Steering control device

Abstract

The present application relates to a steering manipulation control device. A processor (52) is configured to execute a reaction force setting process, a reaction force application process, an axial force gradient calculation process, and a linkage process. The reaction force setting process is a process of setting a steering manipulation reaction force using a phase compensation process. The reaction force application process is a process of operating a reaction force motor (22) with the reaction force set by the reaction force setting process as input. The axial force gradient calculation process is a process for calculating an axial force gradient as a variable that indicates a ratio of a change in resistance against rotation of a steering manipulation shaft (14) to a change in a rotation angle of the steering manipulation shaft (14). The linkage process is a process of causing one of the value of a phase compensation adjustment variable as a variable for adjusting a phase compensation manner and the axial force gradient to change according to the other.

Description

Technical Field

[0001] This disclosure relates to steering control devices. Background Technology

[0002] For example, Japanese Unexamined Patent Application Publication No. 2017-144887, described below, is a control device for controlling an electric power steering system as a control objective. This control device sets the torque of the motor used to generate the auxiliary force by using phase compensation processing. This setting is intended to stabilize the system. Summary of the Invention

[0003] The inventors investigated the control of a steering system when power transmission between the steering shaft and the steering wheels is interrupted. In this situation, there is a high degree of freedom in adjusting the characteristics of the steering system through control. However, when the characteristics of the steering system are arbitrarily set, there is a risk that the stabilization effect achieved through phase compensation may be compromised.

[0004] The steering control device according to a first aspect of this disclosure is configured to control a steering system, which includes a reaction force motor that applies a steering reaction force to a steering shaft and a steering motor that steers the steering wheels when power transmission from the steering shaft is cut off. The steering control device includes a processor. The processor is configured to perform a reaction force setting process, a reaction force application process, an axial force gradient calculation process, and a linkage process. The reaction force setting process is a process of setting the steering reaction force using a phase compensation process. The reaction force application process is a process of operating the reaction force motor using the reaction force set by the reaction force setting process as input. The phase compensation process is a process of performing phase compensation on the steering reaction force. The axial force gradient calculation process is a process of calculating the axial force gradient. The axial force gradient is a variable indicating the ratio of the change in resistance to rotation of the steering shaft to the change in the rotation angle of the steering shaft. The linkage process is a process of changing one of the phase compensation adjustment variable and the axial force gradient according to the other. The phase compensation adjustment variable is a variable used to adjust the phase compensation method.

[0005] The magnitude of the axial force gradient for which phase compensation processing is effective varies depending on settings such as the time constant of the phase compensation process. Therefore, in the above configuration, one of the variables used to adjust the phase compensation method and the axial force gradient changes based on the other. This allows for phase compensation processing tailored to the magnitude of the axial force gradient.

[0006] In the steering control device according to a first aspect of this disclosure, the reaction force setting process may include an assist amount setting process and an axial force setting process. The axial force setting process may be a process of setting an axial force as a resistance to the driver's rotational operation of the steering shaft. The assist amount setting process may include a phase compensation process and set an assist amount. The assist amount may be an amount that assists the driver in rotating the steering shaft. The steering reaction force may be an amount determined based on a value obtained by subtracting the assist amount from the axial force. The axial force gradient calculation process may be a process of calculating the change in the rotation angle of the axial force set by the axial force setting process relative to the steering shaft.

[0007] In a steering system that transmits power between the steering shaft and the steering wheels, the axial force from the steering wheels serves as a force to prevent the driver from rotating the steering shaft. Therefore, the assist amount is the amount used to assist the driver's steering maneuver. On the other hand, in the above configuration, when the power transmission between the steering shaft and the steering wheels is cut off, the axial force that effectively resists the rotational operation of the steering shaft can be controlled. Therefore, the assist amount can be set based on the same concept as in a steering system that transmits power between the steering shaft and the steering wheels.

[0008] In the steering control device according to the first aspect of this disclosure, the linkage processing can be a process that uses the axial force gradient as input to change the value of the phase compensation adjustment variable. In the above configuration, the phase compensation method of the phase compensation processing changes according to the axial force gradient. Therefore, appropriate phase compensation can be achieved based on the axial force gradient.

[0009] In the steering control device according to the first aspect of this disclosure, the assist amount setting process may be a process of setting the assist amount based on a detected value of the steering torque input to the steering shaft. The phase compensation process may include a phase lag compensation process. The phase lag compensation process may be a process of delaying the phase of the detected value and inputting the delayed phase to the assist amount setting process. The phase compensation adjustment variable may include a lag adjustment variable. The lag adjustment variable may be a variable that specifies the phase lag compensation process. The linkage process may include a process of changing the value of the lag adjustment variable using an axial force gradient as input.

[0010] In the above configuration, the phase compensation method, which is achieved through phase lag compensation, changes according to the axial force gradient. Therefore, appropriate phase lag compensation can be achieved based on the axial force gradient.

[0011] In the steering control device according to the first aspect of this disclosure, the assist amount setting process may include a basic assist amount setting process. The basic assist amount setting process may be a process of setting a basic assist amount based on a detected value of the steering torque input to the steering shaft. The phase compensation process may include a phase advance compensation process. The phase advance compensation process may be a process of calculating an advance correction amount for the basic assist amount using the detected value as input. The assist amount setting process may be a process of setting the assist amount based on a value obtained by correcting the basic assist amount with the advance correction amount. The phase compensation adjustment variable may include an advance adjustment variable. The advance adjustment variable may be a variable that specifies the phase advance compensation process. The linkage process may include a process of changing the value of the advance adjustment variable using an axial force gradient as input.

