Rotation control system

Abstract

The present invention discloses a rotation control system (40), which includes an electronic control unit. The electronic control unit is configured to execute: a steering operation amount calculation process (M16) for calculating a steering operation amount; an angle command value calculation process for calculating an angle command value; an angle operation amount calculation process (M50) for calculating an angle operation amount; an operation process for operating a drive circuit of an electric motor; an adjustment process for adjusting the size of a value obtained by subtracting the angle operation amount reflected in the operation process from the angle operation amount; and a correction process for correcting the size of an input when calculating an angle command value in the angle command value calculation process to be smaller when the size of the subtracted value is large than when the size of the subtracted value is small.

Description

Technical Field

[0001] The present invention relates to a rotation control system which controls a rotation actuator having an electric motor incorporated therein and which rotates a rotation wheel. Background Art

[0002] For example, Japanese Patent Application Publication No. 2006-175940 (JP 2006-175940 A) discloses a device for operating an electric motor incorporated in a rotary actuator, which rotates a rotary wheel based on an operation amount based on a difference between a target steering torque and an actual steering torque in feedback control and an operation amount based on a difference between a target turning angle and a turning angle in feedback control. Summary of the invention

[0003] When the turning angle is controlled to the target turning angle by feedback control as described above, although reverse input vibration from the turning wheel can be suppressed, there is a concern that the driver will not be able to understand road surface state information (road information).

[0004] According to one aspect of the present invention, there is provided a rotation control system including an electronic control unit, and the rotation control system operates a rotation actuator including an electric motor incorporated in the rotation actuator and causing a rotating wheel to rotate. The electronic control unit is configured to perform the following processing: a steering operation amount calculation processing, which calculates a steering operation amount, which is an operation amount that can be converted into a torque required by the electric motor as an operation amount of the electric motor used to rotate the rotating wheel to control the steering torque input by the driver to a target steering torque through feedback control; an angle command value calculation processing, which calculates an angle command value based on the steering operation amount, which is an instruction value that can be converted into a convertible angle of the rotation angle of the rotating wheel; an angle operation amount calculation processing, which calculates an angle operation amount, which is an operation amount that can be converted into a torque required by the electric motor as an operation amount used to control the convertible angle to an angle command value through feedback control; an operation processing, which operates a drive circuit of an electric motor to control the torque of the electric motor; an adjustment processing, which adjusts the size of a value obtained by subtracting the angle operation amount reflected in the operation processing from the angle operation amount calculated in the angle operation amount calculation processing and inputs the adjusted angle operation amount to the operation processing; and a correction processing, which corrects the size of the input when calculating the angle command value in the angle command value calculation processing to be smaller when the size of the subtracted value is large than when the size of the subtracted value is small.

[0005] In this configuration, the size of the value obtained by subtracting the angle operation amount reflected in the operation process from the angle operation amount calculated in the angle operation amount calculation process is adjusted in the adjustment process. Here, since the angle operation amount is an operation amount for controlling the convertible angle to the angle command value by feedback control regardless of the road surface state, the angle operation amount includes an amount for eliminating the road surface state information. Therefore, the subtraction value includes an amount for eliminating the road surface state information. Therefore, the driver can understand the road surface state information according to the size of the subtraction value.

[0006] The angle operation amount calculated in the angle operation amount calculation process is an operation amount applicable to the angle command value. Therefore, when the angle operation amount as the input of the operation process is insufficient for the angle operation amount calculated in the angle operation amount calculation process, there is a concern that the convertible angle may deviate greatly from the angle command value. When the convertible angle deviates greatly from the angle command value, the absolute value of the angle operation amount calculated in the angle operation amount calculation process increases excessively, and the convertible angle is no longer a value applicable to the angle command value. Therefore, in the above configuration, by correcting the input of the angle operation amount calculation process based on the value obtained by subtraction, the angle command value can be made close to the convertible angle and the excessive increase in the absolute value of the angle operation amount can be suppressed.

[0007] In this aspect, the adjustment process may be a process of adjusting a value within a range of 0 to 1 obtained by dividing the angle operation amount reflected in the operation process by the angle operation amount calculated in the angle operation amount calculation process (M50).

[0008] In this configuration, the size of the value obtained by subtracting the angle operation amount reflected in the operation process from the angle operation amount calculated in the angle operation amount calculation process can be adjusted based on the size of the predetermined coefficient.

[0009] In this aspect, the angle operation amount calculation process may be a process of calculating the angle operation amount based on the sum of a feedforward operation amount, which is an operation amount for feedforward control of the angle command value, and an estimated disturbance torque, which is an output of a disturbance observer based on a difference between a convertible angle and the angle command value. The adjustment process may be a process of adjusting the magnitude of an input when calculating the angle command value in the angle command value calculation process based on a value obtained by subtracting the estimated disturbance torque reflected in the operation process from the estimated disturbance torque reflected in the output of the angle operation amount calculation process.

[0010] The estimated disturbance torque is a quantity obtained by excluding at least the feedforward operation amount from the torque affecting the turning angle. Therefore, by using the feedforward operation amount as a quantity for controlling the convertible angle to the angle command value with high accuracy in reflecting the influence of factors other than the factors affecting the turning angle outside the vehicle, the estimated disturbance torque can be used as a quantity for expressing road surface state information with high accuracy.

[0011] In this aspect, the operation process may include a process of controlling the torque of the electric motor based on the angle operation amount regardless of the steering operation amount. In this aspect, the angle command value calculation process may include a change process of changing the relationship between the output and the input based on the magnitude of the subtracted value.

[0012] When the value obtained by subtraction is large and the angle operation amount calculation process is not fully reflected in the control of the rotation angle, there is a concern that the stability of the angle command value calculation process may be impaired. Therefore, in the above configuration, by changing the relationship between the input and the output in the angle command value calculation process based on the size of the value obtained by subtraction, even if the angle operation amount calculation process is not reflected in the control of the rotation angle, the relationship between the output and the input can be used as a relationship that can suppress the decrease in stability.

[0013] In this aspect, the adjustment process may include a process of reducing the size of the subtraction value when the vehicle speed is high compared to the case where the vehicle speed is low. When the vehicle speed is high, the reverse input vibration generated at the time of straight-line braking, etc. may increase and the stability of the vehicle's travel may be impaired. Therefore, in the above configuration, by reducing the size of the subtraction value when the vehicle speed is high, the reverse input from the turning wheel side can be eliminated and the stability of the vehicle's travel can be ensured. By increasing the size of the subtraction value when the vehicle speed is low, the driver can understand the road surface state information.

[0014] In this aspect, the electronic control unit may be configured to perform a detection process for detecting a sideslip of the vehicle, and the adjustment process may include a process for increasing the size of the subtracted value when a sideslip is detected in the detection process compared to a case where the sideslip is not detected in the detection process.

[0015] In this configuration, when skidding is detected, the driver can be made aware that the road surface on which the vehicle is currently traveling is a road surface on which skidding may occur by increasing the size of the subtracted value.

