Vehicle control system and vehicle control method

Abstract

To suppress inconvenience and other issues caused by the simultaneous operation of driver assistance control and reaction force control in steer-by-wire vehicles. [Solution] A vehicle control system for controlling a steer-by-wire vehicle is configured to perform road surface information transmission control, which applies a steering reaction force component to the vehicle's steering wheel that corresponds to vibrations caused by road surface irregularities, and lane departure suppression control, which vibrates the steering wheel to inform the driver of the possibility of the vehicle deviating from its lane. When the vehicle control system changes from a first state in which lane departure suppression control is not activated to a second state in which lane departure suppression control is activated, it gradually dampens the steering reaction force component due to road surface information transmission control to zero.

Description

Technical Field

[0005] , , ,

[0001] The present disclosure relates to a technique for controlling a vehicle using a Steer-By-Wire system.

Background Art

[0003] Patent Document 2 discloses "road surface information transmission control" as a type of reaction force control. Road surface information transmission control is 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 corresponding to the high-frequency vibrations to the steering wheel.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As an example, let's consider the road surface information transmission control disclosed in Patent Document 2. When driver assistance control is activated, the driver does not necessarily have a steering intention. If road surface information transmission control is performed when the driver does not have a steering intention, the driver will feel annoyed by the high-frequency vibration of the steering wheel.

[0007] Thus, there is room for improvement in reaction force control when steer-by-wire vehicles also have driver assistance control functions. [Means for solving the problem]

[0008] The first aspect relates to vehicle control systems that control steer-by-wire vehicles. The vehicle control system comprises one or more processors. One or more processors, Road surface information transmission control that applies a steering reaction force component to the vehicle's steering wheel that corresponds to vibrations caused by road surface irregularities, Lane departure prevention control vibrates the steering wheel to inform the driver of the possibility of the vehicle deviating from its lane, and It is configured to execute. When the vehicle changes from a first state in which lane departure prevention control is not active to a second state in which lane departure prevention control is active, one or more processors gradually reduce the steering reaction force component due to road surface information transmission control to zero.

[0009] The second aspect relates to vehicle control systems that control steer-by-wire vehicles. The vehicle control system comprises one or more processors. One or more processors, Road surface information transmission control that applies a steering reaction force component to the vehicle's steering wheel that corresponds to vibrations caused by road surface irregularities, Lane departure prevention control vibrates the steering wheel to inform the driver of the possibility of the vehicle deviating from its lane, and It is configured to execute. One or more processors, In the second state, where lane departure prevention control is activated, the steering reaction force component due to road surface information transmission control is set to zero. When transitioning from the second state to the first state where lane departure prevention control is not activated, the steering reaction force component generated by road surface information transmission control is gradually amplified from zero.

[0010] The third aspect concerns vehicle control systems for vehicles using a steer-by-wire system. The vehicle control system comprises one or more processors. One or more processors, Road surface information transmission control that applies a steering reaction force component to the vehicle's steering wheel that corresponds to vibrations caused by road surface irregularities, Lane departure prevention control vibrates the steering wheel to inform the driver of the possibility of the vehicle deviating from its lane, and It is configured to execute. One or more processors further, By multiplying the target control amount required by road surface information transmission control by a gain, the final target control amount related to road surface information transmission control is calculated. In the first state where lane departure prevention control is not activated, the gain is set to a predetermined value greater than zero. In the second state, when lane departure prevention control is activated, set the gain to zero. When transitioning from the first state to the second state, the gain is gradually changed from a predetermined value to zero.

[0011] The fourth perspective concerns vehicle control systems for vehicles using a steer-by-wire system. The vehicle control system includes one or more processors. The one or more processors are configured to execute road surface information transmission control for applying a steering reaction force component corresponding to vibrations caused by road surface unevenness to the vehicle's steering wheel, and lane departure suppression control for vibrating the steering wheel to inform the driver of the possibility of the vehicle departing from the lane. The one or more processors are further configured to calculate a final target control amount related to the road surface information transmission control by multiplying a gain by the target control amount required by the road surface information transmission control, set the gain to a predetermined value greater than zero in a first state where the lane departure suppression control is not operating, set the gain to zero in a second state where the lane departure suppression control is operating, and gradually change the gain from zero to the predetermined value when changing from the second state to the first state. <00>