[0012] In the above configuration, the phase compensation method, achieved through phase advance compensation, changes according to the axial force gradient. Therefore, appropriate phase advance compensation can be achieved based on the axial force gradient.

[0013] In the steering control device according to a first aspect of this disclosure, the axial force setting process may include a process of setting the axial force based on the value of an axial force adjustment variable. The axial force adjustment variable may be a variable used to adjust the relationship between the axial force and the value of an angle variable of the steering system. The linkage process may include a process of changing the value of the axial force adjustment variable by using the value of a phase compensation adjustment variable as input.

[0014] In the above configuration, since the value of the axial force adjustment variable changes according to the value of the phase compensation adjustment variable, the axial force gradient can be set within a range suitable for phase compensation processing. Attached Figure Description

[0015] 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 the same reference numerals denote the same elements, and in the drawings:

[0016] Figure 1 This is a diagram showing the configuration of the steering control system according to the first embodiment;

[0017] Figure 2 This is a block diagram illustrating the process to be performed by the control device according to an embodiment;

[0018] Figure 3 This is a block diagram illustrating the process to be performed by the control device according to an embodiment;

[0019] Figure 4 This is a block diagram illustrating the process to be performed by the control device according to an embodiment;

[0020] Figure 5This is a block diagram illustrating the process to be performed by the control device according to the second embodiment; and

[0021] Figure 6 This is a block diagram illustrating the process to be performed by the control device according to the second embodiment. Detailed Implementation

[0022] First Implementation Method

[0023] The first embodiment will now be described with reference to the accompanying drawings.

[0024] Prerequisite configuration

[0025] Figure 1 The vehicle steering control device 10 shown is a steer-by-wire type device. The steering control device 10 includes a steering wheel 12, a steering shaft 14, a reaction force actuator 20, and a steering actuator 30. The steering shaft 14 is connected to the steering wheel 12. The reaction force actuator 20 is an actuator used to apply resistance against the force exerted by the driver operating the steering wheel 12. The reaction force actuator 20 includes a reaction force motor 22, a reaction force inverter 24, and a reaction force reduction mechanism 26. The reaction force motor 22 applies a steering reaction force as resistance against steering operation to the steering wheel 12 via the steering shaft 14. The reaction force motor 22 is connected to the steering shaft 14 via the reaction force reduction mechanism 26. For example, a three-phase synchronous motor is used as the reaction force motor 22. The reaction force reduction mechanism 26 consists of, for example, a worm gear and a worm wheel.

[0026] Steering actuator 30 is an actuator used to turn steering wheel 34 according to the driver's steering intention indicated by the driver's operation of steering wheel 12. Steering actuator 30 includes rack and pinion 32, steering motor 42, steering inverter 44, steering transmission mechanism 46, and conversion mechanism 48. As an example, a three-phase surface magnet synchronous motor (SPM) is used as steering motor 42. Steering transmission mechanism 46 consists of a belt drive mechanism. The rotational power of steering motor 42 is transmitted to conversion mechanism 48 via steering transmission mechanism 46. Conversion mechanism 48 converts the transmitted rotational power into displacement power in the axial direction of rack and pinion 32. The axial displacement of rack and pinion 32 causes steering wheel 34 to turn.

[0027] The steering control device 50 controls the steering wheel 12 and steering wheels 34, which are the objects of control. In other words, the steering control device 50 controls the steering reaction force against the driver's steering operation, which is the control amount of the steering wheel 12, which is the control target. Furthermore, the steering control device 50 controls the steering angle of the steering wheels 34, which are the control targets. The steering angle is the cutting angle of the tires of the steering wheels 34.

[0028] The steering control unit 50 references the steering torque Th detected by the torque sensor 60 to control the control amount. The steering torque Th is the torque applied to the steering shaft 14 by the driver's operation of the steering wheel 12. The steering control unit 50 references the rotation angle θa to control the control amount, which is the angle of the rotation shaft of the reaction force motor 22 and is detected by the steering side rotation angle sensor 62. Furthermore, the steering control unit 50 references the currents ius, ivs, and iws flowing through the reaction force motor 22 to control the control amount. The currents ius, ivs, and iws can be the currents to be detected, for example, as the voltage drop across the shunt resistors in the corresponding branches of the reaction force inverter 24. The steering control unit 50 references the rotation angle θb to control the control amount, which is the angle of the rotation shaft of the steering motor 42 and is detected by the steering side rotation angle sensor 64. Furthermore, the steering control unit 50 references the currents iut, ivt, and iwt flowing through the steering motor 42 to control the control amount. The currents iut, ivt, and iwt can be the currents to be detected, for example, as the voltage drop across a shunt resistor in the corresponding branch of the steering inverter 44. The steering control unit 50 references the vehicle speed V detected by the vehicle speed sensor 66.

[0029] The steering control unit 50 includes a PU 52 and a storage device 54. The PU 52 is a software processing unit, such as a CPU, GPU, or TPU. The storage device 54 may be a non-volatile memory that cannot be electrically rewritable. Alternatively, the storage device 54 may be a recording medium, such as electrically rewritable non-volatile memory or a disk medium.

[0030] Overview of Control

[0031] Figure 2 The process to be performed by the steering control unit 50 is shown. Figure 2 The process shown is achieved by PU 52 repeatedly executing, for example, a program stored in storage device 54 at predetermined intervals.