[0016] In this aspect, the electronic control unit may be configured to perform an acquisition process of acquiring a request signal from the driver, and the adjustment process may include a process of increasing the subtracted value based on the request signal acquired in the acquisition process.

[0017] In this configuration, since the subtracted value can be adjusted based on a request from the driver, a steering feel corresponding to the driver's preference can be achieved.

[0018] In this aspect, the electronic control unit may be configured to execute a target steering torque calculation process that calculates the target steering torque based on a sum of amounts obtained by converting the steering operation amount and the steering torque into amounts of force acting on the same object.

[0019] Since the steering operation amount can be converted into the torque required by the electric motor, the force applied from the vehicle side for turning the turning wheel is determined based on the steering operation amount and the steering torque, and the force can be converted into a lateral force. On the other hand, the target steering torque required to improve the steering feeling for the driver can be determined based on the lateral force. Therefore, with the above configuration, the target steering torque calculation process can be easily designed by determining the target steering torque based on the sum of the steering operation amount and the force. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals denote like elements, and in which:

[0021] Figure 1 is a diagram showing an electric power steering system according to a first embodiment;

[0022] Figure 2 is a block diagram showing a process performed by the rotation control system according to the first embodiment;

[0023] Figure 3 is a flowchart showing the flow of road information adjustment processing according to the first embodiment;

[0024] Figure 4 is a flowchart showing the flow of road information adjustment processing according to the second embodiment;

[0025] Figure 5 is a flowchart showing the flow of a road information adjustment process according to a third embodiment;

[0026] Figure 6 is a flowchart showing the flow of a road information adjustment process according to a fourth embodiment;

[0027] Figure 7 is a flowchart showing the flow of a road information adjustment process according to a fifth embodiment;

[0028] Figure 8 is a block diagram showing a process performed by a rotation control system according to a sixth embodiment;

[0029] Fig. 9 is a flowchart showing the flow of a road information adjustment process according to a sixth embodiment;

[0030] Fig.10 is a diagram showing an electric power steering system according to a seventh embodiment; and

[0031] Fig.11 is a block diagram showing processing performed by a rotation control system according to the seventh embodiment. DETAILED DESCRIPTION

[0032] First embodiment

[0033] Hereinafter, a rotation control system according to a first embodiment will be described with reference to the accompanying drawings. Figure 1 As shown, the electric power steering system 10 includes a steering mechanism 20 that rotates the rotating wheel 12 based on the driver's operation of a steering wheel 22 , and a rotating actuator 30 that electrically rotates the rotating wheel 12 .

[0034] The steering mechanism 20 includes a steering wheel 22, a steering shaft 24 fixed to the steering wheel 22, and a rack and pinion mechanism 27. The steering shaft 24 includes a column shaft 24a connected to the steering wheel 22, an intermediate shaft 24b connected to the bottom end of the column shaft 24a, and a pinion shaft 24c connected to the bottom end of the intermediate shaft 24b. The bottom end of the pinion shaft 24c is connected to the rack shaft 26 via the rack and pinion mechanism 27. The left and right turning wheels 12 are connected to both ends of the rack shaft 26 via tie rods 28. Therefore, the rotational movement of the steering wheel 22, that is, the steering shaft 24, is converted into the rotation of the rack shaft 26 in the axial direction ( Figure 1 The translational movement is transmitted to the rotating wheel 12 via the tie rods 28 connected to both ends of the rack shaft 26, thereby changing the rotation angle of the rotating wheel 12.

[0035] On the other hand, the rotating actuator 30 shares the rack shaft 26 with the steering mechanism 20, and the rotating actuator 30 includes an electric motor 32, an inverter 33, a ball screw mechanism 34, and a belt reduction gear mechanism 36. The electric motor 32 is a power source for rotating the rotating wheel 12, and, for example, a three-phase surface magnetic synchronous electric motor (SPMSM) can be used as the electric motor 32 in the present embodiment. The ball screw mechanism 34 is integrally attached to the periphery of the rack shaft 26, and the belt reduction gear mechanism 36 transmits the rotational force of the output shaft 32a of the electric motor 32 to the ball screw mechanism 34. The rotational force of the output shaft 32a of the electric motor 32 is converted into a force for translating the rack shaft 26 in the axial direction via the belt reduction gear mechanism 36 and the ball screw mechanism 34. The rotating wheel 12 can be rotated by the force in the axial direction applied to the rack shaft 26.

[0036] The turning control system 40 controls the turning wheel 12 and operates the turning actuator 30 to control the turning angle as a control parameter of the turning actuator 30. The turning control system 40 controls the following control parameters with reference to the steering torque Th as the torque input by the driver via the steering wheel 22 and detected by the torque sensor 50: the turning angle θm of the output shaft 32a detected by the turning angle sensor 52, or the currents iu, iv, and iw flowing in the electric motor 32. The currents iu, iv, and iw can be detected as a voltage drop provided in a shunt resistor provided in each branch of the inverter 33. The turning control system 40 refers to the vehicle speed V detected by the vehicle speed sensor 54, the yaw rate γ detected by the yaw rate sensor 56, or the operation state of the mode selection switch 58 on which the driving mode selection operation is performed by the driver. In the present embodiment, the mode selection switch 58 is a switch for selecting the normal mode or the sport mode. The sport mode is a mode in which the rotation speed of the vehicle-mounted electric motor is set to a higher rotation speed than that in the normal mode at the same vehicle speed.

[0037] The rotation control system 40 includes a CPU 42, a ROM 44, and a peripheral circuit 46, which are connected to each other via a communication line 48. The peripheral circuit 46 includes a circuit for generating a clock signal for defining internal operations, a power supply circuit, and a reset circuit. In other words, the rotation control system 40 includes an electronic control unit.

[0038] Figure 2 Some of the processing performed by the rotation control system 40 is shown. Figure 2The processing shown in is implemented by causing the CPU 42 to execute the program stored in the ROM 44. The basic target torque calculation processing M10 is a processing for calculating the basic target torque Thb* based on the axial force Taf0, which is the basic value of the target steering torque Th* input by the driver to the steering shaft 24 via the steering wheel 22. Here, the axial force Taf0 is an axial force in the axial direction applied to the rack shaft 26. Since the axial force Taf0 is an amount corresponding to the lateral force acting on the rotating wheel 12, the lateral force can be determined based on the axial force Taf0. On the other hand, it is preferable to determine the torque input by the driver to the steering shaft 24 via the steering wheel 22 based on the lateral force. Therefore, the basic target torque calculation processing M10 is a processing for calculating the basic target torque Thb* based on the lateral force determined based on the axial force Taf0.

