Control device, steering device, control method, and storage medium

Abstract

The present disclosure relates to a control device, a steering device, a control method, and a storage medium. The control device is configured to execute the following processing: calculating a command torque to be applied to a steering mechanism; calculating an adjustment gain based on the steering torque to calculate an adjustment gain for the command torque; calculating an adjusted command torque obtained by applying the adjustment gain to the command torque; and controlling a torque steering mechanism based on the adjustment command. The adjustment gain calculation includes calculating an adjusted steering torque having a predetermined hysteresis characteristic relative to changes in the steering torque based on the steering torque; and converting the adjusted steering torque into an adjustment gain.

Description

Technical Field

[0001] The present disclosure relates to a technology for controlling a steering mechanism of a vehicle, and more particularly to a technology for controlling a steering mechanism so that the vehicle follows a target trajectory. Background Art

[0002] Japanese Patent Application Laid-Open No. 2018-030481 discloses a steering control device as described below, comprising: a state determination unit configured to determine at least whether the steering state is in a steering normally state or a steering back state based on the steering torque and the motor angular velocity; an intervention detection unit that calculates an intervention coefficient for the steering torque based on a transformation characteristic that changes according to the steering state; and an internal value calculation unit that changes the ratio of the automatic steering torque and the assist torque according to the intervention coefficient.

[0003] In recent years, a function that enables a vehicle to follow a target trajectory (hereinafter referred to as a "follow-up steering function") has been considered as a driving assistance and autonomous driving function. In the following steering function, the steering mechanism is controlled so that the vehicle follows the target trajectory. Generally, the torque applied to the steering mechanism is controlled during steering control.

[0004] On the other hand, while the following steering function is in operation, the driver may decide to steer the vehicle in a direction different from the target trajectory. In this case, the driver operates the steering wheel or other driving control devices to steer the vehicle in the desired direction. In this case, the driver must overcome the torque applied by the following steering function to generate a steering torque through the operation of the driving control devices. Therefore, the torque applied by the following steering function is generally adjusted based on the steering torque.

[0005] The driver experiences a different driving feel when attempting to generate a steering torque in a direction opposite to the torque applied by the follow-up steering function than when attempting to generate a steering torque in the same direction. Therefore, there is a concern that the driver's steering state relative to the target trajectory may impart an extreme driving feel to the driver, further compromising the driver's controllability of the vehicle.

[0006] Japanese Patent Application Laid-Open No. 2018-030481 discloses a technique for determining the driver's steering state based on whether the vehicle is holding, turning, returning, or releasing its steering wheel, and calculating an intervention coefficient based on a change characteristic that varies depending on the steering state. Specifically, the technique discloses applying a change characteristic when the steering state is returning to minimize intervention in the following control.

[0007] However, the technology disclosed in Japanese Patent Application Laid-Open No. 2018-030481 envisions scenarios where the driver's steering state relative to the target trajectory may not adequately improve the vehicle's controllability. For example, if the driver wishes to make a minor correction to the vehicle's trajectory, the adjustment gain must be adjusted within a small range of state changes, raising concerns that both tracking the vehicle to the target trajectory and improving the driver's controllability of the vehicle may not be achieved. Summary of the Invention

[0008] In view of the above problems, one object of the present disclosure is to provide a technology that can appropriately improve the driver's controllability of the vehicle according to the steering state relative to a target trajectory when the driver intends to steer the vehicle while the follow-up steering function is operating.

[0009] The first disclosure relates to a control device for a vehicle.

[0010] The control device according to the first disclosure is configured to execute the following processes: a process for calculating a command torque to be applied to a steering mechanism for causing the vehicle to follow a target trajectory; an adjustment gain calculation process for calculating an adjustment gain for the command torque based on the steering torque; an adjustment command torque calculation process for calculating an adjusted command torque obtained by applying the adjustment gain to the command torque; and a process for controlling the steering mechanism based on the adjusted command torque. The adjustment gain calculation process includes a first process for calculating an adjusted steering torque having a predetermined hysteresis characteristic relative to changes in the steering torque based on the steering torque; and a second process for converting the adjusted steering torque into the adjustment gain.

[0011] The second disclosure relates to a control device that further has the following features compared to the control device according to the first disclosure.

[0012] The above-mentioned first processing includes: accepting that the absolute value of the difference between the above-mentioned steering torque and the above-mentioned adjusted steering torque of the previous processing is greater than the specified torque lag, and calculating the above-mentioned adjusted steering torque of the current processing in the direction of reducing the above-mentioned absolute value; and accepting that the above-mentioned absolute value is less than the above-mentioned torque lag, and calculating the above-mentioned adjusted steering torque of the previous processing as the above-mentioned adjusted steering torque of the current processing.

[0013] The third disclosure relates to a control device that further has the following features compared to the control device according to the second disclosure.

[0014] Calculating the above-mentioned adjusted steering torque of this processing in the direction of decreasing the above-mentioned absolute value in the above-mentioned first processing includes: when the above-mentioned steering torque is greater than the above-mentioned adjusted steering torque of the previous processing, calculating the value obtained by subtracting the above-mentioned torque lag from the above-mentioned steering torque as the above-mentioned adjusted steering torque of this processing; and when the above-mentioned steering torque is less than the above-mentioned adjusted steering torque of the previous processing, calculating the value obtained by adding the above-mentioned torque lag to the above-mentioned steering torque as the above-mentioned adjusted steering torque of this processing.

[0015] The fourth disclosure relates to a control device that further has the following features compared to the control device according to the first disclosure.

[0016] The above-mentioned first processing includes: when the absolute value of the difference between the above-mentioned steering torque and the above-mentioned steering torque of the previous processing is greater than the specified torque lag, calculating the above-mentioned adjusted steering torque of this processing in the direction of reducing the above-mentioned absolute value; and when the above-mentioned absolute value is less than the above-mentioned torque lag, calculating the above-mentioned adjusted steering torque of this processing in a manner that changes according to a specified slope.

[0017] The fifth disclosure relates to a control device that further has the following features compared to the control device according to any one of the second to fourth disclosures.

[0018] The adjustment gain calculation process further includes causing the torque to change with a hysteresis according to the steering torque.

[0019] The sixth disclosure relates to a control device that further has the following features compared to the control device according to any one of the first to fifth disclosures.

[0020] The above-mentioned command torque includes an FF command torque and an FB command torque. The above-mentioned FF command torque becomes a feedforward control quantity based on the target state quantity for following the above-mentioned target track, and the above-mentioned FB command torque becomes a feedback control quantity based on the difference between the above-mentioned target state quantity and the current state quantity. In addition, the above-mentioned adjustment gain includes a first adjustment gain and a second adjustment gain. In addition, the above-mentioned adjustment gain calculation process includes the above-mentioned first process or the above-mentioned second process corresponding to the above-mentioned first adjustment gain and the above-mentioned second adjustment gain, respectively. Moreover, the above-mentioned adjustment command torque calculation process calculates the adjusted FB command torque obtained by applying the above-mentioned first adjustment gain to the above-mentioned FB command torque, and calculates the value obtained by applying the above-mentioned second adjustment gain to the sum of the above-mentioned FF command torque and the above-mentioned adjusted FB command torque, or the sum of the value obtained by applying the above-mentioned second adjustment gain to the above-mentioned FF command torque and the above-mentioned adjusted FB command torque as the above-mentioned adjustment command torque.

