Control device, steering device, control method, and program

Abstract

To provide a vehicle control device that can appropriately improve controllability of a vehicle by a driver in accordance with a steering state with respect to a target track in a case where the driver tries to steer the vehicle when a function for allowing the vehicle to track the target track is in operation.SOLUTION: A control device according to the present disclosure is configured to execute: processing of calculating a command torque to be applied to a steering mechanism; adjustment gain calculation processing of calculating, based on a steering torque, an adjustment gain with respect to the command torque; processing of calculating an adjustment command torque obtained by allocating the adjustment gain to the command torque; and processing of controlling the steering mechanism in accordance with the adjustment command torque. Here, the adjustment gain calculation processing includes: processing of calculating, based on the steering torque, an adjustment steering torque having predetermined hysteresis characteristics with respect to changes in the steering torque; and processing of converting the adjustment steering torque to the adjustment gain.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to a technique for controlling a steering mechanism of a vehicle, and more particularly to a technique for controlling a steering mechanism to cause a vehicle to follow a target trajectory. [Background technology]

[0002] Patent Document 1 discloses a steering control device that includes a state determination unit configured to determine at least whether the steering state is in a turning-in state or a turning-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 using a conversion 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-030481 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, a function for making a vehicle follow a target trajectory (hereinafter also referred to as a "follow-up steering function") has been considered as a driving assistance or autonomous driving function. In the follow-up steering function, a steering mechanism is controlled so that the vehicle follows a target trajectory. In general, the control of the steering mechanism involves controlling the torque applied to the steering mechanism.

[0005] On the other hand, when the tracking steering function is operating, the driver of the vehicle may wish to steer in a direction different from the target trajectory. In this case, the driver operates a driving operation device such as a steering wheel so that the vehicle is steered in the desired direction. At this time, the driver needs to generate a steering torque by operating the driving operation device against the torque provided by the tracking steering function. For this reason, the torque provided by the tracking steering function is generally adjusted according to the steering torque.

[0006] Here, the driving sensation felt by the driver is different when the driver tries to generate a steering torque in the opposite direction to the direction of the torque applied by the following steering function and when the driver tries to generate a steering torque in the same direction. Therefore, depending on the steering state of the driver with respect to the target trajectory, there is a risk that the driver will be given an extreme driving sensation. In turn, there is a risk that the driver's controllability of the vehicle will be reduced.

[0007] Patent Document 1 discloses a technique for determining the driver's steering state as holding the steering wheel, turning the steering wheel, returning the steering wheel, and releasing the steering wheel, and for calculating an intervention coefficient by a conversion characteristic that changes according to the steering state. In particular, it discloses that a conversion characteristic is given so as to reduce the intervention of the tracking control when the steering state is returning the steering wheel.

[0008] However, in the technology disclosed in Patent Document 1, it is assumed that there are cases where the driver's controllability of the vehicle cannot be sufficiently improved depending on the steering state of the driver with respect to the target trajectory. For example, when the driver tries to make fine corrections to the trajectory of the vehicle, it is necessary to change the adjustment gain within a range of small changes in the state quantity, and there is a risk that it will not be possible to achieve both the ability to follow the target trajectory and the improvement of the driver's controllability of the vehicle.

[0009] In consideration of the above-mentioned problems, one object of the present disclosure is to provide a technology that can appropriately improve the driver's controllability of the vehicle in accordance with the steering state relative to the target trajectory when the driver attempts to steer the vehicle while the tracking steering function is operating. [Means for solving the problem]

[0010] The first disclosure relates to a vehicle control device.

[0011] The control device according to the first disclosure is configured to execute a process of calculating a command torque to be applied to a steering mechanism for making the vehicle follow a target trajectory, an adjustment gain calculation process of calculating an adjustment gain for the command torque based on a steering torque, an adjustment command torque calculation process of calculating an adjustment command torque by applying the adjustment gain to the command torque, and a process of controlling the steering mechanism according to the adjustment command torque. Here, the adjustment gain calculation process includes a first process of calculating an adjustment steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque based on the steering torque, and a second process of converting the adjustment steering torque into the adjustment gain.

[0012] The second disclosure relates to a control device having the following characteristics in addition to the control device according to the first disclosure.

[0013] The first processing includes: in response to an absolute value of a difference between the steering torque and the adjusted steering torque of the previous processing being greater than a predetermined torque hysteresis, calculating the adjusted steering torque of the current processing in a direction in which the absolute value decreases; and in response to the absolute value being equal to or less than the torque hysteresis, calculating the adjusted steering torque of the previous processing as the adjusted steering torque of the current processing.

[0014] The third disclosure relates to a control device further having the following features in addition to the control device according to the second disclosure.

[0015] Calculating the adjusted steering torque for the current processing in a direction in which the absolute value decreases in the first processing includes calculating a value obtained by subtracting the torque hysteresis from the steering torque as the adjusted steering torque for the current processing when the steering torque is larger than the adjusted steering torque for the previous processing, and calculating a value obtained by adding the torque hysteresis to the steering torque as the adjusted steering torque for the current processing when the steering torque is smaller than the adjusted steering torque for the previous processing.

[0016] The fourth disclosure relates to a control device having the following characteristics in addition to the control device according to the first disclosure.

[0017] The first processing includes calculating the adjustment steering torque for the current processing in a direction in which the absolute value decreases when an absolute value of a difference between the steering torque and the steering torque of the previous processing is greater than a predetermined torque hysteresis, and calculating the adjustment steering torque for the current processing so as to change at a predetermined gradient when the absolute value is equal to or less than the torque hysteresis.

[0018] The fifth disclosure relates to a control device according to any one of the second to fourth disclosures, further having the following features.

[0019] The adjustment gain calculation process further includes changing the torque hysteresis in response to the steering torque.

[0020] The sixth disclosure relates to a control device according to any one of the first to fifth disclosures, further having the following features.

[0021] The command torque includes an FF command torque that is a feedforward control amount based on a target state amount for making the torque follow the target trajectory, and an FB command torque that is a feedback control amount based on a difference between the target state amount and a current state amount. The adjustment gains include 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 an adjusted FB command torque by applying the first adjustment gain to the FB command torque, and calculates, as the adjusted command torque, a value obtained by applying the second adjustment gain to the sum of the FF command torque and the adjusted FB command torque, or a sum of the value obtained by applying the second adjustment gain to the FF command torque and the adjusted FB command torque, as the adjusted command torque.

[0022] The seventh disclosure relates to a steering device for a vehicle.

[0023] A steering device according to a 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, wherein the steering mechanism is an electric power steering.

[0024] The eighth disclosure relates to a vehicle control method.