[0032] The steering angle calculation process M10 includes the following processing: for example, converting the rotation angle θa into an integral angle covering a range of more than 360 degrees by counting the number of rotations of the reaction force motor 22 starting from the steering neutral position, which is the position of the steering wheel 12 when the vehicle is traveling straight. The steering angle calculation process M10 includes the processing of calculating the steering angle θs by multiplying the converted integral angle by a conversion factor based on the rotational speed ratio of the reaction force reduction mechanism 26.

[0033] The steering angle calculation process M12 includes the following steps: For example, by counting the number of rotations of the steering motor 42 starting from the rack neutral position, the rotation angle θb is converted into an integral angle covering a range of more than 360 degrees, where the rack neutral position is the position of the rack shaft 32 when the vehicle is traveling straight. The steering angle calculation process M12 also includes the following steps: By multiplying the converted integral angle by a conversion factor corresponding to the reduction ratio of the steering transmission mechanism 46, the advance of the conversion mechanism 48, etc., the steering angle θp corresponding to the steering angle of the steering wheel 34 is calculated. The steering angle θp is a quantity proportional to the steering angle. As an example, the steering angle θp is positive when it is the angle to the right of the rack neutral position, and negative when it is the angle to the left of the rack neutral position.

[0034] The target steering angle calculation process M18 is a process that calculates the target steering angle θp* based on the steering angle θs and the vehicle speed V.

[0035] The steering assist setting process M20 calculates the steering assist amount Ta using steering torque Th and vehicle speed V as inputs. The steering assist amount Ta is a quantity in the same direction as the driver's steering input. The magnitude of the steering assist amount Ta is set to a larger value when the force used to assist the driver's steering input is increased.

[0036] The axial force setting process M22 calculates the axial force F acting on the rack shaft 32 via the steering wheel 34, using the vehicle speed V, the q-axis current iqt of the steering motor 42, and the target steering angle θp* as inputs. The axial force F represents the value of the force acting on the rack shaft 32 via the steering wheel 34. However, it is not required that the axial force F be estimated with high accuracy to represent the force acting on the rack shaft 32. The axial force F can be, for example, a practically determined force acting on the rack shaft 32. The axial force F is converted into a torque to be applied to the steering control shaft 14. In other words, assuming that power transmission between the steering wheel 34 and the steering control shaft 14 is possible, the axial force F is converted into a torque to be applied to the steering control shaft 14. The axial force F is the amount acting in the direction opposite to the driver's steering direction. The axial force setting process M22 can be a process that calculates the axial force F such that the absolute value of the axial force F increases as the absolute value of the target steering angle θp* increases. Furthermore, for example, the axial force setting process M22 can be as follows: calculate the axial force F such that the absolute value of the axial force F increases with the increase of vehicle speed V. Furthermore, the axial force setting process M22 can be as follows: calculate the axial force F such that the absolute value of the axial force F increases with the increase of the absolute value of the q-axis current iqt. Here, the q-axis current iqt is calculated by PU 52 based on the steering angle θp and the currents iut, ivt, and iwt.

[0037] Subtraction processing M24 involves substituting the value obtained by subtracting the axial force F from the auxiliary quantity Ta into the target reaction torque Ts. The target reaction torque Ts is the target value of the torque applied to the steering control shaft 14 by the reaction force motor 22.

[0038] The reaction force operation signal generation process M26 is as follows: It generates an operation signal MSs for the reaction force inverter 24 to control the torque of the reaction force motor 22 such that the torque to be applied to the steering control shaft 14 is equal to the target reaction force torque Ts. Specifically, the reaction force operation signal generation process M26 includes a process of converting the target reaction force torque Ts into the target torque of the reaction force motor 22. Furthermore, the reaction force operation signal generation process M26 includes the following process: It calculates the operation signal MSs for the reaction force inverter 24 so that the current flowing through the reaction force motor 22 is closer to the current determined according to the target reaction force torque Ts through current feedback control. Note that the operation signal MSs is actually the operation signal for each of the six switching elements of the reaction force inverter 24. Since the torque of the reaction force motor 22 is set to the target reaction force torque Ts, the steering control reaction force against the force attempting to rotate the steering wheel 12 is equal to "(-1)·Ts".

[0039] The steering feedback processing M30 performs the following process: It substitutes the target steering torque Tt* into the target steering torque of the feedback control, which uses the steering angle θp as the control variable and the target steering angle θp* as the control variable. The target steering torque Tt* has a constant ratio to the torque of the steering motor 42.

[0040] The steering operation signal generation process M32 generates an operation signal MSt for the steering inverter 44 to control the torque of the steering motor 42, such that the torque of the steering motor 42 has a constant ratio to the target steering torque Tt*. Specifically, the steering operation signal generation process M32 includes a process of converting the target steering torque Tt* into a target torque for the steering motor 42. Furthermore, the steering operation signal generation process M32 includes a process of calculating the operation signal MSt for the steering inverter 44 to make the current flowing through the steering motor 42 closer to the current determined based on the target torque through current feedback control. Note that the operation signal MSt is actually an operation signal for each of the six switching elements of the steering inverter 44.

[0041] Axial force setting processing

[0042] Figure 3 Details of the axial force setting process M22 are shown.

