are used, a large phase lag at the gain crossover frequency is the main cause of open-loop characteristics instability. Therefore, it is believed that stabilization can be achieved by adjusting the phase to advance at the gain crossover frequency and frequencies nearby. Therefore, the frequency characteristic adjuster 5 includes a phase-lead compensator having frequency characteristics that advance the phase in a frequency band within a predetermined range from the gain crossover frequency. FIG. 5 illustrates the transfer function of the frequency characteristic adjuster 5 including the phase-lead compensator. In addition to the open-loop characteristics illustrated in FIG. 4 , FIG. 6 further illustrates the open-loop characteristics of the control device 2, in which the sum of the filtered signal obtained by arranging the frequency characteristic adjuster 5 downstream of the first controller 3 and the compensation torque indicated by the second control signal is used as the output torque command value. This open-loop characteristic is indicated by a dashed-dotted line in FIG. 6 . The gain at the phase crossover frequency is −2 dB and less than 0 dB, and the phase delay at the gain crossover frequency is 170 degrees and less than 180 degrees. This shows that the open-loop characteristics that became unstable when the first controller 3 and the second controller 4 were applied can be improved by providing the frequency characteristic adjuster 5, ensuring a gain margin and a phase margin, thereby stabilizing the operation of the control device 2.

[0031] However, if phase compensation is always applied downstream of the first controller 3, the first controller 3 and the second controller 4 will not be able to perform to their full potential, even if the open-loop characteristics of the control device 2 are not destabilized. For example, the gain due to phase compensation, as illustrated in FIG. 5 , increases with increasing frequency. This may amplify high-frequency noise contained in the first control signal output from the first controller 3 and disrupt base control. The high-frequency noise may be caused by, for example, sensor noise. Therefore, in this embodiment, the control device 2 includes a switch 9s downstream of the frequency characteristic adjuster 5. When the second controller 4 is operating, the filtered signal output from the frequency characteristic adjuster 5 is output to the adder 9a and combined with the second control signal. When the second controller 4 is not operating, the first control signal output from the first controller 3 is output to the adder 9a, and the base torque is used as the command value for the output torque.

[0032] In the above example, the second controller 4 switches whether to enable its operation by referring to the vehicle's traveling state. That is, the second controller 4 is enabled when the vehicle speed exceeds the traveling determination threshold, and disabled when the vehicle speed is equal to or less than the traveling determination threshold. The switch 9s refers to the vehicle speed as reference information, and when the vehicle speed exceeds the traveling determination threshold, outputs the filtered signal output from the frequency characteristic adjuster 5 to the adder 9a as a switched output signal. When the vehicle speed is equal to or less than the traveling determination threshold, the switch 9s outputs the first control signal input to the frequency characteristic adjuster 5 to the adder 9a as a switched output signal.

[0033] As described above, the control device 2 includes a first controller 3 that outputs a first control signal and a second controller 4 that outputs a second control signal in response to the steering state of the vehicle. The control device 2 includes a frequency characteristic adjuster 5 that adjusts the phase of the first control signal and outputs the filtered signal in a frequency band including a frequency that can oscillate when the first control signal and the second control signal are combined to determine an output torque command value. The control device 2 includes an output torque setter 9 that selects one of the first control signal and the filtered signal as a switched output signal depending on whether both the first controller 3 and the second controller 4 are operating based on reference information related to the vehicle's running state, and determines the output torque command value based on the second control signal and the switched output signal. The frequency that can oscillate when the first control signal and the second control signal are combined to determine an output torque command value corresponds to a frequency at which the open-loop characteristics become unstable and the control device 2 oscillates. In other words, in this application, the term "frequency that can oscillate" is not necessarily limited to a frequency at which vibration actually occurs, but also includes a frequency at which vibration may occur. This frequency corresponds to the gain crossover frequency and phase crossover frequency illustrated in FIG. 4. According to this configuration, under conditions in which the first controller 3 functions and the second controller 4 does not function, the command value of the output torque is determined from the first control signal output from the first controller 3. Under conditions in which both the first controller 3 and the second controller 4 function, the command value of the output torque is determined by combining the second control signal and a filtered signal, which has been adjusted so that the first control signal output from the first controller 3 and the second control signal output from the second controller 4 do not interfere with each other and cause instability, from the frequency characteristic adjuster 5. Therefore, under conditions in which the second controller 4 does not function, the performance of the first controller 3 is exhibited, and stabilization can be achieved by utilizing the function of the frequency characteristic adjuster 5 when the first control signal and the second control signal interfere with each other and cause instability.

