Control device for a steering system

Abstract

A control device for a steering system (10) includes control circuitry configured to execute: an angle control process for controlling a convertible angle that is convertible to a rotation angle of a motor to an angle command value; a predetermined component calculation process for calculating a predetermined component that contains at least one of two components that are a viscosity component and a friction component of the steering system (10) when using a value of a variable related to a control amount of the motor as an input; and a relationship change process for changing a relationship of an output of a control unit for the steering system (10) to an input of the control unit based on the predetermined component calculated by the predetermined component calculation process.

Description

Technical Field

[0001] The present invention relates to a control device for a steering system, namely, a control device configured to control a steering system that steers the steering wheels of a vehicle and includes an electric motor. Background Technology

[0002] For example, Japanese Unexamined Patent Application Publication No. 2009-96265 (JP 2009-96265A) describes a control device that makes the gain of the auxiliary torque variable based on the torque transmitted from the steering wheel. Summary of the Invention

[0003] The frequency response characteristics of force relative to the displacement of the steering system typically exhibit viscosity, causing the gain to increase within a specific frequency range. Therefore, the controllability of controlling the rotation angle equivalent to the displacement of the steering system via the torque of the steering system's electric motor varies depending on the strength of the component within that specific frequency range. It should be noted that the viscosity component of the steering system can vary in amplitude depending on individual differences in the steering system, aging, and temperature. Therefore, it is difficult to pre-adapt the control unit for the steering system to optimally adapt to the viscosity component of the steering system.

[0004] The frequency component and viscosity component of the steering system can vary in amplitude depending on individual differences, aging, and temperature. Therefore, it is difficult to pre-adjust the control unit for the steering system to optimally adapt to the viscosity component of the steering system.

[0005] 1. One aspect of the present invention relates to a control device for a steering system. The steering system is configured to steer the steering wheels of a vehicle and includes an electric motor. The control device is configured to control the steering system. The control device includes a control circuit system configured to perform: angle control processing for controlling a convertible angle, which can be converted into a rotation angle of the electric motor, to an angle command value; predetermined component calculation processing for calculating a predetermined component when using the value of a variable related to the control quantity of the electric motor as input, the predetermined component including at least one of two components, a viscosity component and a friction component of the steering system; and relationship modification processing for changing the relationship between the output of a control unit for the steering system and the input of the control unit based on the predetermined component calculated by the predetermined component calculation processing.

[0006] In the aforementioned configuration, taking into account the fact that a predetermined component affects the control of the motor, the predetermined component is calculated when using the values ​​of variables related to the control quantity of the motor as input. Then, by changing the relationship between the input and output of the control unit for the steering system based on the predetermined component, the inconvenience caused by the difference in the controllability of the steering system when the predetermined component is large versus small can be compensated for.

[0007] 2. The predetermined component calculation process may include a viscosity component calculation process for calculating a viscosity component as a predetermined component, and the relationship change process may include the following process: the process is used to change the relationship between the output of the control unit for the steering system and the input of the control unit based on the viscosity component calculated by the viscosity component calculation process.

[0008] In the aforementioned configuration, considering the fact that the viscosity component affects the control of the motor, the viscosity component is calculated when using the values ​​of variables related to the control quantity of the motor as input. Then, by changing the relationship between the input and output of the control unit for the steering system based on the viscosity component, the inconvenience caused by the difference in the controllability of the steering system when the viscosity component is large versus small can be compensated for.

[0009] 3. The viscosity component calculation process may include the disturbance torque calculation process, which is used to calculate the torque component affecting the switchable angle, other than the motor torque, as the disturbance torque when using the values ​​of variables related to the motor torque, the detected value of the switchable angle, and the angle command value as the values ​​of variables related to the control quantity.

[0010] In the aforementioned configuration, considering that the torque component affecting the convertible angle, in addition to the motor torque, includes the viscosity component, the viscosity component can be calculated by using interference torque calculation processing.

[0011] 4. The viscosity component calculation process may include filtering to allow selective transmission of specific frequency components of the disturbance torque when using the disturbance torque as input, and the viscosity component calculation process may use the output of the filtering process as the viscosity component.

[0012] In the aforementioned configuration, considering the fact that the viscosity component is significant at a given frequency, when a specific frequency component is a frequency with a particularly large viscosity component, the viscosity component can be accurately calculated by using the output of the filtered process as the viscosity component.

[0013] 5. The filtering process may include intensity change processing: Intensity change processing is used to change the intensity of the output according to the temperature of the steering system, even if the input of the filtering process remains unchanged.

[0014] The intensity of the viscosity component varies with the temperature of the steering system. Therefore, even without performing intensity-changing processing as in the aforementioned configuration, the intensity of the filter output varies depending on the temperature of the steering system. It should be noted that in the aforementioned configuration, the intensity of the filter output is arbitrarily changed based on the temperature of the steering system. Therefore, compared to not using intensity-changing processing, it is easier to increase the degree of freedom in changing the relationship based on the filter output through relationship-changing processing.

[0015] 6. The convertible angle can be an angle that can be converted into the steering angle (turning angle) of the steering wheel. In the aforementioned configuration, the viscosity to be calculated using viscosity component calculation refers to the viscosity relating to the frequency response characteristics between the turning angle and the torque of the electric motor configured to steer the steering wheel. Therefore, in the aforementioned configuration, the influence on the controllability of the steering system caused by the effect of viscosity on the controllability of the turning angle can be compensated.

[0016] 7. The control unit can be a control unit configured to control the convertible angle to an angle command value. In the aforementioned configuration, by changing the relationship between the input and output of the control unit for the turning angle through relational change processing, the decrease in the controllability of the turning angle due to viscosity can be appropriately suppressed.

[0017] 8. The steering system may include a steering wheel that can be moved without transmitting power to the steering wheels. In the aforementioned configuration, the steering wheel can be moved without transmitting power to the steering wheels, and therefore, the reduction in controllability of the turning angle due to viscosity may not be transmitted to the steering wheel. In this case, the driver may experience discomfort, for example, they may feel a decrease in the consistency between steering wheel operation and steering wheel steering. As a countermeasure, in the above configuration, the reduction in consistency can be suppressed by compensating for the reduction in controllability of the turning angle due to viscosity through relational change processing.

[0018] 9. The steering system may include a steering wheel that can be moved without transmitting power to the steering wheels. The electric motor may be a steering-side electric motor. The steering system may include a steering-side electric motor configured to apply torque resisting the movement of the steering wheel. The control unit may be a control unit configured to control the torque of the steering-side electric motor.

[0019] In the aforementioned configuration, the steering wheel can be displaced without transmitting power to the steering wheels, and therefore, the reduced controllability of the turning angle due to viscosity may not be transmitted to the steering wheel. In this situation, the driver may experience discomfort, for example, feeling a decrease in the consistency between steering wheel operation and steering wheel steering. As a countermeasure, in the aforementioned configuration, the relationship between the input and output of the control unit configured to control the torque of the steering-side electric motor can be altered by means of relationship-changing processing to apply torque that resists steering wheel displacement and suppresses the decrease in consistency.

[0020] 10. The steering system may include a steering wheel that can be moved without transmitting power to the steering wheels. The electric motor may be a steering-side electric motor configured to apply torque resisting the movement of the steering wheel.