[0043] The angular axial force setting process M40 calculates the angular axial force Fr using the target steering angle θp* and vehicle speed V as inputs. The angular axial force Fr is an estimate of the axial force defined by an arbitrarily set vehicle model, etc. The angular axial force Fr is calculated as an axial force that does not reflect road surface information. Road surface information includes minor irregularities that do not affect the vehicle's lateral behavior, steps, etc., that do affect the vehicle's lateral behavior. For example, the angular axial force setting process M40 can perform a calculation such that the absolute value of the angular axial force Fr increases as the absolute value of the target steering angle θp* increases. For example, the angular axial force setting process M40 can perform a calculation such that the absolute value of the angular axial force Fr increases as the vehicle speed V increases.

[0044] Specifically, the angular axial force setting process M40 is a process used to perform mapping calculations on the angular axial force Fr using the angular axial force mapping M40a as mapping data. The angular axial force mapping M40a is a mapping that uses the target steering angle θp* and vehicle speed V as input variables and the angular axial force Fr as the output variable.

[0045] Here, the mapping data refers to the discrete values ​​of the input variables and the settings of the output variables corresponding to each value of the input variables. Furthermore, the mapping calculation can be performed such that when the value of the input variable matches any value of the input variable in the mapping data, the corresponding value of the output variable in the mapping data is used as the calculation result. Alternatively, when the value of the input variable does not match any value of the input variable in the mapping data, the value obtained by interpolating multiple values ​​of the output variable contained in the mapping data is used as the calculation result. Or, instead of this, the mapping calculation can be performed such that when the value of the input variable does not match any value of the input variable in the mapping data, the value of the output variable in the mapping data corresponding to the closest value among the multiple values ​​of the input variable contained in the mapping data is used as the calculation result.

[0046] The current axial force setting process M42 calculates the current axial force Fi using the q-axis current iqt of the steering motor 42 as input. The current axial force Fi is an estimate of the axial force actually acting on the rack shaft 32 that rotates the steering wheel 34 (i.e., the axial force actually transmitted to the rack shaft 32). The current axial force Fi is calculated as an axial force reflecting the aforementioned road surface information. For example, the current axial force setting process M42 can be performed by calculating the current axial force Fi under the assumption that the torque to be applied to the rack shaft 32 by the steering motor 42 and the torque corresponding to the force to be applied to the rack shaft 32 through the steering wheel 34 are balanced. In other words, the current axial force setting process M42 calculates a larger absolute value of the current axial force Fi as the absolute value of the q-axis current iqt increases.

[0047] Specifically, the current axial force setting process M42 is a process that performs mapping calculations on the current axial force Fi using the current axial force mapping M42a. The current axial force mapping M42a is a mapping that uses the q-axis current iqt as the input variable and the current axial force Fi as the output variable.

[0048] The allocation ratio calculation process M46 calculates the ratio Di using the vehicle speed V and the target steering angle θp*. The ratio Di is the ratio of the current axial force Fi to the sum of the angular axial force Fr and the current axial force Fi. The ratio Di has a value that is zero or greater and one or less. The allocation ratio calculation process M46 can be, for example, a process performed by PU 52 on the ratio Di while the mapped data is stored in storage device 54. Here, the mapped data is data that uses the vehicle speed V and the target steering angle θp* as input variables and the ratio Di as the output variable.

[0049] The second allocation ratio calculation process M48 is a process of calculating the second ratio "1-Di" by subtracting the ratio Di from "1". The second ratio is the ratio of the angular axial force Fr to the sum of the angular axial force Fr and the current axial force Fi.

[0050] The first ratio multiplication process M50 multiplies the current axial force Fi by a ratio Di. The second ratio multiplication process M52 multiplies the angular axial force Fr by a second ratio. The addition process M54 substitutes the value obtained by adding the output values ​​of the first ratio multiplication process M50 and the second ratio multiplication process M52 into the axial force F. In other words, the axial force F is a weighted average of the angular axial force Fr and the current axial force Fi.

[0051] Auxiliary quantity setting processing

[0052] Figure 4 Details of the auxiliary quantity setting process M20 are shown.

[0053] Phase lag compensation processing M60 is a process that delays the phase of the steering torque Th. This can be a process designed, for example, to perform phase compensation on the steering torque Th to adjust the frequency characteristics of the phase difference between the two sides of the torsion bar included in the torque sensor 60. The phase-compensated steering torque Th, as the output value of phase lag compensation processing M60, is steering torque Thr. Phase lag compensation processing M60 includes filter processing M62 and filter coefficient setting processing M64.

[0054] The filter processing M62 includes a phase lag filter and a low-pass filter. The transfer function of the phase lag filter is "(1+α·T1·s) / (1+T1·s)". The transfer function of the low-pass filter is "1 / (1+T2·s)". The steering torque Thr is the value obtained by processing the steering torque Thr using the phase lag filter and the low-pass filter.

[0055] The filter coefficient setting process M64 sets the filter coefficients α and T1 for the phase lag filter and the filter coefficient T2 for the low-pass filter. The filter coefficient setting process M64 sets the filter coefficients α, T1, and T2 based on the vehicle speed V, the auxiliary gradient R (described later), and the axial force gradient dF (described later).

[0056] The basic assist quantity setting process M66 is a process that sets the basic assist quantity Tab using steering torque Thr and vehicle speed V as inputs. The basic assist quantity setting process M66 sets the basic assist quantity Tab to a value that is positively correlated with the steering torque Thr. This process can, for example, be performed by PU52 to calculate the mapping of the basic assist quantity Tab while the mapping data is pre-stored in storage device 54. The mapping data is data that uses steering torque Thr and vehicle speed V as input variables and the basic assist quantity Tab as an output variable.