[0034] While FIG. 2 illustrates a control device 2 including a frequency characteristic adjuster 5 having a phase compensator function downstream of the first controller 3, the present invention is not limited to this. As illustrated in FIG. 7 , the control device 2 may include a frequency characteristic adjuster 5 downstream of the second controller 4, instead of the first controller 3. The frequency characteristic adjuster 5 outputs a filtered signal obtained by adjusting the phase of the second control signal, instead of the first control signal, to the output torque setter 9 in a frequency band including the frequency of vibration that may occur when a combined signal obtained by combining the first control signal and the second control signal is used as the output torque command value. The output torque setter 9 selects one of the second control signal and the filtered signal as the switched output signal based on reference information, and combines the first control signal and the switched output signal to determine the output torque command value. In this case, the same effects as those of the control device 2 illustrated in FIG. 2 can be obtained.

[0035] 8 , the control device 2 may include a first frequency characteristic adjuster 10 downstream of the first controller 3 and a second frequency characteristic adjuster 12 downstream of the second controller 4. The first frequency characteristic adjuster 10 and the second frequency characteristic adjuster 12 each have the same phase compensator function as the frequency characteristic adjuster 5. The output torque setter 9 may include a first switch 11, a second switch 13, and an adder 9a. The first frequency characteristic adjuster 10 outputs a first filtered signal to the output torque setter 9 by adjusting the phase of the first control signal in a frequency band including a frequency at which oscillation may occur when the first control signal and the second control signal are combined to determine an output torque command value. The second frequency characteristic adjuster 12 outputs a second filtered signal to the output torque setter 9 by adjusting the phase of the second control signal in a frequency band including a frequency at which vibration may occur when the first control signal and the second control signal are combined to determine an output torque command value. The first switch 11 selects one of the first control signal and the first filtered signal as a first switched output signal based on the reference information. The second switch 13 selects one of the second control signal and the second filtered signal as a second switched output signal based on the reference information. The adder 9a combines the first switched output signal and the second switched output signal to determine an output torque command value. In the example of FIG. 8, the inclusion of the second frequency characteristic adjuster 12 and the second switch 13 increases the amount of calculation, but increases the degree of freedom of the phase adjusted by the control device 2. Therefore, compared to the example of FIG. 2 using one frequency characteristic adjuster 5, it is possible to stabilize the open-loop characteristics and improve the steering feel.

[0036] Furthermore, the frequency characteristic adjuster 5 determines, based on the reference information, whether the conditions for operating the second controller 4 are met, and when the determination result indicates a change from the first control signal to the filtered signal, the frequency characteristic adjuster 5 immediately starts outputting the filtered signal as the switched output signal and stops outputting the first control signal. Therefore, even if the second controller 4 starts operating and the first control signal and the second control signal interfere with each other, causing vibration, the filtered signal is immediately supplied in place of the first control signal. This allows vibration due to interference to be quickly suppressed. The first frequency characteristic adjuster 10 and the second frequency characteristic adjuster 12 also have such operating characteristics and can quickly suppress vibration due to interference, similar to the frequency characteristic adjuster 5.

[0037] In the above description, the frequency characteristic adjuster 5, the first frequency characteristic adjuster 10, and the second frequency characteristic adjuster 12 combine the first control signal and the second control signal to adjust the phase by applying a phase lag adjuster when the phase margin of the open-loop characteristics of the control device 2 is no longer ensured. However, this is not limiting. The frequency characteristic adjuster 5, the first frequency characteristic adjuster 10, and the second frequency characteristic adjuster 12 may ensure the phase margin by reducing the gain instead of or in addition to the phase. For example, in the open-loop characteristics of the control device 2 illustrated by the dashed line in FIG. 6 , the frequency characteristic adjuster 5 can reduce the gain in a frequency band including the gain crossover frequency and the phase crossover frequency to reduce the phase lag at the gain crossover frequency to less than 180 degrees and the gain at the phase crossover frequency to less than 0 dB. In addition, the frequency characteristic adjuster 5 may reduce the gain in the frequency band and advance the phase to reduce the phase delay at the gain crossover frequency to less than 180 degrees, and reduce the gain at the phase crossover frequency to less than 0 dB.

