Vehicle control system and vehicle control method

Abstract

To suppress troublesome feeling or the like caused by a simultaneous operation of driving support control and reaction force control in a vehicle of a steer-by-wire system.SOLUTION: A vehicle control system for controlling a vehicle of a steer-by-wire system is configured to execute road surface information transmission control for giving a steering reaction force component corresponding to vibration caused by road surface unevenness to handle of the vehicle and lane deviation suppression control for vibrating the handle to transmit the possibility of lane deviation of the vehicle to a driver. The vehicle control system further sets the steering reaction force component by the road surface information transmission control to zero when the lane deviation suppression control is in operation.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present disclosure relates to a technique for controlling a steer-by-wire vehicle. [Background technology]

[0002] Patent Document 1 discloses a vehicle that employs a steer-by-wire system. In the case of a steer-by-wire system, the steering device that steers the wheels is mechanically separated from the steering wheel. Instead, reaction force control is performed to apply a pseudo steering reaction force to the steering wheel in order to give the driver a steering feeling.

[0003] Patent Document 2 discloses "road surface information transmission control" as a type of reaction force control. Road surface information transmission control is a reaction force control aimed at transmitting road surface irregularities (road surface information) to the driver. Road surface information transmission control detects high-frequency vibrations caused by road surface irregularities and applies a steering reaction force component equivalent to the high-frequency vibrations to the steering wheel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-002223 A [Patent Document 2] JP 2020-142704 A Summary of the Invention [Problem to be solved by the invention]

[0005] Consider the case where a steer-by-wire vehicle is also equipped with a driving assistance control function. For example, driving assistance control automatically steers the vehicle without the driver's steering operation. On the other hand, there are various possible purposes (types) of reaction force control that applies a steering reaction force to the steering wheel. When driving assistance control and reaction force control are activated simultaneously, the driver may feel annoyed or the operability of the steering wheel may decrease, depending on the purpose (type) of the reaction force control.

[0006] As an example, consider the road surface information transmission control disclosed in Patent Document 2. When the driving assistance control is operating, the driver does not necessarily have the intention to steer. If the road surface information transmission control is performed even though the driver does not have the intention to steer, the driver feels annoyed by the high-frequency vibration of the steering wheel.

[0007] Thus, there is room for improvement in reaction force control when a steer-by-wire vehicle is also equipped with a driving assistance control function. [Means for solving the problem]

[0008] The first aspect relates to a vehicle control system that controls a steer-by-wire vehicle. The vehicle control system includes one or more processors. The one or more processors A road surface information transmission control that applies a steering reaction force component corresponding to vibrations caused by unevenness of the road surface to a steering wheel of the vehicle; Lane departure prevention control that vibrates the steering wheel to inform the driver of the possibility of the vehicle leaving its lane; The apparatus is configured to execute the following steps: The one or more processors further set the steering reaction force component due to the road surface information transmission control to zero when the lane departure prevention control is in operation.

[0009] The second aspect relates to a vehicle control method for controlling a steer-by-wire vehicle. The vehicle control method includes: A road surface information transmission control that applies a steering reaction force component corresponding to vibrations caused by unevenness of the road surface to a steering wheel of the vehicle; Lane departure prevention control that vibrates the steering wheel to inform the driver of the possibility of the vehicle leaving its lane; Includes. The vehicle control method further includes a process of setting the steering reaction force component due to the road surface information transmission control to zero when the lane departure prevention control is in operation. Effect of the Invention

[0010] According to the first aspect, when a release condition is satisfied, the steering reaction force component due to the road surface information transmission control is set to zero.

[0011] The release condition is that the lane departure prevention control, which vibrates the steering wheel to notify the driver of the possibility of lane departure, is in operation.

[0012] This release condition prevents the steering wheel vibration caused by the road surface information transmission control from interfering with or resonating with the steering wheel vibration caused by the lane departure prevention control, thereby making it possible to prevent a decrease in the warning effect caused by the lane departure prevention control.

[0013] According to the second aspect, the same effects as those of the first aspect can be obtained. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing a configuration example of a vehicle and a vehicle control system according to an embodiment; [Diagram 2] 2 is a block diagram showing a functional configuration of a control device of the vehicle control system according to the embodiment; FIG. [Diagram 3] FIG. 2 is a conceptual diagram for explaining risk avoidance control, which is an example of driving assistance control. [Figure 4] FIG. 11 is a conceptual diagram for explaining lane keeping assist control, which is another example of driving assist control. [Diagram 5] FIG. 11 is a conceptual diagram for explaining lane departure suppression control, which is yet another example of driving assistance control. [Figure 6] 5 is a diagram for explaining road surface information transmission control according to the embodiment. FIG. [Figure 7] 10A and 10B are diagrams for explaining an example of release of road surface information transmission control according to the embodiment. [Figure 8] 10A and 10B are diagrams for explaining another example of the release of the road surface information transmission control according to the embodiment. [Figure 9] 2 is a block diagram showing an example of a functional configuration related to road surface information transmission control according to an embodiment; FIG. [Figure 10] 6 is a diagram for explaining a change in a controlled variable gain in the embodiment. FIG. [Figure 11] FIG. 13 is a block diagram showing an example of a functional configuration related to a road surface information transmission control according to a modified example. [Figure 12] FIG. 2 is a block diagram for explaining deviation compensation control according to the embodiment. [Figure 13] 5A to 5C are diagrams for explaining an example of steering angle distribution control according to the embodiment. [Figure 14] 5A to 5C are diagrams for explaining an example of steering angle distribution control according to the embodiment. [Figure 15] FIG. 4 is a block diagram for explaining processing related to steering angle distribution control according to the embodiment. [Figure 16] 10A and 10B are diagrams for explaining problems that arise when steering angle distribution control and deviation compensation control are simultaneously operated. [Figure 17] FIG. 11 is a diagram for explaining an example of release of deviation compensation control according to the embodiment. [Figure 18] 10A and 10B are diagrams for explaining another example of release of deviation compensation control according to the embodiment. [Figure 19] 2 is a block diagram showing an example of a functional configuration related to deviation compensation control according to an embodiment; FIG. [Figure 20] 6 is a diagram for explaining a change in a controlled variable gain in the embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0016] 1. Vehicle Control System 1-1. Configuration example 1 is a schematic diagram showing an example of the configuration of a vehicle 1 and a vehicle control system 10 according to this embodiment. The vehicle 1 is equipped with wheels 2 and a handle (steering wheel) 3. The handle 3 is an operating member used by a driver of the vehicle 1 to perform steering operations. A steering shaft 4 is connected to the handle 3 and rotates together with the handle 3. The vehicle 1 is a steer-by-wire type vehicle, and the wheels 2 and the handle 3 (steering shaft 4) are mechanically separated.