[0025] A control method according to an eighth disclosure includes calculating a command torque to be applied to a steering mechanism for making the vehicle follow a target trajectory, calculating an adjustment gain for the command torque based on a steering torque, calculating an adjusted command torque by applying the adjustment gain to the command torque, and controlling the steering mechanism in accordance with the adjusted command torque. Here, calculating the adjustment gain includes calculating an adjusted steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque based on the steering torque, and converting the adjusted steering torque into the adjustment gain.

[0026] The ninth disclosure relates to a program for controlling a vehicle.

[0027] The program according to the ninth disclosure is configured to cause a computer to execute the following processes: calculating a command torque to be applied to a steering mechanism for making the vehicle follow a target trajectory, calculating an adjustment gain for the command torque based on a steering torque, calculating an adjustment command torque by applying the adjustment gain to the command torque, and controlling the steering mechanism according to the adjustment command torque. Here, the adjustment gain calculation process includes: calculating an adjustment steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque based on the steering torque; and converting the adjustment steering torque into the adjustment gain. Effect of the Invention

[0028] According to this embodiment, an adjustment steering torque having a predetermined hysteresis characteristic with respect to a change in steering torque is calculated. Then, an adjustment gain is calculated by converting the calculated adjustment steering torque. This makes it possible to calculate an adjustment gain having different characteristics with respect to the steering torque depending on the steering state with respect to the target trajectory. In addition, the adjustment gain is held for a while when the steering is turned back. As a result, the controllability of the vehicle by the driver can be appropriately improved depending on the steering state with respect to the target trajectory. [Brief description of the drawings]

[0029] [Figure 1] 3 is a conceptual diagram for explaining control of a steering mechanism by a control device according to the present embodiment. FIG. [Diagram 2] 2 is a block diagram showing a schematic configuration of a process executed by the ECU shown in FIG. 1 when adjusting a command torque in accordance with a steering torque. [Diagram 3] FIG. 13 is a diagram showing an example of a map for calculating an adjustment gain according to the steering torque with respect to the magnitude of the steering torque; [Figure 4] 5 is a graph showing an example of an adjustment steering torque calculated in the control device according to the present embodiment. [Diagram 5] 6 is a graph showing an example of an adjustment steering torque calculated when a steering torque is applied so as to turn the steering wheel back after turning it inward; [Figure 6] 4 is a diagram showing an example of an adjustment gain relative to the magnitude of steering torque when the adjustment gain is calculated by converting the adjustment steering torque using the map shown in FIG. 3. FIG. [Figure 7] 4 is a block diagram showing an example of the configuration of an adjustment gain calculation processing unit in the control device according to the present embodiment. FIG. [Figure 8] FIG. 2 is a block diagram showing a configuration example of a control device according to the present embodiment. [Figure 9] 2 is a block diagram showing an example of the configuration of a process executed by a control device according to the embodiment; FIG. [Figure 10] 5 is a flowchart showing a preferred example of a processing routine in an adjustment steering torque calculation processing unit. [Figure 11] 11 is a graph showing a comparison result between the conventional technology and an example according to the present embodiment in a case where a driver performs sign steering when a target trajectory is a straight trajectory. [Figure 12] 11 is a graph showing a comparison result between the conventional technology and an example according to the present embodiment in a case where a driver performs sign steering in the inside direction of a turn when a target trajectory is a turning trajectory. [Figure 13] 13 is a graph showing an example of an adjustment steering torque calculated in an adjustment steering torque calculation processing unit according to a second modified example. [Figure 14] 10 is a flowchart showing an example of a processing routine in an adjustment steering torque calculation processing unit according to a second modified example. [Figure 15] 10 is a flowchart showing an example of a processing routine in an adjustment steering torque calculation processing unit according to a second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, the embodiments of the present disclosure will be described with reference to the drawings. However, when the number, quantity, amount, range, etc. of each element is mentioned in the embodiments shown below, the idea of ​​the present disclosure is not limited to the mentioned number unless it is specifically stated or the number is clearly specified in principle. Furthermore, the configurations etc. described in the embodiments shown below are not necessarily essential to the idea of ​​the present disclosure unless it is specifically stated or the number is clearly specified in principle. In addition, the same reference numerals are attached to the same or corresponding parts in each drawing, and the duplicated explanation is appropriately simplified or omitted.

[0031] 1. Adaptive steering function The control device according to this embodiment controls the steering mechanism so as to make the vehicle follow a target trajectory. With reference to the steering device shown in FIG.

[0032] FIG. 1 shows a typical steering mechanism 10 including a steering shaft 11, a gear box 12, and a tie rod 13. That is, the steering shaft 11 is connected to the gear box 12, and rotates in accordance with the operation of the steering wheel 1. The gear box 12 causes the tie rod 13 to move linearly in response to the rotational movement of the steering shaft 11. Typically, the gear box 12 has a rack-and-pinion structure, and the rotational movement of the steering shaft 11 is converted into the linear movement of the rack via the pinion, causing the tie rod 13 connected to the rack to move linearly. The linear movement of the tie rod 13 can change the steering angle of the vehicle, thereby realizing steering of the vehicle.

[0033] A motor 200 is attached to the rack portion of the steering mechanism 10. The steering mechanism 10 is configured so that the motor 200 can operate to generate torque to linearly move the rack. In other words, the steering mechanism 10 is a rack-assist type electric power steering. However, in this embodiment, the steering mechanism 10 may be a column-assist type or pinion-assist type electric power steering.

[0034] In Fig. 1, the control device is realized as an ECU (Electronic Control Unit) 100. The ECU 100 generates and outputs a control signal by executing processing. In particular, the ECU 100 generates and outputs a command torque for a motor 200 as a control signal. The motor 200 operates to generate a command torque obtained from the ECU 100, thereby realizing control of a steering mechanism by the ECU 100. For example, an inverter control is performed in the motor 200 so as to generate a command torque.

[0035] The ECU 100 is configured to acquire a target steering angle (target state quantity) for making the vehicle follow the target trajectory, and vehicle speed and other vehicle information. The ECU 100 then generates and outputs a command torque so that the vehicle will have the target steering angle. This realizes a function for making the vehicle follow the target trajectory (following steering function). Here, the target steering angle is typically calculated in another ECU that provides the following steering function, and is transmitted to the ECU 100. The following steering function may be one of the driving assistance functions provided by the other ECU, or may be a part of an automatic driving function. In addition, examples of other vehicle information include acceleration, yaw rate, current steering angle, vehicle specifications, and the like. The vehicle speed and other vehicle information can be acquired from a sensor provided in the vehicle or another ECU. Alternatively, the information may be acquired as data to be stored in a memory.

[0036] Furthermore, the ECU 100 may have a function related to steering stability control. For example, the ECU 100 may be configured to generate an assist torque as a command torque in response to the steering angle or steering angular velocity of the steering wheel 1 or the steering torque due to 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 a steering angle sensor 21. The steering torque due to the operation of the steering wheel 1 can be obtained from a torque sensor 22.