[0057] The basic assist setting process M66 includes the calculation and output of the assist gradient R. The assist gradient R indicates the ratio of the change in the basic assist amount Tab to the change in the steering torque Thr.

[0058] Phase advance compensation processing M70 is the processing of the phase of the advance assist quantity Ta. This can be for purposes such as performing phase compensation on the assist quantity Ta to adjust the response delay of changes in steering wheel 12 to changes in steering torque Th. Phase advance compensation processing M70 includes differential calculation M72, gain setting processing M74, and multiplication processing M76.

[0059] Differential calculation M72 is the process of calculating the first-order time derivative dTh of the steering torque Th. Gain setting process M74 is the process of setting the gain Gad using the auxiliary gradient R, vehicle speed V, and axial force gradient dF as inputs. Gain setting process M74 can be performed on the gain Gad while the mapping data is pre-stored in the storage device 54. This mapping data uses the auxiliary gradient R, vehicle speed V, and axial force gradient dF as input variables and the gain Gad as the output variable.

[0060] Multiplication process M76 multiplies the time derivative dTh by the gain Gad. The product of the time derivative dTh and the gain Gad is the advance compensation amount Tad, which is the output of phase advance compensation process M70.

[0061] The synthesis process M80 is a process that adds the advance compensation amount Tad to the basic auxiliary amount Tab. The value calculated from this is the auxiliary amount Ta.

[0062] The axial force gradient calculation process M90 uses vehicle speed V, the target steering angle θp*, and q-axis current iqt as inputs to calculate the axial force gradient dF. The axial force gradient dF is a variable indicating the ratio of the change in axial force F to the change in steering angle θs. For example... Figure 3 As shown, the angular axial force Fr is calculated using the target steering angle θp* and vehicle speed V as inputs. The target steering angle θp* is a variable correlated with the steering angle θs. Therefore, the ratio of the change in angular axial force Fr to the change in steering angle θs can be calculated based on the target steering angle θp* and vehicle speed V.

[0063] On the other hand, Figure 3 In the illustrated process, the axial force Fi is set independently of the variable indicating the angle. However, since the q-axis current iqt is implemented through feedback control using the steering angle θp as a control variable, the change in the axial force Fi is related to the change in the steering angle θs. Therefore, the ratio of the change in the axial force Fi to the change in the steering angle θs can be determined by using the target steering angle θp* and the q-axis current iqt as inputs.

[0064] Specifically, the axial force gradient calculation process M90 can be a process that performs a mapping calculation on the axial force gradient dF using vehicle speed V, the target steering angle θp*, and q-axis current iqt as inputs. Here, the mapping uses vehicle speed V, the target steering angle θp*, and q-axis current iqt as input variables and the axial force gradient dF as output variables.

[0065] The function and effects of this implementation method

[0066] PU 52 sets the target reaction torque Ts by subtracting the axial force F from the auxiliary amount Ta. Then, the torque of the reaction force motor 22 is controlled according to the target reaction torque Ts. The axial force F is a value that can be adjusted through control design. Therefore, the steering reaction force to be applied to the driver can be freely designed through control design. However, the greater the change in axial force F relative to the change in steering angle θs, the more likely the stability of the steering system is to deteriorate. Therefore, appropriate phase lag compensation in phase lag compensation processing M60 and appropriate phase advance compensation in phase advance compensation processing M70 depend on the axial force gradient dF.

[0067] Therefore, PU 52 changes the filter coefficients α, T1, T2, and gain Gad according to the axial force gradient dF. Thus, appropriate phase compensation can be achieved based on the magnitude of the axial force gradient dF.

[0068] Furthermore, as an example, PU 52 can change the filter coefficients α, T1, and T2 according to the axial force gradient dF, provided that the phase lag when the magnitude of the axial force gradient dF is large is equal to or greater than the phase lag when the magnitude of the axial force gradient dF is small. Furthermore, as an example, PU 52 can change the gain Gad according to the axial force gradient dF, provided that the phase advance when the magnitude of the axial force gradient dF is large is equal to or less than the phase advance when the magnitude of the axial force gradient dF is small.

[0069] Second Implementation Method

[0070] The following description of the second embodiment will focus on its differences from the first embodiment, with reference to the accompanying drawings.

[0071] Figure 5 The details of the auxiliary quantity setting process M20 are shown. Note that in Figure 5 For convenience, the following is a simplified explanation of the Chinese text. Figure 4 The processes shown are assigned the same step numbers. For example... Figure 5 As shown, in this embodiment, the filter coefficient setting process M64 of the phase lag compensation process M60 does not use the axial force gradient dF as input. Furthermore, the gain setting process M74 of the phase advance compensation process M70 also does not use the axial force gradient dF as input.

[0072] Figure 6 The details of the axial force setting process for M22 are shown. Note that in Figure 6 For convenience, the following is a simplified explanation of the Chinese text. Figure 3 The processes shown are assigned the same step numbers.