[0038] Furthermore, in the above example, the second controller 4 refers to the vehicle speed as the vehicle driving state, but this is not limiting. The second controller 4 may refer to the yaw rate or lateral acceleration instead of or in addition to the vehicle speed. The yaw rate corresponds to the horizontal rotational speed of the vehicle. The lateral acceleration corresponds to the lateral acceleration of the vehicle and is also called lateral G. In other words, the yaw rate and lateral acceleration can be considered indicators of the lateral motion state of the vehicle. The lateral direction of the vehicle is a direction perpendicular to the vehicle's straight-ahead direction. As an example of referring to lateral motion, the second controller 4 may determine whether the vehicle is in a slip state or whether the vehicle is traveling on a road surface that slopes in the roll angle direction. The roll angle direction is the rotation direction with the vehicle orientation as the axial direction. When the second controller 4 determines that the vehicle is in a slip state, the second controller 4 may set a compensation gain to encourage the vehicle to eliminate the slip state and return to a stable state. Furthermore, when determining that the vehicle is traveling on an inclined road surface, the second controller 4 may determine a compensation torque to reduce the burden on the driver. For example, the second controller 4 determines a compensation gain that is proportional to the lateral momentum and directed in the opposite direction to the lateral momentum.

[0039] Furthermore, in the above example, the steering torque is referred to as the steering state, but this is not limiting. The second controller 4 may refer to an index other than the steering torque, such as one or a combination of the steering angle, steering speed, etc., as an index indicating the steering state. Examples of referring to the steering angle or steering speed include control that determines a compensation torque for a steering wheel return operation, and control that determines a compensation torque to vary the steering feeling according to the steering speed or steering angle. The steering wheel return operation corresponds to an operation of reducing the steering angle commanded by the steering operation to approach neutral.

[0040] Second Embodiment Next, a second embodiment according to the present disclosure will be described. The following description will mainly focus on differences from the first embodiment. In the control device 2 according to this embodiment, the frequency characteristic adjuster 5 reduces the gain for the first control signal or the second control signal in a specific frequency band. The frequency characteristic adjuster 5 includes, for example, a band-stop filter. A band-stop filter is a filter circuit whose gain in a specific frequency band is significantly smaller than the gain in other frequency bands. A band-stop filter is also called a band-elimination filter. In other respects, as illustrated in FIG. 9 , the hardware configuration of the control device 2 according to this embodiment is similar to the hardware configuration of the control device 2 according to the first embodiment.

[0041] Note that steering angle control is not limited to assisting the driver in steering, but may also be performed as part of an automatic driving function. In this case, the automatic driving system 16 ( FIG. 16 ) may intervene in the driver's steering while the automatic driving function is being executed. The automatic driving function may include, for example, element functions that involve steering angle control, such as lane-keep assist and a lane change function. The automatic driving system 16 may be configured separately from the electric power steering device S1. An execution flag indicating the start or end of steering angle control is input from the automatic driving system 16 to the control device 2. The second controller 4 can determine whether or not to execute steering angle control using the execution flag as reference information. In the steering angle control, the second controller 4 executes feedback control based on the deviation between the steering angle command input from the automatic driving system and the steering angle detection value input from a steering angle sensor (not shown). For example, PI control can be applied as a feedback control method. PI control is a method of determining, as an input value to a controlled object, a weighted sum of a proportional term proportional to the deviation and an integral term obtained by integrating the deviation over time. In this embodiment, the second controller 4 outputs a second control signal indicating the weighted sum as a compensation torque to the output torque setter 9.