[0021] In the aforementioned configuration, the viscosity calculated via viscosity component calculation refers to the viscosity relating the frequency response characteristics between the torque of the steering-side motor (configured to rotate and shift the steering wheel) and the steering angle (as the steering wheel's rotation angle). On the other hand, in the aforementioned configuration, the steering wheel can be shifted without transmitting power to the steering wheels, and therefore, the reduction in controllability of the steering angle due to viscosity may not be transmitted to the steering wheels. In this situation, the driver may experience discomfort, for example, feeling a decrease in the consistency between steering wheel operation and steering wheel steering. As a countermeasure, in the aforementioned configuration, the decrease in consistency between steering wheel operation and steering wheel steering can be suppressed through relationship-changing processing.

[0022] 11. The control unit may be a control unit configured to control the torque of the steering-side motor. In the aforementioned configuration, by changing the relationship between the input and output of the control unit configured to control the torque of the steering-side motor through relational change processing, it is possible to suppress the torque generated by the steering-side motor for the operation relative to the steering wheel from deviating from an appropriate value due to viscosity.

[0023] 12. The steering system may include a rotation-side electric motor configured to steer the steering wheels, and the control unit may be a control unit configured to control the torque of the rotation-side electric motor.

[0024] In the aforementioned configuration, by altering the relationship between the input and output of the control unit configured to control the torque of the rotary side motor through relational change processing, the decrease in consistency between steering wheel operation and steering wheel steering can be suppressed. Attached Figure Description

[0025] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which similar reference numerals denote similar elements, and wherein:

[0026] Figure 1 This is a diagram showing the control device and steering system according to the first embodiment;

[0027] Figure 2 This is a block diagram illustrating the process performed by the control device according to an embodiment;

[0028] Figure 3 This is a graph showing the frequency response characteristics of the steering system according to an embodiment;

[0029] Figure 4 This is a flowchart illustrating the process performed by the control device according to the embodiment;

[0030] Figure 5 This is a block diagram illustrating the process performed by the control device according to the second embodiment;

[0031] Figure 6 This is a block diagram illustrating the process performed by the control device according to the third embodiment;

[0032] Figure 7 This is a flowchart illustrating the process performed by the control device according to the embodiment;

[0033] Figure 8 This is a block diagram illustrating the process performed by the control device according to the fourth embodiment; and

[0034] Figure 9 This is a block diagram illustrating the process performed by the control device according to the fifth embodiment. Detailed Implementation

[0035] First Implementation Method

[0036] The first embodiment of the control device for a steering system will now be described with reference to the accompanying drawings.

[0037] like Figure 1 As shown, the steering system 10 includes a steering mechanism 20, a rotation actuator 50 for steering the steering wheel 42, and the steering wheel 42. The steering mechanism 20 includes a steering wheel 22, a resistance actuator 30 that applies resistance as a force against the driver's operation on the steering wheel 22, a rack-and-pinion mechanism 27, and a clutch 24 between an input shaft 32 that rotates integrally with the steering wheel 22 and the rack-and-pinion mechanism 27.

[0038] The drag actuator 30 includes an input shaft 32, a reducer 34, a steering-side motor 36, and an inverter 38, and applies power from the steering-side motor 36 to the input shaft 32 via the reducer 34. In this embodiment, a three-phase surface magnet synchronous motor (SPMSM) is used as an example of the steering-side motor 36. The rack and pinion mechanism 27 includes a pinion shaft 26 and a rack shaft 28 mechanically coupled to the input shaft 32 via a clutch 24, and converts the rotational power of the pinion shaft 26 into axial displacement of the rack shaft 28. The clutch 24 is engaged to transmit power from the input shaft 32 to the pinion shaft 26, and is released to disconnect the power transmission between the input shaft 32 and the pinion shaft 26. When the clutch 24 is engaged, the rotational power of the steering wheel 22 is converted into axial displacement of the rack shaft 28. This axial displacement is transmitted to the steering wheel 42 via levers 40 coupled to both ends of the rack shaft 28. Therefore, the turning angle of the steering wheel 42 changes.

[0039] On the other hand, the rotary actuator 50 shares the rack shaft 28 with the steering mechanism 20, and the rotary actuator 50 includes a rotary-side motor 52, an inverter 54, a ball screw mechanism 56, and a belt reduction mechanism 58. The rotary-side motor 52 is the source of power for generating the power to steer the steering wheel 42. In this embodiment, a three-phase surface magnet synchronous motor (SPMSM) is used as an example of the rotary-side motor 52. The ball screw mechanism 56 is integrally attached to the periphery of the rack shaft 28, and the belt reduction mechanism 58 transmits the rotational force of the output shaft 52a of the rotary-side motor 52 to the ball screw mechanism 56. The rotational force of the output shaft 52a of the rotary-side motor 52 is converted via the belt reduction mechanism 58 and the ball screw mechanism 56 into a force for linearly moving the rack shaft 28 in a reciprocating manner in the axial direction. The steering wheel 42 can be steered by the axial force applied to the rack shaft 28.

[0040] The control device 60 is configured to control the steering system 10 and operates the rotary actuator 50 to control the turning angle, which is a control quantity of the steering system 10. With the clutch 24 in the released state, the control device 60 controls the steering system 10 and operates the resistance actuator 30 to control the resistance, which is a control quantity of the steering system 10. When controlling the control quantity, the control device 60 references the steering torque Th, which is the torque detected by the torque sensor 70 (input by the driver via the steering wheel 22), the rotation angle θs of the rotation shaft of the steering-side motor 36, detected by the steering-side rotation angle sensor 72, and the vehicle speed V, detected by the vehicle speed sensor 74. The control device 60 references the temperature TS of the steering system 10, detected by the temperature sensor 76, and the rotation angle θt of the output shaft 52a, detected by the rotation angle sensor 78. It should be noted that the temperature TS can be the temperature of the rotary-side motor 52, the temperature of the steering-side motor 36, the temperature of the inverter 54 or 38, the temperature of the ball screw mechanism 56, etc. Temperature sensor 76 is attached to control device 60, and control device 60 is positioned close to steering system 10; therefore, the temperature of control device 60 can be considered the temperature of steering system 10. Control device 60 references the currents ius, ivs, and iws flowing through steering-side motor 36 and the currents iut, ivt, and iwt flowing through steering-side motor 52. Currents ius, ivs, and iws can be detected as voltage drops at shunt resistors respectively located in the branch of inverter 38, and currents iut, ivt, and iwt can be detected as voltage drops at shunt resistors respectively located in the branch of inverter 54.

[0041] The control device 60 includes a CPU 62, a ROM 64, and peripheral circuitry 66, which can communicate with each other via a local area network 68. The peripheral circuitry 66 includes circuitry for generating clock signals that define internal operations, power supply circuitry, reset circuitry, etc. In other words, the control device 60 includes a control circuitry system.

[0042] Figure 2 This illustrates some processes performed by control device 60. These are implemented by CPU 62 executing programs stored in ROM 64. Figure 2 The process is shown. It is executed when clutch 24 is released. Figure 2 The processing is shown.