[0037] The ECU 100 is typically provided in a vehicle. However, the control device according to the present embodiment may be a device external to the vehicle. For example, the control device according to the present embodiment may be realized as a server that communicates with the vehicle via the Internet. In this case, the control device acquires information through communication and transmits a control signal.

[0038] Incidentally, when the tracking steering function is operating, the driver of the vehicle may wish to steer in a direction different from the target trajectory. For example, when the target trajectory is a straight trajectory, the driver may wish to distance himself from an obstacle ahead, or when the target trajectory is a turning trajectory, the driver may wish to drive with a smaller turning radius. In this case, the driver will operate the steering wheel 1 so that the vehicle is steered in the desired direction. For example, when the driver wishes to distance himself from an obstacle ahead, the driver is expected to turn the steering wheel 1 in such a way that the driver distances himself from the obstacle, and then turn the steering wheel 1 back when a certain distance has been gained.

[0039] When the driver operates the steering wheel 1 while the following steering function is operating in this manner, the driver is required to generate a steering torque by operating the steering wheel 1 against the torque generated by the motor 200 by the following steering function. Therefore, the torque generated by the motor 200 by the following steering function is generally adjusted according to the steering torque. That is, the ECU 100 adjusts the command torque according to the steering torque.

[0040] Fig. 2 is a block diagram showing a schematic configuration of a process executed by the ECU 100 when adjusting a command torque according to a steering torque. In Fig. 2, the process executed by the ECU 100 is composed of 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 provided as a program or may be provided by separate processors.

[0041] The command torque calculation processing unit P100 receives a target steering angle θt as an input and calculates a command torque Tf so that the vehicle will reach the target steering angle θt. For example, the command torque Tf is calculated by 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 quantity). Furthermore, the vehicle speed and other vehicle information may be taken into consideration when calculating the command torque Tf.

[0042] The adjustment gain calculation processing unit P200 receives the steering torque T as an input and calculates a gain (adjustment gain) α for the command torque Tf in accordance with the steering torque T. For example, the steering torque T is converted into the adjustment gain α using a map for the magnitude of the steering torque T. Fig. 3 shows an example of the map for the magnitude |T| of the steering torque T.

[0043] 2 again. The adjustment command torque calculation processing unit P300 receives the command torque Tf calculated in the command torque calculation processing unit P100 and the adjustment gain α calculated in the adjustment gain calculation processing unit P200 as input, and generates an adjustment command torque Tc by applying the adjustment gain α to the command torque Tf. The adjustment command torque Tc generated in the adjustment command torque calculation processing unit P300 is output from the ECU 100 and transmitted to the motor 200. The motor 200 operates to generate the adjustment command torque Tc.

[0044] The adjustment gain α is typically given as a value between 0 and 1 so as to reduce the command torque Tf according to the magnitude of the steering torque T. In other words, the adjustment command torque Tc is adjusted so as to become smaller with respect to the command torque Tf as the steering torque T increases. This makes it possible to reduce the influence of the torque generated by the motor 200 when the driver operates the steering wheel 1 to steer in a direction different from the target trajectory. As a result, the steering load on the driver can be reduced.

[0045] Here, the driving sensation felt by the driver is different when the driver tries to generate a steering torque in the opposite direction to the direction of the torque generated by the motor 200 by the following steering function and when the driver tries to generate a steering torque in the same direction. For example, when the driver turns the steering wheel 1 away from the target trajectory (when trying to generate a steering torque in the opposite direction), the driver feels the operation of the steering wheel 1 heavy, and when the driver turns the steering wheel 1 back afterwards (when trying to generate a steering torque in the same direction), the driver feels the operation of the steering wheel 1 as if it is being returned strongly. For this reason, depending on the steering state of the driver with respect to the target trajectory, there is a risk that the driver will be given an extreme driving sensation. In turn, there is a risk that the driver's controllability of the vehicle may be reduced.

[0046] In order to solve the above problem, the control device according to this embodiment has a feature in the adjustment gain calculation processing unit P200. Below, an overview of the characteristic processing of the adjustment gain calculation processing unit P200 of the control device according to this embodiment will be described.

[0047] 2. Overview In the control device according to this embodiment, an adjustment steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque T is calculated in an adjustment gain calculation processing section P200.

[0048] FIG. 4 shows an example of the adjustment steering torque Tr calculated in the control device according to this embodiment. As shown in FIG. 4, the calculated adjustment steering torque Tr has a hysteresis characteristic, so that while the steering torque T is increasing or decreasing, the adjustment steering torque Tr increases or decreases according to the steering torque T, and when the steering torque T changes from increasing to decreasing or from decreasing to increasing, the adjustment steering torque Tr maintains a constant value until the steering torque T decreases or increases by a predetermined value or more. That is, when the driver turns the steering wheel 1, the adjustment steering torque Tr increases or decreases according to the steering torque T, and when the driver turns the steering wheel 1 back, the adjustment steering torque Tr is maintained for a while. Also, by having the hysteresis characteristic, the magnitude |Tr| of the adjustment steering torque Tr when the driver turns the steering wheel 1 is smaller than the magnitude |Tr| of the adjustment steering torque Tr when the driver turns the steering wheel 1 back.

[0049] The adjusted steering torque Tr having such a hysteresis characteristic can be calculated with 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 adjusted steering torque Tr of the previous process (hereinafter also referred to as "adjusted steering torque deviation") is equal to or less than the torque hysteresis Th, the adjusted steering torque Tr of the previous process is calculated as the adjusted steering torque Tr of the current process, and since the adjusted steering torque deviation is greater than the torque hysteresis Th, the adjusted steering torque Tr of the current process can be calculated in a direction in which the adjusted steering torque deviation decreases. 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 the torque hysteresis Th or more. On the other hand, when the driver turns the steering wheel 1 back, the magnitude |Tr| of the adjusted steering torque Tr becomes larger than the magnitude |T| of the steering torque T by the torque hysteresis Th or more. Furthermore, when the driver turns the steering wheel 1, the adjusted steering torque Tr is maintained at a constant value until the steering torque T decreases or increases by at least twice the torque hysteresis Th.