[0021] The seventh disclosure relates to a steering system for a vehicle.

[0022] The steering system according to the seventh disclosure includes: the control device according to any one of the first to fifth disclosures; and a steering mechanism controlled by the control device. Here, the steering mechanism is an electric power steering device.

[0023] The eighth disclosure relates to a method for controlling a vehicle.

[0024] The control method according to the eighth disclosure includes: calculating a command torque to be applied to a steering mechanism for causing the vehicle to follow a target trajectory; calculating an adjustment gain for the command torque based on the steering torque; calculating an adjusted command torque obtained by applying the adjustment gain to the command torque; and controlling the steering mechanism based on the adjusted command torque. Calculating the adjustment gain includes: calculating an adjusted steering torque having a predetermined hysteresis characteristic relative to changes in the steering torque based on the steering torque; and converting the adjusted steering torque into the adjustment gain.

[0025] The ninth disclosure relates to a storage medium storing a program related to vehicle control.

[0026] The storage medium according to the ninth disclosure stores a program configured to cause a computer to execute the following processing: calculating a command torque to be applied to a steering mechanism for causing the vehicle to follow a target trajectory; calculating an adjustment gain based on the steering torque to calculate an adjustment gain for the command torque; calculating an adjusted command torque obtained by applying the adjustment gain to the command torque; and controlling the steering mechanism based on the adjusted command torque. The adjustment gain calculation includes calculating an adjusted steering torque having a predetermined hysteresis characteristic relative to changes in the steering torque based on the steering torque; and converting the adjusted steering torque into the adjustment gain.

[0027] According to the present disclosure, an adjusted steering torque having a predetermined hysteresis characteristic relative to changes in the steering torque can be calculated. Furthermore, an adjustment gain can be calculated by transforming the calculated adjusted steering torque. Thus, an adjustment gain with different characteristics for the steering torque can be calculated based on the steering state relative to the target trajectory. Furthermore, the adjustment gain is maintained for a period of time during steering adjustment. Furthermore, the driver's controllability of the vehicle can be appropriately improved based on the steering state relative to the target trajectory. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Hereinafter, features, advantages, technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0029] Figure 1 This is a schematic diagram for explaining control of the steering mechanism by the control device according to the present embodiment.

[0030] Figure 2 Indicates that the command torque is adjusted according to the steering torque. Figure 1 A block diagram showing a schematic structure of the processing executed by the ECU is shown.

[0031] Figure 3 This is a diagram showing an example of a map relative to the magnitude of the steering torque for calculating the adjustment gain based on the steering torque.

[0032] Figure 4 : is a graph showing an example of the adjustment steering torque calculated by the control device according to the present embodiment.

[0033] Figure 5 This is a graph showing an example of an adjusted steering torque calculated when a steering torque is applied so that the steering wheel is turned and then returned.

[0034] Figure 6 It means in use Figure 3 The map shown is a diagram showing an example of the adjustment gain with respect to the magnitude of the steering torque when the adjustment gain is calculated by converting the adjustment steering torque.

[0035] Figure 7 This is a block diagram showing a configuration example of an adjustment gain calculation processing unit in the control device according to the present embodiment.

[0036] Figure 8 It is a block diagram showing a configuration example of a control device according to the present embodiment.

[0037] Figure 9 This is a block diagram showing a configuration example of processing executed by the control device according to the present embodiment.

[0038] Figure 10 This is a flowchart showing a preferred example of a processing routine in the adjustment steering torque calculation processing unit.

[0039] Figure 11A This is a graph showing the comparison results between the conventional technology and the example according to the present embodiment when the driver performs sign steering when the target track is a straight track.

[0040] Figure 11B This is a graph showing the comparison results between the conventional technology and the example according to the present embodiment when the driver performs the marker steering operation when the target track is a straight track.

[0041] Figure 12A This is a graph showing the comparison results between the conventional technology and the example according to the present embodiment when the driver performs the marker steering operation toward the inside of the curve when the target track is a curve track.

[0042] Figure 12B This is a graph showing the comparison results between the conventional technology and the example according to the present embodiment when the driver performs the marker steering operation toward the inside of the curve when the target track is a curve track.

[0043] Figure 13 This is a graph showing an example of the adjusted steering torque calculated by the adjusted steering torque calculation processing unit according to the second modification.

[0044] Figure 14 This is a flowchart showing an example of a processing routine in the adjustment steering torque calculation processing unit according to the second modification.

[0045] Figure 15 This is a flowchart showing an example of a processing routine in the adjustment steering torque calculation processing unit according to the second modification. DETAILED DESCRIPTION

[0046] Hereinafter, the embodiments of the present disclosure will be described with reference to the accompanying drawings. Where the numbers such as the number, quantity, amount, range, etc. of each element are mentioned in the embodiments shown below, the ideas involved in the present disclosure are not limited to the mentioned numbers, except for the cases where it is specifically stated or the cases where the numbers can be clearly determined in principle. In addition, except for the cases where it is specifically stated or the cases where it can be clearly determined in principle, the structures and the like described in the embodiments shown below are not essential to the ideas involved in the present disclosure. In addition, the same or equivalent parts are marked with the same figure numerals in each figure, and their repeated descriptions are appropriately simplified or omitted.

[0047] 1.Follow-up steering control function

[0048] The control device according to this embodiment controls the steering mechanism so that the vehicle follows the target track. Figure 1 The control of the steering mechanism 10 by the control device (ECU 100) will be described with reference to the steering control device shown.

[0049] Figure 11 shows a general steering mechanism 10 including a steering shaft 11, a gearbox 12, and a tie rod 13. Specifically, the steering shaft 11 is connected to the gearbox 12 and rotates in response to the operation of the steering wheel 1. Furthermore, the gearbox 12 allows the tie rod 13 to move linearly in response to the rotation of the steering shaft 11. Typically, the gearbox 12 has a rack and pinion structure, where the rotation of the steering shaft 11 is converted into linear motion of the rack via the pinion, causing the tie rod 13 connected to the rack to move linearly. The linear motion of the tie rod 13 changes the steering angle of the vehicle, enabling steering control of the vehicle.

[0050] In the steering mechanism 10, a motor 200 is mounted on the rack portion. The steering mechanism 10 is configured so that the torque generated by the operation of the motor 200 can also cause the rack to move linearly. In other words, the steering mechanism 10 is a rack-assisted electric power steering device. However, in this embodiment, the steering mechanism 10 may also be a column-assisted or pinion-assisted electric power steering device.

[0051] exist Figure 1 In the present invention, the control device is implemented as an ECU (Electronic Control Unit) 100. ECU 100 generates and outputs control signals through execution of processing. Specifically, ECU 100 generates and outputs a commanded torque for motor 200 as a control signal. By operating motor 200 to generate the commanded torque received from ECU 100, ECU 100 controls the steering mechanism. For example, in motor 200, inverter control is performed to generate the commanded torque.