Advantages of the Invention

[0012] According to the first and third aspects, when changing from the first state where the lane departure suppression control is not operating to the second state where the lane departure suppression control is operating, the steering reaction force component due to the road surface information transmission control is gradually attenuated to zero. Thereby, interference or resonance between the steering wheel vibration due to the road surface information transmission control and the steering wheel vibration due to the lane departure suppression control is suppressed. Therefore, it is possible to suppress a decrease in the warning effect due to the lane departure suppression control. Also, since the steering reaction force component due to the road surface information transmission control gradually attenuates to zero, a sudden change in the steering reaction force is prevented.

[0013] According to the second and fourth aspects, when changing from the second state where the lane departure suppression control is operating to the first state where the lane departure suppression control is not operating, the steering reaction force component due to the road surface information transmission control is gradually amplified from zero. Thereby, the effect of the road surface information transmission control is obtained. Also, since the steering reaction force component due to the road surface information transmission control gradually amplifies from zero, a sudden change in the steering reaction force is prevented.

Brief Description of the Drawings

[0014] [Figure 1] It is a schematic diagram showing a configuration example of a vehicle and a vehicle control system according to an embodiment. [Figure 2] It is a block diagram showing a functional configuration of a control device of a vehicle control system according to an embodiment. [Figure 3] It is a conceptual diagram for explaining risk avoidance control which is an example of driving support control. [Figure 4] It is a conceptual diagram for explaining lane keeping support control which is another example of driving support control. [Figure 5] It is a conceptual diagram for explaining lane departure suppression control which is yet another example of driving support control. [Figure 6] It is a diagram for explaining road surface information transmission control according to an embodiment. [Figure 7] It is a diagram for explaining an example of cancellation of road surface information transmission control according to an embodiment. [Figure 8] It is a diagram for explaining another example of cancellation of road surface information transmission control according to an embodiment. [Figure 9] It is a block diagram showing a functional configuration example related to road surface information transmission control according to an embodiment. [Figure 10] It is a diagram for explaining the change of a control amount gain in an embodiment. [Figure 11] It is a block diagram showing a functional configuration example related to road surface information transmission control according to a modification. [Figure 12] It is a block diagram for explaining deviation compensation control according to an embodiment. [Figure 13] It is a diagram for explaining an example of steering angle distribution control according to an embodiment. [Figure 14] It is a diagram for explaining an example of steering angle distribution control according to an embodiment. [Figure 15] It is a block diagram for explaining a process related to steering angle distribution control according to an embodiment. [Figure 16] It is a diagram for explaining a problem when steering angle distribution control and deviation compensation control operate simultaneously. [Figure 17] This figure illustrates an example of releasing the deviation compensation control according to the embodiment. [Figure 18] This figure illustrates another example of releasing the deviation compensation control according to the embodiment. [Figure 19] This is a block diagram showing an example of a functional configuration related to deviation compensation control according to the embodiment. [Figure 20] This figure illustrates the change in the control variable gain in the embodiment. [Modes for carrying out the invention]

[0015] Embodiments of this disclosure will be described with reference to the attached drawings.

[0016] 1. Vehicle control system 1-1. Example Configuration Figure 1 is a schematic diagram showing an example 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 steering wheel 3. The steering wheel 3 is an operating member used by the driver of the vehicle 1 for steering operations. The steering shaft 4 is connected to the steering wheel 3 and rotates together with the steering wheel 3. The vehicle 1 is a steer-by-wire vehicle, and the wheels 2 and the steering wheel 3 (steering shaft 4) are mechanically separated.

[0017] The vehicle control system 10 controls the 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 wheel 2. The steering device 20 includes a steering actuator 21 for steering the wheel 2. For example, the steering actuator 21 is a steering motor. The rotor of the steering motor is connected to the steering shaft 23 via a reduction gear 22. The steering shaft 23 is connected to the wheel 2. When the steering motor rotates, its rotational motion is converted into linear motion of the steering shaft 23, thereby steering the wheel 2. In other words, the wheel 2 can be steered by the operation of 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 the steering reaction force to the steering wheel 3. For example, the reaction force actuator 31 is a reaction force motor. The rotor of the reaction force motor is connected to the steering shaft 4 via a reduction gear 32. By operating the reaction force motor, a steering reaction force can be applied to the steering shaft 4 and, consequently, 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, which indicates the driving environment of vehicle 1. The driving environment information acquisition device 40 includes a vehicle condition sensor 50, a recognition sensor 60, etc.