[0017] The vehicle control system 10 controls a steer-by-wire vehicle 1. The vehicle control system 10 includes a steering device 20, a reaction force device 30, a driving environment information acquisition device 40, and a control device 100.

[0018] The steering device 20 steers the wheels 2. The steering device 20 includes a steering actuator 21 for steering the wheels 2. For example, the steering actuator 21 is a steering motor. A rotor of the steering motor is connected to a steering shaft 23 via a reducer 22. The steering shaft 23 is connected to the wheels 2. When the steering motor rotates, the rotational motion is converted into linear motion of the steering shaft 23, thereby steering the wheels 2. That is, the wheels 2 can be steered by operating the steering motor. The operation of the steering actuator 21 is controlled by the control device 100.

[0019] The reaction force device 30 applies a steering reaction force (reaction torque) to the steering wheel 3. The reaction force device 30 includes a reaction force actuator 31 for applying a steering reaction force to the steering wheel 3. For example, the reaction force actuator 31 is a reaction force motor. A rotor of the reaction force motor is connected to the steering shaft 4 via a reducer 32. By operating the reaction force motor, a steering reaction force can be applied to the steering shaft 4 and ultimately to the steering wheel 3. The operation of the reaction force actuator 31 is controlled by the control device 100.

[0020] The driving environment information acquisition device 40 acquires driving environment information ENV indicating the driving environment of the vehicle 1. The driving environment information acquisition device 40 includes a vehicle state sensor 50, a recognition sensor 60, and the like.

[0021] Vehicle state sensor 50 detects the state of vehicle 1. Vehicle state sensor 50 includes steering angle sensor 51, steering torque sensor 52, rotation angle sensor 53, rotation angle sensor 54, steering current sensor 55, vehicle speed sensor 56, etc. Steering angle sensor 51 detects steering angle θs (steering wheel angle) of steering wheel 3. Steering torque sensor 52 detects steering torque Ts applied to steering shaft 4. Rotation angle sensor 53 detects rotation angle Φ of reaction force actuator 31 (reaction force motor). Rotation angle sensor 54 detects the rotation angle of steering actuator 21 (steering motor). The rotation angle of the steering motor corresponds to the steering angle (actual steering angle δa) of wheels 2. Therefore, it can be said that rotation angle sensor 54 detects actual steering angle δa of wheels 2. Steering current sensor 55 detects steering current Im that drives steering actuator 21. Vehicle speed sensor 56 detects vehicle speed V that is the speed of vehicle 1. Additionally, the vehicle state sensor 50 may include a yaw rate sensor and an acceleration sensor.

[0022] The recognition sensor 60 recognizes (detects) the situation around the vehicle 1. Examples of the recognition sensor 60 include a camera, a LIDAR (Laser Imaging Detection and Ranging), a radar, and the like.

[0023] The driving environment information acquisition device 40 may include a position sensor that acquires the position of the vehicle 1. An example of the position sensor is a GPS (Global Positioning System) sensor. The driving environment information acquisition device 40 may acquire map information.

[0024] The driving environment information ENV includes vehicle state information and surrounding situation information. The vehicle state information indicates the vehicle state detected by the vehicle state sensor 50. The surrounding situation information indicates the recognition result by the recognition sensor 60. For example, the surrounding situation information includes an image captured by a camera. The surrounding situation information may include object information related to objects around the vehicle 1. Examples of objects around the vehicle 1 include pedestrians, other vehicles (preceding vehicles, parked vehicles, etc.), signs, white lines, roadside structures, etc. The object information indicates the relative position and relative speed of the object with respect to the vehicle 1. The driving environment information ENV may further include position information of the vehicle 1, map information, etc.

[0025] The control device 100 controls the vehicle 1. The control device 100 includes one or more processors 110 (hereinafter simply referred to as processor 110) and one or more storage devices 120 (hereinafter simply referred to as storage devices 120). The processor 110 executes various processes. For example, the processor 110 includes a CPU (Central Processing Unit). The storage device 120 stores various information required for processing by the processor 110. Examples of the storage device 120 include a volatile memory, a non-volatile memory, an HDD (Hard Disk Drive), an SSD (Solid State Drive), and the like. The control device 100 may include one or more ECUs (Electronic Control Units).

[0026] The processor 110 executes a control program, which is a computer program, to realize various processes by the control device 100. The control program is stored in the storage device 120. Alternatively, the control program may be recorded in a computer-readable recording medium.

[0027] The control device 100 (processor 110) acquires the driving environment information ENV from the driving environment information acquisition device 40. The driving environment information ENV is stored in the storage device 120.