[0039] Specifically, the basic target torque calculation process M10 is a process of calculating the magnitude of the basic target torque Thb* to be smaller when the magnitude (absolute value) of the axial force Taf0 is the same and the vehicle speed V is low than when the vehicle speed V is high. For example, this can be achieved by causing the CPU 42 to map the basic target torque Thb* in a state where mapping data in which the axial force Taf0 or the lateral acceleration determined according to the axial force Taf0 and the vehicle speed V are used as input variables and the basic target torque Thb* is used as an output variable is pre-stored in the ROM 44. Here, the mapping data is paired data of a discrete value of the input variable and a value of an output variable corresponding to the value of the input variable. For example, the mapping calculation is a process in which the value of the corresponding output variable in the mapping data is output as a calculation result when the value of one input variable matches one of the values ​​of the input variable in the mapping data; and the value obtained by interpolating the values ​​of a plurality of output variables included in the mapping data is output as a calculation result when the value of one input variable does not match one of the values ​​of the input variable.

[0040] The hysteresis processing M14 is a processing for calculating and outputting the hysteresis correction amount Thys for correcting the basic target torque Thb* based on the rotation angle (pinion angle θp) of the pinion shaft 24c, which is a convertible angle that can be converted into the rotation angle of the rotating wheel 12. Specifically, the hysteresis processing M14 includes the following processing: based on the change of the pinion angle θp and the like, the forward switching and the reverse switching of the steering wheel 22 are recognized and the hysteresis correction amount Thys is calculated so that the magnitude (absolute value) of the target steering torque Th* is larger at the time of the forward switching than at the time of the reverse switching. More specifically, the hysteresis processing M14 includes the processing of setting the hysteresis correction amount Thys to be variable based on the vehicle speed V.

[0041] The addition process M12 is a process for calculating the target steering torque Th* by adding the hysteresis correction amount Thys to the basic target torque Thb*. The steering operation amount calculation process M16 is a process for calculating the steering operation amount Ts*, which is the operation amount for controlling the steering torque Th to the target steering torque Th* by feedback control. The steering operation amount Ts* is an amount including the operation amount for controlling the steering torque Th to the target steering torque Th* by feedback control and may include a feedforward term. The operation amount for feedback control is an amount for increasing the magnitude (absolute value) of the required torque of the electric motor 32, for example, when the signs of both the steering torque Th and the target steering torque Th* are positive and the steering torque Th is greater than the target steering torque Th*. The steering operation amount Ts* is an amount corresponding to the required torque Td of the electric motor 32 in the feedback control of the steering torque Th to the target steering torque Th*, and the steering operation amount Ts* is an amount converted into a torque applied to the steering shaft 24 in the present embodiment.

[0042] The axial force calculation process M18 is a process for calculating the axial force Taf0 by adding the steering torque Th to the steering operation amount Ts*. Since the steering torque Th is the torque applied to the steering shaft 24, the axial force Taf0 in this embodiment has a value obtained by converting the force in the axial direction applied to the rack shaft 26 into the torque applied to the steering shaft 24.

[0043] The subtraction process M20 is a process for calculating the axial force Taf by subtracting the adjustment amount ΔTt* from the axial force Taf0. The standard model calculation process M30 is a process for calculating the pinion angle command value θp* based on the axial force Taf, and the pinion angle command value θp* is the command value of the pinion angle θp. Specifically, the standard model calculation process M30 is a process for calculating the pinion angle command value θp* using the model formula represented by the expression (c1).

[0044] Taf=K·θp*+C·θp*'+J·θp*”…(c1)

[0045] The model represented by the expression (c1) is a model of the value indicated by the pinion angle θp when the same amount of torque as the axial force Taf is input to the steering shaft 24. In the expression (c1), the viscosity coefficient C is a model of the friction of the electric power steering system 10, the inertia coefficient J is a model of the inertia of the electric power steering system 10, and the elastic coefficient K is a model of the specifications of the vehicle in which the electric power steering system 10 is installed, such as suspension, wheel alignment, etc. This model is not a model that accurately expresses the actual electric power steering system or the vehicle in which the electric power steering system 10 is installed, but is a standard model designed to change the behavior of the turning angle into an ideal behavior using input. In the present embodiment, the steering feel can be adjusted by designing a standard model.

[0046] The integration process M40 is a process of calculating the integral value Inθ of the rotation angle θm of the electric motor 32. In the present embodiment, the rotation angle of the turning wheel 12 when the vehicle moves in a straight line is set to "0", and the integral value Inθ when the rotation angle is "0" is set to "0". The conversion process M42 is a process of calculating the pinion angle θp by dividing the integral value Inθ by the reduction gear ratio Km from the steering shaft 24 to the electric motor 32. When the pinion angle θp is "0", it indicates the straight-line driving direction, and indicates the right turning angle or the left turning angle depending on whether the pinion angle θp is positive or negative.

[0047] The angle operation amount calculation process M50 is a process for calculating the angle operation amount Tt1*, which is an operation amount for controlling the pinion angle θp to the pinion angle command value θp* by feedback control. The angle operation amount Tt1* is an amount corresponding to the required torque Td of the electric motor 32 in the feedback control of the pinion angle θp to the pinion angle command value θp*, and the angle operation amount Tt1* is an amount converted into a torque applied to the steering shaft 24 in the present embodiment.

[0048] The angle operation amount calculation process M50 includes a disturbance observer M52 that estimates the torque affecting the pinion angle θp as a disturbance torque other than the angle operation amount Tt1* and the steering torque Th and sets the disturbance torque as an estimated disturbance torque Tlde. In the present embodiment, the estimated disturbance torque Tlde is converted into a torque applied to the steering shaft 24.

[0049] The disturbance observer M52 calculates the estimated disturbance torque Tlde or the estimated value θpe by expression (c2) using the inertia coefficient Jp, the estimated value θpe of the pinion angle θp, the angle operation amount Tt0*, and a matrix L of three rows and one column for defining the observer gains l1, l2, and l3. The inertia coefficient Jp is an inertia model of the electric power steering system 10 and represents the actual inertia of the electric power steering system 10 with a higher accuracy than the accuracy of the inertia coefficient J.

[0050]

[0051]

[0052] The differential calculation process M54 is a process for calculating the pinion angular velocity command value by performing a differential calculation on the pinion angle command value θp*.

[0053] Feedback term calculation processing M56 is processing for calculating feedback operation amount Ttfb which is the sum of a proportional term based on the difference between the pinion angle command value θp* and the estimated value θpe and a differential term based on the difference between the differential value of the pinion angle command value θp* and the differential value of the estimated value θpe.

[0054] The second-order differential processing M58 is a processing for calculating the second-order time differential value of the pinion angle command value θp*. The feedforward term calculation processing M60 is a processing for calculating the feedforward operation amount Ttff by multiplying the output value of the second-order differential processing M58 by the inertia coefficient Jp. The two-degree-of-freedom operation amount calculation processing M62 is a processing for calculating the angle operation amount Tt0* by subtracting the estimated disturbance torque Tlde from the sum of the feedback operation amount Ttfb and the feedforward operation amount Ttff.