[0042] FIG. 10 is a Bode diagram illustrating the transfer functions of the first controller 3 and the second controller 4 according to this embodiment. However, while FIG. 10 shows the relationship between the input steering torque and the base torque output by base control, the transfer function of the second controller 4 shows the relationship between the input steering angle and the compensation torque output by performing steering angle control as compensation control. FIG. 11 is a Bode diagram illustrating the open-loop characteristics of the control device 2. The open-loop characteristics are shown for a case in which the base torque indicated by the first control signal output from the first controller 3 is output as the output torque command value, and a case in which the output torque command value obtained by combining the first control signal output from the first controller 3 and the second control signal output from the second controller 4 is output. When the first control signal and the second control signal are combined, the gain exceeds 0 dB at 5 Hz, which corresponds to the phase crossover frequency, resulting in an insufficient gain margin. Furthermore, because the gain exceeds 0 dB across the entire frequency band that can occur during steering operation, the gain crossover frequency cannot be determined.

[0043] In this embodiment, a bandstop filter is applied to the frequency characteristic adjuster 5 provided downstream of the first controller 3. The bandstop filter reduces the gain in a predetermined frequency band including the phase crossover frequency compared to the gain in other frequency bands. As a result, the gain in the frequency band is less than 0 dB, ensuring a gain margin. FIG. 12 illustrates the frequency characteristics of the bandstop filter. In the example of FIG. 12, the gain is minimized at a frequency of 6 Hz. At frequencies higher than 6 Hz, the gain increases with increasing frequency and approaches 0 dB. At frequencies lower than 6 Hz, the gain increases with decreasing frequency and approaches 0 dB. In other words, the frequency characteristics illustrated in FIG. 12 have a characteristic that reduces the open-loop gain of the control device 2 in a specific frequency band including the phase crossover frequency. Note that the phase is negative at frequencies lower than 6 Hz, 0 degrees at 6 Hz, and positive at frequencies higher than 6 Hz. Therefore, by applying the band-stop filter, the phase lags at frequencies lower than 6 Hz and advances at frequencies higher than 6 Hz relative to the open loop characteristics of the control device 2 .

[0044] 13 illustrates the open-loop characteristics of the control device 2 to which a band-stop filter is applied. The output torque command value is obtained from the output torque setter 9 by combining the filtered signal obtained by applying the band-stop filter to the first control signal with the second control signal. By applying the band-stop filter, the phase crossover frequency changes from 5 Hz to 7 Hz, and the gain at the phase crossover frequency decreases from 1.5 dB to −1.0 dB, which is less than 0 dB. Therefore, a stability margin is ensured in the frequency band including the phase crossover frequency, and the open-loop characteristics of the control device 2 are stabilized.

[0045] However, if a band-stop filter is always applied downstream of the first controller 3, the first controller 3 and the second controller 4 may not be able to perform to their full potential, even if the open-loop characteristics of the control device 2 are not destabilized. In the example of FIG. 13 , the gain for the first control signal drops to −3 dB or less in the frequency band from 3 to 15 Hz. Therefore, when the first controller 3 operates and the second controller 4 does not operate, disturbance suppression performance for vibrations having components in the frequency band where the gain drops may be reduced. Vibrations having components in this frequency band are caused by, for example, road disturbances. Therefore, the control device 2 includes a switch 9 s downstream of the frequency characteristic adjuster 5. When the second controller 4 functions, the switch 9 s outputs the filtered signal output from the frequency characteristic adjuster 5 to the adder 9 a and combines it with the second control signal. When the second controller 4 does not function, the switch 9 s outputs the first control signal output from the first controller 3 to the adder 9 a and applies the base torque as the output torque command value.

[0046] In the above example, the second controller 4 determines whether to execute steering angle control based on the execution flag of the steering angle control. The switch 9s also refers to the execution flag as reference information, and when it is determined that the steering angle control is to be executed, it outputs the filtered signal output from the frequency characteristic adjuster 5 to the adder 9a as a switched output signal. When it is determined that the steering angle control is not to be executed, the switch 9s outputs the first control signal input to the frequency characteristic adjuster 5 to the adder 9a as a switched output signal.