[0050] In particular, the adjustment steering torque Tr of the current processing can be calculated in a direction in which the adjustment steering torque deviation decreases by subtracting the torque hysteresis Th from the current value of the steering torque T when the current value of the steering torque T is greater than the adjustment steering torque Tr of the previous processing, and by adding the torque hysteresis Th to the current value of the steering torque T when the current value of the steering torque T is smaller than the adjustment steering torque Tr of the previous processing. By calculating the adjustment steering torque Tr in this manner, as shown in FIG. 4, when the driver turns the steering wheel 1, the magnitude |Tr| of the adjustment steering torque Tr becomes smaller than the magnitude |T| of the steering torque T by the torque hysteresis Th. On the other hand, when the driver turns the steering wheel 1 back, the magnitude |Tr| of the adjustment steering torque Tr becomes 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 adjusted steering torque Tr is maintained at a constant value until the steering torque T decreases or increases by twice the torque hysteresis Th.

[0051] FIG. 5 shows an example of the adjustment steering torque Tr calculated when applying a steering torque T to turn the steering wheel 1 back after turning it. In the example shown in FIG. 5, in the steering of the steering wheel 1 up to time t1, the adjustment steering torque Tr is smaller than the steering torque T by the torque hysteresis Th, and in the steering of the steering wheel back after time t2, the adjustment steering torque Tr is larger than the steering torque T by the torque hysteresis Th. In addition, in the steering of the steering wheel back from time t1 to time t2, the adjustment steering torque Tr is a constant value. In this way, according to this embodiment, the adjustment steering torque Tr can be calculated so that the characteristic with respect to the steering torque T differs between the steering of the steering wheel 1 and the steering of the steering wheel back. In particular, a configuration that is a time delay element such as a low-pass filter is not included, and a sudden change in value does not occur.

[0052] Next, in the control device according to this embodiment, the adjustment gain calculation processing unit P200 calculates the adjustment gain α by converting the calculated adjustment steering torque Tr. The conversion of the adjustment steering torque Tr is performed, for example, by using a map. Here, the map may be the same as the map for the magnitude |T| of the steering torque T as shown in FIG. 3. In this case, in FIG. 3, the horizontal axis represents the magnitude |Tr| of the adjustment steering torque Tr. However, it is also possible to provide a suitable map depending on the environment in which the control device according to this embodiment is applied. For example, the map may be such that the adjustment gain α decreases nonlinearly from 1 to 0 as the magnitude |Tr| of the adjustment steering torque Tr increases.

[0053] According to this embodiment, the adjusted steering torque Tr has a predetermined hysteresis characteristic, so that the characteristic with respect to the steering torque T is different between the steering of the steering wheel and the steering of the steering wheel. Therefore, by calculating the adjustment gain α by converting the adjusted steering torque Tr, the adjustment gain α can be given so that the characteristic with respect to the steering torque T is different between the steering of the steering wheel and the steering of the steering wheel. FIG. 6 shows an example of the adjustment gain α with respect to the magnitude |T| of the steering torque T when the adjustment gain α is calculated by converting the adjusted steering torque Tr using the map shown in FIG. 3. Here, the graph shown in FIG. 6 shows the adjustment gain α calculated with respect to the steering torque T in quasi-steady steering (steering speed ≒ 0). As shown in FIG. 6, the adjustment gain α is given so that the characteristic with respect to the steering torque T is different between the steering of the steering wheel (dash line) and the steering of the steering wheel (dotted line). In particular, the adjustment gain α in the steering of the steering wheel can be given so as to be a smaller value than the adjustment gain α in the steering of the steering wheel. Also, when turning, the adjustment gain α can be held for a while.

[0054] Thus, according to this embodiment, the adjustment gain calculation processing unit P200 calculates an adjustment gain α having different characteristics with respect to the steering torque in the steering of the turning and the steering of the return. As a result, the torque generated by the motor 200 can be made different by the tracking steering function in the steering of the turning and the steering of the return. In particular, the adjustment gain α in the steering of the turning is given to be a smaller value than the adjustment gain α in the steering of the return. That is, the torque generated by the motor 200 in the steering of the return can be made smaller than the torque generated by the motor 200 in the steering of the turning. In addition, the feeling that the steering of the steering wheel 1 is strongly returned when the steering is returned can be reduced. In addition, when the steering is turned back, the adjustment gain α is held for a while. That is, when the steering is turned back, the torque generated by the motor 200 does not change suddenly. Thus, according to this embodiment, the controllability of the vehicle by the driver can be appropriately improved according to the steering state with respect to the target trajectory.

[0055] The control device according to the present embodiment may be configured to change the torque hysteresis Th used in calculating the adjustment steering torque Tr in accordance with the steering torque T. For example, the torque hysteresis Th is changed to a larger value as the magnitude |T| of the steering torque T increases. This can be configured, for example, by providing the torque hysteresis Th using a map for the magnitude |T| of the steering torque T.

[0056] With this configuration, for example, when the magnitude |T| of the steering torque T is large, by setting a large torque hysteresis Th, the steering load on the driver can be more appropriately reduced. Furthermore, by providing a nonlinear map to ensure that the adjustment gain α calculated when the steering torque T is 0 is 1, it is possible to prevent the range of values ​​that the adjustment gain α can take from being limited by the value of the steering torque T (particularly in steering back). In turn, it is possible to achieve both the objective of reducing the steering load on the driver and the objective of ensuring the performance of the tracking steering function when the driver is not steering.

[0057] Fig. 7 shows an example of the configuration of the adjustment gain calculation processing unit P200 in the control device according to this embodiment. In Fig. 7, the adjustment gain calculation processing unit P200 is composed of a torque hysteresis calculation processing unit P201, an adjustment steering torque calculation processing unit P210, and a conversion processing unit P220.

[0058] The torque hysteresis calculation processing unit P201 receives the steering torque T as an input and calculates the torque hysteresis Th according to the steering torque T. In the configuration example shown in Fig. 7, the torque hysteresis Th is calculated using a map for the magnitude |T| of the steering torque T.

[0059] The adjustment steering torque calculation processing unit P210 receives the steering torque T and the torque hysteresis Th calculated by the torque hysteresis calculation processing unit P201 as input, and calculates the adjustment steering torque Tr (first process) based on the steering torque T. As described above, the adjustment steering torque Tr is calculated using the torque hysteresis Th so as to have a predetermined hysteresis characteristic with respect to the change in the steering torque.

[0060] The conversion processing unit P220 receives the adjustment steering torque Tr calculated by the adjustment steering torque calculation processing unit P210 and calculates the adjustment gain α by converting the adjustment steering torque Tr (second process). In the configuration example shown in Fig. 7, the adjustment gain α is calculated using a map for the magnitude |Tr| of the adjustment steering torque Tr.

[0061] 2. Configuration A configuration example of the control device (ECU 100) according to this embodiment and a configuration example of the process executed by the control device (ECU 100) according to this embodiment will be described below.

[0062] 2-1.Control device configuration 8 is a block diagram showing an example of the configuration of a control device (ECU 100) according to this embodiment. The ECU 100 is a computer including a memory 110 and a processor 120. The memory 110 is coupled to the processor 120 and stores a plurality of executable instructions 112 and various data 113 required for executing processing. The instructions 112 are provided by a program 111. In this sense, the memory 110 can also be called a "program memory."

