Steering control device and steering control method

Abstract

The steering operation control device (40) performs operation amount calculation processing, estimation processing, correction processing, and operation processing. The operation amount calculation processing is processing that calculates an operation amount of control that uses a steering operation torque as a control amount and uses a target steering operation torque as a target value of the control amount. The estimation processing is processing that estimates a disturbance torque using a nominal model and a filter. The correction processing is processing that corrects the operation amount in accordance with the disturbance torque estimated by the estimation processing. The operation processing is processing that operates a motor of the steering operation device in a manner that generates a torque corresponding to the operation amount corrected by the correction processing. The degree of a polynomial of a denominator of a transfer function of the filter is greater than the degree of a polynomial of a denominator of a transfer function of the nominal model.

Description

Technical Field

[0001] This invention relates to a steering control device and a steering control method. Background Technology

[0002] For example, Patent Document 1 describes a device for operating a motor that steers the steering wheel based on an operating quantity controlled by feedback control, using the steering torque as the control quantity and a target value of the steering torque as the target value of the control quantity. Specifically, the operating quantity of the feedback control is calculated based on the output values ​​of the proportional component, the derivative component, and the integral component.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2004-203089

[0004] However, when setting the feedback gain to meet the requirements of improving the responsiveness of the feedback control, there is a concern that the operating time of the component to make the values ​​of the feedback control parameters meet the above requirements becomes too long. Summary of the Invention

[0005] In one embodiment of the present invention, a steering control device is provided. The steering control device is configured to perform operation quantity calculation processing, inference processing, correction processing, and operation processing. The operation quantity calculation processing calculates a control operation quantity using steering torque as a control quantity and a target steering torque as a target value of the control quantity. The steering torque is the torque input by the driver to the steering control device, and the target steering torque is the target value of the steering torque. The inference processing infers a disturbance torque using a nominal model and a filter. The correction processing corrects the operation quantity based on the disturbance torque inferred by the inference processing. The operation processing operates the motor of the steering control device in a manner that generates a torque corresponding to the operation quantity corrected by the correction processing. The degree of the polynomial in the denominator of the transfer function of the filter is greater than the degree of the polynomial in the denominator of the transfer function of the nominal model.

[0006] In another embodiment of the present invention, a steering control method is provided. The steering control method includes the steps of performing operation quantity calculation processing, inference processing, correction processing, and operation processing. The operation quantity calculation processing calculates a control operation quantity using steering torque as a control quantity and a target steering torque as a target value of the control quantity. The steering torque is the torque input by the driver to the steering control device, and the target steering torque is the target value of the steering torque. The inference processing infers a disturbance torque using a nominal model and a filter. The correction processing corrects the operation quantity based on the disturbance torque inferred by the inference processing. The operation processing operates the motor of the steering control device in a manner that generates a torque corresponding to the operation quantity corrected by the correction processing. The degree of the polynomial in the denominator of the transfer function of the filter is greater than the degree of the polynomial in the denominator of the transfer function of the nominal model. Attached Figure Description

[0007] Figure 1 This is a diagram showing the steering control device and the structure of the steering device according to the first embodiment.

[0008] Figure 2 It means Figure 1 A block diagram of the processes performed by the steering control device.

[0009] Figure 3 It means Figure 2 The characteristics of the filter in the example and the characteristics of the filter in the comparative example are shown in the figure.

[0010] Figure 4 This is a block diagram illustrating the processing performed by the steering control device in the second embodiment.

[0011] Figure 5 This is a diagram showing the steering control device and the structure of the steering device according to the third embodiment.

[0012] Figure 6 It means Figure 5 A block diagram of the processes performed by the steering control device. Detailed Implementation

[0013] <First Implementation Method>

[0014] The first embodiment will now be described with reference to the accompanying drawings.

[0015] "Prerequisite Structure"

[0016] like Figure 1As shown, the steering control device 10 includes a steering wheel 12. The steering wheel 12 is a mechanism for transmitting the driver's steering input. The steering wheel 12 is connected to a transmission shaft 14. Therefore, if the steering wheel 12 rotates, the transmission shaft 14 rotates as well. The rotational power of the transmission shaft 14 is transmitted to the steering shaft 16. The steering shaft 16 runs along the vehicle width direction (…). Figure 1 It extends in the left and right direction. Steering wheels 20 are connected to both ends of the steering shaft 16 via steering tie rods 18.

[0017] The transmission shaft 14 is configured to intersect with the steering shaft 16. Both the transmission shaft 14 and the steering shaft 16 have meshing teeth. Furthermore, through the meshing of these teeth, power can be transmitted from the transmission shaft 14 to the steering shaft 16. That is, the rotational power of the transmission shaft 14 is converted into axial displacement power of the steering shaft 16. The axial displacement of the steering shaft 16 is transmitted to the steering wheel 20 via the steering tie rod 18. As a result, the steering angle of the steering wheel 20 is changed. Furthermore, the steering angle is the rotation angle of the tires.