[0052] ECU100 is configured to obtain a target steering angle (target state quantity), vehicle speed, and other vehicle information for making the vehicle follow the target track. Moreover, ECU100 generates and outputs a command torque in such a way that the vehicle reaches the target steering angle. In this way, a function of making the vehicle follow the target track (following steering function) can be realized. Here, typically, the target steering angle is calculated in other ECUs that provide the following steering function and transmitted to ECU100. The following steering function can be one of the driving assistance functions provided by other ECUs, or it can be part of the automatic driving function. In addition, as other vehicle information, acceleration, yaw rate, current steering angle, vehicle specifications, etc. can be exemplified. Vehicle speed and other vehicle information can be obtained from sensors equipped on the vehicle or other ECUs. Alternatively, it can be obtained as data stored in a memory (storage medium).

[0053] Furthermore, the ECU 100 may include functions related to steering stability control. For example, the ECU 100 may be configured to generate an assist torque as a command torque based on the steering angle or steering angular velocity of the steering wheel 1 or the steering torque resulting from the operation of the steering wheel 1. In this case, the steering angle or steering angular velocity of the steering wheel 1 can be obtained from the steering angle sensor 21. The steering torque resulting from the operation of the steering wheel 1 can be obtained from the torque sensor 22.

[0054] Typically, ECU 100 is installed in a vehicle. However, the control device of this embodiment may be a device external to the vehicle. For example, the control device of this embodiment may be implemented as a server that communicates with the vehicle via the Internet. In this case, the control device obtains information through communication and sends control signals.

[0055] It should be noted that when the follow-up steering function is in operation, the driver of the vehicle may sometimes consider steering in a direction different from the target track. For example, when the target track is a straight track, the driver may consider wanting to separate the vehicle from the obstacle ahead, or when the target track is a curved track, the driver may consider wanting to drive with a shorter turning radius. In this case, the driver operates the steering wheel 1 to steer the vehicle in the desired direction. For example, when the driver considers wanting to separate the vehicle from the obstacle ahead, the driver may conceivably operate the steering wheel 1 in a manner that separates the vehicle from the obstacle and then return the steering wheel 1 when the vehicle has separated by a certain distance.

[0056] As described above, when the driver operates the steering wheel 1 during the following steering function, the driver must overcome the torque generated by the motor 200 due to the following steering function to generate the steering torque through the operation of the steering wheel 1. Therefore, the torque generated by the motor 200 due to the following steering function is generally adjusted based on the steering torque. In other words, the ECU 100 adjusts the command torque based on the steering torque.

[0057] Figure 2 1 is a block diagram showing a schematic configuration of a process executed by the ECU 100 when adjusting the command torque according to the steering torque. Figure 2 The processes executed by the ECU 100 are configured to be executed by a command torque calculation processing unit P100, an adjustment gain calculation processing unit P200, and an adjustment command torque calculation processing unit P300. These processing units may be assigned as programs or implemented by independent processors.

[0058] The command torque calculation processing unit P100 receives the target steering angle θt as input and calculates the command torque Tf so that the vehicle reaches the target steering angle θt. For example, command torque Tf is calculated through feedforward control based on the target steering angle θt, or feedback control based on the target steering angle θt and the current steering angle (current state variable). Furthermore, the calculation of command torque Tf may take vehicle speed and other vehicle information into consideration.

[0059] The adjustment gain calculation processing unit P200 receives the steering torque T as input and calculates a gain (adjustment gain) α with respect to the command torque Tf based on the steering torque T. For example, the steering torque T is converted into the adjustment gain α using a map corresponding to the magnitude of the steering torque T. Figure 3 An example of a map |T| with respect to the magnitude of the steering torque T is shown in FIG.

[0060] Refer again Figure 2 The adjustment command torque calculation processing unit P300 receives the command torque Tf calculated by the command torque calculation processing unit P100 and the adjustment gain α calculated by the adjustment gain calculation processing unit P200 as input, and generates an adjustment command torque Tc obtained by applying the adjustment gain α to the command torque Tf. The adjustment command torque Tc generated by the adjustment command torque calculation processing unit P300 is output from the ECU 100 and transmitted to the motor 200. The motor 200 operates in a manner to generate the adjustment command torque Tc.

[0061] Typically, adjustment gain α is assigned a value between 0 and 1 so that command torque Tf is reduced according to the magnitude of steering torque T. Specifically, adjustment command torque Tc is adjusted so that the larger the steering torque T, the smaller the command torque Tf becomes. This reduces the effect of the torque generated by motor 200 when the driver attempts to steer the steering wheel 1 in a direction different from the target trajectory. This, in turn, reduces the steering load on the driver.

[0062] Here, the driving feel experienced by the driver differs when the driver intends to generate a steering torque in a direction opposite to the direction of the torque generated by the motor 200 through the follow-up steering function and when the driver intends to generate a steering torque in the same direction. For example, when the driver turns the steering wheel 1 away from the target track (in order to generate a steering torque in the opposite direction), the driver feels a heavy feeling when turning the steering wheel 1. When the driver then turns the steering wheel 1 back (in order to generate a steering torque in the same direction), the driver feels a strong return of the steering wheel 1. Therefore, there is a concern that the driver may be given an extreme driving feel depending on the driver's steering state relative to the target track. Furthermore, there is a concern that the driver's controllability of the vehicle may be reduced.

[0063] In view of this, in order to solve the above-mentioned problems, the control device according to this embodiment has a characteristic feature in the adjustment gain calculation processing unit P200. Hereinafter, the control device according to this embodiment will be described with respect to an overview of the characteristic processing of the adjustment gain calculation processing unit P200.

[0064] 2. Summary

[0065] In the control device according to the present embodiment, the adjustment gain calculation processing unit P200 calculates an adjustment steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque T.

[0066] Figure 4 FIG. 2 shows an example of the adjustment steering torque Tr calculated in the control device according to the present embodiment. Figure 4 As shown, the calculated adjusted steering torque Tr has a hysteresis characteristic, so that it increases or decreases according to the steering torque T while the steering torque T is increasing or decreasing. When the steering torque T changes from increasing to decreasing or from decreasing to increasing, the steering torque T remains constant until it decreases or increases by a predetermined value or more. Specifically, when the driver turns the steering wheel 1, the adjusted steering torque Tr increases or decreases according to the steering torque T. When the driver returns the steering wheel 1, the adjusted steering torque Tr remains constant for a certain period. Furthermore, the hysteresis characteristic ensures that the magnitude |Tr| of the adjusted steering torque Tr when the driver turns the steering wheel 1 is smaller than the magnitude |Tr| of the adjusted steering torque Tr when the driver adjusts the steering wheel 1.

[0067] The adjusted steering torque Tr having such a hysteresis characteristic can be calculated using a simple configuration by using a predetermined torque hysteresis Th. Specifically, when the absolute value of the difference between the current value of the steering torque T and the previously processed adjusted steering torque Tr (hereinafter also referred to as the "adjusted steering torque deviation") is less than or equal to the torque hysteresis Th, the previously processed adjusted steering torque Tr is calculated as the currently processed adjusted steering torque Tr. In response to the fact that the adjusted steering torque deviation is greater than the torque hysteresis Th, the currently processed adjusted steering torque Tr is calculated in a direction that decreases the adjusted steering torque deviation. By calculating the adjusted steering torque Tr in this manner, when the driver turns the steering wheel 1, the magnitude |Tr| of the adjusted steering torque Tr becomes smaller than the magnitude |T| of the steering torque T by at least the torque hysteresis Th. On the other hand, when the driver returns the steering wheel 1, the magnitude |Tr| of the adjusted steering torque Tr becomes larger than the magnitude |T| of the steering torque T by at least the torque hysteresis Th. Furthermore, when the driver adjusts and turns the steering wheel 1 , the steering torque Tr is adjusted to maintain a constant value until the steering torque T decreases or increases by more than twice the torque hysteresis Th.