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

[0022] The recognition sensor 60 recognizes (detects) the surrounding conditions of vehicle 1. Examples of recognition sensors 60 include cameras, LIDAR (Laser Imaging Detection and Ranging), radar, etc.

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

[0024] The driving environment information (ENV) includes vehicle status information and surrounding environment information. The vehicle status information indicates the vehicle status detected by the vehicle status sensor 50. The surrounding environment information indicates the recognition results by the recognition sensor 60. For example, the surrounding environment information includes images captured by the camera. The surrounding environment information may also include object information regarding 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 location 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 processors 110 execute various processes. For example, the processor 110 includes a CPU (Central Processing Unit). The storage devices 120 store various information necessary for processing by the processors 110. Examples of storage devices 120 include volatile memory, non-volatile memory, HDD (Hard Disk Drive), SSD (Solid State Drive), etc. The control device 100 may also include one or more ECUs (Electronic Control Units).

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

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

[0028] Figure 2 is a block diagram showing the functional configuration of the control device 100. The control device 100 includes a steering control unit 200, a reaction force control unit 300, and a driving support control unit 400 as functional blocks. These functional blocks are realized through the cooperation of a processor 110 that executes a control program and a storage device 120. Note that the steering control unit 200, the reaction force control unit 300, and the driving support control unit 400 may each be realized by separate control devices. In that case, each control device is connected to each other in a communicative manner and exchanges necessary information with each other.

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

[0030] 1-2. Steering Control The steering control unit 200 performs "steering control" to steer the wheel 2. More specifically, the steering control unit 200 steers the wheel 2 by controlling the steering actuator 21 of the steering device 20.

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

[0032] Furthermore, the steering control unit 200 performs steering control in accordance with requests from the driver assistance control unit 400, which will be described later. In this case, the steering control unit 200 obtains a target control amount from the driver assistance control unit 400 and performs steering control according to that 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) corresponding to the self-aligning torque applied to the wheel 2 based on the steering angle θs and the vehicle speed V. The target steering reaction force may further include a damping component corresponding to the steering speed (dθs / dt). The reaction force control unit 300 then controls the reaction force actuator 31 so that the target steering reaction force is generated. More specifically, the reaction force control unit 300 generates a control signal to drive 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 the steering reaction force.

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

[0036] 1-4. Driver Assistance Control The driver assistance control unit 400 performs "driver assistance control" to assist in the driving of vehicle 1. Driver assistance control automatically controls the movement of vehicle 1 without relying on driver operation. In this embodiment, we will consider driver assistance control related to steering in particular. Examples of such driver assistance control include automatic driving control, risk avoidance control, lane keeping assist control (LTA), lane departure prevention control (LDA), etc.

[0037] Automated driving control controls the automated driving of vehicle 1. Specifically, the driver assistance control unit 400 generates a driving plan for vehicle 1 based on driving environment information ENV. Examples of driving plans include maintaining the current driving lane, changing lanes, making right or left turns, avoiding obstacles, etc. Furthermore, the driver assistance control unit 400 generates a target trajectory TRJ necessary for 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. The driver assistance control unit 400 then performs vehicle driving control so that vehicle 1 follows the target trajectory TRJ.

[0038] More specifically, the driver assistance control unit 400 calculates the deviations (lateral deviation, yaw angle deviation, and velocity deviation) between the vehicle 1 and the target trajectory TRJ, and calculates the target control quantities necessary to reduce these deviations. Examples of target control quantities include target steering angle, target yaw rate, target speed, target acceleration, target deceleration, and target current. The driver assistance control unit 400 performs vehicle driving control according to the target control quantities. Vehicle driving control includes steering control, acceleration control, and deceleration control. Steering control is performed via the steering control unit 200 described above. Acceleration control and deceleration control are performed by controlling the drive system and braking system (not shown) of the vehicle 1.