[0018] Additionally, the steering control device 10 includes an auxiliary motor 30. The auxiliary motor 30 generates a force, or auxiliary force, to assist the driver in steering. The rotational power of the auxiliary motor 30 is applied to the drive shaft 34. Meshing teeth are formed on the drive shaft 34 and the steering shaft 16. Furthermore, the meshing of these teeth enables the transmission of power from the drive shaft 34 to the steering shaft 16. That is, the rotational power of the drive shaft 34 is converted into axial displacement power of the steering shaft 16. Thus, the rotational power of the auxiliary motor 30 is converted into axial displacement power of the steering shaft 16 via the drive shaft 34. Specifically, the auxiliary motor 30, as an example, is a three-phase brushless motor. Furthermore, the output voltage of the inverter 32 is applied to the terminals of the auxiliary motor 30.

[0019] The steering control unit 40 controls the control quantity of the steering control unit 10, which is the controlled object. To control the control quantity, the steering control unit 40 refers to the steering torque Th input to the steering wheel 12. The steering torque Th is detected by the torque sensor 50. The torque sensor 50 is a sensor that detects the steering torque Th based on the degree of torsion of a part of the transmission shaft 14, namely the torsion bar 52. Additionally, the steering control unit 40 refers to the vehicle speed SPD detected by the vehicle speed sensor 54. Furthermore, the steering control unit 40 refers to the rotation angle θa of the auxiliary motor 30 detected by the rotation angle sensor 56. Finally, the steering control unit 40 refers to the currents iu, iv, and iw flowing in the auxiliary motor 30.

[0020] The steering control unit 40 includes a PU 42 and a storage device 44. The PU 42 is a software processing device such as a CPU, GPU, or TPU. The storage device 44 includes a storage medium such as electrically erasable and rewritable non-volatile memory or a disk medium. The steering control program 44a is stored in the storage device 44. The steering control unit 40 executes the steering control program 44a stored in the storage device 44 via the PU 42 to control the control quantity.

[0021] "Processing performed by the steering control device 40"

[0022] exist Figure 2 The diagram shows the processing performed by the steering control device 40. Figure 2 The processing shown is achieved by PU42 executing steering control program 44a, for example, at a predetermined cycle.

[0023] The target steering torque calculation process M10 calculates the target value of the steering torque Th, i.e., the target steering torque Th*, based on the axial force Fa. The axial force Fa is the force applied to the steering shaft 16. However, the axial force Fa is converted into a torque transmitted to the shaft 14. Furthermore, the target steering torque calculation process M10 includes a process that sets the target steering torque Th* to a different value based on the vehicle speed SPD, even if the axial force Fa is the same. This is a setting designed to provide the driver with the optimal steering feel corresponding to the vehicle speed SPD.

[0024] The open-loop operation quantity calculation process M12 is the process for calculating the open-loop operation quantity Mff. The open-loop operation quantity Mff is the operation quantity of open-loop control using the steering torque Th as the control quantity and the target steering torque Th* as the target value of the control quantity. The open-loop operation quantity calculation process M12 calculates the open-loop operation quantity Mff by inputting the target steering torque Th*. The open-loop operation quantity calculation process M12 calculates the open-loop operation quantity Mff based on the inverse model of the nominal model Pn. The nominal model Pn is a model that uses the torque of the auxiliary motor 30, i.e., the auxiliary torque Ta, as input and outputs the inferred value of the steering torque Th, i.e., the inferred steering torque The. Here, the auxiliary torque Ta is the value converted to the torque of the transmission shaft 14. The inverse model is a model that uses the inferred steering torque The as input and outputs the auxiliary torque Ta. Furthermore, the nominal model Pn will be described in detail later.

[0025] Deviation calculation processing M14 is the process of calculating the deviation obtained by subtracting the target steering torque Th* from the steering torque Th.

[0026] The feedback operation quantity calculation process M16 is a process that uses the deviation as input to calculate the feedback operation quantity Mfb. The feedback operation quantity Mfb is the operation quantity of feedback control that uses the steering torque Th as the control quantity and the target steering torque Th* as the target value of the control quantity. The feedback operation quantity Mfb is the sum of the output value of the proportional component using the deviation as input and the output value of the differential component using the deviation as input. Furthermore, the feedback operation quantity Mfb is a value converted into the torque of the transmission shaft 14. Specifically, the feedback operation quantity calculation process M16 includes a process of changing at least one of the gain of the proportional component and the gain of the differential component according to the vehicle speed SPD.

[0027] The torque command value calculation process M20 is a process that uses the open-loop operating quantity Mff, the feedback operating quantity Mfb, and the inferred second disturbance torque de as inputs to calculate the auxiliary torque Ta. In the torque command value calculation process M20, the value obtained by subtracting the inferred second disturbance torque de from the sum of the open-loop operating quantity Mff and the feedback operating quantity Mfb is substituted into the auxiliary torque Ta.