[0043] The base target torque calculation process M10 is used to calculate the base target torque Thb* based on the axial force Taf, which will be described later. The base target torque Thb* is the base value of the target steering torque Th* input by the driver via the steering wheel 22 to the input shaft 32. It should be noted that the axial force Taf is the force applied to the rack shaft 28 in the axial direction. The axial force Taf is a quantity corresponding to the lateral force acting on the steering wheel 42, and therefore, the lateral force can be determined based on the axial force Taf. On the other hand, it is desirable to determine the torque input by the driver via the steering wheel 22 to the input shaft 32 based on this lateral force. Therefore, the base target torque calculation process M10 is used to calculate the base target torque Thb* based on the lateral force determined by the axial force Taf.

[0044] More specifically, the base target torque calculation process M10 is as follows: the process calculates the base target torque Thb* such that the absolute value of the base target torque Thb* is smaller at low vehicle speeds V than at high vehicle speeds V, even when the absolute value of the axial force Taf remains constant. This can be achieved, for example, by a mapping calculation of the base target torque Thb* performed by the CPU 62 with mapping data pre-stored in ROM 64, the mapping data including the axial force Taf as an input variable or the lateral acceleration and vehicle speed V determined based on the axial force Taf, and the base target torque Thb* as an output variable. It should be noted that the mapping data is set data including discrete values ​​of the input variables and values ​​of output variables corresponding to the values ​​of the input variables. The mapping calculation can be, for example, the process using the corresponding value of the output variable in the mapping data as the calculation result when the value of the input variable matches the value of the input variable in the mapping data, and using the value obtained by interpolating the value of the output variable contained in the mapping data as the calculation result when the value of the input variable does not match the value of the input variable in the mapping data.

[0045] Addition processing M12 is used to calculate the target steering torque Th* by adding the hysteresis correction amount Thys to the base target torque Thb*. Hysteresis processing M14 is used to calculate and output the hysteresis correction amount Thys for correcting the base target torque Thb* based on the pinion angle θp, where θp is a convertible angle that can be converted into the turning angle of the steering wheel 42. More specifically, hysteresis processing M14 includes the following process: the process is used to identify whether the steering wheel 22 is turning in one direction or turning back in another direction based on changes in the pinion angle θp, etc., and calculates the hysteresis correction amount Thys such that the absolute value of the target steering torque Th* is greater when the steering wheel 22 is turning in one direction than when the steering wheel 22 is turning back in another direction. More specifically, hysteresis processing M14 includes the process of variably setting the hysteresis correction amount Thys according to the vehicle speed V. The pinion angle θp is the rotation angle of the pinion shaft 26.

[0046] Steering operation calculation process M16 is used to calculate the steering operation amount Ts*, which is the operation amount used to control the steering torque Th to the target steering torque Th* via feedback. The steering operation amount Ts* includes the operation amount used to control the steering torque Th to the target steering torque Th* via feedback, but may include feedforward terms. The steering operation amount Ts* is converted into the amount of torque that needs to be applied to the input shaft 32 when controlling the steering torque Th to the target steering torque Th* via feedback.

[0047] The axial force calculation process M18 is used to calculate the axial force Taf by adding the steering torque Th to the steering operation amount Ts*. In this embodiment, the steering torque Th is the torque applied to the input shaft 32, and therefore, the axial force Taf is a value obtained by converting the force applied in the axial direction of the rack shaft 28 into the torque applied to the input shaft 32, assuming that the clutch 24 is engaged.

[0048] The standard model calculation process M20 is used to calculate the steering angle command value θh* as the command value of the steering angle θh based on the axial force Taf. More specifically, the standard model calculation process M20 is used to calculate the steering angle command value θh* by using the model equation expressed as equation (c1) shown below.

[0049] Taf=K·θh*+C·θh*'+J·θh*”...(c1)

[0050] The model represented by equation (c1) above is a model of the value indicated by the steering angle θh when a torque quantitatively equal to the axial force Taf is input to the input shaft 32 when the clutch 24 is engaged. In equation (c1) above, the viscosity coefficient C is a model of the viscosity of the steering system 10, the inertia coefficient J is a model of the inertia of the steering system 10, and the elasticity coefficient K is a model of the specifications (e.g., suspension and wheel alignment) of the vehicle equipped with the steering system 10. This model is not a model that precisely represents the actual steering system 10, but is designed as a specification model that idealizes the behavior relative to the input steering angle. In this embodiment, the steering feel can be adjusted by designing the specification model.

[0051] More specifically, in subtraction process M22, the viscosity term "C·θh*" and the elastic term "K·θh*" are subtracted from the axial force Taf. The output of subtraction process M22 is divided by the inertia coefficient J using inertia coefficient division process M24, and the steering angle acceleration command value αh* (=θh*”) is calculated. Then, using the steering angle acceleration command value αh* as input, the steering angle velocity command value ωh* (=θh*’) is calculated using integration process M26. Using the steering angle velocity command value ωh* as input, the steering angle command value θh* is calculated using integration process M28.

[0052] Viscosity coefficient multiplication processing M30 is used to calculate the viscosity term "C·θh*'" by multiplying the steering angle command value ωh* by the viscosity coefficient C. Elasticity coefficient multiplication processing M32 is used to calculate the elasticity term "K·θh*" by multiplying the steering angle command value θh* by the elasticity coefficient K.

[0053] Steering angle calculation processing M40 is a process for calculating the steering angle θh, which is the rotation angle of the steering wheel 22, based on the integral processing of the rotation angle θs (i.e., the process of integrating the rotation angle θs). Resistance calculation processing M42 is a process for calculating the torque of the steering-side motor 36 (as an operational amount used to control the steering angle θh to the steering angle command value θh* via feedback) as a resistance command value Tr*. Operation signal generation processing M44 generates an operation signal MSs for operating the inverter 38 and outputs the generated operation signal MSs to the inverter 38 to control the torque of the steering-side motor 36 to the resistance command value Tr*. More specifically, operation signal generation processing M44 is a process for operating the output line voltage of the inverter 38 by an operational amount—for controlling the currents ius, ivs, and iws flowing through the steering-side motor 36 to a command value determined according to the resistance command value Tr*.

[0054] The variable steering angle ratio processing M46 is a process for variably setting an adjustment amount Δθa (which is the ratio of the pinion angle command value θp* to the steering angle command value θh*) based on the vehicle speed V. More specifically, the adjustment amount Δθa is set such that the change in the pinion angle command value θp* relative to the change in the steering angle command value θh* is greater at lower vehicle speeds V than at higher vehicle speeds V. In the additive processing M48, the pinion angle command value θp* is set by adding the adjustment amount Δθa to the steering angle command value θh*.

[0055] The pinion angle calculation process M50 is used to calculate the pinion angle θp based on the cumulative processing of the rotation angle θt of the rotating side motor 52. When it equals "0", the pinion angle θp indicates that the vehicle is going straight. Depending on whether the sign of the pinion angle θp is positive or negative, the pinion angle θp indicates a turning angle to the right or to the left.