[0055] The steering torque compensation process M66 is a process for calculating the angular operation amount Tt1*, which is the output of the angular operation amount calculation process M50, by subtracting the steering torque Th from the angular operation amount Tt0*. The road information adjustment process M70 is a process for calculating the adjustment amount ΔTt* based on the angular operation amount Tt1*.

[0056] The subtraction process M72 is a process for calculating the angle operation amount Tt* by subtracting the adjustment amount ΔTt* from the angle operation amount Tt1*. The addition process M74 is a process for calculating the required torque Td of the electric motor 32 by adding the angle operation amount Tt* to the steering operation amount Ts*. The required torque Td is obtained by converting the torque to be generated by the electric motor 32 into the torque of the steering shaft 24.

[0057] The conversion process M76 is a process of converting the required torque Td into a torque command value Tm*, which is a command value of torque for the electric motor 32, by dividing the required torque Td by the reduction gear ratio Km.

[0058] The operation signal generation process M78 is a process of generating and outputting an operation signal MSt of the inverter 33 for controlling the torque for the electric motor 32 to the torque command value Tm*. The operation signal MSt is actually an operation signal for each arm of each branch of the inverter 33.

[0059] Figure 3 The flow of the road information adjustment process M70 is shown. Figure 3 The illustrated processing flow is realized by causing the CPU 42 to repeatedly execute, for example, at intervals of a predetermined cycle, a program stored in the ROM 44. In the following description, a numeral with "S" added to the front thereof indicates a step number of each process.

[0060] exist Figure 3 In the series of processing shown, the CPU 42 first obtains the vehicle speed V (S10). Then, the CPU 42 calculates the adjustment amount ΔTt* by multiplying the angle operation amount Tt1* by the coefficient α (S12). Here, when the vehicle speed V is equal to or higher than the predetermined speed Vth, the CPU 42 sets the coefficient α to "0", and when the vehicle speed V is lower than the predetermined speed Vth and the vehicle speed V is low, the CPU 42 calculates the coefficient α as a larger value than when the vehicle speed V is high. The coefficient α has a value from "0" to "1". Specifically, the CPU 42 performs mapping calculation on the coefficient α in a state in which mapping data with the vehicle speed V as an input variable and the coefficient α as an output variable is pre-stored in the ROM 44.

[0061] When the processing of S12 is completed, the CPU 42 temporarily terminates the Figure 3 The operation and advantages of this embodiment will be described below.

[0062] When the vehicle speed V is equal to or higher than the predetermined speed Vth, the CPU 42 sets the adjustment amount ΔTt* to "0". Therefore, the difference between the angle operation amount Tt1* output from the angle operation amount calculation processing M50 and the angle operation amount Tt* used to calculate the required torque Td becomes "0". Therefore, the required torque Td does not fully include the operation amount required for the feedback control of the pinion angle θp to the pinion angle command value θp*. Here, since the pinion angle command value θp* is determined based on the specification model expressed by the expression (c1), the rotation angle is controlled based on the specification model. Therefore, the reverse input from the road surface on which the vehicle is traveling is eliminated. When the vehicle speed V is high, the reverse input vibration generated during straight-line braking, etc. may increase, and thus the driving stability may be impaired, but the driving stability can be ensured by suppressing the reverse input vibration.

[0063] On the other hand, when the vehicle speed V is lower than the predetermined speed Vth, the adjustment amount ΔTt* is set to increase as the vehicle speed V decreases. Here, since the adjustment amount ΔTt* includes an amount for eliminating the road surface state information, as the adjustment amount ΔTt*, which is the difference between the angle operation amount Tt1* and the angle operation amount Tt* reflected in the torque command value Tm*, increases, the road surface state information is less likely to be eliminated by control. Therefore, by increasing the size of the adjustment amount ΔTt* as the vehicle speed V decreases, the driver can be made to know more about the road surface state information as the vehicle speed V becomes lower.

[0064] The CPU 42 subtracts the adjustment amount ΔTt*, which is a value obtained by subtracting the angle operation amount Tt* from the angle operation amount Tt1*, from the axial force Taf0 and sets the resultant value as the axial force Taf as an input of the specification model calculation process M30. Therefore, it is possible to prevent the magnitude of the estimated disturbance torque Tlde from increasing excessively. That is, the angle operation amount Tt1* calculated by the angle operation amount calculation process M50 is an operation amount suitable for controlling the pinion angle θp to the pinion angle command value θp*. Therefore, when the value obtained by subtracting the angle operation amount Tt* from the angle operation amount Tt1* is not "0", there is a concern that the pinion angle θp may deviate greatly from the pinion angle command value θp* and the magnitude of the estimated disturbance torque Tlde may increase excessively. In this case, since the angle operation amount Tt1* deviates from the value suitable for controlling the pinion angle θp to the pinion angle command value θp*, there is a concern that the controllability of the pinion angle θp is reduced when the angle operation amount Tt* is controlled to the angle operation amount Tt1*.

[0065] According to the above-mentioned embodiment, the following advantages are additionally achieved. The target steering torque Th* is set based on the sum of the steering operation amount Ts* and the steering torque Th. Here, the target torque required to improve the steering feel for the driver can be determined based on the lateral force. On the other hand, since the sum of the steering operation amount Ts* and the steering torque Th can be converted into the lateral force of the vehicle, the process of calculating the target steering torque Th* can be easily designed by determining the target steering torque Th* based on the sum.

[0066] Second embodiment

[0067] Hereinafter, the second embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment.

[0068] In the first embodiment, the adjustment amount ΔTt* is set to be variable according to the vehicle speed V, but in the present embodiment, the adjustment amount ΔTt* is set to be variable according to the degree of side slip of the vehicle. Figure 4 The flow of the road information adjustment process M70 according to the present embodiment is shown. Figure 4 The illustrated processing flow is realized by causing the CPU 42 to repeatedly execute a program stored in the ROM 44 at intervals of a predetermined cycle, for example.

[0069] exist Figure 4 In the series of processes shown, the CPU 42 first acquires the pinion angle θp (S20). Then, the CPU 42 calculates the estimated yaw rate γe based on the pinion angle θp (S22). For example, this can be achieved by causing the CPU 42 to perform map calculation on the estimated yaw rate γe in a state in which map data having the pinion angle θp as an input variable and the estimated yaw rate γe as an output variable is pre-stored in the ROM 44.

[0070] Then, the CPU 42 substitutes the value obtained by multiplying the angle operation amount Tt1* by the coefficient β into the adjustment amount ΔTt* (S24). Here, when the absolute value of the difference between the yaw rate γ and the estimated yaw rate γe is equal to or less than the predetermined value Δth, the CPU 42 sets the coefficient β to "0", and when the absolute value of the difference is greater than the predetermined value Δth and the absolute value of the difference is large, the CPU 42 sets the coefficient β to a value larger than when the absolute value of the difference is small. The coefficient β has a value from "0" to "1". Specifically, the CPU 42 performs mapping calculation on the coefficient β in a state in which mapping data with the vehicle speed V as an input variable and the coefficient β as an output variable is pre-stored in the ROM 44.