[0028] The auxiliary torque Ta is input into the axial force calculation process M22. The axial force calculation process M22 is the process of substituting the sum of the auxiliary torque Ta and the steering torque Th into the axial force Fa.

[0029] The auxiliary torque Ta is input to the disturbance observer M30. The disturbance observer M30 includes a steering torque inference process M32, a first disturbance calculation process M34, and a second disturbance calculation process M36.

[0030] The steering torque inference process M32 is a process that inputs the auxiliary torque Ta into the nominal model Pn and outputs the inferred steering torque The. The inferred steering torque The is the steering torque assumed by the nominal model Pn.

[0031] The first disturbance calculation process M34 is the process of calculating the inferred first disturbance torque dhe. The inferred first disturbance torque dhe is the disturbance component in the actual steering torque Th of the controlled object. The inferred first disturbance torque dhe is the difference between the actual torque and the torque inferred from the nominal model Pn. In other words, the inferred first disturbance torque dhe is the difference between the steering torque assumed by the nominal model Pn and the actual steering torque Th. In detail, the first disturbance calculation process M34 is the process of substituting the value obtained by subtracting the inferred steering torque The from the steering torque Th into the inferred first disturbance torque dhe.

[0032] The second interference calculation process M36 takes the inferred first interference torque dhe as input to calculate the inferred second interference torque de. The inferred second interference torque de is the interference torque converted into the torque of the auxiliary motor 30. The second interference calculation process M36 uses the inverse model of the nominal model Pn and the filter Hd to calculate the inferred second interference torque de.

[0033] The filter Hd is configured to reduce noise caused by the differential operations contained in the nominal model Pn. In this embodiment, filter Hd is, as an example, a third-order low-pass filter.

[0034] As described above, the auxiliary torque Ta is obtained by subtracting the inferred second disturbance torque de from the sum of the open-loop operating quantity Mff and the feedback operating quantity Mfb. On the other hand, the inferred second disturbance torque de is obtained by converting the difference between the steering torque assumed by the nominal model Pn and the actual steering torque Th into the torque of the auxiliary motor 30. This means that the inferred second disturbance torque de is the quantity corresponding to the difference between the steering torque assumed by the nominal model Pn and the actual steering torque Th. Therefore, the auxiliary torque Ta is obtained by correcting the sum of the open-loop operating quantity Mff and the feedback operating quantity Mfb according to the correction amount corresponding to the difference between the steering torque assumed by the nominal model Pn and the actual steering torque Th.

[0035] The operation signal generation process M40 operates the inverter 32 by inputting the auxiliary torque Ta. Specifically, the operation signal generation process M40 calculates the operation quantity using the torque of the auxiliary motor 30 as the control quantity and converting the target value of the auxiliary torque Ta into the torque of the auxiliary motor 30. Additionally, the operation signal generation process M40 includes a process for operating the inverter 32 in a manner that yields the same operation quantity. The operation quantity can, for example, be the ratio of the off-time of the switching elements of the inverter 32 to one cycle of its on / off operation. Figure 2 The document describes the operation signal MS for inverter 32. However, in reality, the operation signal MS is a separate operation signal for each switching element of inverter 32.

[0036] "Nominal model Pn"

[0037] The steering torque Th, when using the inertia coefficient Jh, viscosity coefficient Ch, and steering angle θh, is expressed by the following equation (c1). Furthermore, the inertia coefficient Jh represents the inertia of the portion of the transmission shaft 14 closer to the steering wheel 12 than the torsion bar 52, i.e., the first portion. Additionally, the viscosity coefficient Ch represents the viscosity of the first portion of the transmission shaft 14. Finally, the steering angle θh is the rotation angle of the steering wheel 12.

[0038] -Th=(Jh·s·s+Ch·s)·θh…(c1)

[0039] On the other hand, when using the rotation angle θl and the torsional stiffness coefficient Ktb of the torsion bar 52, the following equation (c2) holds. Furthermore, the rotation angle θl is the rotation angle of the portion of the transmission shaft 14 that is further away from the steering wheel 12 than the torsion bar 52, i.e., the second portion.

[0040] Th=Ktb·(θh-θl)…(c2)

[0041] Furthermore, when using the inertia coefficient J, viscosity coefficient C, and elasticity coefficient K, the following equation (c3) holds true regarding the rotation angle θl, auxiliary torque Ta, and steering torque Th. The inertia coefficient J represents the inertia of the second part of the transmission shaft 14. The viscosity coefficient C represents the viscosity of the second part of the transmission shaft 14. The elasticity coefficient K represents the elasticity of the second part of the transmission shaft 14. Moreover, the viscosity coefficient C and the elasticity coefficient K actually reflect the influence of the steering shaft 16, steering tie rod 18, and steering wheel 20 on the transmission shaft 14.

[0042] Th+Ta=(J·s·s+C·s+K)·θl...(c3)

[0043] Here, if the steering torque Th is input with the steering angle θh set to zero, then the steering angle θh will always be zero. When the steering angle θh is set to zero and the transfer function from the auxiliary torque Ta to the steering torque Th is calculated based on the above equations (c1) to (c3), the following equation (c4) can be obtained.