[0039] Figure 3 is a conceptual diagram illustrating risk avoidance control. Risk avoidance control is a driver assistance control system designed to reduce the risk of collision with an object in front of vehicle 1. Examples of objects to be avoided include pedestrians, bicycles, motorcycles, animals, other vehicles, etc. The driver assistance control unit 400 recognizes an object in front of vehicle 1 based on surrounding situation information (object information) included in the driving environment information ENV. For example, if the risk of collision with a recognized object exceeds a threshold, the driver assistance control unit 400 performs risk avoidance control. Specifically, the driver assistance control unit 400 generates a target trajectory TRJ that moves away from the object in order to secure a lateral distance from the object. The driver assistance control unit 400 then performs vehicle driving control so that vehicle 1 follows the target trajectory TRJ. This vehicle driving control includes at least one of steering control and deceleration control. Steering control is performed via the steering control unit 200 described above.

[0040] Figure 4 is a conceptual diagram illustrating lane keeping assist control. Lane keeping assist control is a driver assistance control that helps vehicle 1 to travel along the lane center LC. A lane is the area enclosed by the left and right lane boundaries LB. Examples of lane boundaries LB include white lines (road markings), curbs, etc. The lane center LC is the center line of the lane. The driver assistance 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. If vehicle 1 deviates from the lane center LC, the driver assistance control unit 400 performs lane keeping assist control. Specifically, the driver assistance control unit 400 performs steering control to return vehicle 1 to the lane center LC. The steering control is performed via the steering control unit 200 described above.

[0041] Figure 5 is a conceptual diagram illustrating lane departure prevention control. Lane departure prevention control is a driver assistance control system designed to prevent vehicle 1 from deviating from its lane. The driver assistance control unit 400 recognizes the lane boundary LB based on surrounding condition information included in the driving environment information ENV. When the distance between vehicle 1 and the lane boundary LB falls below a predetermined threshold, the driver assistance control unit 400 performs lane departure prevention control. Specifically, the driver assistance control unit 400 informs the driver of the possibility of lane departure. For example, the driver assistance control unit 400 controls a steering wheel vibration mechanism (not shown) to vibrate the steering wheel 3. The driver assistance control unit 400 may also output a warning through display and / or sound. Furthermore, the driver assistance control unit 400 may perform steering control to move vehicle 1 towards the lane center LC. The steering control is performed via the steering control unit 200 described above.

[0042] 2. Coordination between reaction force control and driver assistance control There are various possible purposes (types) for the reaction force control that applies steering reaction force to the steering wheel 3. When driver 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 be reduced. In that sense, there is room for improvement in the reaction force control when a steer-by-wire vehicle 1 also has driver assistance control functions.

[0043] In this embodiment, we consider two types of reaction force control with a special purpose: "road surface information transmission control" and "deviation compensation control." The reaction force control according to this embodiment includes, in addition to general reaction force control that simulates self-aligning torque, at least one of "road surface information transmission control" and "deviation compensation control." The cases of "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 Road surface information transmission control is a reaction force control system 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 corresponding to those high-frequency vibrations to the steering wheel 3 (see Patent Document 2).

[0045] Figure 6 is a diagram illustrating 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. The road surface information transmission control unit 310 detects high-frequency vibrations caused by road surface irregularities based on the steering current Im. The steering current Im is detected by the steering current sensor 55. The road surface information transmission control unit 310 then calculates a target control amount CON_RI to generate a steering reaction force component corresponding to the high-frequency vibration.

[0046] More specifically, the road surface information transmission control unit 310 includes a bandpass filter 311, a road surface condition determination unit 312, and a control amount calculation unit 313. The bandpass filter 311 extracts signals in a predetermined frequency band from the steering current Im signal. The predetermined frequency band is set to correspond to the frequency band of high-frequency vibrations caused by road surface irregularities.

[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 the steering current Im exceeds the predetermined current threshold within a certain period. 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 road surface irregularities exist. As another example, the road surface condition determination unit 312 may also determine that road surface irregularities exist if the steering current Im exceeds the dead zone.

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

[0049] The reaction force control unit 300 calculates the final target control amount by combining the target control amount CON_RI obtained by road surface information transmission control with the target control amount obtained 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 and performs reaction force control.