[0063] The processor 120 operates according to the instructions 112 to execute various processes based on the data 113. This causes the ECU 100 to execute processes related to the command torque calculation processing unit P100, the adjustment gain calculation processing unit P200, and the adjustment command torque calculation processing unit P300. In addition, when the ECU 100 has a function related to steering stability control, the ECU 100 executes processes related to steering stability control.

[0064] 2-2. Processing configuration FIG. 9 is a block diagram showing an example of the configuration of the process executed by the control device (ECU 100) according to this embodiment, in particular the process related to calculation of the torque (adjustment command torque Tc) to be generated by the motor 200 as the follow-up steering function.

[0065] In the configuration example of the process shown in Fig. 9, the command torque Tf calculated in the command torque calculation processing unit P100 includes an FF command torque Tff which is a feedforward control amount based on a target steering angle θt, and an FB command torque Tfb which is a feedback control amount based on the difference between the target steering angle θt and the current steering angle θ. Therefore, in the configuration example shown in Fig. 9, 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.

[0066] The FF command torque calculation processor P110 receives the target steering angle θt as an input and calculates the FF command torque Tff based on the target steering angle θt. The FB command torque calculation processor P120 receives the difference between the target steering angle θt and the current steering angle θ and calculates the FB command torque Tfb based on the difference between the target steering angle θt and the current steering angle θ.

[0067] The feedforward control and the feedback control in the FF command torque calculation processor P110 and the FB command torque calculation processor P120 may be performed using a suitable known technique. In particular, the present steering angle θ may be obtained from the steering angle sensor 21.

[0068] In the configuration example of the process shown in FIG. 9, the adjustment gain α calculated in the adjustment gain calculation processing unit P200 includes the first adjustment gain α1 and the second adjustment gain α2. Therefore, in the configuration example shown in FIG. 9, the adjustment gain calculation processing unit P200 includes the same configuration as that described in FIG. 7 for each of the first adjustment gain α1 and the second adjustment gain α2. However, the torque hysteresis calculation processing unit P201, the adjusted steering torque calculation processing unit P210, and the conversion processing unit P220 for each of the first adjustment gain α1 and the second adjustment gain α2 may be given different characteristics. For example, the torque hysteresis calculation processing unit P201 related to the first adjustment gain α1 and the torque hysteresis calculation processing unit P201 related to the second adjustment gain α2, or the conversion processing unit P220 related to the first adjustment gain α1 and the conversion processing unit P220 related to the second adjustment gain α2 may adopt different maps. In other words, characteristics according to the first adjustment gain α1 and the second adjustment gain α2 may be given.

[0069] 9, an adjustment command torque calculation processing unit P300 calculates an adjusted FB command torque Tbr by applying a first adjustment gain α1 to the FB command torque Tfb (P301). Then, a value obtained by applying a second adjustment gain α2 to the sum Tsum of the FF command torque Tff and the adjusted FB command torque Tbr is calculated as an adjusted command torque Tc (P302).

[0070] According to the exemplary process configuration shown in Fig. 9, the first adjustment gain α1 and the second adjustment gain α2 are calculated by the same configuration as that described in Fig. 7. Therefore, as described above, it is possible to improve the controllability of the vehicle by the driver.

[0071] Incidentally, the configuration example shown in Fig. 9 is characterized in that the first adjustment gain α1 applied to the FB command torque Tfb and the second adjustment gain α2 applied to the sum Tsum of the FF command torque Tff and the adjusted FB command torque Tbr are calculated separately in the adjustment gain calculation processing unit P200. By configuring in this way, it becomes possible to appropriately improve the controllability of the vehicle by the driver both when the target trajectory is a straight trajectory and when the target trajectory is a turning trajectory. This is for the following reason.

[0072] In general, when the target trajectory is a turning trajectory, the FF command torque Tff contributes greatly to the tracking ability to the target trajectory. On the other hand, when the target trajectory is a straight trajectory, the FB command torque Tfb contributes greatly to the tracking ability to the target trajectory. In particular, when the target trajectory is a straight trajectory, the FF command torque Tff is typically 0. For this reason, in order to ensure sufficient tracking ability of the tracking steering function, 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.

[0073] Here, consider a 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, it is assumed that the adjustment gain α is given so that the controllability of the vehicle by the driver can be sufficiently improved when the target trajectory is a straight trajectory. In other words, it is assumed that the adjustment gain α is given which is sufficiently small with respect to the magnitude |T| of the steering torque T. In this case, for example, when the target trajectory is a turning trajectory, if the driver tries to steer to the inside of the turning trajectory, the contribution of the FF command torque Tff becomes excessively small because the adjustment gain α is small, and there is a risk that the torque required for turning cannot be generated. In addition, there is a risk that a phenomenon occurs in which the vehicle moves to the outside of the turning trajectory even though the driver wants to steer to the inside of the turning trajectory.

[0074] On the other hand, if the adjustment gain α is given so as to ensure the torque required for turning when the target trajectory is a turning trajectory, it will not be possible to sufficiently improve the driver's controllability of the vehicle when the target trajectory is a straight trajectory.

[0075] Therefore, the above-mentioned trade-off can be eliminated by configuring the adjustment gain calculation processing unit P200 to calculate the first adjustment gain α1 and the second adjustment gain α2 separately. In other words, appropriate characteristics can be given to the first adjustment gain α1 and the second adjustment gain α2 so that the controllability of the vehicle by the driver can be appropriately improved both when the target trajectory is a straight trajectory and when the target trajectory is a turning trajectory.

[0076] According to the above description, the adjustment command torque calculation processing unit P300 may be configured to calculate the sum of the FF command torque Tff applied with the second adjustment gain α2 and the adjusted FB command torque Tbr as the adjustment command torque Tc. Even with such a configuration, it is possible to achieve the same effect.

[0077] 3. Adjustment steering torque calculation process Hereinafter, the processing routine in the adjustment steering torque calculation processing unit P210 will be described with reference to Fig. 10. Fig. 10 is a flowchart showing a preferred example of the processing routine in the adjustment steering torque calculation processing unit P210. The processing routine shown in Fig. 10 may be executed at a predetermined processing cycle (for example, 5 msec). In Fig. 10, the adjustment steering torque Tr in the previous process is expressed as Tr'.

[0078] In step S100, it is determined 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 set to 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. Note that step S110 is typically executed when the following steering function is started.

[0079] In step S120, it is determined whether the steering torque T is greater than the sum of the adjusted steering torque Tr' of the previous process and the torque hysteresis Th.