[0044] Th / Ta=(-Ktb) / {J·s·s+C·s+K+Ktb}…(c4)

[0045] Furthermore, the differential operator s is used in equation (c4) above. Equation (c4) above is the nominal model Pn. Moreover, equation (c4) above holds even if "θh" and "θl" are read differently in equations (c1) to (c3) above, as follows.

[0046] θh: The phase difference between the rotation angle of the first part of the transmission shaft 14 and the rotation angle of the steering wheel 12. It is always zero.

[0047] θl: The phase difference between the rotation angle of the second part of the transmission shaft 14 and the rotation angle of the steering wheel 12.

[0048] Therefore, the above equation (c4) holds true for any steering angle θh.

[0049] Regarding filter Hd

[0050] In this embodiment, the degree of the polynomial in the denominator of the filter's transfer function is 3, and the degree of the polynomial in the numerator is 0. Specifically, the filter's transfer function is the cube of "ω / (s+ω)". Here, the cutoff frequency ω and the differential operator s are used for the filter's transfer function. Furthermore, the degree of the polynomial is the highest degree of the differential operator. Additionally, from this point onward, monomials are considered polynomials where all but one term are zero.

[0051] The above settings for the filter's transfer function are intended to effectively attenuate high-frequency noise.

[0052] In other words, the purpose of filter Hd is to suppress high-frequency noise generated by the differential components contained in the inverse model of the nominal model Pn. Here, the polynomial in the denominator of the transfer function of the nominal model Pn is quadratic, so as long as the polynomial in the denominator of the transfer function of filter Hd is set to quadratic, the influence caused by the differential components can be suppressed.

[0053] However, as Figure 3 As shown, compared to a second-order filter, a third-order filter can further attenuate the signal in the high-frequency region beyond the cutoff frequency ω. Therefore, a third-order filter is used in this embodiment. Furthermore, Figure 3 The transfer function of the second-order filter in the comparative example is the square of “ω / (s+ω)”.

[0054] <Function and Effects of This Implementation Method>

[0055] PU42 uses the difference between the steering torque Th and the inferred steering torque The, i.e., the inferred first disturbance torque dhe, as input to calculate the inferred second disturbance torque de. The inferred second disturbance torque de represents the disturbance component that transmits the torque of the second part of the shaft 14. That is, it represents the disturbance component in the torque that is converted into the force that causes the steering shaft 16 to shift.

[0056] PU42 uses the value obtained by correcting the open-loop operating quantity Mff and the feedback operating quantity Mfb through the inferred second disturbance torque de as the auxiliary torque Ta. Furthermore, PU42 operates the inverter 32 in a manner where the torque of the auxiliary motor 30 is close to the auxiliary torque Ta. Thus, it is possible to perform control that compensates for the error between the nominal model Pn and the actual controlled object, i.e., the disturbance components, and uses the target steering torque Th* as the target value of the control quantity. In other words, it is possible to compensate for the error between the nominal model Pn and the actual controlled object through the disturbance observer M30 and perform control that uses the target steering torque Th* as the target value of the control quantity.

[0057] In this way, the error equivalent value is immediately compensated, thus improving the responsiveness of the steering torque Th relative to the target steering torque Th*.

[0058] In addition, compared to designing the controller based on the actual controlled object without using the disturbance observer M30, the time required for controller design can be reduced.

[0059] Furthermore, the second interference calculation process M36 is set as the synthesis process of the inverse model of the nominal model Pn and the filter Hd. Moreover, the polynomial in the denominator of the transfer function of the filter Hd is set to cubic. Therefore, compared to setting the polynomial in the denominator of the transfer function of the filter Hd to quadratic, the attenuation effect of high-frequency noise can be improved.

[0060] According to the above-described implementation method, the following functions and effects are also achieved.

[0061] In (1-1) Figure 2 In the process shown, when the actual controlled object is set as the actual device P, the transfer function from the auxiliary torque Ta to the steering torque Th is as follows.

[0062] 1 / {(1-Hd) / P+Hd / Pn}

[0063] Here, in the low-frequency region below the cutoff frequency ω, such as Figure 3 As shown, the gain of filter Hd is close to "1". Therefore, the transfer function from the auxiliary torque Ta to the steering torque Th is approximately the same as the nominal model Pn itself.

[0064] On the other hand, PU42 calculates the open-loop operating amount Mff by inputting the target steering torque Th* into the inverse model of the nominal model Pn. Therefore, the transfer function from the target steering torque Th* to the steering torque Th is approximately "1". In other words, the transfer function of the steering torque Th, which is output by taking the input of the open-loop operating amount calculation process M12 as input and including the disturbance observer M30 and the actual device P, is approximately "1". Therefore, it is possible to linearize the steering torque Th from the target steering torque Th* as input to the steering torque Th as output.