[0068] In particular, the calculation of the current processing adjustment steering torque Tr in the direction of reducing the adjustment steering torque deviation can be performed as follows: when the current value of the steering torque T is greater than the adjustment steering torque Tr of the previous processing, the value obtained by subtracting the torque hysteresis Th from the current value of the steering torque T is calculated as the current processing adjustment steering torque Tr; when the current value of the steering torque T is less than the adjustment steering torque Tr of the previous processing, the value obtained by adding the torque hysteresis Th to the current value of the steering torque T is calculated as the current processing adjustment steering torque Tr. By calculating the adjustment steering torque Tr in this way, as shown in FIG. Figure 4 As shown, when the driver turns the steering wheel 1, the magnitude |Tr| of the steering torque Tr is adjusted to a value that is smaller than the magnitude |T| of the steering torque T by the torque hysteresis Th. On the other hand, when the driver returns the steering wheel 1, the magnitude |Tr| of the steering torque Tr is adjusted to a value that is larger than the magnitude |T| of the steering torque T by the torque hysteresis Th. Furthermore, when the driver turns the steering wheel 1, the magnitude |Tr| of the steering torque Tr remains constant until the steering torque T decreases or increases by twice the torque hysteresis Th.

[0069] Figure 5 The embodiment of the adjustment steering torque Tr calculated when the steering torque T is applied by turning the steering wheel 1 and then returning the steering wheel is shown. Figure 5In the illustrated embodiment, it can be seen that during the turning steering maneuver until time t1, the adjusted steering torque Tr is less than the steering torque T by the torque hysteresis Th. During the return steering maneuver after time t2, the adjusted steering torque Tr is greater than the steering torque T by the torque hysteresis Th. Furthermore, it can be seen that during the turning steering maneuver from time t1 to time t2, the adjusted steering torque Tr remains constant. Thus, according to this embodiment, the adjusted steering torque Tr can be calculated with different characteristics relative to the steering torque T for the turning and return steering maneuvers. In particular, since no time-delay elements such as low-pass filters are included, abrupt changes in value are avoided.

[0070] Next, in the control device according to the present embodiment, the adjustment gain calculation processing unit P200 calculates the adjustment gain α based on the transformation of the calculated adjustment steering torque Tr. The transformation of the adjustment steering torque Tr is performed, for example, by using a map. Here, the map may be Figure 3 The mapping of the magnitude |T| of the steering torque T is equivalent to the mapping shown in FIG. Figure 3 In the example, the horizontal axis represents the magnitude |Tr| of the adjusted steering torque Tr. However, a preferred mapping can be assigned depending on the environment in which the control device according to this embodiment is applied. For example, a mapping can be used in which the adjustment gain α decreases nonlinearly from 1 to 0 as the magnitude |Tr| of the adjusted steering torque Tr increases.

[0071] According to this embodiment, by adjusting the steering torque Tr to have a predetermined hysteresis characteristic, the characteristics of the steering torque T for turning and returning the wheel differ. Therefore, by calculating the adjustment gain α based on the transformation of the adjusted steering torque Tr, the adjustment gain α can be applied so that the characteristics of the steering torque T for turning and returning the wheel differ. Figure 6 Shows the use of Figure 3 The map shown is an example of calculating the adjustment gain α relative to the magnitude |T| of the steering torque T when the adjustment gain α is calculated based on the transformation of the adjustment steering torque Tr. Figure 6 The graph shown shows the adjustment gain α calculated with respect to the steering torque T in quasi-stable steering (steering speed ≈ 0). Figure 6As shown, an adjustment gain α is assigned so that the characteristics of the steering torque T differ between the steering operation for turning (single-dotted dash line) and the steering operation for returning (dashed line). In particular, the adjustment gain α for turning can be assigned so that it is smaller than the adjustment gain α for returning. Furthermore, the adjustment gain α can be maintained for a period of time during turning.

[0072] Thus, according to this embodiment, the adjustment gain calculation processing unit P200 calculates an adjustment gain α with different characteristics relative to the steering torque for steering during turning and steering during reverse steering. This allows the torque generated by the motor 200 due to the steering follow-up function to differ between steering during turning and steering during reverse steering. In particular, the adjustment gain α for steering during turning is set to a value smaller than the adjustment gain α for steering during reverse steering. In other words, the torque generated by the motor 200 during reverse steering can be made smaller than the torque generated by the motor 200 during reverse steering. Furthermore, the feeling of a strong return of the steering wheel 1 during reverse steering can be reduced. Furthermore, when adjusting the steering (reverse steering the vehicle), the adjustment gain α is maintained for a period of time. In other words, the torque generated by the motor 200 does not change suddenly during turning. Thus, according to this embodiment, the driver's controllability of the vehicle can be appropriately improved according to the steering state relative to the target trajectory.

[0073] Furthermore, the control device according to this embodiment may be configured to vary the torque hysteresis Th used when calculating the steering torque Tr according to the steering torque T. For example, the torque hysteresis Th may be varied so that it takes on a larger value as the magnitude |T| of the steering torque T increases. For example, this may be achieved by assigning the torque hysteresis Th using a map corresponding to the magnitude |T| of the steering torque T.

[0074] This configuration, for example, allows for a greater torque hysteresis Th when the magnitude of the steering torque T, |T|, is large, thereby more appropriately reducing the driver's steering load. Furthermore, by applying a nonlinear mapping to ensure that the calculated adjustment gain α is equal to 1 when the steering torque T is zero, it is possible to prevent the range of possible values ​​of the adjustment gain α from being limited by the value of the steering torque T (particularly during back-wheel steering). This achieves a balance between reducing the driver's steering load and ensuring the performance of the steering follow-up function when the driver is not steering.

[0075] Figure 7 FIG. 2 shows a configuration example of the adjustment gain calculation processing unit P200 in the control device according to the present embodiment. Figure 7In FIG. 2 , the adjustment gain calculation processing unit P200 is composed of a torque lag calculation processing unit P201 , an adjustment steering torque calculation processing unit P210 , and a conversion processing unit P220 .

[0076] The torque hysteresis calculation processing unit P201 takes the steering torque T as input and calculates the torque hysteresis Th based on the steering torque T. Figure 7 In the illustrated configuration example, the torque hysteresis Th is calculated using a map |T| relative to the magnitude of the steering torque T.

[0077] The adjusted steering torque calculation processing unit P210 receives as input the steering torque T and the torque hysteresis Th calculated in the torque hysteresis calculation processing unit P201, and calculates the adjusted steering torque Tr based on the steering torque T (first process). As described above, the torque hysteresis Th is used to calculate the adjusted steering torque Tr so that it has a predetermined hysteresis characteristic relative to changes in the steering torque.