[0056] The rotation operation amount calculation process M60 is used to calculate the rotation operation amount Tt*, which is the operation amount used to control the pinion angle θp to the pinion angle command value θp* via feedback. The rotation operation amount Tt* is a quantity corresponding to the required torque of the rotating side motor 52 (i.e., the torque required by the rotating side motor 52) when the pinion angle θp is controlled to the pinion angle command value θp* via feedback. In this embodiment, the rotation operation amount Tt* is converted into the amount of torque applied to the pinion shaft 26 assuming that torque is applied to the pinion shaft 26.

[0057] The rotation operation amount calculation process M60 includes an interference torque calculation process M62. The interference torque calculation process M62 estimates the torque affecting the pinion angle θp, other than the rotation operation amount Tt*, as the interference torque, and uses this value as the estimated interference torque Tlde. In this embodiment, assuming that the interference torque is applied to the pinion shaft 26, the estimated interference torque Tlde is converted into the torque applied to the pinion shaft 26.

[0058] In the disturbance torque calculation process M62, the estimated disturbance torque Tlde and the estimated value θpe are calculated according to equation (c2) shown below, using the inertia coefficient Jp, pinion angle θp, rotational operation amount Tt*, and a 3x1 matrix L specifying the observer gains l1, l2, and l3. The inertia coefficient Jp is a model of the inertia of the steering system 10 and is a value that represents the actual inertia of the steering system 10 with higher accuracy compared to the inertia coefficient J.

[0059]

[0060]

[0061] The differential calculation processing M64 is used to calculate the pinion angular velocity command value by performing differential calculations on the pinion angular command value θp*.

[0062] The feedback term calculation process M66 is used to calculate the feedback term Ttfb. The feedback term Ttfb is the sum of the proportional term corresponding to the difference between the pinion angle command value θp* and the estimated value θpe, and the differential term corresponding to the difference between the first-order time derivative of the pinion angle command value θp* and the estimated value θpe.

[0063] The second-order differential processing M68 is used to calculate the second-order time differential value of the pinion angle command value θp*. The feedforward calculation processing M70 is used to calculate the feedforward term Ttff by multiplying the output value of the second-order differential processing M68 by the inertia coefficient Jp. The two-degree-of-freedom maneuver calculation processing M72 is used to calculate the rotational maneuver Tt* by subtracting the estimated disturbance torque Tlde from the sum of the feedback term Ttfb and the feedforward term Ttff.

[0064] The conversion process M80 is used to convert the rotation operation amount Tt* into a torque command value Tm* (as a command value of the torque of the rotation side motor 52) by dividing the rotation operation amount Tt* by the reduction ratio Kt.

[0065] The operation signal generation process M82 is a process for generating and outputting an operation signal MSt for the inverter 54 to control the torque of the rotating-side motor 52 to the torque command value Tm*. More specifically, the operation signal generation process M82 is a process for operating the output line voltage of the inverter 54 by an operation quantity—for controlling the currents iut, ivt, and iwt flowing through the rotating-side motor 52 to the command value of the current determined according to the torque command value Tm*. In fact, the operation signal MSt is the operation signal for each arm at each branch of the inverter 54.

[0066] The bandpass filter M90 performs processing to extract specific frequency components of the estimated interference torque Tlde when using it as input. These specific frequency components will now be described. Figure 3 The frequency response characteristics of the steering system 10 are shown. More specifically, in the case where the input to the steering system 10 is a displacement, such as a change in steering angle, and the output of the steering system 10 is the torque of the turn-side motor 52 (i.e., the force required for that displacement), Figure 3 The horizontal axis in the diagram represents the frequency f, and Figure 3 The vertical axis in the graph represents the gain G. For example... Figure 3As shown, the gain G is large when the frequency is between the lower limit frequency fL and the upper limit frequency fH. This is due to the viscosity of the steering system 10. Furthermore, the large gain G caused by viscosity means that the response of the steering angle to the torque of the turning-side motor 52 is low.

[0067] When extracting the viscosity component of the steering system 10, it is desirable to set the center frequency that allows passage through the bandpass filter M90 to, for example, "7Hz to 9Hz". Furthermore, it is desirable to set the bandwidth to, for example, "4Hz to 6Hz".

[0068] Refer again Figure 2 The relationship change processing M92 is a process used to change the gain of the feedback term calculation processing M66 based on the viscosity component Tc output by the bandpass filter M90. Figure 4 The process of relational change processing M92 and feedback term calculation processing M66 is shown. In the following description, the step number of the corresponding processing is indicated by a number preceded by "S".

[0069] exist Figure 4 In the series of processing steps shown, CPU 62 first acquires the viscosity component Tc (S10). Then, CPU 62 variably sets the feedback term based on the viscosity component Tc to calculate the proportional gain Ktp and differential gain Ktd in processing M66 (S12). It should be noted that CPU 62 sets the proportional gain Ktp and differential gain Ktd in such a way that the responsiveness of the pinion angle θp to changes in the pinion angle command value θp* is higher when the viscosity component Tc is large than when the viscosity component Tc is small. The processing steps S10 and S12 correspond to the relational change processing M92.

[0070] Subsequently, CPU 62 substitutes the sum of the following values ​​into the feedback term Ttfb (S14): the value obtained by multiplying the difference between the pinion angle instruction value θp* and the estimated value θpe by the proportional gain Ktp, and the value obtained by multiplying the difference between the first-order time derivative of the pinion angle instruction value θp* and the estimated value θpe by the differential gain Ktd. This process corresponds to the feedback term calculation process M66.

[0071] When S14 finishes processing, CPU 62 terminates. Figure 4 The following describes a series of processing steps. The operation and effects of this implementation will now be described.

[0072] The CPU 62 sets the steering angle command value θh* and pinion angle command value θp* based on the standard model. It controls the steering angle θh to the steering angle command value θh* through feedback, and also controls the pinion angle θp to the pinion angle command value θp* through feedback. It should be noted that the rotational operation quantity Tt*, which is the amount of operation used to control the pinion angle θp to the pinion angle command value θp*, is obtained by subtracting the estimated disturbance torque Tlde from the feedforward term Ttff and the feedback term Ttfb. It should also be noted that the feedforward term Ttff is a quantity used to compensate for the inertia of the steering system 10, not a quantity used to compensate for the viscosity of the steering system 10. Therefore, the estimated disturbance torque Tlde includes the viscosity component of the steering system 10.

[0073] When using the output value of the bandpass filter M90 (to which the estimated disturbance torque Tlde is input) as the viscosity component Tc, the CPU 62 variably sets the feedback term to calculate the proportional gain Ktp and differential gain Ktd of the processing M66 based on the viscosity component Tc. Therefore, when the viscosity component Tc is large, the reduced responsiveness of the pinion angle θp to changes in the pinion angle command value θp* can be suppressed.

[0074] Based on the embodiment described above, the following operations and effects are further obtained. (1) A so-called steer-by-wire system that can cut off the power transmission between the steering wheel 22 and the steering wheel 42 is used as the steering system 10. In this case, when the responsiveness of the pinion angle θp to the change of the pinion angle command value θp* is reduced due to the viscosity of the steering system 10, the steering of the steering wheel 42 becomes less responsive to the operation of the steering wheel 22. Therefore, the driver may feel uncomfortable; for example, the driver may feel a decrease in the consistency between the operation of the steering wheel 22 and the steering of the steering wheel 42. Therefore, the practical value of processing for variably setting the proportional gain Ktp and the derivative gain Ktd based on the viscosity component Tc is particularly great.