[0028] Fig. 2 is a block diagram showing the functional configuration of control device 100. Control device 100 includes, as functional blocks, steering control section 200, reaction force control section 300, and driving assistance control section 400. These functional blocks are realized by cooperation between processor 110, which executes a control program, and storage device 120. Note that steering control section 200, reaction force control section 300, and driving assistance control section 400 may each be realized by a separate control device. In that case, the respective control devices are connected to each other so as to be able to communicate with each other, and exchange necessary information with each other.

[0029] The steering control unit 200, the reaction force control unit 300 and the driving assistance control unit 400 will each be described in detail below.

[0030] 1-2.Steering control The steering control section 200 performs “steering control” for steering the wheels 2. More specifically, the steering control section 200 controls the steering actuator 21 of the steering device 20 to steer the wheels 2.

[0031] Steering control section 200 performs steering control in response to steering operation of steering wheel 3 by the driver. For example, steering control section 200 calculates target steering angle δt based on steering angle θs and vehicle speed V. Steering angle θs is detected by steering angle sensor 51. Alternatively, steering angle θs may be calculated from rotation angle Φ detected by rotation angle sensor 53. Vehicle speed V is detected by vehicle speed sensor 56. Steering control section 200 steers wheels 2 in accordance with target steering angle δt. Actual steering angle δa of wheels 2 is detected by rotation angle sensor 54. Steering control section 200 controls steering actuator 21 so that actual steering angle δa follows target steering angle δt. More specifically, steering control section 200 generates a control signal for driving steering actuator 21 based on the deviation between target steering angle δt and actual steering angle δa of wheels 2. The steering actuator 21 is driven in accordance with the control signal, thereby steering the wheels 2. Note that the current that drives the steering actuator 21 at this time is the steering current Im.

[0032] Furthermore, the steering control section 200 performs steering control in accordance with a request from the driving assistance control section 400, which will be described later. In this case, the steering control section 200 acquires a target control amount from the driving assistance control section 400, and performs steering control in accordance with the target control amount.

[0033] 1-3.Reaction force control The reaction force control unit 300 performs "reaction force control" to apply a steering reaction force (reaction force torque) to the steering wheel 3. More specifically, the reaction force control unit 300 applies the steering reaction force to the steering wheel 3 by controlling the reaction force actuator 31 of the reaction force device 30.

[0034] The reaction force control unit 300 performs reaction force control in response to the steering operation of the steering wheel 3 by the driver. For example, the reaction force control unit 300 calculates a target steering reaction force (spring component) equivalent to a self-aligning torque applied to the wheels 2 based on the steering angle θs and the vehicle speed V. The target steering reaction force may further include a damping component according to the steering speed (dθs / dt). Then, the reaction force control unit 300 controls the reaction force actuator 31 so as to generate the target steering reaction force. More specifically, the reaction force control unit 300 generates a control signal for driving the reaction force actuator 31 based on the target steering reaction force. The reaction force actuator 31 is driven according to the control signal, thereby generating a steering reaction force.

[0035] Furthermore, the reaction force control unit 300 may perform reaction force control in accordance with a request from a driving assistance control unit 400, which will be described later.

[0036] 1-4. Driving assistance control The driving assistance control unit 400 performs "driving assistance control" that assists in driving the vehicle 1. The driving assistance control automatically controls the running of the vehicle 1, regardless of the driving operation by the driver. In this embodiment, in particular, driving assistance control related to steering is considered. Examples of such driving assistance control include automatic driving control, risk avoidance control, lane keeping assistance control (LTA: Lane Tracing Assist), lane departure prevention control (LDA: Lane Departure Alert), and the like.

[0037] The automatic driving control controls the automatic driving of the vehicle 1. Specifically, the driving assistance control unit 400 generates a driving plan for the vehicle 1 based on the driving environment information ENV. Examples of the driving plan include maintaining the current driving lane, changing lanes, turning right or left, and avoiding obstacles. Furthermore, the driving assistance control unit 400 generates a target trajectory TRJ required for the vehicle 1 to drive according to the driving plan based on the driving environment information ENV. The target trajectory TRJ includes a target position and a target speed. Then, the driving assistance control unit 400 performs vehicle driving control so that the vehicle 1 follows the target trajectory TRJ.

[0038] More specifically, the driving assistance control unit 400 calculates the deviation (lateral deviation, yaw angle deviation, speed deviation) between the vehicle 1 and the target trajectory TRJ, and calculates a target control amount required to reduce the deviation. Examples of the target control amount include a target steering angle, a target yaw rate, a target speed, a target acceleration, a target deceleration, and a target current. The driving assistance control unit 400 performs vehicle running control in accordance with the target control amount. The vehicle running control includes steering control, acceleration control, and deceleration control. The steering control is performed via the above-mentioned steering control unit 200. The acceleration control and deceleration control are performed by controlling the drive device and the brake device (not shown) of the vehicle 1.

[0039] FIG. 3 is a conceptual diagram for explaining risk avoidance control. The risk avoidance control is a driving assistance control for reducing the risk of collision with an object in front of the vehicle 1. Examples of objects to be avoided include pedestrians, bicycles, two-wheeled vehicles, animals, other vehicles, and the like. The driving assistance control unit 400 recognizes an object in front of the vehicle 1 based on surrounding situation information (object information) included in the driving environment information ENV. For example, when the risk of collision with the recognized object exceeds a threshold, the driving assistance control unit 400 performs risk avoidance control. Specifically, the driving assistance control unit 400 generates a target trajectory TRJ that moves in a direction away from the object in order to secure a lateral distance from the object. Then, the driving assistance control unit 400 performs vehicle running control so that the vehicle 1 follows the target trajectory TRJ. The vehicle running control here includes at least one of steering control and deceleration control. The steering control is performed via the above-mentioned steering control unit 200.