[0080] If the steering torque T is greater than the sum of the adjusted steering torque Tr' and the torque hysteresis Th in the previous process (step S120; Yes), the steering torque T minus the torque hysteresis Th is set as the adjusted steering torque Tr in 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 in the previous process (step S120; No), the process proceeds to step S140.

[0081] In step S140, it is determined whether the steering torque T is smaller than the difference between the adjusted steering torque Tr' of the previous process and the torque hysteresis Th.

[0082] If the steering torque T is smaller than the difference between the adjusted steering torque Tr' of the previous process and the torque hysteresis Th (step S140; Yes), the steering torque T plus the torque hysteresis Th is set as the adjusted steering torque Tr of the current process (step S150), and the current process is terminated. If the steering torque T is not smaller than the difference between the adjusted steering torque Tr' of the previous process and the torque hysteresis Th (step S140; No), the current process is terminated without performing a calculation on the adjusted steering torque Tr. That is, in this case, the adjusted steering torque Tr of the current process becomes the adjusted steering torque Tr' of the previous process.

[0083] The processes in steps S120 and S140 can also be considered as determining whether the adjusted steering torque deviation is greater than the torque hysteresis Th. That is, when the adjusted steering torque deviation is greater than the torque hysteresis Th, the processes in steps S130 or S150 are executed. In particular, when the steering torque T is greater than the adjusted steering torque Tr' in the previous process, the process in step S130 is executed, and when the steering torque T is smaller than the adjusted steering torque Tr' in the previous process, the process in step S150 is executed. Also, the processes in steps S130 and S150 can be considered as calculating the adjusted steering torque Tr in the current process in a direction that reduces the adjusted steering torque deviation.

[0084] By executing such a processing routine, the adjustment command torque calculation processing unit P300 can calculate the adjustment steering torque Tr having a predetermined hysteresis characteristic with respect to the change in the steering torque T as shown in Fig. 4. Furthermore, the control device configured in this manner realizes the control method according to this embodiment.

[0085] 4.Effects As described above, according to this embodiment, the adjustment gain calculation processing unit P200 calculates an adjustment gain α having different characteristics with respect to the steering torque in each of the steering of the turning and the steering of the return. Then, the adjustment command torque Tc is calculated by applying the adjustment gain α calculated in this way to the command torque Tf, and the steering mechanism 10 is controlled according to the adjustment command torque Tc. This makes it possible to make the torque generated by the motor 200 different by the following steering function in each of the steering of the turning and the return. In particular, the adjustment gain α in the steering of the turning is given to be a smaller value than the adjustment gain α in the steering of the return. That is, the torque generated by the motor 200 in the steering of the return can be made smaller than the torque generated by the motor 200 in the steering of the turning. By extension, it is possible to reduce the feeling that the steering of the steering wheel 1 is strongly returned when the steering is returned. In addition, when the steering is turned back, the adjustment gain α is held for a while. That is, when the steering is turned back, the torque generated by the motor 200 does not change suddenly. In this way, according to this embodiment, the controllability of the vehicle by the driver can be appropriately improved in accordance with the steering state with respect to the target trajectory.

[0086] Furthermore, according to the present embodiment, it is possible to calculate the adjustment gain α having different characteristics according to the steering state without determining the steering state of the driver with respect to the target trajectory. This is advantageous in a situation where the driver is trying to finely correct the trajectory of the vehicle. This is for the following reasons.

[0087] When the driver tries to finely correct the trajectory of the vehicle, the operation amount is generally small. Therefore, when the steering state of the driver is to be judged, the state amount for the judgment is also small. In other words, when the conversion characteristic related to the adjustment gain α is given according to the judged steering state, it is necessary to change the adjustment gain α within a range of small changes in the state amount. However, in actual vehicle driving, even when the driver does not intentionally steer, it is assumed that the operation amount is detected due to road disturbances, etc. In addition, it is assumed that the state amount changes in the vicinity of 0. Therefore, changing the adjustment gain α within a range of small changes in the state amount may cause unintended fluctuations in the adjustment gain α. In this way, when the conversion characteristic related to the adjustment gain α is given according to the judged steering state, there is a risk that it will not be possible to achieve both the ability to follow the target trajectory and the improvement of the controllability of the vehicle by the driver in a situation where the driver tries to finely correct the trajectory of the vehicle.

[0088] It is also possible to reduce the amount of operation unintentional by the driver using a low-pass filter. However, in this case, a response delay occurs due to the low-pass filter, so that the driver may feel uncomfortable when steering or the feeling of the steering being strongly returned may not be sufficiently reduced. On the other hand, according to this embodiment, the low-pass filter is not necessarily required. However, it is also possible to apply a low-pass filter to the calculated adjustment gain α, taking into consideration the effect on responsiveness and steering feeling. This is expected to realize a smoother characteristic with respect to the change in steering torque T.

[0089] 5. Working Example FIG. 11 shows a comparison result between the conventional technology and the embodiment according to the present invention in the case where the driver performs sine steering when the target trajectory is a straight trajectory. Here, the conventional technology embodiment (solid line) is a case where the adjustment gain α is given to the magnitude |T| of the steering torque T as shown in FIG. 3. In addition, two embodiments according to the present invention are shown, one in which only the second adjustment gain α2 is effective and applied in the adjustment command torque calculation processing unit P300 (broken line) and the other in which both the first adjustment gain α1 and the second adjustment gain α2 are effective and applied (chain line). Note that A in FIG. 11 shows the Lissajous characteristic of the steering angle θ with respect to the steering torque T, and B in FIG. 11 shows the Lissajous characteristic of the yaw rate with respect to the steering torque T.

[0090] As shown in Fig. 11, according to this embodiment, the vehicle can be steered with a margin during steering when turning back, as compared with the conventional technology. In addition, it can be seen that the controllability of the vehicle during steering back is improved. In addition, when the target trajectory is a straight trajectory, even when only the second adjustment gain α2 is applied as an effective gain, it can be seen that a characteristic similar to that when both the first adjustment gain α1 and the second adjustment gain α2 are applied as an effective gain can be realized.

[0091] Fig. 12 shows a comparison result between the conventional technology and the embodiment according to the present invention when the driver performs sign steering in the turning inside direction when the target trajectory is a turning trajectory. In particular, Fig. 12 shows an example in which the vehicle is traveling at 80 km / h on a 500R road. As with Fig. 11A and Fig. 11B, Fig. 12A shows the Lissajous characteristic of the steering angle θ with respect to the steering torque T, and Fig. 12B shows the Lissajous characteristic of the yaw rate with respect to the steering torque T.