[0065] (1-2) The auxiliary torque Ta includes the feedback operation amount Mfb. Therefore, the error equivalent value of the inferred second disturbance torque de can be compensated by the feedback operation amount Mfb. Thus, the steering torque Th can be approximated to the target steering torque Th* with higher accuracy.

[0066] (1-3) The nominal model Pn is composed of not only the inertia coefficient J, but also the viscosity coefficient C, the elastic coefficient K, and the torsional stiffness coefficient Ktb. Thus, the nominal model Pn can be set as a model that approximates the actual control object with high accuracy.

[0067] <Second Implementation Method>

[0068] Hereinafter, the second embodiment will be described with reference to the accompanying drawings, focusing on the differences from the first embodiment.

[0069] In this embodiment, the nominal model Pn is simplified.

[0070] exist Figure 4 The diagram illustrates the processing performed by the steering control device 40 of this embodiment. Figure 4 For convenience, the processing shown is as follows: Figure 2 The processing shown corresponds to the processing labeled with the same reference numerals in the attached figures.

[0071] like Figure 4 As shown in the steering torque inference process M32a, in this embodiment, the nominal model Pn is represented by the following equation (c5).

[0072] (-Ktb) / {J·s·s}…(c5)

[0073] That is, the nominal model Pn does not have terms for the viscosity coefficient C and the elastic coefficient K. Here, the viscosity coefficient C and the elastic coefficient K need to be estimated and determined based on the actual vehicle. In contrast, the inertia coefficient J is roughly determined by the inertia of the auxiliary motor 30 and the ratio of the rotational speed of the transmission shaft 14 in the steering control device 10 to the rotational speed of the auxiliary motor 30, i.e., the attenuation ratio. In addition, the torsional stiffness coefficient Ktb is determined by the characteristics of the torsion bar 52 of the torque sensor 50. Therefore, by omitting the terms for the viscosity coefficient C and the elastic coefficient K from the nominal model Pn, the design time of the nominal model Pn can be reduced.

[0074] <Third Implementation Method>

[0075] Hereinafter, the third embodiment will be described with reference to the accompanying drawings and focusing on the differences from the first embodiment.

[0076] "Prerequisite Structure"

[0077] exist Figure 5 The structure of the steering control system of this embodiment is shown in the diagram. Furthermore, in... Figure 5 For convenience, the Chinese text is incomplete and contains numerous errors. A direct translation is not possible without further context. Figure 1 The components shown are labeled with the same reference numerals as the corresponding components in the attached drawings.

[0078] like Figure 5 As shown, in the steering control device 10, the transmission shaft 14 is separated into an input shaft 14a connected to the steering wheel 12 and an output shaft 14b engaging with the steering shaft 16. Furthermore, in this embodiment, the output shaft 14b is not actually required. However, it is provided for the convenience of the following explanation.

[0079] A reaction force motor 70 is provided on the input shaft 14a. The reaction force motor 70 is a motor used to apply torque, i.e., reaction force, to the steering wheel 12 in the opposite direction to the torque input by the driver. As an example, the reaction force motor 70 is a three-phase brushless motor. In addition, the output voltage of the inverter 72 is applied to the terminals of the reaction force motor 70.

[0080] The torque of the steering motor 80 is applied to the steering shaft 16 via the drive shaft 34. As an example, the steering motor 80 is a three-phase brushless motor. In addition, the output voltage of the inverter 82 is applied to the terminals of the steering motor 80.

[0081] The steering control device 40 uses the steering control device 10 as the controlled object. The steering control device 40 operates the inverter 72 to control the control quantity of the controlled object, i.e., the reaction force. Additionally, the steering control device 40 operates the inverter 82 to control the control quantity of the controlled object, i.e., the steering angle of the steering wheel 20.

[0082] In order to control the control quantity, i.e., the reaction force, the steering control device 40 refers to the rotation angle θs of the reaction force motor 70 detected by the rotation angle sensor 90. Furthermore, in order to control the reaction force, the steering control device 40 refers to the currents ius, ivs, and iws flowing into the reaction force motor 70. Additionally, in order to control the control quantity, i.e., the steering angle, the steering control device 40 refers to the rotation angle θt of the steering motor 80 detected by the rotation angle sensor 92. Furthermore, in order to control the steering angle, the steering control device 40 refers to the currents iut, ivt, and iwt flowing in the steering motor 80.

[0083] "Processing performed by the steering control device 40"

[0084] exist Figure 6 The diagram shows the processing performed by the steering control device 40. In other words, Figure 6 This illustrates the processing performed by the steering control device 40 when the power transmission from the steering wheel 12 to the steering wheel 20 is cut off. Furthermore, in... Figure 6 For convenience, the Chinese text is incomplete and contains numerous errors. A direct translation is not possible without further context. Figure 2 The processing shown corresponds to the processing labeled with the same reference numerals in the attached figures.