[0040] FIG. 4 is a conceptual diagram for explaining lane keeping assist control. Lane keeping assist control is driving assist control that assists the vehicle 1 to travel along the lane center LC. A lane is a range between left and right lane boundaries LB. Examples of the lane boundary LB include a white line (dividing line), a curb, and the like. The lane center LC is the center line of the lane. The driving assist control unit 400 recognizes the lane boundary LB and the lane center LC based on the surrounding situation information included in the driving environment information ENV. When the vehicle 1 deviates from the lane center LC, the driving assist control unit 400 performs lane keeping assist control. Specifically, the driving assist control unit 400 performs steering control so that the vehicle 1 returns to the lane center LC. The steering control is performed via the above-mentioned steering control unit 200.

[0041] FIG. 5 is a conceptual diagram for explaining lane departure suppression control. The lane departure suppression control is a driving support control for suppressing the vehicle 1 from deviating from the driving lane. The driving support control unit 400 recognizes the lane boundary LB based on the surrounding situation information included in the driving environment information ENV. When the distance between the vehicle 1 and the lane boundary LB becomes less than a predetermined threshold, the driving support control unit 400 performs lane departure suppression control. Specifically, the driving support control unit 400 notifies the driver of the possibility of lane departure. For example, the driving support control unit 400 controls a steering wheel vibration mechanism (not shown) to vibrate the steering wheel 3. The driving support control unit 400 may output a warning through a display and / or a sound. The driving support control unit 400 may also perform a steering control so that the vehicle 1 moves toward the lane center LC. The steering control is performed via the above-mentioned steering control unit 200.

[0042] 2. Coordination of reaction force control and driving assistance control There are various possible purposes (types) of reaction force control that applies a steering reaction force to the steering wheel 3. When driving assistance control and reaction force control are activated simultaneously, depending on the purpose (type) of the reaction force control, the driver may feel annoyed or the operability of the steering wheel 3 may decrease. In that sense, there is room for improvement in reaction force control when the steer-by-wire vehicle 1 also has a driving assistance control function.

[0043] In this embodiment, two types of reaction force control having a special purpose are considered as examples: "road surface information transmission control" and "deviation compensation control." The reaction force control according to this embodiment includes at least one of "road surface information transmission control" and "deviation compensation control" in addition to general reaction force control that simulates self-aligning torque. Each of the "road surface information transmission control" and "deviation compensation control" will be described in detail below.

[0044] 3. Road surface information transmission control 3-1. Basic explanation The road surface information transmission control is a reaction force control aimed at transmitting road surface irregularities (road surface information) to the driver. The road surface information transmission control detects high-frequency vibrations caused by road surface irregularities and applies a steering reaction force component equivalent to the high-frequency vibrations to the steering wheel 3 (see Patent Document 2).

[0045] 6 is a diagram for explaining the road surface information transmission control according to this embodiment. Reaction force control unit 300 includes road surface information transmission control unit 310. Road surface information transmission control unit 310 detects high-frequency vibrations caused by road surface unevenness based on turning current Im. Turning current Im is detected by turning current sensor 55. Then, road surface information transmission control unit 310 calculates a target control amount CON_RI for generating a steering reaction force component equivalent to the high-frequency vibration.

[0046] More specifically, road surface information transmission control section 310 includes band pass filter 311, road surface condition determination section 312, and control amount calculation section 313. Band pass filter 311 extracts a signal of a predetermined frequency band from the signal of steering current Im. The predetermined frequency band is set so as to correspond to the frequency band of high frequency vibration caused by road surface unevenness.

[0047] The road surface condition determination unit 312 determines whether the road surface is flat or uneven based on the filtered steering current Im. For example, the road surface condition determination unit 312 compares the steering current Im with a predetermined current threshold and counts the number of times that the steering current Im exceeds the predetermined current threshold within a certain period of time. If the number of times is equal to or greater than the threshold, the road surface condition determination unit 312 determines that the road surface is uneven, that is, that unevenness exists on the road surface. As another example, the road surface condition determination unit 312 may determine that unevenness exists on the road surface when the steering current Im exceeds a dead zone.

[0048] The control amount calculation unit 313 calculates a target control amount CON_RI for generating a steering reaction force component corresponding to high-frequency vibration caused by road surface unevenness. For example, the control amount calculation unit 313 calculates the target control amount CON_RI by multiplying the filtered steering current Im by a predetermined gain.

[0049] The reaction force control unit 300 calculates a final target control amount by combining the target control amount CON_RI by the road surface information transmission control with target control amounts by other types of reaction force control. Then, the reaction force control unit 300 controls the reaction force actuator 31 of the reaction force device 30 according to the final target control amount, thereby performing reaction force control.

[0050] 3-2. Release of road surface information transmission control Assuming that the driving assistance control and the road surface information transmission control are operated simultaneously, the following problem occurs. When the driving assistance control is operating, the driver does not necessarily have the intention to steer. If the road surface information transmission control is performed even though the driver does not have the intention to steer, the driver feels annoyed by the high frequency vibration of the steering wheel 3.

[0051] Therefore, according to this embodiment, when the driving assist control is in operation and the driver has no or weak steering intention, the reaction force control unit 300 cancels the road surface information transmission control. "Canceling the road surface information transmission control" means setting the steering reaction force component due to the road surface information transmission control to zero.

[0052] More specifically, the reaction force control unit 300 acquires a steering parameter reflecting the driver's steering intention. For example, the steering torque Ts is used as the steering parameter reflecting the driver's steering intention. The steering torque Ts is detected by the steering torque sensor 52. Then, the reaction force control unit 300 sets a threshold value Tth_RI and compares the steering parameter with the threshold value Tth_RI. The release condition for releasing the road surface information transmission control is that "the driving assistance control is operating and the steering parameter is less than the threshold value Tth_RI". When this release condition is satisfied, the reaction force control unit 300 releases the road surface information transmission control, that is, sets the steering reaction force component by the road surface information transmission control to zero. This suppresses the driver from feeling annoyed when the driver has no or weak steering intention.