[0092] As shown in Fig. 12, according to this embodiment, even when the target trajectory is a turning trajectory, the vehicle can be steered with ease in the turning steering, as in the case where the target trajectory is a straight trajectory. However, when only the second adjustment gain α2 is applied as an effective gain, the steering angle θ and the yaw rate change with respect to the steering torque T is small, and it may be difficult for the driver to steer to the inside of the turn. On the other hand, it can be seen that by applying both the first adjustment gain α1 and the second adjustment gain α2 as an effective gain, the vehicle can be steered with ease, and the driver can easily steer to the inside of the turn.

[0093] 6. Variations This embodiment may adopt the following modified aspects: In the following description, the description of matters that overlap with the above content will be omitted as appropriate.

[0094] 6-1. First modified example In the adjustment gain calculation processing unit P200, the torque hysteresis calculation processing unit P201 or the conversion processing unit P220 may be configured to change the characteristics according to the vehicle speed. For example, the map in the torque hysteresis calculation processing unit P201 or the conversion processing unit P220 may be changed according to the vehicle speed. Alternatively, the adjustment command torque calculation processing unit P300 may be configured to further apply a vehicle speed gain given according to the vehicle speed to the command torque Tf.

[0095] Generally, the driving sensation of a driver varies depending on the vehicle speed. Therefore, by adopting the first modified example, it is possible to improve the controllability of the vehicle more appropriately according to the vehicle speed.

[0096] 6-2. Second modified example The adjustment steering torque calculation processing unit P210 may be configured to calculate the adjustment steering torque Tr so as to change it at a predetermined gradient when the adjustment steering torque deviation is equal to or less than the torque hysteresis Th. FIG. 13 shows an example of the adjustment steering torque Tr calculated in the adjustment steering torque calculation processing unit P210 according to the second modification. FIG. 13 shows three examples with different values ​​of Tslp defined to correspond to the predetermined gradient. When Tslp=1, it is equivalent to the example shown in FIG. 4. That is, in this case, when the adjustment steering torque deviation is equal to or less than the torque hysteresis Th, the adjustment steering torque Tr maintains a constant value (gradient 0). On the other hand, when Tslp=0.5 or Tslp=2, the characteristics in the steering during turning are different compared to the example shown in FIG. 4.

[0097] In this way, by adopting the second modified example, it is possible to provide a degree of freedom in the steering characteristics during turning. Furthermore, by appropriately setting the predetermined gradient, it is possible to further optimize the improvement of the controllability of the vehicle.

[0098] Here, the second modified example can be realized by executing a processing routine in the adjustment steering torque calculation processing unit P210 as follows. Fig. 14 is a flowchart showing an example of a processing routine in the adjustment steering torque calculation processing unit P210 according to the second modified example. The processing routine shown in Fig. 14 may be executed at every predetermined processing cycle.

[0099] In step S200, it is determined whether the reference torque Tref has been initialized. Here, the reference torque Tref is calculated so as to have a predetermined hysteresis characteristic with respect to the change in the steering torque T, similar to the adjustment steering torque Tr, as will be made clear in the processing described below. However, the hysteresis width is in accordance with the deviation upper limit value ΔT described below. In particular, when the adjustment steering torque deviation is larger than the torque hysteresis Th, the reference torque Tref is equivalent to the adjustment steering torque Tr calculated in the processing routine shown in FIG.

[0100] If the reference torque Tref has not been initialized (step S200; No), the reference torque Tref is set to 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.

[0101] In step S220, a deviation upper limit value ΔT is calculated. Here, the deviation upper limit value ΔT is calculated by dividing the torque hysteresis Th by Tslp. By calculating in this manner, Tslp becomes a value corresponding to a predetermined gradient by a processing routine shown in FIG. 14 described below. Note that Tslp may be a value given in advance as data 113, for example. In particular, Tslp may be suitably determined depending on the environment in which the control device according to the second modified example is applied.

[0102] After step S220, the process proceeds to step S230.

[0103] In step S230, it is determined whether the steering torque T is greater than the sum of the reference torque Tref' of the previous process and the deviation upper limit value ΔT.

[0104] If the steering torque T is greater than the sum of the reference torque Tref' and the deviation upper limit value ΔT in the previous process (step S230; Yes), the steering torque T minus the deviation upper limit value ΔT is set as the reference torque Tref in 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 reference torque Tref' and the deviation upper limit value ΔT in the previous process (step S230; No), the process proceeds to step S250.

[0105] In step S250, it is determined whether the steering torque T is smaller than the difference between the reference torque Tref' of the previous process and the deviation upper limit value ΔT.

[0106] If the steering torque T is smaller than the difference between the reference torque Tref' of the previous processing and the deviation upper limit value ΔT (step S250; Yes), the steering torque T plus the deviation upper limit value ΔT is set as the reference torque Tref of the current processing (step S260), and the process proceeds to step S270. If the steering torque T is not smaller than the difference between the reference torque Tref' of the previous processing and the deviation upper limit value ΔT (step S250; No), the process proceeds to step S270 without performing any calculation on the reference torque Tref. That is, in this case, the reference torque Tref of the current processing becomes the reference torque Tref' of the previous processing.

[0107] In step S270, a temporary value Ttmp is calculated by multiplying a value obtained by subtracting the reference torque Tref from the steering torque T by Tslp.

[0108] After step S270, the process proceeds to step S280.

[0109] In step S280, the steering torque T minus the temporary value Ttmp calculated in step S270 is calculated as the adjusted steering torque Tr of the current process, and the current process ends.

[0110] By executing such a processing routine, the adjustment command torque calculation processing unit P300 can calculate the adjustment steering torque Tr having a predetermined hysteresis characteristic with respect to the change in the steering torque T as shown in Fig. 13. In particular, the characteristic in the turning steering can be changed according to the value of Tslp.

[0111] The second embodiment can also be realized by focusing on the steering angle θ and executing a processing routine in the adjustment steering torque calculation processing unit P210 as follows. Fig. 15 is a flowchart showing another example of the processing routine in the adjustment steering torque calculation processing unit P210 according to the second modified example. The processing routine shown in Fig. 15 may be executed at every predetermined processing cycle.

[0112] In step S300, it is determined whether the reference steering angle θref has been initialized. Here, the reference steering angle θref is calculated so as to have a predetermined hysteresis characteristic with respect to the change in the steering angle θ, as will be made clear in the process described below. In particular, the hysteresis width is in accordance with the deviation upper limit value Δθ described below.

[0113] If the reference steering angle θref has not been initialized (step S300; No), the reference steering angle θref is set to 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.

[0114] In step S320, the deviation upper limit value Δθ is calculated. Here, the deviation upper limit value Δθ is calculated by dividing the torque hysteresis Th by a predetermined value K. By calculating in this manner, K becomes a value corresponding to a predetermined gradient by a processing routine shown in FIG. 15 described below. K can also be considered to define the "rigidity" of the reference steering angle θref with respect to changes in the steering angle θ. Note that K may be a value given in advance as data 113, for example. In particular, K may be suitably determined depending on the environment in which the control device according to the second modified example is applied.