[0050] 3-2. Deactivation of road surface information transmission control When considering the simultaneous operation of driver assistance control and road surface information transmission control, the following problems arise: When driver assistance control is active, the driver does not necessarily have a steering intention. If road surface information transmission control is performed when the driver does not have a steering intention, the driver will feel annoyed by the high-frequency vibration of the steering wheel 3.

[0051] Therefore, according to this embodiment, if the driver assistance 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. "Cancelling 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 steering parameters that reflect the driver's steering intention. For example, steering torque Ts is used as a steering parameter that reflects the driver's steering intention. Steering torque Ts is detected by the steering torque sensor 52. The reaction force control unit 300 then sets a threshold Tth_RI and compares the steering parameters with the threshold Tth_RI. The release condition for disabling the road surface information transmission control is that "driving assistance control is active and the steering parameters are less than the threshold Tth_RI." If this release condition is met, the reaction force control unit 300 disabling the road surface information transmission control, that is, setting the steering reaction force component due to the road surface information transmission control to zero. This suppresses the driver from feeling annoyed when there is no or weak steering intention.

[0053] When setting the threshold Tth_RI for road surface information transmission control, we consider the "steering judgment threshold Tth_S" for driver steering determination as one criterion. During the operation of driver assistance control, it is necessary to determine whether the driver is steering or not in order to detect driver overrides, etc. The steering judgment threshold Tth_S is used for this driver steering determination. If the steering parameter is less than the steering judgment threshold Tth_S, the control device 100 determines that the driver is not steering the steering wheel 3 and sets the driver steering flag to OFF. On the other hand, if the steering parameter is greater than or equal to the steering judgment threshold Tth_S, the control device 100 determines that the driver is steering the steering wheel 3 and sets the driver steering flag to ON. Note that the steering judgment threshold Tth_S may be set to a different value for each type of driver assistance control in operation. For example, in the case of automatic driving control, the steering judgment threshold Tth_S is set relatively high in order to suppress misjudgments. As another example, in the case of lane keeping assistance control, the steering judgment threshold Tth_S is set relatively low.

[0054] Figure 7 illustrates an example of disabling 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 Figure 7, the threshold Tth_RI for road surface information transmission control is set to the same value as the steering judgment threshold Tth_S (Tth_RI = Tth_S). In this case, the condition for disabling road surface information transmission control can also be said to be "the driver assistance control is active, and the driver steering flag is OFF."

[0055] Figure 8 illustrates another example of disabling road surface information transmission control. In the example shown in Figure 8, the threshold Tth_RI for road surface information transmission control is set to be higher than 0 and lower than the steering judgment threshold Tth_S. Even in this case, at least some effect is obtained in reducing the annoyance felt by the driver.

[0056] If the threshold Tth_RI is lower than the steering determination threshold 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 Tth_S from the threshold Tth_RI.

[0057] 3-3. Example of a functional configuration related to road surface information transmission control Figure 9 is a block diagram showing an example of a functional configuration related to 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, the road surface information transmission control unit 310 calculates the target control amount CON_RI based on the steering current Im (see Figure 6). For convenience, the target control amount CON_RI calculated by the road surface information transmission control unit 310 is referred to as "target control amount CON_RI0".

[0059] The release condition determination unit 320 determines whether the release condition is met based on the driver assistance control state information STA and the steering parameter (e.g., steering torque Ts). The driver assistance control state information STA includes information indicating whether the driver assistance control is active or not. This driver assistance control state information STA is provided by the driver assistance control unit 400. As described above, the release condition is that "the driver assistance control is active and the steering parameter is less than the threshold Tth_RI".

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

[0061] The multiplication unit 322 calculates the final target control amount CON_RI for road surface information transmission control by multiplying the target control amount CON_RI0 calculated by the road surface information transmission control unit 310 by the control amount gain Ga (CON_RI = Ga × CON_RI0).

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

[0063] The guard unit 323 gradually changes the control variable gain Ga when switching the control variable gain Ga in order to suppress abrupt changes in steering reaction force. Figure 10 is a diagram illustrating the change in the control variable gain Ga. In the example shown in Figure 10, the control variable gain Ga gradually changes from "0" to "1". Figure 10 also shows the time evolution of the target control variables CON_RI0 and CON_RI, respectively. For example, the change time of the control variable gain Ga is set to "the reciprocal of the main frequency component of the target control variable CON_RI0" × 1 / 2. As a result, the change gradient of the target control variable CON_RI becomes less than the change gradient of the original target control variable CON_RI0. Therefore, abrupt changes in steering reaction force are suppressed.