[0053] As one criterion for setting the threshold value Tth_RI for the road surface information transmission control, the "steering judgment threshold value Tth_S" for driver steering judgment is considered. During the operation of the driving assistance control, it is necessary to judge whether the driver is steering or not in order to detect an override by the driver. The steering judgment threshold value Tth_S is used for the driver steering judgment. When the steering parameter is less than the steering judgment threshold value Tth_S, the control device 100 judges that the driver is not steering the steering wheel 3 and sets the driver steering flag to OFF. On the other hand, when the steering parameter is equal to or greater than the steering judgment threshold value Tth_S, the control device 100 judges that the driver is steering the steering wheel 3 and sets the driver steering flag to ON. The steering judgment threshold value Tth_S may be set to a different value for each type of driving assistance control in operation. For example, in the case of the automatic driving control, the steering judgment threshold value Tth_S is set relatively high in order to suppress erroneous judgment. As another example, in the case of the lane keeping assistance control, the steering judgment threshold value Tth_S is set relatively low.

[0054] FIG. 7 is a diagram for explaining an example of the release of road surface information transmission control. The horizontal axis represents time, and the vertical axis represents steering parameters (steering torque Ts). In the example shown in FIG. 7, the threshold value Tth_RI related to the road surface information transmission control is set to be the same as the steering determination threshold value Tth_S (Tth_RI=Tth_S). In this case, it can be said that the release condition for releasing the road surface information transmission control is "the driving assistance control is operating, and the driver steering flag is OFF."

[0055] Fig. 8 is a diagram for explaining another example of the release of road surface information transmission control. In the example shown in Fig. 8, the threshold value Tth_RI for the road surface information transmission control is set to be higher than 0 and lower than the steering determination threshold value Tth_S. Even in this case, the effect of reducing the annoyance felt by the driver can be obtained at least.

[0056] When the threshold value Tth_RI is lower than the steering determination threshold value Tth_S, the reaction force control unit 300 may gradually increase the output gain of the road surface information transmission control as the steering torque Ts approaches the steering determination threshold value Tth_S from the threshold value Tth_RI.

[0057] 3-3. Example of functional configuration related to road surface information transmission control 9 is a block diagram showing an example of a functional configuration related to the road surface information transmission control according to this embodiment. The reaction force control unit 300 includes a road surface information transmission control unit 310, a release condition determination unit 320, a gain switching unit 321, and a multiplication unit 322. The reaction force control unit 300 may further include a guard unit 323.

[0058] As described above, road surface information transmission control section 310 calculates the target control amount CON_RI based on the steering current Im (see FIG. 6). For convenience, the target control amount CON_RI calculated by road surface information transmission control section 310 will be referred to as the "target control amount CON_RI0."

[0059] The cancellation condition determination unit 320 determines whether or not the cancellation condition is satisfied based on the driving assist control state information STA and a steering parameter (e.g., steering torque Ts). The driving assist control state information STA includes information indicating whether or not driving assist control is in operation. This driving assist control state information STA is provided by the driving assist control unit 400. As described above, the cancellation condition is that "driving assist control is in operation, and the steering parameter is less than the threshold value Tth_RI."

[0060] The gain switching unit 321 switches the control amount gain Ga depending on the result of the determination by the release condition determination unit 320. Specifically, when the release condition is satisfied, the gain switching unit 321 sets the control amount gain Ga to "0." On the other hand, when the release condition is not satisfied, the gain switching unit 321 sets the control amount gain Ga to "1."

[0061] A multiplication unit 322 multiplies the target control amount CON_RI0 calculated by the road surface information transmission control unit 310 by a control amount gain Ga to calculate a final target control amount CON_RI related to the road surface information transmission control (CON_RI=Ga×CON_RI0).

[0062] When the release condition is satisfied, the control variable gain Ga is set to "0." As a result, the target control variable CON_RI also becomes zero, and the steering reaction force component due to the road surface information transmission control also becomes zero. In other words, the road surface information transmission control is released (OFF).

[0063] The guard unit 323 gradually changes the control amount gain Ga when the control amount gain Ga is switched in order to suppress a sudden change in the steering reaction force. FIG. 10 is a diagram for explaining the change in the control amount gain Ga. In the example shown in FIG. 10, the control amount gain Ga gradually changes from "0" to "1". FIG. 10 also shows the time changes of the target control amounts CON_RI0 and CON_RI. For example, the change time of the control amount gain Ga is set to "the reciprocal of the main frequency component of the target control amount CON_RI0"×1 / 2. As a result, the change gradient of the target control amount CON_RI becomes less than the change gradient of the original target control amount CON_RI0. Therefore, a sudden change in the steering reaction force is suppressed.

[0064] 3-4.Modifications Another example of the release condition for releasing the road surface information transmission control will be described. Here, we will consider the case where the driving assistance control is "lane departure prevention control (LDA)". As described above, the lane departure prevention control vibrates the steering wheel 3 to inform the driver of the possibility of lane departure. If the road surface information transmission control is also activated while such lane departure prevention control is activated, there is a risk that the steering wheel vibrations caused by both controls will interfere with or resonate. If interference or resonance occurs in the steering wheel vibrations, the amount of steering wheel vibration will be insufficient or excessive, reducing the warning effect of the lane departure prevention control.

[0065] Therefore, according to the modified example, when the lane departure prevention control is in operation, the reaction force control unit 300 sets the steering reaction force component due to the road surface information transmission control to zero. In other words, the release condition according to the modified example is that "the lane departure prevention control is in operation." This suppresses interference or resonance of the steering wheel vibration during operation of the lane departure prevention control, and suppresses a decrease in the warning effect due to the lane departure prevention control.