[0075] Second Implementation Method

[0076] In the following description, the second embodiment will be described with reference to the accompanying drawings, focusing on the differences from the first embodiment.

[0077] Figure 5 The process performed by the control device 60 according to this embodiment is shown. For convenience, it is compared with... Figure 2 The corresponding processing shown is in Figure 5 The same reference numerals are used to represent them respectively. For example, Figure 5 As shown, in this embodiment, the CPU 62 makes the filtering characteristics of the bandpass filter M90 variable according to the temperature TS. More specifically, the intensity of the viscosity component Tc is made higher at a lower temperature TS than at a higher temperature TS.

[0078] This is based on the fact that when the temperature is low, the lubricant used in the steering system 10, such as grease, solidifies and becomes highly viscous. The bandpass filter M90 makes the output value larger when the intensity of the viscosity component included in the estimated disturbance torque Tlde is high than when the intensity of the viscosity component included in the estimated disturbance torque Tlde is low. Therefore, even when the filter characteristics are not variable, the intensity of the viscosity component Tc output by the bandpass filter M90 is higher when the temperature TS is low than when the temperature TS is high. In contrast, according to this embodiment, the filter characteristics are made variable according to the temperature TS, and the intensity of the viscosity component Tc when the temperature TS is low is higher than when the filter characteristics are not variable. Therefore, when the temperature TS is low, the feedback term Ttfb in the feedback term calculation process M66 can be changed to a value for further improving the responsiveness of the pinion angle θp to changes in the pinion angle command value θp*.

[0079] Third Implementation Method

[0080] In the following description, the third embodiment will be described with reference to the accompanying drawings, focusing on the differences from the first embodiment.

[0081] Figure 6 The process performed by the control device 60 according to this embodiment is shown. For convenience, it is compared with... Figure 2 The corresponding processing shown is in Figure 6 The same reference numerals are used to represent them respectively. For example, Figure 6 As shown, in this embodiment, the relationship change processing M92 is a process used to change the gain in the resistance calculation processing M42 (rather than the gain in the feedback term calculation processing M66).

[0082] Figure 7 The process of relational change processing M92 and resistance calculation processing M42 is shown. For convenience, [the following is omitted]. Figure 7 The shown and Figure 4 The processing content in the code is represented by the same step number. Figure 7 In the series of processing steps shown, when processing S10 is completed, CPU 62 variably sets the proportional gain Khp, differential gain Khd, and integral gain Khi (S12a) in the resistance calculation processing M42 based on the viscosity component Tc. CPU 62 sets the proportional gain Khp, differential gain Khd, and integral gain Khi so that the responsiveness of the steering angle θh to changes in the steering angle command value θh* is lower when the viscosity component Tc is large than when the viscosity component Tc is small. Processes S10 and S12a correspond to the relationship change processing M92.

[0083] Subsequently, CPU 62 substitutes the following values ​​into the drag command value Tr*: the value obtained by multiplying the difference between the steering angle command value θh* and the steering angle θh by the proportional gain Khp; the value obtained by multiplying the difference between the first-order time derivative of the steering angle command value θh* and the first-order time derivative of the steering angle θh by the differential gain Khd; and the integral value obtained by multiplying the difference between the steering angle command value θh* and the steering angle θh by the integral gain Khi (S20). This process corresponds to the drag calculation process M42.

[0084] When S20 finishes processing, CPU 62 terminates. Figure 7 The following describes a series of processing steps. The operation and effects of this implementation will now be described.

[0085] The CPU 62 sets a gain in the resistance calculation processing M42 such that when the viscosity component Tc is large, the responsiveness of the steering angle θh to changes in the steering angle command value θh* decreases. Therefore, when the viscosity of the steering system 10 causes a decrease in the responsiveness of the pinion angle θp to changes in the pinion angle command value θp*, the resistance to the operation of the steering wheel 22 can be increased. This allows the driver to be notified that a greater force is needed to steer the steering wheel 42. Furthermore, the driver can perform the operation of turning the steering wheel 22 without perceiving a decrease in the consistency between this operation and the steering of the steering wheel 42.

[0086] Fourth Implementation Method

[0087] In the following description, the fourth embodiment will be described with reference to the accompanying drawings, focusing on the differences from the first embodiment.

[0088] Figure 8 The process performed by the control device 60 according to this embodiment is shown. For convenience, it is compared with... Figure 2 The corresponding processing shown is in Figure 8 The same reference numerals are used to represent them respectively. For example, Figure 8 As shown, the bandpass filter M90 according to this embodiment performs a process for outputting the viscosity component included in the resistance command value Tr* as a viscosity component Tc when using the resistance command value Tr* as input. The relationship change process M92 is a process for variably setting the gain in the resistance calculation process M42 based on the viscosity component Tc included in the resistance command value Tr*.

[0089] According to this embodiment, the relationship change processing M92 and the resistance calculation processing M42 are respectively related to... Figure 7The relationship change processing and resistance calculation processing shown are the same. However, it should be noted that in the processing of S12a, the CPU 62 sets the proportional gain Khp, differential gain Khd, and integral gain Khi in a way that limits the reduced responsiveness of the steering angle θh to changes in the steering angle command value θh* due to the viscosity component Tc.

[0090] That is, when the displacement of the steering wheel 22 due to viscosity is small relative to the torque input to the steering wheel 22, and the pinion angle θp is highly responsive to changes in the pinion angle command value θp*, the driver may experience discomfort. For example, the driver may feel a decrease in the consistency between the operation of the steering wheel 22 and the steering of the steering wheel 42. As a countermeasure to this, in this embodiment, by suppressing the decrease in the responsiveness of the steering angle θh to changes in the steering angle command value θh* due to the viscosity component Tc, driver discomfort can be suppressed.

[0091] Fifth Implementation Method

[0092] In the following description, the fifth embodiment will be described with reference to the accompanying drawings, focusing on the differences from the fourth embodiment.

[0093] Figure 9 The process performed by the control device 60 according to this embodiment is shown. For convenience, it is compared with... Figure 8 The corresponding processing shown is in Figure 9 The same reference numerals are used to denote the components. In this embodiment, the relationship change process M92 is a process used to variably set the gain in the feedback term calculation process M66 based on the viscosity component Tc of the resistance command value Tr*. According to this embodiment, the relationship change process M92 and the feedback term calculation process M66 are respectively related to... Figure 4 The relationship change processing and feedback term calculation processing shown are the same. However, it should be noted that the CPU 62 changes the gain so that the responsiveness of the pinion angle θp to changes in the pinion angle instruction value θp* is lower when the viscosity component Tc is large than when the viscosity component Tc is small.

[0094] That is, when the displacement of the steering wheel 22 due to viscosity is small relative to the torque input to the steering wheel 22, and the pinion angle θp is highly responsive to changes in the pinion angle command value θp*, the driver may experience discomfort. For example, the driver may feel a decrease in the consistency between the operation of the steering wheel 22 and the steering of the steering wheel 42. As a countermeasure to this, in this embodiment, when the displacement of the steering wheel 22 due to viscosity is small relative to the torque input to the steering wheel 22, the responsiveness of the pinion angle θp to changes in the pinion angle command value θp* can be reduced. Therefore, driver discomfort can be suppressed.