[0085] like Figure 6As shown, deviation calculation process M14 calculates the value obtained by subtracting the steering torque Th from the target steering torque Th*. Torque command value calculation process M20 outputs the reaction force command value Tr*. Torque command value calculation process M20 substitutes the value obtained by subtracting the inferred second disturbance torque de from the sum of the open-loop operation amount Mff and the feedback operation amount Mfb into the reaction force command value Tr*. The reaction force command value Tr* is the command value of the reaction torque applied to the steering wheel 12. The reaction force command value Tr* is converted into the angle of the transmission shaft 14.

[0086] The steering operation signal generation process M40a operates the inverter 72 by inputting a reaction force command value Tr*. Specifically, the steering operation signal generation process M40a includes processing the calculation of an operation quantity using the torque of the reaction force motor 70 as a control quantity and converting the reaction force command value Tr* as a target value of the control quantity into the torque of the reaction force motor 70. The calculation of the operation quantity refers to the rotation angle θs and the currents ius, ivs, and iws. Furthermore, the steering operation signal generation process M40a includes processing the operation of the inverter 72 based on this operation quantity. Figure 5 The document describes the operation signal MSs of inverter 72. Furthermore, the operation signal MSs is actually a separate operation signal for each switching element of inverter 72.

[0087] The target angle calculation process M50 is the process of calculating the target value of the rotation angle of the drive shaft 34, i.e., the target angle θp*. The rotation angle of the drive shaft 34 has a one-to-one correspondence with the steering angle. The target angle calculation process M50 can also be, for example, a process that uses the model of the steering control device 10 and calculates the target angle θp* based on the reaction force command value Tr*. In this model, for example, it can also be assumed that the input shaft 14a and the output shaft 14b are mechanically connected, and the reaction force command value Tr* can be regarded as the torque applied to the transmission shaft 14.

[0088] The angle control process M52 is a process that calculates the operating amount used to control the rotation angle of the drive shaft 34 to the target angle θp*. This operating amount is the command value for the torque of the steering motor 80, i.e., the steering torque command value Tt*.

[0089] The steering operation signal generation process M54 operates the inverter 82 by inputting a steering torque command value Tt*. The steering operation signal generation process M54 includes processing for calculating the control quantity using the torque of the steering motor 80 as the control quantity and converting the steering torque command value Tt* into the torque of the steering motor 80 as the target value of the control quantity. The calculation of the control quantity refers to the rotation angle θt and the currents iut, ivt, and iwt. Furthermore, the steering operation signal generation process M54 includes processing for operating the inverter 82 according to this control quantity. Figure 5 The document describes the operating signal MSt of inverter 82. Furthermore, the operating signal MSt is actually a separate operating signal for each switching element of inverter 82.

[0090] <Other Implementation Methods>

[0091] Furthermore, the above embodiments can be modified as follows. The above embodiments and the following modifications can be combined with each other to the extent that they are not technically contradictory.

[0092] "Regarding the calculation and processing of target steering torque M10"

[0093] It is not mandatory for the target steering torque calculation process M10 to calculate the target steering torque Th* based on the axial force Fa. For example, the target steering torque calculation process M10 can also be a process that uses the steering torque Th and the auxiliary torque Ta as inputs to calculate the target steering torque Th*.

[0094] Using vehicle speed SPD as input is not mandatory for the target steering torque calculation and processing M10.

[0095] The input to the target steering torque calculation process M10 is not limited to the above-described cases. For example, two or more sampled values ​​of the steering angle at different sampling times can be input to the target steering torque calculation process M10. In this case, based on this input, it is possible to perform identification processing when the steering wheel 12 is turned and when it is returned to its original position. Therefore, for example, the absolute value of the target steering torque Th* can be set to a larger value when turning the wheel compared to when returning to its original position.

[0096] Regarding the calculation and processing of open-loop operation quantities

[0097] The open-loop maneuvering calculation process M12 is not limited to a process that uses the target steering torque Th* as input. For example, the open-loop maneuvering calculation process M12 can also be a process that uses the axial force Fa as input. In this case, the transfer function of the open-loop maneuvering calculation process M12 is simply the product of the transfer function of the target steering torque Th* calculated based on the axial force Fa and the inverse model of the nominal model Pn.

[0098] Regarding the calculation and processing of feedback operation quantities

[0099] The feedback operation quantity Mfb does not necessarily have to be the sum of the output value of the proportional component that uses the deviation as input and the output value of the differential component that uses the deviation as input. For example, the feedback operation quantity Mfb can also be the sum of the output value of the proportional component that uses the deviation as input, the output value of the differential component that uses the deviation as input, and the output value of the integral component that uses the value corresponding to the deviation as input. Moreover, for example, the feedback operation quantity Mfb can also be the sum of the output value of the proportional component that uses the deviation as input and the output value of the integral component that uses the value corresponding to the deviation as input. In this case, the gain of the integral component can also be changed according to the vehicle speed SPD.

[0100] Furthermore, the differential component is not limited to the case of input deviation. For example, the differential component can also use the steering torque Th as input. In other words, the differential component can also constitute a leading differential type controller.