[0064] 3-4. Variations Let's discuss another example of the conditions for disabling the road surface information transmission control. Here, we will consider the case where the driver assistance control is "Lane Departure Prevention Control (LDA)". As mentioned above, 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 in operation, the steering wheel vibrations from both controls may interfere with or resonate with each other. If interference or resonance of steering wheel vibrations occurs, 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 version, when lane departure prevention control is in operation, the reaction force control unit 300 sets the steering reaction force component due to road surface information transmission control to zero. In other words, the release condition in the modified version is "when lane departure prevention control is in operation." As a result, interference or resonance of steering wheel vibration is suppressed while lane departure prevention control is in operation, and the reduction in the warning effect of lane departure prevention control is suppressed.

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

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

[0068] The first deactivation condition is that the driver assistance control is active and the steering parameter, which reflects the driver's steering intention, is below the threshold Tth_RI. This deactivation condition makes it possible to suppress the driver from feeling annoyed when there is no or weak steering intention.

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

[0070] 4. Deviation compensation control 4-1. Basic Explanation As described above, the steering control unit 200 performs steering control in response to the driver's steering operation of the steering wheel 3. For example, the steering control unit 200 calculates a target steering angle δt based on the steering angle θs and the vehicle speed V. The steering control unit 200 then controls the steering actuator 21 so that the actual steering angle δa of the wheel 2 follows the target steering angle δt. However, a discrepancy may occur between the driver's steering operation and the steering of the wheel 2. For example, if the driver turns the steering wheel 3 at a considerable speed, a discrepancy may occur between the target steering angle δt and the actual steering angle δa due to a delay in the response of the steering actuator 21.

[0071] Deviation compensation control is a reaction force control system aimed at reducing the discrepancy between the driver's steering input and the actual steering of the wheels 2. For convenience, the target steering angle δt corresponding to the driver's steering input is called the "first target steering angle δt1". 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 this deviation. In other words, deviation compensation control applies a steering reaction force component to the steering wheel 3 in a direction that hinders the driver's steering input. As a result, it is expected that the driver will find it more difficult to turn the steering wheel 3, and the deviation will decrease.

[0072] Figure 12 is a block diagram illustrating 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] The deviation calculation unit 331 calculates the deviation between the first target steering angle δt1 and the actual steering angle δa. The first target steering angle δt1 is calculated by the steering control unit 200. The actual steering angle δa is obtained from the rotation angle sensor 54.

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

[0075] The reaction force control unit 300 calculates the final target control amount by combining the target control amount CON_DC obtained by deviation compensation control with the target control amount obtained 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 and performs reaction force control.

[0076] 4-2. Steering Angle Distribution Control Next, consider the case where the driver begins steering while the driver assistance control is active. In this case, mediation may occur between the driver's steering operation and the steering control by the driver assistance control. For convenience, the target steering angle δt requested by the driver assistance control will be called the "second target steering angle δt2". If certain conditions are met, the final target steering angle δt is determined by combining the first target steering angle δt1 and the second target steering angle δt2. This process of determining the target steering angle δt by combining the first target steering angle δt1 and the second target steering angle δt2 will be referred to as "steering angle distribution control" below. The certain conditions for performing steering angle distribution control will be referred to as "steering angle distribution conditions" below.

[0077] Figure 13 illustrates an example of steering angle distribution control. The horizontal axis represents time, and the vertical axis represents steering parameters. Steering parameters are parameters that reflect the driver's steering intentions, such as steering torque Ts.