[0071] When the processing of S24 is completed, the CPU 42 temporarily terminates the Figure 4The operation and advantages of this embodiment will be described below.

[0072] When the absolute value of the difference between the yaw rate γ and the estimated yaw rate γe is greater than the predetermined value Δth, the CPU 42 increases the magnitude of the value obtained by subtracting the angular operation amount Tt* from the angular operation amount Tt1* as the absolute value of the difference increases. Here, since the side slip of the vehicle is more likely to occur as the absolute value of the difference increases, the driver can be made to understand the road surface state information more easily as the side slip degree increases. Therefore, the driver can be made to realize that the vehicle is traveling on a road surface where side slip is likely to occur.

[0073] Third embodiment

[0074] Hereinafter, the third embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment.

[0075] In the present embodiment, the adjustment amount ΔTt* is set to be variable according to the driving mode. Figure 5 The flow of the road information adjustment process M70 according to the present embodiment is shown. Figure 5 The illustrated processing flow is realized by causing the CPU 42 to repeatedly execute a program stored in the ROM 44 at intervals of a predetermined cycle, for example.

[0076] exist Figure 5 In the series of processes shown, the CPU 42 first detects the operation state of the mode selection switch 58 (S30). Then, the CPU 42 determines whether the sports mode is selected based on the state detected in the process of S30 (S32). Then, when it is determined that the normal mode is selected (S32: No), the CPU 42 substitutes "0" into the adjustment amount ΔTt* (S34). On the other hand, when it is determined that the sports mode is selected (S32: Yes), the CPU 42 substitutes a value obtained by multiplying the angle operation amount Tt1* by the coefficient ε into the adjustment amount ΔTt* (S36). Here, the coefficient ε has a value from "0" to "1".

[0077] When the processing of S34 and S36 is completed, the CPU 42 temporarily terminates the Figure 5 The operation and advantages of this embodiment will be described below.

[0078] When the normal mode is selected, the CPU 42 can sufficiently eliminate the reverse input from the road surface on which the vehicle is traveling and reduce the driving load of the driver by setting the adjustment amount ΔTt* to "0". On the other hand, when the sport mode is selected, the CPU 42 can enable the driver to understand the road surface state information by setting the magnitude of the adjustment amount ΔTt* to be greater than "0". Since it is conceivable that a driver who likes the sport mode wants to understand the road surface state information, a steering feel corresponding to the driver's taste can be achieved.

[0079] Fourth embodiment

[0080] Hereinafter, the fourth embodiment will be described with reference to the drawings, focusing on the differences from the third embodiment.

[0081] In the third embodiment, the size of the adjustment amount ΔTt* is set to be greater than "0" in the sports mode. Here, when the difference between ε and "1" is small, the angle operation amount calculation processing M50 is not fully reflected in the control of the rotation angle and therefore there is a concern that self-excited vibration occurs in the specification model calculation processing M30. In this case, the absolute value of the difference between the pinion angle command value θp* and the pinion angle θp increases and there is a problem that the controllability of the switching deteriorates when switching to the normal mode. Therefore, in the present embodiment, self-excited vibration is suppressed by the following processing.

[0082] Figure 6 The flow of the road information adjustment process M70 according to the present embodiment is shown. Figure 6 The processing flow shown is realized by causing the CPU 42 to repeatedly execute a program stored in the ROM 44 at intervals of a predetermined cycle, for example. Figure 6 in Figure 5 Processes corresponding to the processes shown are referred to by the same step numbers.

[0083] exist Figure 6In the series of processes shown, when the process of S34 is completed, the CPU 42 substitutes the normal value K0 into the elastic coefficient K used for the specification model calculation process M30 to calculate the pinion angle command value θp* and substitutes the normal value C0 into the viscosity coefficient C (S38). When the angle operation amount calculation process M50 is fully reflected in the control of the rotation angle, the normal values ​​K0 and C0 are suitable for the values ​​used to stabilize the specification model calculation process M30. On the other hand, when the process of S36 is completed, the CPU 42 substitutes the change value K1 into the elastic coefficient K used for the specification model calculation process M30 to calculate the pinion angle command value θp* and substitutes the change value C1 into the viscosity coefficient C (S40). When the angle operation amount calculation process M50 is not reflected in the control of the rotation angle, the change values ​​K1 and C1 are suitable for the values ​​used to stabilize the specification model calculation process M30.

[0084] In addition, when the processing of S38 and S40 is completed, the CPU 42 temporarily ends Figure 6 A series of processing shown.

[0085] Fifth embodiment

[0086] Hereinafter, the fifth embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment.

[0087] Figure 7 The flow of the road information adjustment process M70 according to the present embodiment is shown. Figure 7 The processing flow shown is realized by causing the CPU 42 to repeatedly execute a program stored in the ROM 44 at intervals of a predetermined cycle, for example. Figure 7 in Figure 3 Processes corresponding to the processes shown are referred to by the same step numbers.

[0088] exist Figure 7In the series of processing shown, when the processing of S10 is completed, the CPU 42 calculates the adjustment amount ΔTt* (S12a) by multiplying the estimated disturbance torque Tlde by "-1" and the coefficient α. Here, "-1" is set to exclude at least a part of the estimated disturbance torque Tlde from the angle operation amount Tt1*. That is, the angle operation amount Tt1* is "Ttff+Ttfb-Tlde-Th". Therefore, in order to remove all contributions of the estimated disturbance torque Tlde from the angle operation amount Tt1*, it is necessary to add the estimated disturbance torque Tlde to the angle operation amount Tt1*. On the other hand, in the subtraction processing M72, the adjustment amount ΔTt* is subtracted from the angle operation amount Tt1*. Therefore, since the adjustment amount ΔTt* needs to have a sign opposite to that of the estimated disturbance torque Tlde, in the processing of S12a, the value obtained by multiplying the estimated disturbance torque Tlde by "-1" is multiplied by the coefficient α.

[0089] When the vehicle speed V is equal to or higher than the predetermined speed Vth, the CPU 42 sets the coefficient α to "0", and when the vehicle speed V is lower than the predetermined speed Vth and the vehicle speed V is low, the CPU 42 calculates the coefficient α to a larger value than when the vehicle speed V is high. The coefficient α has a value from "0" to "1". Specifically, the CPU 42 performs mapping calculation on the coefficient α in a state in which mapping data with the vehicle speed V as an input variable and the coefficient α as an output variable is pre-stored in the ROM 44.

[0090] When the processing of S12a is completed, the CPU 42 temporarily terminates the Figure 7 The operation and advantages of this embodiment will be described below.

[0091] The CPU 42 calculates the adjustment amount ΔTt* based on the estimated disturbance torque Tlde. The estimated disturbance torque Tlde is an amount corresponding to the force applied to the turning wheel 12 in addition to the sum of the feedforward operation amount Ttff and the feedback operation amount Ttfb and the steering torque Th in achieving the current turning angle (pinion angle θp). Therefore, in the estimated disturbance torque Tlde, the ratio of the amount based on the road surface state is greater than the ratio of the amount based on the angle operation amount Tt1*. Therefore, by calculating the adjustment amount ΔTt*a based on the estimated disturbance torque Tlde, the driver can more appropriately understand the road surface state information.