[0073] like Figure 6As shown, the angular axial force setting process M40 takes the filter coefficients α, T1, and T2 of the phase lag compensation process M60 and the gain Gad of the phase advance compensation process M70 as inputs. Specifically, the angular axial force setting process M40 includes a process of calculating the value of the mapping specification variable Vm1 based on the filter coefficients α, T1, T2, and the gain Gad. On the other hand, in this embodiment, there are multiple types of angular axial force mappings M40a that use the target steering angle θp* and vehicle speed V as input variables and the angular axial force Fr as the output variable. The angular axial force setting process M40 includes a process of determining which of the multiple types of angular axial force mappings M40a is used to perform the mapping calculation for the angular axial force Fr based on the mapping specification variable Vm1.

[0074] Therefore, the ratio of the change in axial force Fr to the change in steering angle θs can be adjusted based on the filter coefficients α, T1, T2, and gain Gad.

[0075] Furthermore, the current axial force setting process M42 takes the filter coefficients α, T1, and T2 of the phase lag compensation process M60 and the gain Gad of the phase advance compensation process M70 as inputs. Specifically, the current axial force setting process M42 includes a process of calculating the value of the mapping specification variable Vm2 based on the filter coefficients α, T1, T2, and the gain Gad. In addition, in this embodiment, there are multiple types of current axial force mappings M42a that use the q-axis current iqt as the input variable and the current axial force Fi as the output variable. The current axial force setting process M42 includes a process of determining which of the multiple types of current axial force mappings M42a is used to perform the mapping calculation on the current axial force Fi based on the mapping specification variable Vm2.

[0076] Therefore, the ratio of the change in the current axial force Fi to the change in the steering angle θs can be changed according to the filter coefficients α, T1, T2 and the gain Gad.

[0077] Correspondence

[0078] The correspondence between the items in the above embodiments and the items described in the "Summary of the Invention" column above is as follows. In the following description, "(-1)·Ts" is an example of steering reaction force. Auxiliary quantity setting process M20, axial force setting process M22, and subtraction process M24 are examples of reaction force setting processes. Reaction force operation signal generation process M26 is an example of reaction force application process. Axial force gradient calculation process M90 is an example of axial force gradient calculation process. In Figure 4 In the example, the axial force gradient dF acting as an input to the filter coefficient setting process M64 and the gain setting process M74 is an example of a linked process. Figure 6In the examples, the inputs to filter coefficients α, T1, T2, and gain Gaad (axial force setting processing M40 and current axial force setting processing M42) are examples of linkage processing. Phase lag compensation processing M60 and phase advance compensation processing M70 are examples of phase compensation processing. Auxiliary quantity setting processing M20 is an example of auxiliary quantity setting processing. Axial force setting processing M22 is an example of axial force setting processing. Filter coefficients α, T1, and T2 are examples of lag adjustment variables. Gaad is an example of advance adjustment variables. Filter coefficients α, T1, T2, and gain Gaad are examples of phase adjustment variables. Figure 6 The process shown is an example of a chained process.

[0079] Other implementation methods

[0080] Note that this implementation can be achieved through the following modifications. This implementation and the following modified examples can be combined with each other within a technically consistent scope.

[0081] Regarding phase lag compensation processing

[0082] exist Figure 4 In this example, the filter coefficient setting process M64 takes the vehicle speed V, the auxiliary gradient R, and the axial force gradient dF as inputs; however, this disclosure is not limited to this example. For instance, the inputs to the filter coefficient setting process M64 could be the auxiliary gradient R and the axial force gradient dF. Furthermore, for example, the inputs to the filter coefficient setting process M64 could be the vehicle speed V and the axial force gradient dF.

[0083] exist Figure 5 In this example, the filter coefficient setting process M64 takes the vehicle speed V and the auxiliary gradient R as inputs, but this disclosure is not limited to this example. For instance, only one of the vehicle speed V and the auxiliary gradient R can be input to the filter coefficient setting process M64.

[0084] The phase lag filter included in filter processing M62 is not limited to the filters mentioned above, wherein the order of the Laplace operator for each of the denominator and numerator is 1.

[0085] The inclusion of a phase lag filter and a low-pass filter in the M62 filter processing is not mandatory. For example, it may only include a phase lag filter.

[0086] In the embodiments mentioned above, filter coefficients α, T1, and T2 are set as targets to be processed by changing M64 through filter coefficient settings; however, this disclosure is not limited to this example. For example, only two of the three filter coefficients α, T1, and T2 can be set as targets to be changed. Furthermore, for example, only one of the three filter coefficients α, T1, and T2 can be set as a target to be changed.

[0087] Regarding phase advance compensation processing

[0088] exist Figure 4 In this example, the gain setting process M74 takes the vehicle speed V, the auxiliary gradient R, and the axial force gradient dF as inputs; however, this disclosure is not limited to this example. For instance, the inputs to the gain setting process M74 could be the auxiliary gradient R and the axial force gradient dF. Furthermore, for example, the inputs to the gain setting process M74 could be the vehicle speed V and the axial force gradient dF.

[0089] exist Figure 5 In this example, the gain setting process M74 takes the vehicle speed V and the auxiliary gradient R as inputs, but this disclosure is not limited to this example. For example, either the vehicle speed V or the auxiliary gradient R can be input to the gain setting process M74.

[0090] A low-pass filter can be provided between the differential calculation M72 and the multiplication process M76. In this case, the filter coefficients of the low-pass filter can be changed according to the axial force gradient dF.

[0091] Instead of multiplying the time derivative dTh by the gain Gad in the multiplication process M76, it is possible to provide mapped data with the time derivative dTh as input and the advance compensation amount Tad as output.