[0078] As described above, the steering determination threshold Tth_S is the threshold used for determining driver steering. If the steering parameter is greater than or equal to the steering determination threshold Tth_S, the control device 100 determines that the driver is steering the steering wheel 3 and sets the driver steering flag to ON. In this case, it is preferable for the steering control unit 200 to perform 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 smaller than the steering decision threshold Tth_S. If the steering parameter is less than or equal to the intervention threshold Tth_I, the steering control unit 200 performs steering control according to the second target steering angle δt2 required by the driver assistance 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 parameters are within the range from the intervention threshold Tth_I (first threshold) to the steering decision threshold Tth_S (second threshold). When this steering angle distribution condition is met, 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 Figure 13, the steering parameter gradually increases over time. At time t1, the steering parameter reaches the intervention threshold Tth_I. As a result, steering angle distribution control begins. At time t2, which is after time t1, the steering parameter reaches the steering decision threshold Tth_S. As a result, steering angle distribution control ends. The period Pd from time t1 to time t2 is the period during which the steering angle distribution condition is met and steering angle distribution control is performed.

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

[0083] Figure 15 is a block diagram illustrating the processes related to steering angle distribution control. The steering control unit 200 includes a target steering angle calculation unit 210 and a steering angle distribution control unit 220.

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

[0085] The steering angle distribution control unit 220 receives a first target steering angle δt1, a second target steering angle δt2, driver assistance control status information STA, and steering parameters. The second target steering angle δt2 is provided by the driver assistance control unit 400. Alternatively, the second target steering angle δt2 may be calculated based on a target control amount provided by the driver assistance control unit 400. The driver assistance control status information STA includes information indicating whether or not driver assistance control is active, and is provided by the driver assistance control unit 400.

[0086] During the operation of the driver assistance control, the steering angle distribution control unit 220 determines whether the steering angle distribution condition is met based on the steering parameters. The steering angle distribution condition is that the steering parameters are within the range from the intervention threshold Tth_I (first threshold) to the steering judgment threshold Tth_S (second threshold). If the steering angle distribution condition is met, the steering angle distribution control unit 220 determines the target steering angle δt by combining the first target steering angle δt1 and the second target steering angle δt2. Then, the steering control unit 200 performs steering control according to the target steering angle δt.

[0087] 4-3. Disabling deviation compensation control Assuming that steering angle distribution control and deviation compensation control operate simultaneously, the following problems arise. Figure 16 illustrates these problems. 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 equivalent.

[0088] The driver begins steering while the driver assistance control is active. The first target steering angle δt1, which corresponds to the driver's steering input, increases over time. Assume that the period Pd during which steering angle distribution control is performed is the same as shown in Figure 13 above. From time t2 onward, 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, during the period prior to time t2, the target steering angle δt differs from the first target steering angle δt1, resulting in a deviation between the actual steering angle δa and the first target steering angle δt1. At least during the period Pd in ​​which steering angle distribution control is performed, the target steering angle δt differs from the first target steering angle δt1, resulting in a deviation between the actual steering angle δa and the first target steering angle δt1. Deviation compensation control applies a steering reaction force component to the steering wheel 3 in a direction that reduces this deviation. In other words, deviation compensation control applies a steering reaction force component in a direction that hinders the driver's steering operation. However, since the deviation here is not due to a response delay of the steering actuator 21, the deviation compensation control does not produce its intended effect. Rather, the deviation compensation control unnecessarily hinders the driver's steering operation and unnecessarily reduces the operability of the steering wheel 3.

[0090] Therefore, according to this embodiment, the reaction force control unit 300 releases the deviation compensation control for at least a portion of the period Pd during which the steering angle distribution condition is met. "Releasing the deviation compensation control" means setting the steering reaction force component due to the deviation compensation control to zero. This suppresses the deviation compensation control from unnecessarily interfering with the steering operation. In other words, it suppresses a decrease in the operability of the steering wheel 3.

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

[0092] As described above, the steering angle distribution condition is that the steering parameter is within the range from the intervention threshold Tth_I (first threshold) to the steering judgment 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 greater than the intervention threshold Tth_I and less than or equal to the steering judgment threshold Tth_S. If the steering parameter is less than the threshold Tth_DC, the reaction force control unit 300 releases the deviation compensation control. As a result, the deviation compensation control is released for at least a portion of the period Pd in ​​which the steering angle distribution condition is met. The release condition for releasing the deviation compensation control can also be said to be "the driving assistance control is in operation and the steering parameter is less than the threshold Tth_DC."