[0092] Sixth Embodiment

[0093] Hereinafter, the sixth embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment.

[0094] Figure 8 Some of the processes performed by the rotation control system 40 according to the present embodiment are shown. Figure 8 The processing flow shown is achieved by causing the CPU 42 to repeatedly execute the program stored in the ROM 44. For convenience, Figure 8 in Figure 2 Processes corresponding to the processes shown are referred to by the same step numbers.

[0095] like Figure 8 As shown, in this embodiment, the steering operation amount Ts* output from the steering operation amount calculation process M16 is multiplied by the gain G through the gain multiplication process M84, and then the multiplication result is input to the addition process M74. Therefore, in this embodiment, the required torque Td is "G·Ts*+Tt*".

[0096] Fig. 9 The flow of the road information adjustment process M70 according to the present embodiment is shown. Fig. 9 The processing flow shown is realized by causing the CPU 42 to repeatedly execute a program stored in the ROM 44 at intervals of a predetermined cycle, for example. Fig. 9 in Figure 3 Processes corresponding to the processes shown are referred to by the same step numbers.

[0097] exist Fig. 9 In the series of processes shown, when the process of S12 is completed, the CPU 42 sets the gain G to be variable according to the vehicle speed V (S40). Specifically, when the vehicle speed V is equal to or higher than the predetermined speed Vth, the CPU 42 sets the gain G to "0", and when the vehicle speed V is lower than the predetermined speed Vth and the vehicle speed V is low, the CPU 42 sets the gain G to a larger value than when the vehicle speed V is high. The gain G has a value from "0" to "1". This is a process for suppressing the lack of torque required to control the turning angle.

[0098] When the processing of S40 is completed, the CPU 42 temporarily terminates the Fig. 9 The operation and advantages of this embodiment will be described below.

[0099] When the vehicle speed V is equal to or higher than the predetermined speed Vth, regardless of the steering operation amount Ts*, the CPU 42 determines the torque command value Tm* with the angle operation amount Tt* as the required torque Td and controls the torque for the electric motor 32. On the other hand, when the vehicle speed V is lower than the predetermined speed Vth, as the vehicle speed V decreases, the CPU 42 reduces the ratio of reflecting the angle operation amount Tt1* in the required torque Td, thereby enabling the driver to understand the road surface state information. In this case, there is a concern that the torque for the electric motor 32 is excessively reduced. In particular, when the coefficient α is close to "1", it is difficult to control the steering torque Th to the target steering torque Th*. Therefore, when the coefficient α is set to be small, the CPU 42 reflects the steering operation amount Ts* in the required torque Td.

[0100] Seventh embodiment

[0101] Hereinafter, the seventh embodiment will be described with reference to the drawings, focusing on the differences from the third embodiment.

[0102] Fig.10 1 shows the structure of the electric power steering system 10. For convenience, Fig.10 in Figure 1 Elements which correspond to the elements shown are denoted by the same reference numerals.

[0103] In the present embodiment, a clutch 60 is provided in the pinion shaft 24c, and the clutch 60 can cut off the power transmission to and from the steering wheel 22. That is, the pinion shaft 24c is connected to one end of the clutch 60, and the input shaft 24d connected to the steering wheel 22 is connected to the other end of the clutch 60. In the present embodiment, the input shaft 24d and the pinion shaft 24c are referred to as the steering shaft 24.

[0104] The power of the electric motor 72 is applied to the input shaft 24d via the reduction gear 70. The voltage of the inverter 74 is applied to the terminals of the electric motor 72. The resistance actuator 80 is composed of the input shaft 24d, the reduction gear 70, the electric motor 72 and the inverter 74. In the present embodiment, the rotation control system 40 refers to the rotation angle (steering angle θh) of the steering wheel 22 detected by the steering angle sensor 82.

[0105] Fig.11 Some processes performed by the electric control system 40 according to the present embodiment are shown. Fig.11 The processing flow shown is achieved by causing the CPU 42 to repeatedly execute the program stored in the ROM 44. For convenience, Fig.11 in Figure 2 Processes corresponding to the processes shown are referred to by the same step numbers.

[0106] like Fig.11 As shown, in the present embodiment, the command value of the steering angle (steering angle command value θh*) is calculated in the specification model calculation process M30 instead of the pinion angle command value θp*. On the other hand, the steering angle ratio change process M90 is a process of setting an offset Δa for changing the steering angle ratio, which is a ratio of a target value of the turning angle (pinion angle command value θp*) and a steering angle command value θh* that is variable based on the vehicle speed V. Specifically, the offset Δa is set so that the change in the turning angle caused by the change in the steering angle is greater when the vehicle speed V is low than when the vehicle speed V is high. The addition process M92 sets the pinion angle command value θp* by adding the offset Δa to the steering angle command value θh*.

[0107] The resistance calculation process M94 is a process for calculating the torque command value Tr* for the electric motor 72 as an operation amount for feedback control of the steering angle θh to the steering angle command value θh*. The operation signal generation process M96 is a process for operating the inverter 74 by outputting the operation signal MSs to the inverter 74 to control the torque for the electric motor 72 to the torque command value Tr*.

[0108] In the present embodiment, the steering torque compensation process M66 is not provided, and the angle operation amount Tt1* output from the angle operation amount calculation process M50 is the same as the angle operation amount Tt0*. In the present embodiment, the angle operation amount Tt* is the required torque Td. That is, in the present embodiment, the torque command value Tm* is calculated only based on the angle operation amount Tt*.

[0109] Correspondence

[0110] The angle command value calculation process corresponds to Figure 2 and Figure 8 The canonical model calculation process in M30 or Fig.11 The specification model calculation process M30, the steering angle ratio change process M90 and the addition process M92 in the embodiment. The convertible angle corresponds to the pinion angle θp. The operation process corresponds to Figure 2 and Figure 8 The addition process M74, the conversion process M76 and the operation signal generation process M78 in the Fig.11 The conversion process M76 and the operation signal generation process M78 in the adjustment process correspond to the process of S12, S12a, S24 or S32 to S34 and the subtraction process M72. The correction process corresponds to the subtraction process M20. The drive circuit corresponds to the inverter 33. This process corresponds to the process of S12a. When the gain G is "0", this process corresponds to Figure 8 The processing shown or Fig.11 The processing shown in FIG. This processing corresponds to the processing of S38 and S40. Figure 3 , Figure 7 and Fig. 9 The detection process corresponds to the processes of S22 and S24. That is, when the magnitude of |γe-γ| is large, it can be considered that a side slip is detected. The acquisition process corresponds to the process of S30. The target steering torque calculation process corresponds to the basic target torque calculation process M10, the addition process M12 and the hysteresis process M14.