[0101] It is not necessary to make at least one of the gain of the component constituting the feedback operation quantity calculation process variable according to the vehicle speed SPD.

[0102] Regarding the calculation and processing of operational quantities

[0103] For example, it is also possible to omit feedback operation calculation processing and instead consist solely of open-loop operation calculation processing. Furthermore, for example, it is also possible to omit open-loop operation calculation processing and instead consist solely of feedback operation calculation processing.

[0104] Regarding the nominal model Pn

[0105] The nominal model Pn is not limited to the model illustrated in the above embodiments. For example, instead of the nominal model Pn used in the steering torque inference process M32a, a model represented by the following equation (c6) may be used.

[0106] (-Ktb) / {J·s·s+Ktb}…(c6)

[0107] That is, the polynomial in the denominator of the transfer function of the nominal model Pn can also contain zero-degree terms. In other words, the denominator of the transfer function of the nominal model Pn can also contain zero-degree terms of the differential operator.

[0108] Furthermore, the degree of the polynomial in the denominator of the transfer function of the nominal model Pn does not necessarily have to be second order.

[0109] Regarding filter Hd

[0110] The degree of the polynomial in the denominator of the transfer function of filter Hd is not limited to that of a third degree. For example, the degree of the polynomial in the denominator of the transfer function of filter Hd can also be fourth degree or higher. Furthermore, for example, if the degree of the polynomial in the denominator of the transfer function of the nominal model Pn is first degree, the degree of the polynomial in the denominator of the transfer function of filter Hd can also be set to second degree or higher.

[0111] Regarding the correction process

[0112] The correction process is not limited to the process that includes steering torque inference process M32, first disturbance calculation process M34, second disturbance calculation process M36, and torque command value calculation process M20. For example, firstly, the steering torque Th can be used as input to a combination process that combines the inverse model of the nominal model Pn and the filter Hd to calculate the inferred motor torque Tae. In this case, secondly, it is only necessary to perform a difference calculation process that calculates the difference between the sum of the open-loop operating quantity Mff and the feedback operating quantity Mfb and the inferred motor torque Tae. Moreover, thirdly, the torque command value calculation process M20 can also perform a process that uses the output of the difference calculation process to correct the sum of the open-loop operating quantity Mff and the feedback operating quantity Mfb. In this case, the correction process consists of the combination process, the difference calculation process, and the torque command value calculation process M20. Furthermore, the output of the above difference calculation process is a quantity corresponding to the difference between the steering torque assumed by the nominal model Pn and the actual steering torque Th.

[0113] Regarding operational procedures

[0114] exist Figure 2The illustrated process, while setting the operation process to use the torque of the auxiliary motor 30 as the control quantity and using the value obtained by converting the target value of the auxiliary torque Ta as the control quantity into the torque of the auxiliary motor 30, is not limited to this. For example, the operation process may also include a process for calculating the target value of the rotation angle of the auxiliary motor 30 based on the axial force Fa. In this case, the operation process is a process of operating the auxiliary motor 30 based on the operation quantity of feedback control using the rotation angle of the auxiliary motor 30 as the control quantity. Furthermore, here, the axial force Fa is the sum of the value obtained by the operation quantity determined by the inferred second disturbance torque de based on the open-loop operation quantity Mff and the feedback operation quantity Mfb, and the steering control torque Th. Therefore, the operation process becomes a process of operating the inverter 32 based on the value obtained by the operation quantity determined by the inferred second disturbance torque de based on the open-loop operation quantity Mff and the feedback operation quantity Mfb. This is a process of controlling the torque of the auxiliary motor 30 in a manner that generates the torque corresponding to the value obtained by the operation quantity determined by the inferred second disturbance torque de based on the open-loop operation quantity Mff and the feedback operation quantity Mfb.

[0115] Furthermore, the embodiments that can apply changes including angle feedback control are not limited to... Figure 2 The illustrated embodiment. For example, it can also be applied to... Figure 4 as well as Figure 6 The example shown.

[0116] Regarding the steering control device

[0117] exist Figure 5 In the illustrated structure, the device for operating the reaction force motor 70 and the device for operating the steering motor 80 can also be independent.

[0118] The steering control device is not limited to a device that includes a PU42 and a storage device 44 and performs software processing. For example, it may also include dedicated hardware circuitry such as an ASIC that performs at least a portion of the processing performed in the above embodiments. That is, the steering control device may also include a processing circuit having any of the structures of (a) to (c) below.

[0119] (a) A processing circuit having all the processing devices that perform the above processing according to the program, and a program storage device such as a storage device for storing the program.

[0120] (b) A processing circuit having a processing device for performing a portion of the above-described processing according to a program, a program storage device, and dedicated hardware circuitry for performing the remaining processing.

[0121] (c) A processing circuit that has all the dedicated hardware circuits to perform the above processing.