[0115] After step S320, the process proceeds to step S330.

[0116] In step S330, it is determined whether the steering angle θ is greater than the sum of the reference steering angle θref′ of the previous process and the deviation upper limit value Δθ.

[0117] If the steering angle θ is greater than the sum of the reference steering angle θref' and the deviation upper limit value Δθ in the previous process (step S330; Yes), the steering angle θ minus the deviation upper limit value Δθ is set as the reference steering angle θref in 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 deviation upper limit value Δθ in the previous process (step S330; No), the process proceeds to step S350.

[0118] In step S350, it is determined whether the steering angle θ is smaller than the difference between the reference steering angle θref′ of the previous process and the deviation upper limit value Δθ.

[0119] If the steering angle θ is smaller than the difference between the reference steering angle θref' of the previous processing and the deviation upper limit value Δθ (step S350; Yes), the steering angle θ plus the deviation upper limit value Δθ is set as the reference steering angle θref of the current processing (step S360), and the processing proceeds to step S370. If the steering angle θ is not smaller than the difference between the reference steering angle θref' of the previous processing and the deviation upper limit value Δθ (step S350; No), the processing proceeds to step S370 without performing any calculation on the reference steering angle θref. In other words, in this case, the reference steering angle θref of the current processing becomes the reference steering angle θref' of the previous processing.

[0120] In step S370, a temporary value Ttmp is calculated by multiplying a value obtained by subtracting the reference steering angle θref from the steering angle θ by K.

[0121] After step S370, the process proceeds to step S380.

[0122] In step S380, the steering torque T minus the temporary value Ttmp calculated in step S370 is calculated as the adjusted steering torque Tr for the current process, and the current process ends.

[0123] By executing such a processing routine, the adjustment command torque calculation processing unit P300 can calculate the adjustment steering torque Tr having a predetermined hysteresis characteristic with respect to the change in the steering torque T as shown in Fig. 13. However, the characteristic in the turning steering changes depending on the value of K. [Explanation of symbols]

[0124] 1 Steering wheel 10 Steering mechanism 21 Steering angle sensor 22 Torque sensor 100 Control Unit (ECU) 110 Memory 120 processors P100 Command torque calculation processing section P110 FF command torque calculation processing section P120 FB command torque calculation processing section P200 Adjustment gain calculation processing section P201 Torque hysteresis calculation processing unit P210 Adjusted steering torque calculation processing unit P220 Conversion processing section P300 Adjustment command torque calculation processing section

Claims

1. A control device for a vehicle, 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 for calculating an adjustment gain for the command torque based on a steering torque; an adjustment command torque calculation process for calculating an adjustment command torque by applying the adjustment gain to the command torque; a process of controlling the steering mechanism in accordance with the adjustment command torque; configured to run The adjustment gain calculation process includes: a first process of calculating an adjustment steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque based on the steering torque; A second process of converting the adjusted steering torque into the adjusted gain; Including, The first process includes: calculating the adjustment steering torque of the current processing in a direction in which the absolute value of the difference between the steering torque and the adjusted steering torque of the previous processing is decreased in response to the fact that the absolute value of the difference between the steering torque and the adjusted steering torque of the previous processing is larger than a predetermined torque hysteresis; When the absolute value is equal to or less than the torque hysteresis, calculating the adjusted steering torque of the previous process as the adjusted steering torque of the current process; Includes A control device comprising:

2. The control device according to claim 1, Calculating the adjusted steering torque in the current process in a direction in which the absolute value decreases in the first process When the steering torque is larger than the adjusted steering torque of the previous processing, a value obtained by subtracting the torque hysteresis from the steering torque is calculated as the adjusted steering torque of the current processing; When the steering torque is smaller than the adjusted steering torque of the previous processing, a value obtained by adding the torque hysteresis to the steering torque is calculated as the adjusted steering torque of the current processing; Includes A control device comprising:

3. A control device according to claim 1 or claim 2, The adjustment gain calculation process further includes changing the torque hysteresis in response to the steering torque. A control device comprising:

4. A control device according to any one of claims 1 to 3, the command torque includes an FF command torque serving as a feedforward control amount based on a target state amount for following the target trajectory, and an FB command torque serving as a feedback control amount based on a difference between the target state amount and a current state amount, The adjustment gains include 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 includes: calculating an adjusted FB command torque by applying the first adjustment gain to the FB command torque; A value obtained by applying the second adjustment gain to the sum of the FF command torque and the adjusted FB command torque, or a sum of the value obtained by applying the second adjustment gain to the FF command torque and the adjusted FB command torque is calculated as the adjusted command torque. A control device comprising:

5. A steering device for a vehicle, comprising: A control device according to any one of claims 1 to 4; a steering mechanism controlled by the control device; Equipped with The steering mechanism is an electric power steering mechanism. A steering device characterized by:

6. A method for controlling a vehicle, comprising: 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 a steering torque; calculating an adjusted command torque by applying the adjustment gain to the command torque; controlling the steering mechanism in accordance with the adjustment command torque; Including, Calculating the adjustment gain includes: calculating an adjustment steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque based on the steering torque; Converting the adjusted steering torque into the adjusted gain; Including, Calculating the adjusted steering torque calculating the adjustment steering torque of the current processing in a direction in which the absolute value of the difference between the steering torque and the adjusted steering torque of the previous processing is decreased in response to the fact that the absolute value of the difference between the steering torque and the adjusted steering torque of the previous processing is larger than a predetermined torque hysteresis; When the absolute value is equal to or less than the torque hysteresis, calculating the adjusted steering torque of the previous process as the adjusted steering torque of the current process; Includes A control method comprising:

7. A program for controlling a vehicle, comprising: 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 for calculating an adjustment gain for the command torque based on a steering torque; A process of calculating an adjusted command torque by applying the adjustment gain to the command torque; a process of controlling the steering mechanism in accordance with the adjustment command torque; configured to cause a computer to execute The adjustment gain calculation process includes: a first process of calculating an adjustment steering torque having a predetermined hysteresis characteristic with respect to a change in the steering torque based on the steering torque; A second process of converting the adjusted steering torque into the adjusted gain; Including, The first process includes: calculating the adjustment steering torque of the current processing in a direction in which the absolute value of the difference between the steering torque and the adjusted steering torque of the previous processing is decreased in response to the fact that the absolute value of the difference between the steering torque and the adjusted steering torque of the previous processing is larger than a predetermined torque hysteresis; When the absolute value is equal to or less than the torque hysteresis, calculating the adjusted steering torque of the previous process as the adjusted steering torque of the current process; Includes A program characterized by:

Images