[0092] Phase advance compensation processing does not necessarily include the calculation of the time derivative dTh. For example, instead of calculating the time derivative dTh, it can include the process of inputting the steering torque Th to the phase advance compensation filter.

[0093] Regarding phase compensation processing

[0094] The phase compensation process is not necessarily composed of phase lag compensation process M60 and phase advance compensation process M70. For example, it may include only one of the two processes, phase lag compensation process M60 and phase advance compensation process M70. In addition, for example, it may include processes other than the two processes, phase lag compensation process M60 and phase advance compensation process M70.

[0095] Regarding the handling of axial force settings

[0096] The angular axial force setting process M40 is not necessarily a process that performs mapping calculations on the angular axial force Fr using the angular axial force mapping M40a. For example, the angular axial force setting process M40 could be a process that substitutes the value obtained by multiplying the target steering angle θp* by a gain into the angular axial force Fr. Here, the gain can be variable according to the vehicle speed V.

[0097] The inputs to the angular axial force setting process M40, including the target steering angle θp* and vehicle speed V, are not required. For example, the vehicle speed V may not be included in the inputs to the angular axial force setting process M40. Furthermore, for example, the angle variable of the steering system, which is an input variable to the angular axial force setting process M40, is not limited to the target steering angle θp*. For example, the angle variable of the steering system could be the steering angle θp. Furthermore, for example, the angle variable of the steering system could be the steering angle θs.

[0098] The current axial force setting process M42 is not limited to the process of performing mapping calculations on the current axial force Fi using the current axial force mapping M42a. For example, the current axial force setting process M42 could be a process that substitutes the value obtained by multiplying the q-axis current iqt by the gain into the current axial force Fi.

[0099] The input to the current axial force setting process M42 is not limited to the q-axis current iqt. For example, the input to the current axial force setting process M42 can be the q-axis current iqt and the vehicle speed V. Furthermore, the input to the current axial force setting process M42 can include, for example, angular variables of the steering system, such as the target steering angle θp*, the steering angle θp, and the steering angle θs.

[0100] The inputs to the allocation ratio calculation process M46, including the target steering angle θp* and vehicle speed V, are not mandatory. For example, the vehicle speed V may not be included in the inputs to the allocation ratio calculation process M46. Furthermore, for example, the steering system angle variable, which is an input variable to the allocation ratio calculation process M46, is not limited to the target steering angle θp*. For example, the steering system angle variable could be the steering angle θp. Furthermore, for example, the steering system angle variable could be the steering angle θs.

[0101] The axial force setting process includes both angular axial force setting process M40 and current axial force setting process M42, but these two processes are not mandatory. For example, either of the two processes, angular axial force setting process M40 and current axial force setting process M42, may be included to a limited extent.

[0102] Regarding the calculation and processing of axial force gradient

[0103] The inputs to the axial force gradient calculation process M90 are not limited to the q-axis current iqt, the target steering angle θp*, and the vehicle speed V. For example, the steering angle θp can be used as an angle variable for the steering system. Furthermore, for example, the steering angle θs can be used as an angle variable for the steering system.

[0104] The axial force gradient calculation process is not limited to using vehicle speed V, steering system angle variables, and q-axis current iqt as inputs to calculate the axial force gradient dF. For example, the axial force gradient calculation process can use the axial force F as input.

[0105] Regarding linkage processing

[0106] exist Figure 4 In the example, all filter coefficients α, T1, and T2 of the phase lag compensation process M60 change as the axial force gradient dF is used as input; however, this disclosure is not limited to this example. For instance, only two of the three filter coefficients α, T1, and T2 may change as the axial force gradient dF is used as input. Furthermore, for example, only one of the three filter coefficients α, T1, and T2 may change as the axial force gradient dF is used as input.

[0107] exist Figure 6 In this example, the value of the mapping specification variable Vm1, which specifies which of the various types of angular axial force mappings M40a is used, is set based on the filter coefficients α, T1, T2, and gain Gad. However, this disclosure is not limited to this example. For instance, the value of the mapping specification variable Vm1 can be set by inputting three of the four: filter coefficients α, T1, T2, and gain Gad. Furthermore, for instance, the value of the mapping specification variable Vm1 can be set by inputting two of the four: filter coefficients α, T1, T2, and gain Gad. Additionally, for instance, the value of the mapping specification variable Vm1 can be set by inputting one of the four: filter coefficients α, T1, T2, and gain Gad.

[0108] exist Figure 6 In this example, the value of the mapping specification variable Vm2, which specifies which of the various types of current axial force mappings M42a is used, is set based on the filter coefficients α, T1, T2, and gain Gad. However, this disclosure is not limited to this example. For instance, the value of the mapping specification variable Vm2 can be set by inputting three of the four: filter coefficients α, T1, T2, and gain Gad. Furthermore, for instance, the value of the mapping specification variable Vm2 can be set by inputting two of the four: filter coefficients α, T1, T2, and gain Gad. Additionally, for instance, the value of the mapping specification variable Vm2 can be set by inputting one of the four: filter coefficients α, T1, T2, and gain Gad.

[0109] exist Figure 6In this example, the value of the mapping specification variable Vm1, which specifies which of the various types of angular axial force mappings M40a to use, is set based on the filter coefficients α, T1, T2, and the gain Gad. However, this disclosure is not limited to this example. For instance, a protective process that limits the magnitude of the variation in the angular axial force Fr can be provided, and its protection value can be changed based on the filter coefficients α, T1, T2, and the gain Gad.