[0066] Fig. 11 is a block diagram showing a functional configuration example related to road surface information transmission control according to a modified example. The release condition determination unit 320 determines whether or not the release condition is satisfied based on the driving assistance control state information STA. The driving assistance control state information STA indicates not only whether or not the driving assistance control is in operation, but also the type of driving assistance control in operation. The rest is the same as the functional configuration example shown in Fig. 9.

[0067] 3-5.Effects As described above, according to this embodiment, when the release condition is satisfied, the steering reaction force component due to the road surface information transmission control is set to zero.

[0068] The first cancellation condition is that the driving assistance control is in operation and the steering parameter reflecting the driver's steering intention is less than the threshold Tth_RI. This cancellation condition makes it possible to suppress the driver from feeling annoyed when the driver has no or weak steering intention.

[0069] The second release condition is that the lane departure prevention control is operating, which vibrates the steering wheel 3 to inform the driver of the possibility of lane departure. This release condition makes it possible to suppress interference or resonance of the steering wheel vibration and suppress a decrease in the warning effect of the lane departure prevention control.

[0070] 4. Deviation compensation control 4-1. Basic explanation As described above, steering control section 200 performs steering control in response to the steering operation of steering wheel 3 by the driver. For example, steering control section 200 calculates target steering angle δt based on steering angle θs and vehicle speed V. Then, steering control section 200 controls steering actuator 21 so that actual steering angle δa of wheels 2 follows target steering angle δt. Here, a deviation may occur between the steering operation by the driver and the steering of wheels 2. For example, if the driver turns steering wheel 3 at a considerable speed, a deviation may occur between target steering angle δt and actual steering angle δa due to a response delay of steering actuator 21.

[0071] The deviation compensation control is a reaction force control aimed at reducing the discrepancy between the steering operation by the driver and the steering of the wheels 2. For convenience, the target steering angle δt according to the steering operation by the driver is called the "first target steering angle δt1." The deviation compensation control detects the deviation between the first target steering angle δt1 and the actual steering angle δa, and applies a steering reaction force component to the steering wheel 3 in a direction that reduces the deviation. In other words, the deviation compensation control applies a steering reaction force component to the steering wheel 3 in a direction that hinders the steering operation by the driver. This makes it more difficult for the driver to turn the steering wheel 3, and it is expected that the deviation will be reduced.

[0072] 12 is a block diagram for explaining the deviation compensation control according to this embodiment. The reaction force control unit 300 includes a deviation compensation control unit 330. The deviation compensation control unit 330 includes a deviation calculation unit 331 and a control amount calculation unit 332.

[0073] Deviation calculation section 331 calculates the deviation between first target steering angle δt1 and actual steering angle δa. First target steering angle δt1 is calculated by steering control section 200. Actual steering angle δa is obtained from rotation angle sensor .

[0074] The control amount calculation unit 332 calculates a target control amount CON_DC for generating a steering reaction force component in a direction that reduces the deviation. For example, the control amount calculation unit 332 calculates the target control amount CON_DC such that the steering reaction force increases as the deviation increases.

[0075] The reaction force control unit 300 calculates a final target control amount by combining the target control amount CON_DC by the deviation compensation control with target control amounts by other types of reaction force control. Then, the reaction force control unit 300 controls the reaction force actuator 31 of the reaction force device 30 according to the final target control amount, thereby performing reaction force control.

[0076] 4-2.Steering angle distribution control Next, consider the case where the driver starts steering while the driving assistance control is operating. At this time, arbitration may be performed between the steering operation by the driver and the steering control by the driving assistance control. For convenience, the target steering angle δt required by the driving assistance control is called the "second target steering angle δt2." When a predetermined condition is satisfied, the final target steering angle δt is determined by combining the first target steering angle δt1 and the second target steering angle δt2. The process of determining the target steering angle δt by combining the first target steering angle δt1 and the second target steering angle δt2 in this manner is hereinafter referred to as the "steering angle distribution control." The predetermined condition for performing the steering angle distribution control is hereinafter referred to as the "steering angle distribution condition."

[0077] 13 is a diagram for explaining an example of the steering angle distribution control. The horizontal axis represents time, and the vertical axis represents a steering parameter. The steering parameter is a parameter that reflects the driver's steering intention, such as the steering torque Ts.

[0078] As described above, the steering judgment threshold Tth_S is a threshold used for driver steering judgment. When the steering parameter is equal to or greater than the steering judgment threshold Tth_S, the control device 100 judges that the driver is steering the steering wheel 3, and sets the driver steering flag to ON. In this case, it is preferable that the steering control unit 200 performs steering control according to the first target steering angle δt1 requested by the driver. Therefore, the first target steering angle δt1 is used as the target steering angle δt (δt=δt1).

[0079] The intervention threshold Tth_I is a value smaller than the steering determination threshold Tth_S. When the steering parameter is equal to or smaller than the intervention threshold Tth_I, the steering control unit 200 performs steering control according to the second target steering angle δt2 required by the driving support control. That is, the target steering angle δt is the second target steering angle δt2 (δt=δt2).

[0080] The steering angle distribution condition is that the steering parameter is in the range from the intervention threshold Tth_I (first threshold) to the steering judgment threshold Tth_S (second threshold). When this steering angle distribution condition is satisfied, the steering control unit 200 determines the final target steering angle δt by combining the first target steering angle δt1 and the second target steering angle δt2. In other words, the target steering angle δt is given as a function of the first target steering angle δt1 and the second target steering angle δt2 (δt=f(δt1, δt2)).