[0122] Here, there can be multiple software execution devices equipped with processing units and program storage units. In addition, there can also be multiple dedicated hardware circuits.

[0123] Regarding steering control methods

[0124] The entity that performs the various controls described above is not limited to the steering control device installed in the vehicle. For example, the driver's mobile terminal can also perform part of the processing for controlling the target steering torque Th*, such as the disturbance observer M30.

[0125] Regarding the Input Department

[0126] The input unit for inputting steering torque is not limited to the steering wheel 12.

[0127] "Regarding the disconnection state of power transmission"

[0128] The structure that achieves the disconnection of power transmission between the input unit for input steering torque and the steering wheel 20 is not limited to... Figure 5 The illustrated structure. For example, a clutch can also be provided between the input shaft 14a and the output shaft 14b.

[0129] Regarding the steering control system

[0130] As an actuator to steer the steering wheel 20, a device may be used that mounts the auxiliary motor 30 or the steering motor 80 on the same axis as the steering shaft 16. Furthermore, a device may be used that transmits power from the auxiliary motor 30 or the steering motor 80 to the steering shaft 16 via a belt reducer using a ball screw mechanism.

[0131] As a steering control device capable of changing the relationship between the steering control angle and the steering angle, it is not limited to, for example... Figure 5 The example illustrates a steering control device that cuts off the transmission of power between the steering wheel 12 and the steering wheel 20. For example, a steering control device capable of changing the relationship between the steering angle and the steering control angle can also be constructed by making the gear capable of transmitting power between the steering wheel 12 and the steering wheel 20 a variable gear.

Claims

1. A steering control device, wherein, Its structure consists of operation quantity calculation processing, inference processing, correction processing, and operation processing. The above-described operation quantity calculation process is the process of calculating the operation quantity for control that uses steering torque as the control quantity and a target steering torque as the target value of the control quantity. The aforementioned steering torque is the torque input by the driver to the steering control device. The aforementioned target steering torque is the target value of the aforementioned steering torque. The above inference process uses a nominal model and filters to infer the disturbance torque. The above correction process is a process of correcting the above operating amount based on the disturbance torque inferred from the above inference process. The above-described operation process is a process of operating the motor of the steering control device in a manner that generates torque corresponding to the operating amount corrected by the above-described correction process. The degree of the polynomial in the denominator of the transfer function of the above filter is greater than the degree of the polynomial in the denominator of the transfer function of the above nominal model.

2. The steering control device according to claim 1, wherein, The polynomial in the denominator of the transfer function of the above nominal model has a degree of 2. The polynomial in the denominator of the transfer function of the above filter has a degree of 3 or higher.

3. The steering control device according to claim 2, wherein, The polynomial in the denominator of the transfer function of the above filter has a degree of 3.

4. The steering control device according to claim 2, wherein, The polynomial in the denominator of the transfer function of the above nominal model contains a first-order term and a zero-order term.

5. The steering control device according to claim 2, wherein, The polynomial in the denominator of the transfer function of the above nominal model does not contain a linear term.

6. The steering control device according to claim 1, wherein, The above-mentioned operation quantity calculation and processing includes open-loop operation quantity calculation and processing. The above-described open-loop operation calculation process involves inputting the target steering torque into the inverse model of the nominal model to calculate the open-loop operation. The aforementioned open-loop operating quantity is the operating quantity of open-loop control that uses the aforementioned steering torque as the aforementioned control quantity and uses the aforementioned target steering torque as the target value of the aforementioned control quantity.

7. The steering control device according to claim 1, wherein, The above-mentioned operation quantity calculation and processing includes feedback operation quantity calculation and processing. The above-described feedback operation quantity calculation process is the process of calculating the feedback operation quantity. The aforementioned feedback operation quantity is the operation quantity of feedback control that uses the aforementioned steering torque as the aforementioned control quantity and uses the aforementioned target steering torque as the target value of the aforementioned control quantity.

8. The steering control device according to claim 1, wherein, The motor mentioned above is the motor that steers the vehicle's steering wheels.

9. The steering control device according to claim 1, wherein, The motor described above applies torque to the input unit when the power transmission between the vehicle's steering wheel and the input unit for steering torque is cut off.

10. A steering control method, comprising the steps of performing operation quantity calculation processing, inference processing, correction processing, and operation processing. The above-described operation quantity calculation process is the process of calculating the operation quantity for control that uses steering torque as the control quantity and a target steering torque as the target value of the control quantity. The aforementioned steering torque is the torque input by the driver to the steering control device. The aforementioned target steering torque is the target value of the aforementioned steering torque. The above inference process uses a nominal model and filters to infer the disturbance torque. The above correction process is a process of correcting the above operating amount based on the disturbance torque inferred from the above inference process. The above-described operation process is a process of operating the motor of the steering control device in a manner that generates torque corresponding to the operating amount corrected by the above-described correction process. The degree of the polynomial in the denominator of the transfer function of the above filter is greater than the degree of the polynomial in the denominator of the transfer function of the above nominal model.

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