[0110] exist Figure 6 In this example, the value of the mapping specification variable Vm2, which specifies which of the various types of current axial force mappings M42a to use, is set based on the filter coefficients α, T1, T2, and gain Gad. However, this disclosure is not limited to this example. For instance, a protection process that limits the magnitude of the variation in current axial force Fi can be provided, and its protection value can be changed based on the filter coefficients α, T1, T2, and gain Gad.

[0111] It is not necessary for the axial force adjustment variable to consist of variables related to the current axial force Fi and variables related to the angular axial force Fr. For example, a protection process that limits the magnitude of the variation in axial force F can be provided, and its protection value can be changed according to the filter coefficients α, T1, T2, and the gain Gad. In this case, the protection value of axial force F is the axial force adjustment variable.

[0112] Regarding the steering control device

[0113] The steering control device is not limited to a device that performs example software processing; it may include dedicated hardware circuitry, such as an ASIC, for performing at least a portion of the processing to be performed, for example, in the above embodiments. In other words, the steering control device may include processing circuitry having any of the following configurations (a) to (c): (a) a processing circuitry including: a processing means for performing all of the above processing according to a program, and a program storage means, such as a storage means for storing the program; (b) a processing circuitry including: a processing means for performing a portion of the above processing according to a program, a program storage means, and dedicated hardware circuitry for performing the remaining processing; and (c) a processing circuitry including dedicated hardware circuitry for performing all of the above processing. Here, multiple software execution means may be present, each including a processing means and a program storage means. Furthermore, multiple dedicated hardware circuitry may be present.

[0114] other

[0115] The steering motor 42 is not required to be a synchronous machine. For example, it could be an induction machine.

[0116] In each of the above embodiments, the steering control device 10 has a linkageless structure in which the steering wheel 12 and the steering wheel 34 are always mechanically separated from each other. However, this disclosure is not limited to this example, and it may have a structure in which the steering wheel 12 and the steering wheel 34 can be mechanically separated from each other via a clutch.

Claims

1. A steering manipulation control device (50) configured to control a steering manipulation system that is a control target, the steering manipulation system including a reaction force motor (22) that applies a steering manipulation reaction force to a steering manipulation shaft (14) and a steering motor (42) that steers a steered wheel (34) in a state where power transmission from the steering manipulation shaft (14) is cut off, characterized by including a processor (52) configured to execute a reaction force setting process, a reaction force application process, a shaft force gradient calculation process, and a linkage process, wherein, The reaction force setting process is a process of setting the steering operation reaction force using a phase compensation process, the reaction force application process is a process of operating the reaction force motor (22) with the reaction force set by the reaction force setting process as an input to the reaction force motor (22), the phase compensation process is a process of performing phase compensation on the steering operation reaction force, the axial force gradient calculation process is a process of calculating an axial force gradient, which is a variable indicating a ratio of a change in a resistance against rotation of the steering operation shaft (14) to a change in a rotation angle of the steering operation shaft (14), the linkage process is a process of changing one of the value of a phase compensation adjustment variable and the axial force gradient according to the other, and the phase compensation adjustment variable is a variable adjusting a manner of the phase compensation.

2. The steering control device (50) according to claim 1, characterized by The reaction force setting process includes an assist amount setting process and an axial force setting process, the axial force setting process is a process of setting an axial force that is a resistance against a rotation operation of the steering operation shaft (14) by a driver, the assist amount setting process is a process of including the phase compensation process and setting an assist amount that is an amount assisting the driver to rotate the steering operation shaft (14), the steering operation reaction force is an amount determined according to a value obtained by subtracting the assist amount from the axial force, and the axial force gradient calculation process is a process of calculating a change amount of the axial force set by the axial force setting process with respect to a change in a rotation angle of the steering operation shaft (14).

3. The steering control device (50) according to claim 1, characterized by The linkage process is a process of changing the value of the phase compensation adjustment variable with the axial force gradient as an input.

4. The steering control device (50) according to claim 2, characterized by The assist amount setting process is a process of setting the assist amount according to a detected value of a steering operation torque input to the steering operation shaft (14), the phase compensation process includes a phase lag compensation process that is a process of delaying a phase of the detected value and inputting the phase-delayed detected value to the assist amount setting process, the phase compensation adjustment variable includes a lag adjustment variable that is a variable for adjusting the phase lag compensation process, and the linkage process includes a process of changing the value of the lag adjustment variable with the axial force gradient as an input.

5. The steering control device (50) according to claim 2, characterized by The assist amount setting process includes a basic assist amount setting process of setting a basic assist amount in accordance with a detected value of a steering manipulation torque input to the steering manipulation shaft (14), the phase compensation process includes a phase advance compensation process of calculating an advance correction amount of the basic assist amount with the detected value as an input, the assist amount setting process is a process of setting the assist amount in accordance with a value obtained by correcting the basic assist amount with the advance correction amount, the phase compensation adjustment variable includes an advance adjustment variable that is a variable for adjusting the phase advance compensation process, and the linkage process includes a process of changing a value of the advance adjustment variable with the axial force gradient as an input.

6. The steering control device (50) according to claim 2, characterized by The axial force setting process includes a process of setting the axial force in accordance with a value of an axial force adjustment variable that is a variable for adjusting a relationship of the axial force and a value of an angle variable of the steering manipulation system, and the linkage process includes a process of changing the value of the axial force adjustment variable with a value of the phase compensation adjustment variable as an input.

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