[0081] In the example shown in FIG. 13, the steering parameter gradually increases over time. At time t1, the steering parameter reaches the intervention threshold Tth_I. As a result, the turning angle distribution control starts. At time t2, which is after time t1, the steering parameter reaches the steering determination threshold Tth_S. As a result, the turning angle distribution control ends. The period Pd from time t1 to time t2 is the period during which the turning angle distribution condition is satisfied and the turning angle distribution control is performed.

[0082] FIG. 14 shows an example of the distribution ratio of the first target turning angle δt1 and the second target turning angle δt2 in the turning angle distribution control. The horizontal axis represents the steering parameter, and the vertical axis represents the distribution ratio. The distribution ratio can also be said to be a contribution rate to the entire target turning angle δt. As the steering parameter increases from the intervention threshold Tth_I to the steering judgment threshold Tth_S, the distribution ratio of the first target turning angle δt1 increases, and the distribution ratio of the second target turning angle δt2 decreases. For example, when the steering parameter is the intervention threshold Tth_I, the distribution ratio of the first target turning angle δt1 is 0%, and the distribution ratio of the second target turning angle δt2 is 100%. When the steering parameter is the steering judgment threshold Tth_S, the distribution ratio of the first target turning angle δt1 is 100%, and the distribution ratio of the second target turning angle δt2 is 0%.

[0083] 15 is a block diagram for explaining the processing related to the steering angle distribution control. The steering control section 200 includes a target steering angle calculation section 210 and a steering angle distribution control section 220.

[0084] Target steering angle calculation section 210 calculates a first target steering angle δt1 corresponding to a steering operation of steering wheel 3 by the driver. For example, target steering angle calculation section 210 calculates first target steering angle δt1 based on steering angle θs and vehicle speed V. Steering angle θs is detected by steering angle sensor 51. Alternatively, steering angle θs may be calculated from rotation angle Φ detected by rotation angle sensor 53. Vehicle speed V is detected by vehicle speed sensor 56.

[0085] Steering angle allocation control unit 220 receives first target steering angle δt1, second target steering angle δt2, driving assist control state information STA, and steering parameters. Second target steering angle δt2 is provided by driving assist control unit 400. Alternatively, second target steering angle δt2 may be calculated based on a target control amount provided by driving assist control unit 400. Driving assist control state information STA includes information indicating whether driving assist control is in operation or not, and is provided by driving assist control unit 400.

[0086] During operation of driving assist control, steering angle allocation control section 220 determines whether or not a steering angle allocation condition is satisfied based on the steering parameters. The steering angle allocation condition is that the steering parameters are in the range from intervention threshold Tth_I (first threshold) to steering determination threshold Tth_S (second threshold). When the steering angle allocation condition is satisfied, steering angle allocation control section 220 determines target steering angle δt by combining first target steering angle δt1 and second target steering angle δt2. Then, steering control section 200 performs steering control in accordance with target steering angle δt.

[0087] 4-3. Cancellation of deviation compensation control When it is assumed that the steering angle distribution control and the deviation compensation control operate simultaneously, the following problem arises. Fig. 16 is a diagram for explaining the problem. The horizontal axis represents time, and the vertical axis represents the first target steering angle δt1, the second target steering angle δt2, and the target steering angle δt. The actual steering angle δa follows the target steering angle δt. Here, the actual steering angle δa and the target steering angle δt are considered to be equivalent.

[0088] The driver starts steering while driving assist control is in operation. The first target steering angle δt1 according to the steering operation by the driver increases over time. The period Pd during which the steering angle distribution control is performed is assumed to be the same as that shown in FIG. 13 above. After time t2, the target steering angle δt is the first target steering angle δt1, and the actual steering angle δa follows the first target steering angle δt1.

[0089] However, in the period before time t2, the target steering angle δt is different from the first target steering angle δt1, and a deviation occurs between the actual steering angle δa and the first target steering angle δt1. At least in the period Pd in ​​which the steering angle distribution control is performed, the target steering angle δt is different from the first target steering angle δt1, and a deviation occurs between the actual steering angle δa and the first target steering angle δt1. The deviation compensation control imparts a steering reaction force component to the steering wheel 3 in a direction that reduces the deviation. In other words, the deviation compensation control imparts a steering reaction force component in a direction that hinders the steering operation by the driver. However, since the deviation here is not due to a response delay of the steering actuator 21, the deviation compensation control does not bring about the original effect. Rather, the deviation compensation control unnecessarily hinders the steering operation by the driver and unnecessarily reduces the operability of the steering wheel 3.

[0090] Therefore, according to this embodiment, during at least a part of the period Pd during which the steering angle distribution condition is satisfied, the reaction force control section 300 cancels the deviation compensation control. "Canceling the deviation compensation control" means setting the steering reaction force component due to the deviation compensation control to zero. This prevents the deviation compensation control from unnecessarily interfering with the steering operation. In other words, a decrease in the operability of the steering wheel 3 is suppressed.

[0091] For example, the reaction force control unit 300 releases the deviation compensation control when at least the steering angle distribution condition is satisfied. This means that the deviation compensation control is released during the entire period Pd during which the steering angle distribution condition is satisfied. This effectively prevents the operability of the steering wheel 3 from deteriorating.

[0092] As described above, the turning angle distribution condition is that the steering parameter is in the range from the intervention threshold Tth_I (first threshold) to the steering determination threshold Tth_S (second threshold). The reaction force control unit 300 may set a threshold Tth_DC and compare the steering parameter with the threshold Tth_DC. The threshold Tth_DC is set to be larger than the intervention threshold Tth_I and equal to or smaller than the steering determination threshold Tth_S. When the steering parameter is less than the threshold Tth_DC, the reaction force control unit 300 releases the deviation compensation control. This releases the deviation compensation control during at least a part of the period Pd during which the turning angle distribution condition is satisfied. It can also be said that the release condition for releasing the deviation compensation control is that "the driving assistance control is operating and the steering parameter is less than the threshold Tth_DC."