[0111] Other Implementations

[0112] The embodiment can be modified as follows. The embodiment described above and the modified examples described below can be combined with each other as long as no technical contradiction occurs.

[0113] exist Fig.11 In the road information adjustment process M70, execute Figure 5 The processing flow shown in FIG. 1 is not limited to this. For example, the processing flow may be performed Figure 6 For example, when the coefficient α is set to a value less than "1", Figure 3 and Figure 7 The processing flow shown in FIG. 1 may be performed in the case where the coefficient β is set to a value less than “1”. Figure 4 The processing flow shown.

[0114] The correction process of correcting the magnitude of the axial force Taf as the input of the specification model calculation process M30 to be smaller when the magnitude of the adjustment amount ΔTt* is large than when the adjustment amount ΔTt* is small is not limited to the example described in the embodiment. For example, the adjustment amount ΔTt* may be superimposed on the target steering torque Th*. In this case, the magnitude of the steering operation amount Ts* may be reduced and the magnitude of the axial force Taf may be reduced.

[0115] For example, a sensor that detects the sideslip angle may be provided and the detection process may be configured using a process of acquiring a detection value from the sensor.

[0116] The acquisition process of acquiring the driver's request signal for determining whether to increase the magnitude of the adjustment amount ΔTt* is not limited to the process of acquiring the operation state of the mode selection switch 58. For example, a process of acquiring a signal associated with the operation state of an input device that inputs a driver's request as to whether to detect the road surface state information regardless of the rotation speed of the electric motor may be adopted.

[0117] For example, in Figure 3 , Figure 7 or Fig. 9In the processing flow shown, the processing of S40 can be performed when the coefficient α is "1", and the processing of S38 can be performed when the coefficient α is less than "1". Alternatively, the processing of S40 can be performed when the coefficient α is equal to or greater than a prescribed value, and the processing of S38 can be performed when the coefficient α is less than a prescribed value.

[0118] For example, in Figure 4 In the processing flow shown, the processing of S40 can be performed when the coefficient β is "1", and the processing of S38 can be performed when the coefficient β is less than "1". Alternatively, the processing of S40 can be performed when the coefficient β is equal to or greater than a prescribed value, and the processing of S38 can be performed when the coefficient β is less than a prescribed value.

[0119] exist Figure 2 In the processing flow shown, the sum of the angle operation amount Tt* and the steering operation amount Ts* is used as the required torque Td, but the present invention is not limited to this. For example, the angle operation amount Tt* can be used as the required torque Td. In this case, Figure 3 The coefficient α in the processing of S12 in Figure 4 The coefficient β in the process of S24 or Figure 7 The coefficient α in the process of S12a in is preferably set to a value smaller than "1".

[0120] exist Fig.11 In the processing flow shown in FIG. 1 , the angle operation amount Tt* is used as the required torque Td, but the present invention is not limited thereto. For example, the sum of the angle operation amount Tt* and the steering operation amount Ts* may be used as the required torque Td. Figure 8 In the processing flow shown, "Tt*+G·Ts*" can be used as the required torque Td.

[0121] In the above-described embodiment, the pinion angle command value θp* or the steering angle command value θh* is calculated using the axial force Taf as an input, but the present invention is not limited thereto, and for example, the steering operation amount Ts* may be used as an input. In the above-described embodiment, although the pinion angle command value θp* or the steering angle command value θh* is calculated using the axial force Taf as an input based on expression (c1) or the like, the logic (model) for calculating the pinion angle command value θp* or the steering angle command value θh* is not limited thereto.

[0122] For example, in Fig.11 In the illustrated processing flow, the steering angle ratio changing process M90 and the adding process M92 may be deleted, and the output of the specification model calculation process M30 may be used as the steering angle command value θh* or the pinion angle command value θp*.

[0123] In the above-described embodiment, the disturbance observer is constituted by a simple model in which the torque acting on the rotating wheel 12 is balanced with the torque proportional to the angular acceleration of the rotation angle, but the present invention is not limited thereto. For example, the disturbance observer may be constituted by a model in which the torque acting on the rotating wheel 12 is balanced with the sum of the torque proportional to the angular acceleration of the rotation angle and the torque proportional to the angular velocity of the rotation angle.

[0124] The method of calculating the estimated disturbance torque Tlde is not limited to the example described in the embodiment. Figure 2 In the processing flow shown, the estimated disturbance torque Tlde can be calculated by subtracting the angle operation amount Tt*, the steering operation amount Ts* and the steering torque Th from the value obtained by multiplying the second-order time differential value of the pinion angle command value θp* or the second-order time differential value of the pinion angle θp by the inertia coefficient Jp.

[0125] In the above embodiment, the feedforward operation amount Ttff is calculated based on the second-order time differential value of the pinion angle command value θp*, but the present invention is not limited to this, and for example, the feedforward operation amount Ttff can be calculated based on the second-order time differential value of the pinion angle θp or the second-order time differential value of the estimated value θpe.

[0126] In the above-described embodiment, the feedforward term is calculated by modeling the electric power steering system 10 using a simple model in which the torque acting on the rotating wheel 12 is balanced with the torque proportional to the angular acceleration of the rotation angle, but the present invention is not limited thereto. For example, the feedforward term may be calculated using a model in which the torque acting on the rotating wheel 12 is balanced with the sum of the torque proportional to the angular acceleration of the rotation angle and the torque proportional to the angular velocity of the rotation angle. This can be achieved, for example, by using the sum of the value obtained by multiplying the second-order time differential value of the pinion angle command value θp* by the inertia coefficient Jp and the value obtained by multiplying the first-order time differential value of the pinion angle command value θp* by the viscosity coefficient Cp as the feedforward operation amount Ttff. Here, the viscosity coefficient Cp of the proportional coefficient of the angular velocity is different from the viscosity coefficient C used in the specification model calculation process M30 in terms of its purpose, and the viscosity coefficient Cp of the proportional coefficient of the angular velocity is preferably obtained by modeling the actual behavior of the electric power steering system 10 with maximum accuracy.

[0127] The feedback control amount among the inputs of the feedback term calculation process M56 is not limited to the estimated value θpe or the first-order time differential value of the estimated value θpe. For example, the pinion angle θp or the time differential value of the pinion angle θp may be used instead of the estimated value θpe or the first-order time differential value of the estimated value θpe.

[0128] The feedback term calculation process M56 is not limited to the process of outputting the sum of the output value of the proportional element and the output value of the differential factor. For example, the output value of the proportional factor may be output, or, for example, the output value of the differential factor may be output. For example, the process of outputting the sum of at least one of the output value of the proportional factor and the output value of the differential factor and the output value of the integral factor may be adopted. When the output value of the integral factor is used, the disturbance observer is preferably deleted. Most importantly, when the output value of the integral factor is not used, the disturbance observer does not have to be used.

[0129] In the above embodiment, the pinion angle θp is used as the convertible angle, but the present invention is not limited thereto. For example, the rotation angle of the rotating wheel may be used.