[0047] As described above, according to the control device 2 of this embodiment, under conditions in which the second controller 4 does not function, the performance of the first controller 3 is demonstrated by using the first control signal as a command value for the base torque output, and when the first control signal and the second control signal interfere with each other and cause instability, the gain for the first control signal is reduced in a specific frequency band by the frequency characteristic adjuster 5. Therefore, when the first control signal and the second control signal interfere with each other and cause instability, the operation of the control device 2 is stabilized.

[0048] In this embodiment, as illustrated in Fig. 7, the control device 2 may include a frequency characteristic adjuster 5 to which a band-stop filter is applied in the subsequent stage of the second controller 4, instead of the first controller 3. Alternatively, as illustrated in Fig. 8, the control device 2 may include a first frequency characteristic adjuster 10 to which a band-stop filter is applied in the subsequent stage of the first controller 3, and a second frequency characteristic adjuster 12 to which a band-stop filter is applied in the subsequent stage of the second controller 4. The output torque setter 9 includes a first switch 11, a second switch 13, and an adder 9a.

[0049] In the above description, the frequency characteristic adjuster 5 applies a filter that cuts off a specific frequency band and reduces the gain compared to other frequency bands to the first control signal or the second control signal, which serves as the input signal. However, this is not limited to this. The frequency characteristic adjuster 5 (or the first frequency characteristic adjuster 10 or the second frequency characteristic adjuster 12) may reduce the gain of the input signal across the entire frequency band, including the components of the first control signal and the second control signal, and output the signal obtained by reducing the gain as the filtered signal. For example, the frequency characteristic adjuster 5 may convert the input signal into a filtered signal by multiplying each signal value constituting the input signal by a predetermined constant gain to attenuate the amplitude. In this case, components in frequency bands other than the frequency at which vibration occurs are also attenuated, increasing the possibility that control performance will not be achieved. However, vibrations caused by interference between the first control signal and the second control signal can be suppressed or avoided more simply than when a band-stop filter is provided.

[0050] Third Embodiment Next, a third embodiment according to the present disclosure will be described. The following description will mainly focus on differences from the first or second embodiment. A control device 2 according to this embodiment includes an adder 15. The adder 15 calculates a composite torque by adding a base torque indicated in a first control signal input from a first controller 3 and a compensation torque indicated in a second control signal input from a second controller 4. The adder 15 outputs a composite signal indicating the calculated composite torque to a frequency characteristic adjuster 5 and an output torque setter 9. The frequency characteristic adjuster 5 receives a composite signal obtained by combining the first control signal and the second control signal from the adder 15. The frequency characteristic adjuster 5 adjusts the phase or gain of the composite signal in a frequency band including a frequency that oscillates when the signal value indicated by the composite signal is set as an output torque command value, and outputs the resultant signal to the output torque setter 9 as a filtered signal.

[0051] The switch 9s determines whether the conditions for operating the second controller 4 are satisfied based on the reference information input thereto. When the switch 9s determines that the conditions for operating the second controller 4 are satisfied, it outputs the filtered signal input from the frequency characteristic adjuster 5 to the current controller 6 as an output signal. When the switch 9s determines that the conditions for operating the second controller 4 are not satisfied, it outputs the combined signal input from the adder 15 to the current controller 6 as an output signal. Note that the adder 9a ( FIG. 2 ) may be omitted from the output torque setter 9 according to this embodiment. In other respects, as illustrated in FIG. 14 , the hardware configuration of the control device 2 according to this embodiment is similar to the hardware configuration of the control device 2 according to the first or second embodiment.

[0052] The control device 2 according to the first and second embodiments includes a frequency characteristic adjuster 5 downstream of either the first controller 3 or the second controller 4, or downstream of both the first controller 3 and the second controller 4. The frequency characteristic adjuster 5 references either the first control signal or the second control signal, but not the other. Therefore, it may be difficult to grasp the effect of the gain or phase manipulation by the frequency characteristic adjuster 5 on the overall open-loop characteristics of the control device 2. However, in the present embodiment, the adder 15 combines the first control signal input from the first controller 3 and the second control signal input from the second controller 4 and outputs a combined signal as the frequency characteristic adjuster 5. That is, the set consisting of the first controller 3, the second controller 4, and the adder 15 is a single controller that outputs a combined signal in response to steering torque, and this controller can be considered to be connected in series with the frequency characteristic adjuster 5. Therefore, if the combined control characteristics obtained by parallelizing the functions of the first controller 3 and the second controller 4 can be grasped, it is possible to intuitively predict the effect of the gain or phase control characteristics of the frequency characteristic adjuster 5 on the entire control device 2. Therefore, when adjusting the gain or phase of the composite signal in accordance with a user operation, the frequency characteristic adjuster 5 can relatively easily adjust the control characteristic of the control device 2. Consequently, the workload of the adjustment-related operations can be reduced.