[0078] The conversion processing unit P220 receives the adjustment steering torque Tr calculated in the adjustment steering torque calculation processing unit P210 as input, and calculates the adjustment gain α by converting the adjustment steering torque Tr (second processing). Figure 7 In the illustrated configuration example, the adjustment gain α is calculated using a map |Tr| for the magnitude of the adjustment steering torque Tr.

[0079] 2. Composition

[0080] Hereinafter, a configuration example of the control device (ECU 100 ) according to the present embodiment and a configuration example of the processing executed by the control device (ECU 100 ) according to the present embodiment will be described.

[0081] 2-1. Configuration of the control device

[0082] Figure 8 This is a block diagram illustrating an example configuration of a control device (ECU 100) according to this embodiment. ECU 100 is a computer comprising a memory 110 and a processor 120. Memory 110, in conjunction with processor 120, stores a plurality of executable instructions 112 and various data 113 required for processing. Instructions 112 are assigned by a program 111. In this context, memory 110 can also be referred to as "program memory."

[0083] By operating processor 120 according to command 112, various processes based on data 113 can be executed. This enables execution of processes related to command torque calculation processing unit P100, adjustment gain calculation processing unit P200, and adjustment command torque calculation processing unit P300 in ECU 100. Furthermore, if ECU 100 includes a function related to steering stability control, execution of processes related to steering stability control can be achieved.

[0084] 2-2. Processing Structure

[0085] Figure 9 This is a block diagram showing a configuration example of processing executed by the control device (ECU 100 ) according to the present embodiment, particularly processing related to calculation of torque (adjustment command torque Tc) generated by the motor 200 as a steering follow-up function.

[0086] exist Figure 9 In the illustrated processing configuration example, the command torque Tf calculated in the command torque calculation processing unit P100 includes the FF command torque Tff and the FB command torque Tfb. The FF command torque Tff becomes a feedforward control amount based on the target steering angle θt, and the FB command torque Tfb becomes a feedback control amount based on the difference between the target steering angle θt and the current steering angle θ. Figure 9 In the illustrated configuration example, the command torque calculation processing unit P100 includes an FF command torque calculation processing unit P110 and an FB command torque calculation processing unit P120 .

[0087] The FF command torque calculation processing unit P110 receives the target steering angle θt as input and calculates the FF command torque Tff based on the target steering angle θt. The FB command torque calculation processing unit P120 receives the difference between the target steering angle θt and the current steering angle θ as input and calculates the FB command torque Tfb based on the difference between the target steering angle θt and the current steering angle θ.

[0088] The feedforward and feedback control processes in the FF command torque calculation processing unit P110 and the FB command torque calculation processing unit P120 can employ preferably known techniques. In particular, the system can be configured to take vehicle speed and other vehicle information into account. Furthermore, the current steering angle θ is typically obtained from the steering angle sensor 21.

[0089] exist Figure 9 In the example of the process shown in FIG. 1 , the adjustment gain α calculated in the adjustment gain calculation processing unit P200 includes a first adjustment gain α1 and a second adjustment gain α2. Figure 9In the configuration example shown, the adjustment gain calculation processing unit P200 includes the first adjustment gain α1 and the second adjustment gain α2 respectively. Figure 7 The structure is the same as that described in . However, the torque lag calculation processing unit P201, the adjusted steering torque calculation processing unit P210, and the conversion processing unit P220 associated with the first adjustment gain α1 and the second adjustment gain α2, respectively, can be assigned different characteristics. For example, the torque lag calculation processing unit P201 associated with the first adjustment gain α1 and the torque lag calculation processing unit P201 associated with the second adjustment gain α2, or the conversion processing unit P220 associated with the first adjustment gain α1 and the conversion processing unit P220 associated with the second adjustment gain α2, respectively, can use different mappings. In other words, characteristics corresponding to the first adjustment gain α1 and the second adjustment gain α2 can be assigned.

[0090] Moreover, in Figure 9 In the illustrated processing example, the adjustment command torque calculation processing unit P300 calculates the adjustment FB command torque Tbr (P301) by applying a first adjustment gain α1 to the FB command torque Tfb. Furthermore, the adjustment command torque Tc is calculated by applying a second adjustment gain α2 to the sum Tsum of the FF command torque Tff and the adjustment FB command torque Tbr (P302).

[0091] according to Figure 9 The processing example shown in the figure is Figure 7 The first adjustment gain α1 and the second adjustment gain α2 are calculated using the same configuration as described in Therefore, as described above, the controllability of the vehicle by the driver can be improved.

[0092] Among them, Figure 9 The illustrated configuration example is characterized in that, in particular, the adjustment gain calculation processing unit P200 independently calculates a first adjustment gain α1 applied to the FB command torque Tfb and a second adjustment gain α2 applied to the sum Tsum of the FF command torque Tff and the adjusted FB command torque Tbr. This configuration allows the driver's controllability of the vehicle to be appropriately improved both when the target track is a straight track and when the target track is a curve. This is due to the following reasons.

[0093] Generally, when the target track is a curve, the FF command torque Tff significantly contributes to the vehicle's ability to follow the target track. On the other hand, when the target track is a straight track, the FB command torque Tfb significantly contributes to the vehicle's ability to follow the target track. In particular, when the target track is a straight track, the FF command torque Tff is typically zero. Therefore, to ensure sufficient followability of the steering control function, the command torque calculation processing unit P100 includes a FF command torque calculation processing unit P110 and a FB command torque calculation processing unit P120.

[0094] Here, consider the case where the adjustment gain α does not include the first adjustment gain α1 and the second adjustment gain α2. In this case, it is assumed that the adjustment gain α is applied to the sum of the FF command torque Tff and the FB command torque Tfb. In this case, the adjustment gain α is given in order to enable the driver to sufficiently improve the controllability of the vehicle when the target track is a straight track. That is, an adjustment gain α that is sufficiently small relative to the magnitude |T| of the steering torque T is given. In this case, for example, if the driver wants to steer toward the inside of the turning track when the target track is a turning track, since the adjustment gain α is small, the contribution of the FF command torque Tff is too small, and there is a concern that the torque required for turning cannot be generated. Furthermore, there is a concern that although the driver wants to steer toward the inside of the turning track, the vehicle will move toward the outside of the turning track.

[0095] On the other hand, if the adjustment gain α is applied in order to ensure the torque required for turning when the target trajectory is a curve trajectory, the driver's controllability of the vehicle cannot be sufficiently improved when the target trajectory is a straight trajectory.

[0096] In view of this, the adjustment gain calculation processing unit P200 is configured to independently calculate the first adjustment gain α1 and the second adjustment gain α2, thereby eliminating the aforementioned trade-off. That is, appropriate characteristics can be given to the first adjustment gain α1 and the second adjustment gain α2, respectively, for both when the target track is a straight track and when the target track is a curve, so that the driver's controllability of the vehicle can be appropriately improved.

[0097] Furthermore, based on the above description, the adjustment command torque calculation processing unit P300 may be configured to calculate the sum of the value obtained by applying the second adjustment gain α2 to the FF command torque Tff and the adjustment FB command torque Tbr as the adjustment command torque Tc.