[0095] Correspondence

[0096] The correspondence between the items in the foregoing embodiments and the items described in the "Summary of the Invention" section is as follows. A correspondence is described for each number mentioned in the "Summary of the Invention" section.

[0097] [1] Angle control processing corresponds to Figure 2 , Figure 5 and Figure 6 The calculation and processing of rotational operation quantity in M60 and Figure 8 and Figure 9 The resistance calculation process is M42. The predetermined component calculation process corresponds to the disturbance torque calculation process M62 and the bandpass filter M90. [2, 3] The viscosity component calculation process corresponds to the disturbance torque calculation process M62 and the bandpass filter M90. [4] The filtering process corresponds to the disturbance torque calculation process M62 and the bandpass filter M90. [5] This corresponds to Figure 5 The processing. [6] The convertible angle corresponds to the pinion angle θp. [7] The control unit corresponds to the rotation operation amount calculation processing M60, the conversion processing M80, and the operation signal generation processing M82. [8] This corresponds to the configuration in which the power between the steering wheel 22 and the steering wheel 42 can be cut off by the clutch 24. [9] The control unit corresponds to the resistance calculation processing M42 and the operation signal generation processing M44.

[10] This corresponds to Figure 8 and Figure 9

[11] The control unit corresponds to the resistance calculation process M42 and the operation signal generation process M44.

[12] The control unit corresponds to the rotation operation amount calculation process M60, the conversion process M80 and the operation signal generation process M82.

[0098] Other implementation methods

[0099] This implementation can be performed after making the following modifications. This implementation and the following modified examples can be combined and implemented without technical inconsistencies.

[0100] Regarding the handling of relationship changes

[0101] The processing for changing the relationship between the input and output of the control unit configured to control the rotary side motor 52 is not limited to the processing described in the foregoing embodiments. For example, a filter can be provided downstream of the addition process M48, and the time constant of the filter can be variably set according to the viscosity component Tc. Therefore, the delay in the responsiveness of the pinion angle θp to the change in the output value of the addition process M48 can be compensated by, for example, advancing the phase of the pinion angle command value θp*. Furthermore, for example, the gain of the current feedback control in the operation signal generation process M82 can be made variable. More specifically, for example, when the control unit configured to control the q-axis current flowing through the rotary side motor 52 to its command value via feedback is composed of proportional and integral elements, the proportional gain and integral gain can be made variable according to the viscosity component Tc. The processing for changing the relationship between the input and output of the control unit configured to control the rotating side motor 52 is also suitably applied to the steering system mentioned below in the "About the Steering System" section (where the input shaft 32 is mechanically coupled to the pinion shaft 26 via a variable gear ratio mechanism that makes the gear ratio variable) and the steering system (where the input shaft 32 and the pinion shaft 26 rotate integrally with each other).

[0102] The processing for changing the relationship between the input and output of the control unit for the steering-side motor 36 is not limited to the processing exemplified in the foregoing embodiments. For example, the viscosity coefficient C, inertia coefficient J, and elastic coefficient K in the specification model calculation processing M20 can be changed according to the viscosity component Tc. Therefore, the responsiveness of the steering angle command value θh* to the axial force Taf can be made lower or higher than, for example, the responsiveness when the viscosity coefficient C, inertia coefficient J, and elastic coefficient K are not changed. Furthermore, for example, the gain of the current feedback control in the operation signal generation processing M44 can be made variable. More specifically, for example, when the control unit configured to control the q-axis current flowing through the steering-side motor 52 to its command value via feedback is composed of proportional and integral elements, the proportional gain and integral gain can be made variable according to the viscosity component Tc. Furthermore, when the steering angle command value θh* is not calculated, as mentioned below in the "Regarding the Control Unit for the Steering-Side Motor 36" section, the correction amount of the auxiliary torque can be variably set according to the viscosity component Tc. Therefore, driver discomfort caused by the influence of the viscosity of the steering system 10 on the controllability of the steering system 10 can be appropriately compensated.

[0103] Two processes can be performed—namely, a process for changing the relationship between the inputs and outputs of the control unit for the rotation-side motor 52 and a process for changing the relationship between the inputs and outputs of the control unit for the steering-side motor 36—instead of performing only one of the aforementioned processes. In this case, it can be based on, for example... Figure 2These two processes are performed based on the viscosity component Tc when controlling the rotating side motor 52, as illustrated in the example. Alternatively, they can be based on, for example, the viscosity component Tc of the rotating side motor 52. Figure 8 These two processes are performed based on the viscosity component Tc related to the control of the steering-side motor 36, as illustrated in the example. However, the invention is not limited to these cases. For example, one of the two processes described above can be performed based on the viscosity component Tc when controlling the steering-side motor 52, and the other process can be performed based on the viscosity component Tc related to the control of the steering-side motor 36.

[0104] In the case of calculating the friction component of the steering system as mentioned in the "Predetermined Component Calculation Process" section below, the influence of the friction component of the steering system 10 on the steering feel can be compensated by changing the relationship between the output of the control unit configured to control the torque of the steering-side motor 36 and the input of the control unit. It should be noted here that the process for changing the relationship between the output of the control unit configured to control the torque of the steering-side motor 36 and the input of the control unit can, for example, be a process for changing the hysteresis correction amount Thys based on the friction component. Furthermore, in the case of a steering system, such as that mentioned in the "Regarding the Steering System" section, where the input shaft 32 and the pinion shaft 26 rotate integrally with each other, the influence of the friction component of the steering system 10 on the steering feel can be compensated by changing the relationship between the output of the control unit configured to control the torque of the rotation-side motor 52 and the input of the control unit. It should be noted here that the process for changing the relationship between the output of the control unit configured to control the torque of the rotation-side motor 52 and the input of the control unit can, for example, be a process for changing the hysteresis correction amount Thys based on the friction component.

[0105] Regarding the handling of intensity changes

[0106] exist Figure 5 In the processing, the filtering characteristics are modified so that the viscosity component Tc is larger at a lower temperature TS than at a higher temperature TS, but the invention is not limited to this. For example, the filtering characteristics can be modified so that the viscosity component Tc is smaller at a lower temperature TS than at a higher temperature TS. In any case, modifying the filtering characteristics in this way is equivalent to modifying the proportional gain Ktp and the derivative gain Ktd according to both the viscosity component Tc and the temperature TS, and therefore, the degree of freedom in the processing of modifying the proportional gain Ktp and the derivative gain Ktd can be increased.

[0107] The processing for changing the filter characteristics based on temperature TS is not limited to the processing for extracting the viscosity component Tc from the rotating side motor 52. The temperature used as input when changing the filter characteristics is not limited to the detection value of temperature sensor 76. For example, the temperature can be estimated based on the history of the current flowing through the rotating side motor 52 and the steering side motor 36. Furthermore, for example, the temperature can be estimated based on the history of the current flowing through the components in the control device 60. Additionally, the detection value of a sensor that detects the outside air temperature can be used when estimating the temperature.