[0053] The frequency characteristic adjuster 5 may be connected to an input device (not shown) and an output device (not shown) wirelessly or via a wire to input and output data. The input device accepts a user's operation and outputs an operation signal indicating information corresponding to the accepted operation to the frequency characteristic adjuster 5. The frequency characteristic adjuster 5 may display a setting screen on the output device. The operation screen presents items that can be set by operation and the setting values ​​that are set at that time. The input device may be, for example, a button, a knob, a touch sensor, a mouse, or the like. The output device may be, for example, a liquid crystal display, an organic light-emitting diode display, or the like. The input device and the output device may be part of an in-vehicle device such as a navigation system.

[0054] As described above, in the control device 2 according to this embodiment, the frequency characteristic adjuster 5 receives a composite signal obtained by combining the first control signal output from the first controller 3 and the second control signal output from the second controller 4. The frequency characteristic adjuster 5 adjusts the phase or gain of the input composite signal in a frequency band including the frequency of vibration that may occur when the signal value indicated by the composite signal is set as the output torque command value, and outputs the resultant signal as a filtered signal to the output torque setter 9. The output torque setter 9 determines whether the conditions for the first controller 3 and the second controller 4 to function are satisfied based on the reference information. If the conditions for both the first controller 3 and the second controller 4 to function are satisfied, the output torque setter 9 outputs the filtered signal as an output signal to the current controller 6. If the conditions for one or both of the first controller 3 and the second controller 4 to function are satisfied, the output torque setter 9 outputs the composite signal as an output signal to the current controller 6. As described above, the reference information may be any one or a combination of the vehicle's running state, steering state, and execution flag. The effect of adjusting the phase or gain of the composite signal on the entire control device 2 can be predicted relatively easily, which reduces the workload involved in the adjustment.

[0055] Fourth Embodiment Next, a fourth embodiment of the present disclosure will be described. The control device 2 according to this embodiment has the same hardware configuration as the control device 2 according to the first to third embodiments. The following description will mainly focus on differences from the first to third embodiments. The first to third embodiments have been described with reference to an example in which the output torque setter 9 immediately switches from the filtered signal output from the frequency characteristic adjuster 5 to the input signal input to the frequency characteristic adjuster 5 upon determining that the switching condition for the other signal is met. In the example of FIG. 2 , satisfying the operating condition of the second controller 4 while the first control signal is being output corresponds to satisfying the switching condition from the first control signal to the filtered signal, and failing to satisfy the operating condition of the second controller 4 while the filtered signal is being output corresponds to satisfying the switching condition from the filtered signal to the first control signal. This operation is effective in quickly suppressing vibrations that occur when a combined value obtained by combining the first control signal and the second control signal is used as the output torque command value. However, if there is a large difference between the value of the input signal to the frequency characteristic adjuster 5 and the value of the filtered signal, the output torque command value will fluctuate abruptly. As a result, the output torque from the motor 1 may fluctuate suddenly, which may cause discomfort to the driver.

[0056] Therefore, when the switch 9s according to this embodiment determines that the condition for switching from one of the filtered signal and the input signal to the other is satisfied, it linearly changes the ratio to the other from 0 to 1 over a predetermined elapsed time from that point in time, and linearly changes the ratio to one from 1 to 0. Because the sum of the ratio to one and the ratio to the other is maintained at 1, the ratio to one and the ratio to the other are determined complementarily. The switch 9s outputs, as the switched output signal, a signal whose signal value is the sum of the multiplied values ​​obtained by multiplying the signal value of the filtered signal and the signal value of the input signal by the determined ratios.