[0098] 3. Adjust the steering torque calculation process

[0099] Below, refer to Figure 10Next, the processing routine in the adjustment steering torque calculation processing unit P210 will be described. Figure 10 This is a flowchart showing a preferred example of a processing routine in the steering torque calculation processing unit P210. The processing can be executed at a predetermined processing cycle (e.g., 5 msec). Figure 10 The processing routine shown in FIG. Figure 10 In FIG, the adjusted steering torque Tr processed last time is expressed as Tr'.

[0100] In step S100, a determination is made as to whether the adjusted steering torque Tr has been initialized. If the adjusted steering torque Tr has not been initialized (step S100: No), the adjusted steering torque Tr is used as the current value of the steering torque T (step S110). If the adjusted steering torque Tr has been initialized (step S100: Yes), the process proceeds to step S120. Typically, step S110 is executed when the follow-up steering function is activated.

[0101] In step S120 , it is determined whether the steering torque T is larger than the sum of the adjustment steering torque Tr′ and the torque hysteresis Th processed last time.

[0102] If the steering torque T is greater than the sum of the adjusted steering torque Tr' and the torque hysteresis Th from the previous process (step S120: Yes), the value obtained by subtracting the torque hysteresis Th from the steering torque T is used as the adjusted steering torque Tr for the current process (step S130), and the current process ends. If the steering torque T is not greater than the sum of the adjusted steering torque Tr' and the torque hysteresis Th from the previous process (step S120: No), the process proceeds to step S140.

[0103] In step S140 , it is determined whether the steering torque T is smaller than the difference between the adjustment steering torque Tr′ processed last time and the torque hysteresis Th.

[0104] If the steering torque T is less than the difference between the adjusted steering torque Tr' and the torque hysteresis Th in the previous process (step S140: Yes), the value obtained by adding the torque hysteresis Th to the steering torque T is used as the adjusted steering torque Tr for the current process (step S150), and the current process ends. If the steering torque T is not less than the difference between the adjusted steering torque Tr' and the torque hysteresis Th in the previous process (step S140: No), the adjusted steering torque Tr is not calculated, and the current process ends. In other words, in this case, the adjusted steering torque Tr for the current process becomes the adjusted steering torque Tr' for the previous process.

[0105] Furthermore, it can be considered that the processing involved in step S120 and step S140 determines whether the adjustment steering torque deviation is greater than the torque hysteresis Th. That is, when the adjustment steering torque deviation is greater than the torque hysteresis Th, the processing involved in step S130 or step S150 is executed. In particular, when the steering torque T is greater than the adjustment steering torque Tr' of the previous processing, the processing involved in step S130 is executed, and when the steering torque T is less than the adjustment steering torque Tr' of the previous processing, the processing involved in step S150 is executed. In addition, it can be considered that the processing involved in step S130 and step S150 calculates the adjustment steering torque Tr of this processing in the direction of reducing the adjustment steering torque deviation.

[0106] By executing such a processing routine, the command torque calculation processing unit P300 can calculate Figure 4 The steering torque Tr shown has a predetermined hysteresis characteristic with respect to changes in the steering torque T. The control method according to the present embodiment can be realized by the control device configured in this manner.

[0107] 4. Effect

[0108] As described above, according to this embodiment, the adjustment gain calculation processing unit P200 calculates an adjustment gain α that differs in the characteristics of the steering torque for turning and returning steering. Furthermore, the adjustment command torque Tc is calculated by applying the thus calculated adjustment gain α to the command torque Tf, and the steering mechanism 10 is controlled based on the adjustment command torque Tc. This allows the torque generated by the motor 200 through the steering follow-up function to differ between turning and returning steering. In particular, the adjustment gain α for turning is assigned to a value smaller than the adjustment gain α for returning steering. In other words, the torque generated by the motor 200 during returning steering can be made smaller than the torque generated by the motor 200 during turning. Furthermore, the feeling of a strong return of the steering wheel 1 during returning steering can be reduced. Furthermore, during turning adjustment, the adjustment gain α is maintained for a period of time. That is, the torque generated by the motor 200 does not change suddenly during turning adjustment. As described above, according to the present embodiment, the driver's controllability of the vehicle can be appropriately improved according to the steering state with respect to the target trajectory.

[0109] Furthermore, this embodiment enables calculation of an adjustment gain α whose characteristics vary depending on the steering state, without determining the driver's steering state relative to the target trajectory. This is advantageous in situations where the driver wishes to make minor corrections to the vehicle's trajectory. This is due to the following reasons.

[0110] When the driver attempts to make minor corrections to the vehicle's trajectory, the amount of control typically decreases. Therefore, if the driver's steering state is to be determined, the state quantity used for determination also decreases. Specifically, when assigning the conversion characteristics associated with the adjustment gain α based on the determined steering state, the adjustment gain α needs to be changed within a small range of state quantity variation. However, it is conceivable that during actual vehicle driving, even if the driver unintentionally performs steering, the amount of control is detected due to road disturbances, etc. Furthermore, it is conceivable that the state quantity varies around 0. Therefore, there is a concern that changing the adjustment gain α within a small range of state quantity variation may cause undesirable changes in the adjustment gain α. Thus, there is a concern that assigning the conversion characteristics associated with the adjustment gain α based on the determined steering state may fail to achieve both tracking to the target trajectory and improved driver controllability of the vehicle, for example, in situations where the driver attempts to make minor corrections to the vehicle's trajectory.

[0111] Alternatively, a low-pass filter could be used to reduce the driver's unwanted steering input. However, in this case, due to the response delay caused by the low-pass filter, there is concern that the driver may experience discomfort during steering and that the sensation of a strong return of steering input may not be sufficiently reduced. On the other hand, according to this embodiment, a low-pass filter is not necessarily required. However, considering the impact on responsiveness and steering feel, a low-pass filter could be applied to the calculated adjustment gain α. This could potentially achieve smoother characteristics relative to changes in steering torque T.

[0112] 5. Examples

[0113] Figure 11A 、 Figure 11B The comparison results of the prior art and the embodiment involved in this embodiment are shown when the driver performs the marker steering operation when the target track is a straight track. Here, the embodiment of the prior art (solid line) is for Figure 3 The magnitude of the steering torque T shown in FIG. 1 is given by the adjustment gain α. In addition, regarding the embodiments involved in this embodiment, two embodiments are shown: an embodiment in which only the second adjustment gain α2 is enabled in the adjustment command torque calculation processing unit P300 (dashed line) and an embodiment in which both the first adjustment gain α1 and the second adjustment gain α2 are enabled (single-dot chain line). Figure 11A represents the Lissajous characteristic of the steering angle θ with respect to the steering torque T, Figure 11B The Lissajous characteristic of the yaw rate with respect to the steering torque T is shown.

[0114] like Figure 11A 、 Figure 11BAs shown, according to this embodiment, the vehicle can be steered with more wiggle room in steering for turning, compared to the conventional technology. Furthermore, it can be seen that the vehicle's controllability during steering for returning the vehicle is improved. Furthermore, it can be seen that when the target track is a straight track, even when only the second adjustment gain α2 is enabled, similar characteristics can be achieved as when both the first adjustment gain α1 and the second adjustment gain α2 are enabled.