[0108] Regarding the calculation and processing of interference torque

[0109] In the foregoing embodiments, the disturbance torque calculation process M62 is used to calculate the rotation operation amount Tt*, but the present invention is not limited thereto. The disturbance torque calculation process M62 can be used to calculate the viscosity component Tc, but may not be used to calculate the rotation operation amount Tt*.

[0110] Regarding viscosity component calculations

[0111] exist Figure 2 , Figure 5 and Figure 6 In this example, the viscosity component Tc is calculated using the output of the perturbation torque calculation process M62, which consists of observers. However, the perturbation torque calculation process is not limited to this. For example, the perturbation torque calculation process can be configured using a Kalman filter.

[0112] The process used to estimate the viscosity component Tc when controlling the rotating side motor 52 does not necessarily include the following: This process is used to estimate the disturbance torque component when using the values ​​of variables relating to the torque of the rotating side motor 52 (rotation operation amount Tt*), the pinion angle θp, and the pinion angle command value θp* as inputs. For example, when performing feedback control to control the feedback control quantity to the pinion angle command value θp* as the command value, the viscosity component Tc can be extracted by a specific frequency component of the command value of the torque (e.g., the rotation operation amount Tt* as the operation amount of the feedback control) and / or the command value of the current, which allows selective transmission. Furthermore, considering the fact that the current is controlled to the command value, when performing feedback control to control the feedback control quantity to the pinion angle command value θp* as the command value, the viscosity component Tc can be extracted by a specific frequency component of the current actually flowing through the rotating side motor 52, which allows selective transmission. The torque and current, as the operation amount of the angle feedback control related to the turning angle, are control quantities for the rotating side motor 52. Therefore, the command values ​​of the torque and current, as well as the torque and current, are variables relating to the control quantities for the rotating side motor 52.

[0113] The processing used to estimate the viscosity component Tc when controlling the steering-side motor 36 does not necessarily use the resistance command value Tr*. For example, in the case of performing feedback control to control the feedback control quantity to the steering angle command value θh* as the command value, the viscosity component Tc can be extracted by a specific frequency component of the command value that allows selective transmission of current in the operation signal generation processing M44. The torque and current, as the operating quantities of the angle feedback control related to the steering angle, are the control quantities for the steering-side motor 36; therefore, the command values ​​of torque and current, as well as torque and current, are variables related to the control quantities for the steering-side motor 36. Alternatively, for example, the resistance calculation processing M42 can consist of a processing for calculating the feedforward and feedback terms and a processing for calculating the disturbance torque, and the viscosity component Tc can be extracted from the disturbance torque. Furthermore, the viscosity component Tc can be calculated by calculating the disturbance torque instead of using the disturbance torque to calculate the resistance command value Tr*.

[0114] The filtering process does not necessarily use a bandpass filter M90. For example, a low-pass filter with a cutoff frequency higher than the frequency range of the viscosity component exemplified in the aforementioned embodiments can be used. In this case, the output of the filtering process includes both the viscosity component and the friction component.

[0115] Regarding the calculation and processing of predetermined components

[0116] The predetermined component used to change the relationship between the output of the control unit for the steering system and the input of the control unit does not necessarily include the viscosity component. For example, the predetermined component calculation process can consist of both a low-pass filter for extracting the friction component and a band-pass filter for extracting the viscosity component, and the relationship can be changed independently by the friction component and the viscosity component. However, it is possible to calculate only the friction component (without calculating the viscosity component) as the predetermined component.

[0117] Regarding corner feedback processing

[0118] In the foregoing embodiments, the feedforward term Ttff is calculated based on the second-order time derivative of the pinion angle command value θp*, but the present invention is not limited thereto. For example, the feedforward term Ttff can be calculated based on the second-order time derivative of the pinion angle θp or the second-order time derivative of the estimated value θpe.

[0119] In the foregoing embodiments, the feedforward term is calculated by modeling the steering system 10 using a simple model (in which the torque applied to the steering wheel 42 is equal to the torque proportional to the angular acceleration of the turning angle), but the present invention is not limited thereto. For example, the feedforward term can be calculated using a model in which the torque applied to the steering wheel 42 is equal to the sum of the torque proportional to the angular acceleration of the turning angle and the viscosity (as the torque proportional to the angular velocity of the turning angle). For example, this can be achieved by using the sum of the value obtained by multiplying the second-order time derivative of the pinion angle command value θp* by the inertia coefficient Jp and the value obtained by multiplying the first-order time derivative of the pinion angle command value θp* by the viscosity coefficient Cp as the feedforward term Ttff. Here, it should be noted that the viscosity coefficient Cp, as the proportionality coefficient of the angular velocity, is different in purpose from the viscosity coefficient C used in the canonical model calculation process M20, and it is desirable to obtain the viscosity coefficient Cp by modeling the actual behavior of the steering system 10 as accurately as possible. In this case, the disturbance torque calculation process M62 can be configured using a model (where the torque applied to the steering wheel 42 is equal to the sum of the torque and viscosity components proportional to the angular acceleration of the turning angle). Also in this case, when there is a difference between the viscosity component of the current feed term Ttff and the actual viscosity component, the estimated disturbance torque Tlde includes the viscosity component, and therefore, the viscosity component Tc can be extracted from the estimated disturbance torque Tlde.

[0120] The feedback control quantity, which is one of the inputs to the M66 feedback term calculation, is not limited to the estimated value θpe or its first-order time derivative. For example, the feedback control quantity can be the pinion angle θp or its time derivative itself, rather than the estimated value θpe or its first-order time derivative.

[0121] The feedback term calculation process M66 is not limited to processing the sum of the output values ​​of the proportional and differential elements. For example, the feedback term calculation process M66 can be processing the output value of the proportional element, or processing the output value of the differential element. Furthermore, for example, the feedback term calculation process M66 can be processing the sum of at least one of the output values ​​of the proportional and differential elements with the output value of the integral element. When using the output value of the integral element, it is desirable to remove the disturbance torque calculation process M62. However, when not using the output value of the integral element, the use of the disturbance torque calculation process M62 is not essential.

[0122] The variable steering angle ratio processing M46 and the additive processing M48 can be removed, and the output of the standard model calculation processing M20 can be the steering angle command value θh* and the pinion angle command value θp*.

[0123] Regarding the calculation and processing of the standard model

[0124] In the aforementioned embodiments, when using axial force Taf as input, the steering angle command value θh* is calculated based on equation (c1), etc., but the logic (model) used to calculate the steering angle command value θh* is not limited to this.

[0125] Regarding the control unit for the steering side motor 36

[0126] The control unit for the steering-side motor 36 does not necessarily include the resistance calculation process M42. For example, the control unit for the steering-side motor 36 can input the steering operation amount Ts* to the operation signal generation process M44.

[0127] Feedback control of steering torque Th is not essential. The auxiliary torque can be calculated based on the steering torque Th, and the value obtained by correcting the auxiliary torque in various ways can be used as the steering operation amount Ts*. The steering operation amount Ts* can be input to the operation signal generation and processing M44.

[0128] Regarding convertible angles

[0129] In the foregoing embodiment, the pinion angle θp is used as a convertible angle for the rotation angle of the rotating side motor 52, but the present invention is not limited thereto. For example, the convertible angle could be the turning angle of the steering wheel 42.