[0093] FIG. 17 is a diagram for explaining an example of the release of deviation compensation control. The format is the same as that of FIG. 13 described above, with the horizontal axis representing time and the vertical axis representing steering parameters (e.g., steering torque Ts). In the example shown in FIG. 17, the threshold value Tth_DC related to the deviation compensation control is set to be the same as the steering determination threshold value Tth_S (Tth_DC=Tth_S). In this case, it can be said that the release condition for releasing the deviation compensation control is that "the driving assistance control is operating and the driver steering flag is OFF." In the period before time t2, the release condition is met and the deviation compensation control is released. This effectively suppresses the deterioration of the operability of the steering wheel 3.

[0094] FIG. 18 is a diagram for explaining another example of canceling the deviation compensation control. In the example shown in FIG. 18, a threshold value Tth_DC for the deviation compensation control is set to a value greater than the intervention threshold value Tth_I and smaller than the steering determination threshold value Tth_S (Tth_I < Tth_DC < Tth_S). Thereby, the deviation compensation control is canceled at least in part of a period Pd during which the steering angle distribution control is performed, and an effect is obtained.

[0095] 4-4. Example of Functional Configuration Related to Deviation Compensation Control FIG. 19 is a block diagram showing an example of a functional configuration related to the deviation compensation control according to the present embodiment. The reaction force control unit 300 includes a deviation compensation control unit 330, a cancellation condition determination unit 340, a gain switching unit 341, and a multiplication unit 342. The reaction force control unit 300 may further include a guard unit 343.

[0096] As described above, the deviation compensation control unit 330 calculates a target control amount CON_DC based on the first target steering angle δt1 and the actual steering angle δa (see FIG. 12). For convenience, the target control amount CON_DC calculated by the deviation compensation control unit 330 is referred to as "target control amount CON_DC0".

[0097] The cancellation condition determination unit 340 determines whether or not a cancellation condition is satisfied based on the driving support control state information STA and the steering parameter (e.g., steering torque Ts). The driving support control state information STA includes information indicating whether or not the driving support control is in operation. This driving support control state information STA is provided from the driving support control unit 400. For example, the cancellation condition is "the steering angle distribution condition is satisfied during the operation of the driving support control". As another example, the cancellation condition is "the driving support control is in operation and the steering parameter is less than the threshold value Tth_DC".

[0098] The gain switching unit 341 switches the control amount gain Gb depending on the result of the determination by the release condition determination unit 340. Specifically, when the release condition is satisfied, the gain switching unit 341 sets the control amount gain Gb to "0." On the other hand, when the release condition is not satisfied, the gain switching unit 341 sets the control amount gain Gb to "1."

[0099] A multiplication unit 342 multiplies the target control amount CON_DC0 calculated by the deviation compensation control unit 330 by a control amount gain Gb to calculate a final target control amount CON_DC related to the deviation compensation control (CON_DC=Gb×CON_DC0).

[0100] When the cancellation condition is satisfied, the control variable gain Gb is set to "0." As a result, the target control variable CON_DC also becomes zero, and the steering reaction force component due to the deviation compensation control also becomes zero. In other words, the deviation compensation control is cancelled (OFF).

[0101] The guard unit 343 gradually changes the control amount gain Gb when switching the control amount gain Gb in order to suppress a sudden change in the steering reaction force. FIG. 20 is a diagram for explaining the change in the control amount gain Gb. In the example shown in FIG. 20, the control amount gain Gb gradually changes from "0" to "1". FIG. 20 also shows the time changes of the target control amounts CON_DC0 and CON_DC. For example, the change time of the control amount gain Gb is set to "the reciprocal of the main frequency component of the target control amount CON_DC0"×1 / 2. As a result, the change gradient of the target control amount CON_DC becomes less than the change gradient of the original target control amount CON_DC0. Therefore, a sudden change in the steering reaction force is suppressed.

[0102] Effects As described above, according to this embodiment, the steering reaction force component by the deviation compensation control is set to zero during at least a part of the period Pd during which the steering angle distribution condition is satisfied. This prevents the deviation compensation control from unnecessarily interfering with the steering operation. In other words, it is possible to prevent a decrease in the operability of the steering wheel 3. [Explanation of symbols]

[0103] 1 vehicle 2 wheels 3 Handle 10 Vehicle Control System 20 Steering gear 30 Reaction Device 40 Driving environment information acquisition device 50 Vehicle condition sensor 60 Recognition Sensor 100 Control device 110 Processor 120 Storage device 200 Steering control unit 210 Target steering angle calculation unit 220 Steering angle distribution control unit 300 Reaction force control unit 310 Road surface information transmission control unit 320 Cancellation condition determination section 330 Deviation compensation control unit 340 Cancellation condition determination section 400 Driving assistance control unit

Claims

1. A vehicle control system for controlling a steer-by-wire vehicle, comprising: One or more processors; The one or more processors: a road surface information transmission control for applying a steering reaction force component corresponding to vibrations caused by unevenness of a road surface to a steering wheel of the vehicle; lane departure prevention control that vibrates the steering wheel to notify the driver of the possibility of the vehicle leaving its lane; configured to run The one or more processors further set the steering reaction force component due to the road surface information transmission control to zero when the lane departure prevention control is in operation. Vehicle control system.

2. A vehicle control method for controlling a steer-by-wire vehicle, comprising: a road surface information transmission control for applying a steering reaction force component corresponding to vibrations caused by unevenness of a road surface to a steering wheel of the vehicle; lane departure prevention control that vibrates the steering wheel to notify the driver of the possibility of the vehicle leaving its lane; Including, The vehicle control method further includes a process of setting the steering reaction force component due to the road surface information transmission control to zero when the lane departure prevention control is in operation. A vehicle control method.

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