[0115] Figure 12A 、 Figure 12B The results of the comparison between the prior art and the embodiment of the present embodiment are shown when the driver performs the marker steering operation toward the inner side of the curve when the target track is a curve track. Figure 12A 、 Figure 12B This is an example of a vehicle traveling at 80 km / h on a 500R road. Figure 11A as well as Figure 11B same, Figure 12A The Lissajous characteristic of the steering angle θ with respect to the steering torque T is represented by Figure 12B The Lissajous characteristic of the yaw rate with respect to the steering torque T is shown.

[0116] like Figure 12A 、 Figure 12B As shown, according to this embodiment, even when the target track is a curve, the vehicle can be steered with a margin in the steering adjustment for wheel turning, similar to when the target track is a straight track. However, when only the second adjustment gain α2 is enabled, the steering angle θ and yaw rate change with respect to the steering torque T is small, which may make it difficult for the driver to steer toward the inside of the turn. On the other hand, by enabling both the first adjustment gain α1 and the second adjustment gain α2, the vehicle can be steered with a margin, and the driver can easily steer toward the inside of the turn.

[0117] 6. Modifications

[0118] This embodiment can be modified as follows: In the following description, matters overlapping with the above-mentioned contents are appropriately omitted.

[0119] 6-1. First Modification

[0120] In the adjustment gain calculation processing unit P200, the torque hysteresis calculation processing unit P201 or the conversion processing unit P220 can be configured to change characteristics according to vehicle speed. For example, the mapping in the torque hysteresis calculation processing unit P201 or the conversion processing unit P220 can be changed according to vehicle speed. Alternatively, the adjustment command torque calculation processing unit P300 can be configured to also apply a vehicle speed gain to the command torque Tf, which is assigned according to vehicle speed.

[0121] Generally, the driver's driving feeling varies depending on the vehicle speed. Therefore, by adopting the first modification, it is possible to more appropriately improve the controllability of the vehicle according to the vehicle speed.

[0122] 6-2. Second Modification

[0123] The adjusted steering torque calculation processing unit P210 may be configured to calculate the adjusted steering torque Tr so as to change at a predetermined gradient when the adjusted steering torque deviation is equal to or smaller than the torque hysteresis Th. Figure 13 An example of the adjusted steering torque Tr calculated in the adjusted steering torque calculation processing unit P210 according to the second modification is shown. Figure 13 3 examples of different values ​​of Tslp defined as corresponding to the prescribed slope are shown in FIG. Figure 4 That is, in this case, when the adjusted steering torque deviation is less than the torque hysteresis Th, the adjusted steering torque Tr is kept constant (slope 0). On the other hand, when Tslp = 0.5 or Tslp = 2, Figure 4 Compared to the example shown, the characteristics of the steering operation when adjusting the wheel are different.

[0124] Thus, by adopting the second modified example, it is possible to provide a degree of freedom in adjusting the characteristics of the steering operation during turning. Furthermore, by appropriately setting the predetermined slope, it is possible to optimize the improvement of the vehicle's controllability.

[0125] Here, the second modification can be realized by adjusting the processing routine in the steering torque calculation processing unit P210 as follows. Figure 14 This is a flowchart showing an example of a processing routine in the adjustment steering torque calculation processing unit P210 according to the second modification. Figure 14 The processing routine shown.

[0126] In step S200, it is determined whether the reference torque Tref has been initialized. Here, as will be made clear in the following process, the reference torque Tref is calculated in a manner that has a predetermined hysteresis characteristic with respect to the change in the steering torque T, similar to the adjustment steering torque Tr. The hysteresis width is in accordance with the deviation upper limit ΔT described below. In addition, especially when the adjustment steering torque deviation is greater than the torque hysteresis Th, the reference torque Tref is Figure 10 The adjustment steering torque Tr calculated in the shown processing routine is identical.

[0127] If the reference torque Tref has not been initialized (step S200; No), the reference torque Tref is used as the current value of the steering torque T (step S210). If the reference torque Tref has been initialized (step S200; Yes), the process proceeds to step S220.

[0128] In step S220, the upper limit deviation value ΔT is calculated. Here, the upper limit deviation value ΔT is calculated by dividing the torque hysteresis Th by Tslp. By calculating in this way, the following Figure 14 In the processing routine shown, Tslp becomes a value corresponding to a predetermined slope. In addition, Tslp may be a value previously assigned as data 113, for example. In particular, Tslp can be appropriately determined according to the environment in which the control device according to the second modification is applied.

[0129] After step S220 , the process proceeds to step S230 .

[0130] In step S230 , it is determined whether the steering torque T is larger than the sum of the reference torque Tref′ processed last time and the upper limit value ΔT of the deviation.

[0131] If the steering torque T is greater than the sum of the previously processed reference torque Tref' and the upper limit deviation value ΔT (step S230: Yes), the value obtained by subtracting the upper limit deviation value ΔT from the steering torque T is used as the reference torque Tref for the current process (step S240), and the process proceeds to step S270. If the steering torque T is not greater than the sum of the previously processed reference torque Tref' and the upper limit deviation value ΔT (step S230: No), the process proceeds to step S250.

[0132] In step S250 , it is determined whether the steering torque T is smaller than the difference between the reference torque Tref′ processed last time and the deviation upper limit value ΔT.

[0133] If the steering torque T is less than the difference between the previously processed reference torque Tref' and the upper limit deviation value ΔT (step S250: Yes), the value obtained by adding the upper limit deviation value ΔT to the steering torque T is used as the reference torque Tref for the current process (step S260), and the process proceeds to step S270. If the steering torque T is not less than the difference between the previously processed reference torque Tref' and the upper limit deviation value ΔT (step S250: No), the reference torque Tref is not calculated and the process proceeds to step S270. In other words, in this case, the reference torque Tref for the current process becomes the reference torque Tref' for the previously processed process.

[0134] In step S270, a temporary value Ttmp is calculated. Here, the temporary value Ttmp is calculated by multiplying a value obtained by subtracting the reference torque Tref from the steering torque T by Tslp.

[0135] After step S270 , the process proceeds to step S280 .

[0136] In step S280 , a value obtained by subtracting the temporary value Ttmp calculated in step S270 from the steering torque T is calculated as the adjustment steering torque Tr for this process, and this process ends.

[0137] By executing such a processing routine, the command torque calculation processing unit P300 can calculate Figure 13 As shown, the steering torque Tr is adjusted to have a predetermined hysteresis characteristic with respect to changes in the steering torque T. In particular, the characteristic of the steering operation during the adjustment of the turning can be changed according to the value of Tslp.

[0138] The second modified example can also be realized by adjusting the processing routine in the steering torque calculation processing unit P210 by focusing on the steering angle θ as follows. Figure 15 This is a flowchart showing another example of the processing routine in the steering torque calculation processing unit P210 according to the second modification. Figure 15 The processing routine shown.

[0139] In step S300, a determination is made as to whether the reference steering angle θref has been initialized. As will become clear in the following processing, the reference steering angle θref is calculated to exhibit a predetermined hysteresis characteristic with respect to changes in the steering angle θ. Specifically, the hysteresis width corresponds to the deviation upper limit Δθ described below.