[0057] FIG. 15 illustrates a time change in the ratio to the filtered signal. Assume, however, that initially, the operating conditions of the second controller 4 are not satisfied, and the first control signal, which is the input signal to the frequency characteristic adjuster 5, is output to the adder 9a as the switched output signal. At this stage, the ratio to the filtered signal is 0. When it is determined at time t1 that the second controller 4 satisfies the operating conditions, the switch 9s starts increasing the ratio to the filtered signal. In response, the switch 9s starts decreasing the ratio to the input signal. When the ratio reaches 1 at time t2, the switch 9s stops increasing the ratio, and thereafter maintains the ratio at 1, and maintains the ratio to the input signal at 0. Time t2 is a predetermined time after time t1. When it is determined at time t3 that the second controller 4 does not satisfy the operating conditions, the switch 9s starts decreasing the ratio to the filtered signal. In response, the switch 9s starts increasing the ratio to the input signal. When the ratio reaches 0 at time t4, switch 9s stops decreasing the ratio and thereafter maintains the ratio at 0, maintaining the ratio to the input signal at 1. Time t4 is a predetermined time after time t3. A period sufficiently longer than a typical vibration period is set in switch 9s in frequency characteristic adjuster 5 as the time elapsed from time t1 to time t2 or the time elapsed from time t2 to time t1. The vibration period corresponds to the reciprocal of the frequency at which vibration occurs.

[0058] Therefore, when the switcher 9s according to this embodiment determines that the condition for switching from one of the filtered signal and the input signal to the other is satisfied, it changes the ratio of the filtered signal to the other from a minimum value of 0 to a maximum value of 1 over a predetermined elapsed time from that point in time, and maintains the sum of the ratio and the ratio to the one signal at a maximum value of 1. Therefore, even if the determination of whether or not there is a possibility of interference between the first control signal and the second control signal changes, a sudden change in the command value of the output torque is suppressed. Therefore, it is possible to suppress or avoid any discomfort caused by a sudden change in the output torque.

[0059] In the above example, the rate of change of the ratio of the input signal to the filtered signal over time is constant, but this is not limited to this. The ratio may also change exponentially with the time elapsed since it is determined that the switching condition is satisfied. Furthermore, the ratio may be expressed as a discrete value discretized into N stages (N is a natural number equal to or greater than 2) between the minimum and maximum values. The switch 9s may repeatedly switch the ratio to the next smallest discrete value so that the ratio reaches the maximum value from the minimum value within the elapsed time, or may repeatedly switch the ratio to the next largest value so that the ratio reaches the minimum value from the maximum value.

[0060] The control device 2 according to each embodiment of the present disclosure may be configured with dedicated hardware or may include a general-purpose computer system. The computer system generally includes a processor and a storage medium. The processor may read a program non-temporarily stored in advance in the storage medium and execute the read program to implement the functions of each part of the control device 2 in cooperation with the storage medium and other hardware. The control device 2 may be implemented, for example, as part of the functions of an electronic control unit (ECU). Furthermore, the current controller 6, drive circuit 7, and current detector 8 may be omitted from the control device 2, and the electric power steering device S1 may be provided separately from the control device 2. The current controller 6, drive circuit 7, and current detector 8 may be integrated with the motor 1 and the motor rotation angle sensor 23, for example.

[0061] As illustrated in FIG. 16 , an electric power steering device S1 according to an embodiment of the present disclosure includes a motor 1 and a control device 2. A vehicle V1 according to an embodiment of the present disclosure includes the electric power steering device S1. A control system S2 according to an embodiment of the present disclosure includes the control device 2, an automatic driving system 16, and various detectors. In the example of FIG. 16 , the torque sensor 22 and the motor rotation angle sensor 23 correspond to detectors that detect the steering state. The speed system 31 and the yaw rate sensor 32 correspond to detectors that detect the running state of the vehicle. The control device 2 and the automatic driving system 16 may be configured as an integrated unit. In the control system S2, the automatic driving system 16 or some of the detectors may be omitted.

[0062] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments and their variations. Addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present disclosure. The direction of arrows shown in block diagrams and other drawings is for the convenience of explanation and does not limit the direction of the flow of information, data, signals, etc. during implementation. Furthermore, the present disclosure is not limited by the above description, but is limited only by the appended claims.