[0130] In the foregoing embodiment, the steering angle θh is used as a convertible angle of the rotation angle of the steering-side motor 36, but the present invention is not limited thereto. For example, the convertible angle can be the rotation angle of the steering-side motor 36 itself.

[0131] Regarding steering input

[0132] In the foregoing embodiment, the steering operation amount Ts* is converted into the torque of the input shaft 32, but the invention is not limited thereto. For example, the steering operation amount Ts* can be the torque of the steering-side motor 36. However, in this case, the axial force Taf is obtained by summing the steering operation amount Ts* with the value obtained by dividing the steering torque Th by the reduction ratio, or the axial force Taf is obtained by summing the steering torque Th with the value obtained by multiplying the steering operation amount Ts* by the reduction ratio.

[0133] Regarding the rotation operation amount

[0134] In the foregoing embodiment, the rotation operation amount Tt* is converted into the torque of the pinion shaft 26, but the present invention is not limited thereto. For example, the rotation operation amount Tt* can be the torque of the rotating side motor 52.

[0135] Regarding the calculation and processing of target torque

[0136] The base target torque calculation process is not limited to the process used to calculate the base target torque Thb* based on the axial force Taf and the vehicle speed V. For example, the base target torque calculation process could be a process used to calculate the base target torque Thb* based solely on the axial force Taf.

[0137] The correction of the base target torque Thb* by the hysteresis correction Thys is not essential in itself.

[0138] Regarding control equipment

[0139] The control device does not necessarily need to include a CPU 62 and a ROM 64 to perform software processing. For example, the control device may include dedicated hardware circuitry (e.g., an ASIC, etc.) that causes at least a portion of the values ​​that undergo software processing in the foregoing embodiments to undergo hardware processing. That is, the control device can be configured according to any of (a) to (c) mentioned below. (a) The control device includes: a processing means for performing all of the above-described processes according to a program; and a program storage means, such as a ROM, for storing the program. (b) The control device includes: a processing means for performing one or more of the above-described processes according to a program; a program storage means; and dedicated hardware circuitry for performing one or more other processes. (c) The control device includes dedicated hardware circuitry for performing all of the above-described processes. Here, it should be noted that the control device may include: multiple software processing circuits, which include processing means and a program storage means; and / or multiple hardware circuits. That is, the foregoing processes may be performed by a processing circuitry including at least one of the following: i) one or more software processing circuits; and ii) one or more dedicated hardware circuits.

[0140] Regarding electric motors and drive circuits

[0141] Each of the motors may not be an SPMSM, but may be an IPMSM, etc. Furthermore, each of the motors may not be a synchronous motor, but may be an induction motor. Additionally, each of the motors may be, for example, a brushed DC motor. In this case, an H-bridge circuit can be used as the drive circuit.

[0142] Regarding rotary actuators

[0143] The rotary actuator is not limited to the actuator exemplified in the foregoing embodiments. For example, the rotary actuator may be a so-called dual-pinion type actuator, which, in addition to the pinion shaft 26, includes a second pinion shaft for transmitting power from the rotary-side motor 52 to the rack shaft 28. Furthermore, for example, the rotary actuator may be configured such that the output shaft 52a of the rotary-side motor 52 is mechanically coupled to the pinion shaft 26. In this case, the rotary actuator shares the input shaft 32 and the pinion shaft 26 with the steering mechanism.

[0144] Regarding the steering system

[0145] exist Figure 1 In this configuration, clutch 24 can be removed, and input shaft 32 can be mechanically coupled to pinion shaft 26 via a gear ratio variable mechanism (instead of using clutch 24). Similarly, in this configuration, processing similar to that exemplified in the case of a steering-by-wire system can also be achieved.

[0146] However, the steering system is not limited to this type and can, for example, be configured such that the input shaft 32 and the pinion shaft 26 rotate integrally with each other. Similarly, in this case, for example, when there is a situation where the steering wheel 42 is unlikely to turn due to the viscosity of the steering system 10, this situation can be suppressed by changing the relationship between the input and output of a control unit configured to control the torque of the rotating side motor 52 according to the viscosity.

Claims

1. A control device for a steering system (10), the steering system (10) being configured to steer the steering wheels (42) of a vehicle and the steering system (10) including an electric motor, the control device being configured to control the steering system (10), and the control device being characterized in that it comprises: The control circuit system is configured to execute Angle control processing is used to convert a convertible angle, which can be converted into the rotation angle of the motor, into an angle command value. A predetermined component calculation process is used to calculate a predetermined component when using the values ​​of variables related to the control quantity of the motor as input. The predetermined component includes at least one of two components: a viscosity component and a friction component, which are components of the steering system (10). The relationship-changing process is used to change the relationship between the output of the control unit for the steering system (10) and the input of the control unit based on the predetermined component calculated by the predetermined component calculation process. The predetermined component calculation process includes a viscosity component calculation process for calculating the viscosity component as the predetermined component; and The relationship-changing process includes the following processing: the processing is used to change the relationship between the output of the control unit for the steering system (10) and the input of the control unit based on the viscosity component calculated by the viscosity component calculation process. The viscosity component calculation process includes a disturbance torque calculation process. This disturbance torque calculation process is used to calculate, when using the values ​​of variables related to the motor torque, the detected value of the switchable angle, and the angle command value as the values ​​of variables related to the control quantity, the torque component affecting the switchable angle, other than the motor torque, as the disturbance torque. The viscosity component calculation process includes a filtering process for selectively transmitting a specific frequency component of the interference torque when using the interference torque as input, and the viscosity component calculation process uses the output of the filtering process as the viscosity component.

2. The control device for the steering system (10) according to claim 1, characterized in that, The filtering process includes an intensity change process, which is used to change the intensity of the output according to the temperature of the steering system (10) even when the input of the filtering process remains unchanged.

3. The control device for the steering system (10) according to claim 1 or 2, characterized in that, The convertible angle is an angle that can be converted into the steering angle of the steering wheel (42).

4. The control device for the steering system (10) according to claim 3, characterized in that, The control unit is configured to control the convertible angle to the angle command value.

5. The control device for the steering system (10) according to claim 4, characterized in that, The steering system (10) includes a steering wheel (22) capable of shifting without transmitting power to the steering wheels (42).

6. The control device for the steering system (10) according to claim 3, characterized in that: The steering system (10) includes a steering wheel (22) capable of shifting without transmitting power to the steering wheels (42); The electric motor is a rotating-side electric motor; The steering system (10) includes a steering-side electric motor configured to apply torque against displacement of the steering wheel (22); and The control unit is configured to control the torque of the steering-side motor.

7. The control device for the steering system (10) according to claim 1 or 2, characterized in that: The steering system (10) includes a steering wheel (22) capable of shifting without transmitting power to the steering wheels (42); and The electric motor is a steering-side motor, which is configured to apply torque to resist displacement of the steering wheel (22).

8. The control device for the steering system (10) according to claim 7, characterized in that, The control unit is configured to control the torque of the steering-side motor.

9. The control device for the steering system (10) according to claim 7, characterized in that: The steering system (10) includes a rotation-side electric motor, which is an electric motor configured to steer the steering wheel (42); and The control unit is configured to control the torque of the rotating side motor.

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