[0130] In the above-described embodiment, the steering operation amount Ts* is converted into a torque for the steering shaft 24, but the present invention is not limited thereto. For example, the steering operation amount Ts* may be converted into a torque for the electric motor 32. In this case, for example, the sum of a value obtained by dividing the steering torque Th by the reduction gear ratio Km and the steering operation amount Ts* may be used as the axial force Taf0, or the sum of a value obtained by multiplying the steering operation amount Ts* by the reduction gear ratio Km and the steering torque Th may be used as the axial force Taf0.

[0131] In the above-described embodiment, the angle operation amount Tt* is converted into a torque for the steering shaft 24, but the present invention is not limited thereto. For example, the angle operation amount Tt* may be converted into a torque for the electric motor 32. Here, for example, when the steering operation amount Ts* is converted into a torque for the steering shaft 24, the sum of a value obtained by multiplying the angle operation amount Tt* by the reduction gear ratio Km and the steering operation amount Ts* may be used as the required torque Td.

[0132] The basic target torque calculation process is not limited to the process of calculating the basic target torque Thb* based on the axial force Taf0 and the vehicle speed V. For example, a process of calculating the basic target torque Thb* based only on the axial force Taf0 may be employed.

[0133] The process of correcting the basic target torque Thb* using the hysteresis correction amount Thys is not necessary. The rotation control system is not limited to a system including a CPU 42 and a ROM 44 and performing software processing. For example, a dedicated hardware circuit (e.g., ASIC) can be set to perform at least a part of the software processing performed in the above-mentioned embodiment in hardware. That is, the rotation control system can have at least one of the following structures (a) to (c). (a) A processor that performs all processing according to a program and a program storage device such as a ROM that stores the program are provided. (b) A processor, a program storage device, and a dedicated hardware circuit that performs other processing are provided that perform some processing in the processing according to the program. (c) A dedicated hardware circuit that performs all processing is provided. Here, the number of software processing circuits including a processor and a program storage device or the number of dedicated hardware circuits can be two or more. That is, the processing is performed only by a processing circuit that includes at least one of one or more software processing circuits and one or more dedicated hardware circuits.

[0134] The electric motor is not limited to SPMSM, but may be IPMSM or the like. The electric motor is not limited to a synchronous machine, but may be an induction machine. In addition, for example, the electric motor may be a DC electric motor with a brush. In this case, an H-bridge circuit may be used as a drive circuit.

[0135] The rotary actuator is not limited to the examples described in the embodiment. For example, a so-called double pinion type including a second pinion shaft that transmits the power of the electric motor 32 to the rack shaft 26 separately from the pinion shaft 24c may be adopted. For example, a configuration in which the output shaft 32a of the electric motor 32 is mechanically connected to the steering shaft 24 may be adopted. In this case, the rotary actuator shares the steering shaft 24 or the rack and pinion mechanism 27 with the steering mechanism.

[0136] For example, in Fig.10 In the embodiment, the input shaft 24d may be mechanically connected to the pinion shaft 24c via a gear ratio changing mechanism that changes the gear ratio instead of the clutch 60. In this case as well, the same processing as that described for the steer-by-wire type can be achieved.

Claims

1. A rotation control system (40), characterized in that: Including electronic control unit, wherein the rotation control system (40) operates a rotation actuator, the rotation actuator includes an electric motor incorporated into the rotation actuator, and the rotation actuator causes the rotation wheel to rotate, and The electronic control unit is configured to perform the following processing: a steering operation amount calculation process (M16) of calculating a steering operation amount, the steering operation amount being an operation amount that can be converted into a torque required by the electric motor and being an operation amount of the electric motor for rotating the steering wheel to control the steering torque input by the driver to a target steering torque by feedback control; an angle command value calculation process of calculating an angle command value based on the axial force calculated according to the steering operation amount, the angle command value being a command value of a convertible angle that can be converted into a rotation angle of the rotating wheel; an angle operation amount calculation process (M50) of calculating an angle operation amount, the angle operation amount being an operation amount that can be converted into a torque required by the electric motor and being an operation amount for controlling the convertible angle to the angle command value by feedback control; an operation process that operates a drive circuit of the electric motor to control the torque of the electric motor; an adjustment process of adjusting the size of a value obtained by subtracting the angle operation amount reflected in the operation process from the angle operation amount calculated in the angle operation amount calculation process (M50) and inputting the adjusted angle operation amount to the operation process; and A correction process is performed to correct the magnitude of the axial force used as input when calculating the angle instruction value in the angle instruction value calculation process so that the axial force when the magnitude of the subtraction value is small is greater than the axial force when the magnitude of the subtraction value is large.

2. The rotation control system (40) according to claim 1, characterized in that: The adjustment process is a process of adjusting a value within a range of 0 to 1 obtained by dividing the angle operation amount reflected in the operation process by the angle operation amount calculated in the angle operation amount calculation process (M50).

3. The rotation control system (40) according to claim 1, characterized in that: The angle operation amount calculation process (M50) is a process for calculating the angle operation amount based on the sum of a feedforward operation amount and an estimated disturbance torque, the feedforward operation amount being an operation amount for feedforward control of the angle command value, the estimated disturbance torque being an output of a disturbance observer based on a difference between the convertible angle and the angle command value, and Among them, the adjustment processing is a processing for adjusting the size of the input when calculating the angle command value in the angle command value calculation processing based on the value obtained by subtracting the estimated disturbance torque reflected in the operation processing from the estimated disturbance torque reflected in the output of the angle operation amount calculation processing (M50).

4. The rotation control system (40) according to any one of claims 1 to 3, characterized in that: The operation process includes a process of controlling the torque of the electric motor based on the angular operation amount regardless of the steering operation amount.

5. The rotation control system (40) according to any one of claims 1 to 3, characterized in that: The angle command value calculation process includes a change process of changing the relationship between the output and the input based on the size of the subtracted value.

6. The rotation control system (40) according to any one of claims 1 to 3, characterized in that: The adjustment process includes a process of reducing the magnitude of the subtracted value when the vehicle speed is high compared to a case in which the vehicle speed is low.

7. The rotation control system (40) according to any one of claims 1 to 3, characterized in that: The electronic control unit is configured to perform a detection process for detecting a sideslip of the vehicle, and The adjustment process includes a process of increasing the magnitude of the subtracted value when the side slip is detected in the detection process, compared to a case where the side slip is not detected in the detection process.

8. The rotation control system (40) according to any one of claims 1 to 3, characterized in that: The electronic control unit is configured to perform an acquisition process of acquiring a request signal from a driver, and The adjustment process includes a process of increasing the subtracted value based on the request signal acquired in the acquisition process.

9. The rotation control system (40) according to any one of claims 1 to 3, characterized in that: The electronic control unit is configured to execute a target steering torque calculation process of calculating the target steering torque based on a sum of amounts obtained by converting the steering operation amount and the steering torque into amounts of force acting on the same object.

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