[0140] If the reference steering angle θref has not been initialized (step S300; No), the reference steering angle θref is set as the current value of the steering angle θ (step S310). If the reference steering angle θref has been initialized (step S300; Yes), the process proceeds to step S320.

[0141] In step S320, the upper limit value of the deviation Δθ is calculated. Here, the upper limit value of the deviation Δθ is calculated by dividing the torque hysteresis Th by the predetermined value K. By calculating in this way, the following explanation is given. Figure 15 In the processing routine shown, K becomes a value corresponding to a predetermined slope. Alternatively, K can be considered to define the "rigidity" of the reference steering angle θref relative to changes in the steering angle θ. Furthermore, K may be a value previously assigned as data 113, for example. In particular, K can be appropriately determined depending on the environment in which the control device according to the second modification is applied.

[0142] After step S320 , the process proceeds to step S330 .

[0143] In step S330 , it is determined whether the steering angle θ is larger than the sum of the reference steering angle θref′ processed last time and the upper limit value Δθ of the deviation.

[0144] If the steering angle θ is greater than the sum of the reference steering angle θref' and the upper limit deviation Δθ from the previous process (step S330: Yes), the value obtained by subtracting the upper limit deviation Δθ from the steering angle θ is used as the reference steering angle θref for the current process (step S340), and the process proceeds to step S370. If the steering angle θ is not greater than the sum of the reference steering angle θref' and the upper limit deviation Δθ from the previous process (step S330: No), the process proceeds to step S350.

[0145] In step S350 , it is determined whether the steering angle θ is smaller than the difference between the reference steering angle θref′ processed last time and the deviation upper limit value Δθ.

[0146] If the steering angle θ is less than the difference between the previously processed reference steering angle θref' and the upper limit deviation value Δθ (step S350: Yes), the value obtained by adding the upper limit deviation value Δθ to the steering angle θ is used as the reference steering angle θref for the current processing (step S360), and the process proceeds to step S370. If the steering angle θ is not less than the difference between the previously processed reference steering angle θref' and the upper limit deviation value Δθ (step S350: No), the reference steering angle θref is not calculated, and the process proceeds to step S370. In other words, in this case, the reference steering angle θref for the current processing becomes the reference steering angle θref' for the previously processed processing.

[0147] In step S370, a temporary value Ttmp is calculated. Here, the temporary value Ttmp is calculated by multiplying K by a value obtained by subtracting the reference steering angle θref from the steering angle θ.

[0148] After step S370 , the process proceeds to step S380 .

[0149] In step S380 , a value obtained by subtracting the temporary value Ttmp calculated in step S370 from the steering torque T is calculated as the adjustment steering torque Tr for this process, and this process ends.

[0150] By executing such a processing routine, the command torque calculation processing unit P300 can also be adjusted to calculate Figure 13 As shown in FIG. 1 , the steering torque Tr is adjusted to have a predetermined hysteresis characteristic with respect to changes in the steering torque T. However, the characteristic of the steering operation during the adjustment of the wheel turning changes according to the value of K.

Claims

1. A control device, which is a control device for a vehicle, characterized in that: The control device is configured to perform the following processing: a process of calculating a command torque to be applied to a steering mechanism for causing the vehicle to follow a target trajectory; an adjustment gain calculation process of calculating an adjustment gain for the command torque based on the steering torque; an adjustment command torque calculation process for calculating an adjustment command torque obtained by applying the adjustment gain to the command torque; as well as controlling the steering mechanism according to the adjustment command torque, The adjustment gain calculation process includes: a first process of calculating, based on the steering torque, an adjusted steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque; and The second process converts the adjusted steering torque into the adjusted gain.

2. The control device according to claim 1, characterized in that The first process includes: Calculating the adjusted steering torque for this processing in a direction of decreasing the absolute value based on the fact that the absolute value of the difference between the steering torque and the adjusted steering torque processed last time is greater than a predetermined torque hysteresis; and Accepting that the absolute value is equal to or smaller than the torque hysteresis, the adjusted steering torque processed last time is calculated as the adjusted steering torque processed this time.

3. The control device according to claim 2, characterized in that Calculating the adjusted steering torque of this process in the direction of decreasing the absolute value in the first process includes: When the steering torque is greater than the adjusted steering torque processed last time, calculating a value obtained by subtracting the torque hysteresis from the steering torque as the adjusted steering torque processed this time; and When the steering torque is smaller than the adjustment steering torque processed last time, a value obtained by adding the torque hysteresis to the steering torque is calculated as the adjustment steering torque processed this time.

4. The control device according to claim 1, characterized in that The first process includes: When an absolute value of a difference between the steering torque and the steering torque processed last time is greater than a predetermined torque hysteresis, calculating the adjustment steering torque processed this time in a direction in which the absolute value is reduced; and When the absolute value is equal to or smaller than the torque hysteresis, the adjustment steering torque in this process is calculated so as to change at a predetermined slope.

5. The control device according to any one of claims 2 to 4, characterized in that: The adjustment gain calculation process further includes causing the torque to change with hysteresis according to the steering torque.

6. The control device according to any one of claims 1 to 5, characterized in that: The command torque includes an FF command torque and an FB command torque, wherein the FF command torque becomes a feedforward control amount based on a target state amount for following the target trajectory, and the FB command torque becomes a feedback control amount based on a difference between the target state amount and the current state amount. The adjustment gain includes a first adjustment gain and a second adjustment gain, The adjustment gain calculation process includes the first process or the second process corresponding to the first adjustment gain and the second adjustment gain, respectively. The adjustment command torque calculation process calculates the adjustment FB command torque obtained by applying the first adjustment gain to the FB command torque. The adjustment command torque calculation process calculates a value obtained by applying the second adjustment gain to the sum of the FF command torque and the adjustment FB command torque, or a sum of a value obtained by applying the second adjustment gain to the FF command torque and the adjustment FB command torque as the adjustment command torque.

7. A steering control device, which is a steering control device for a vehicle, characterized in that: have: The control device according to any one of claims 1 to 5; and A steering mechanism, controlled by the control device, The steering mechanism is an electric power steering device.

8. A control method is a vehicle control method, characterized in that: include: calculating a command torque to be applied to a steering mechanism for causing the vehicle to follow a target trajectory; calculating an adjustment gain for the command torque based on the steering torque; calculating an adjusted command torque obtained by applying the adjustment gain to the command torque; as well as controlling the steering mechanism according to the adjustment command torque, Calculating the adjustment gain includes: calculating, based on the steering torque, an adjusted steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque; and The adjusted steering torque is converted into the adjusted gain.

9. A storage medium storing a program related to vehicle control, characterized in that: The program causes the computer to execute the following processing: a process of calculating a command torque to be applied to a steering mechanism for causing the vehicle to follow a target trajectory; an adjustment gain calculation process of calculating an adjustment gain for the command torque based on the steering torque; a process of calculating an adjusted command torque obtained by applying the adjustment gain to the command torque; as well as controlling the steering mechanism according to the adjustment command torque, The adjustment gain calculation process includes: a process of calculating, based on the steering torque, an adjustment steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque; and A process of converting the adjusted steering torque into the adjusted gain.

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