[0063] The control device 2, control system S2, electric power steering device S1, vehicle V1, and control method of the present disclosure can better demonstrate the performance of the first controller and the second controller, and can suppress vibrations caused by interference between the first control signal and the second control signal.

[0064] S1...electric power steering device, S2...control system, V1...vehicle, 1...motor, 2...control device, 3...first controller, 4...second controller, 5...frequency characteristic adjuster, 6...current controller, 7...drive circuit, 8...current detector, 9...output torque setter, 9a, 15...adder, 9s...switcher, 10...first frequency characteristic adjuster, 11...first switcher, 12...second frequency characteristic adjuster, 13...second switcher, 22...torque sensor, 23...motor rotation angle sensor, 51...steering wheel, 53...steering shaft, 54...rack and pinion gear, 55...wheel, 56...tie rod, 57...knuckle arm

Claims

1. A control device that controls the output torque of a motor based on the running state or steering state of a vehicle, comprising: a first controller that outputs a first control signal in response to the steering state; a second controller that outputs a second control signal; a frequency characteristic adjuster that adjusts at least one of gain and phase in a frequency band that includes a frequency that can oscillate when a combined signal obtained by combining the first control signal and the second control signal is used as the command value for the output torque, for an input signal that includes at least one of the first control signal and the second control signal, and outputs a filtered signal; and an output torque setter that determines either the filtered signal or the input signal as a switched output signal based on whether both the first controller and the second controller are functioning, and determines the command value for the output torque based on at least the switched output signal, wherein the output torque setter determines the switched output signal based on at least one of the running state of the vehicle, the steering state, and an execution state of automatic steering control.

2. The control device according to claim 1, characterized in that the frequency characteristic adjuster obtains one of the first control signal and the second control signal as the input signal, and the output torque setter determines the command value of the output torque by combining the other of the first control signal and the second control signal with the post-switching output signal.

3. The control device according to claim 1, characterized in that the frequency characteristic adjuster comprises: a first frequency characteristic controller that outputs a first filtered signal in response to the first control signal; and a second frequency characteristic controller that outputs a second filtered signal in response to the second control signal; and the output torque setter determines one of the first control signal and the first filtered signal as a first switched output signal, and determines one of the second control signal and the second filtered signal as a second switched output signal, and determines the command value of the output torque by combining the first switched output signal and the second switched output signal.

4. The control device according to claim 1, characterized in that: the frequency characteristic adjuster acquires a composite signal obtained by combining the first control signal and the second control signal as the input signal; and the output torque setter determines a command value for the output torque based on the post-switching output signal.

5. The control device according to any one of claims 1 to 4, wherein the frequency characteristic adjuster has a filter characteristic that reduces the gain in the frequency band.

6. The control device according to any one of claims 1 to 4, wherein the frequency characteristic adjuster has the characteristics of a phase compensator that adjusts the phase in the frequency band.

7. The control device according to claim 1, wherein the output torque setter refers to a state quantity related to the movement of the vehicle in the traveling direction as the running state of the vehicle.

8. The control device according to claim 1, wherein the output torque setter refers to a state quantity related to movement in a direction intersecting the vehicle's traveling direction as the vehicle's running state.

9. The control device according to claim 1, wherein the output torque setter refers to at least one state quantity of steering torque, steering speed, or steering angle as the steering state.

10. The control device according to claim 1, characterized in that the output torque setter immediately changes the post-switching output signal from one of the input signal and the filtered signal to the other after a change in the determination of whether or not both the first controller and the second controller are operating.

11. The control device according to claim 1, characterized in that the output torque setter changes the ratio of the input signal to the filtered signal in the post-switching output signal over a predetermined elapsed time or more after a change in the determination of whether or not both the first controller and the second controller are operating.

12. A control system comprising: a detector that detects the running state or steering state of the vehicle; and the control device according to any one of claims 7 to 9.

13. A control system comprising: an automatic driving system having an automatic steering control function; and the control device according to claim 1.

14. An electric power steering device comprising: the motor; and the control device according to claim 1.

15. A vehicle equipped with the electric power steering device according to claim 14.

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