[0093] Figure 17 illustrates an example of disabling deviation compensation control. The format is the same as that of Figure 13 above, with the horizontal axis representing time and the vertical axis representing steering parameters (e.g., steering torque Ts). In the example shown in Figure 17, the threshold Tth_DC for deviation compensation control is set to the same value as the steering judgment threshold Tth_S (Tth_DC = Tth_S). In this case, the disabling condition for disabling deviation compensation control can also be said to be "the driver assistance control is active AND the driver steering flag is OFF". The disabling condition is met during the period before time t2, and the deviation compensation control is disabling. This effectively suppresses the decrease in 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 that is greater than the intervention threshold value Tth_I and less 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. Functional Configuration Example Related to Deviation Compensation Control FIG. 19 is a block diagram showing a functional configuration example 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 given 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 according to the result of the determination by the release condition determination unit 340. Specifically, if the release condition is met, the gain switching unit 341 sets the control amount gain Gb to "0". On the other hand, if the release condition is not met, the gain switching unit 341 sets the control amount gain Gb to "1".

[0099] The multiplication unit 342 calculates the final target control variable CON_DC for deviation compensation control by multiplying the target control variable CON_DC0 calculated by the deviation compensation control unit 330 by the control variable gain Gb (CON_DC = Gb × CON_DC0).

[0100] If the release condition is met, 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 released (turned OFF).

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

[0102] 4-5. Effects As described above, according to this embodiment, the steering reaction force component due to the deviation compensation control is set to zero for at least a portion of the period Pd during which the steering angle distribution condition is met. This suppresses the deviation compensation control from unnecessarily interfering with the steering operation. In other words, it is possible to suppress a decrease in the operability of the steering wheel 3. [Explanation of symbols]

[0103] 1 vehicle 2 wheels 3 handles 10. Vehicle control system 20 Steering gear 30 Reaction device 40. Operating environment information acquisition device 50 Vehicle condition sensors 60 Recognition Sensors 100 Control device 110 processors 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 Support Control Unit

Claims

1. A vehicle control system for controlling a steer-by-wire vehicle, Equipped with one or more processors, The one or more processors described above are: Road surface information transmission control that applies a steering reaction force component corresponding to vibrations caused by road surface irregularities to the steering wheel of the vehicle, Lane departure prevention control that vibrates the steering wheel to inform the driver of the possibility of the vehicle deviating from its lane, It is configured to perform, The one or more processors, when transitioning from a first state in which the lane departure prevention control is not activated to a second state in which the lane departure prevention control is activated, gradually reduce the steering reaction force component due to the road surface information transmission control to zero. Vehicle control system.

2. A vehicle control system according to claim 1, The one or more processors further increase the steering reaction force component by the road surface information transmission control from zero when the state changes from the second state to the first state. Vehicle control system.

3. A vehicle control system for controlling a steer-by-wire vehicle, Equipped with one or more processors, The one or more processors described above are: Road surface information transmission control that applies a steering reaction force component corresponding to vibrations caused by road surface irregularities to the steering wheel of the vehicle, Lane departure prevention control that vibrates the steering wheel to inform the driver of the possibility of the vehicle deviating from its lane, It is configured to perform, The one or more processors described above are: In the second state in which the lane departure prevention control is in operation, the steering reaction force component by the road surface information transmission control is set to zero. When the vehicle changes from the second state to the first state in which the lane departure prevention control is not activated, the steering reaction force component by the road surface information transmission control is gradually amplified from zero. Vehicle control system.

4. A vehicle control system for controlling a steer-by-wire vehicle, Equipped with one or more processors, The one or more processors described above are: Road surface information transmission control that applies a steering reaction force component corresponding to vibrations caused by road surface irregularities to the steering wheel of the vehicle, Lane departure prevention control that vibrates the steering wheel to inform the driver of the possibility of the vehicle deviating from its lane, It is configured to perform, The one or more processors further include: By multiplying the target control amount required by the aforementioned road surface information transmission control by a gain, the final target control amount related to the aforementioned road surface information transmission control is calculated. In the first state where the lane departure prevention control is not activated, the gain is set to a predetermined value greater than zero. In the second state in which the lane departure prevention control is in operation, the gain is set to zero. When the transition occurs from the first state to the second state, the gain is gradually changed from the predetermined value to zero. Vehicle control system.

5. A vehicle control system according to claim 4, The one or more processors further gradually change the gain from zero to the predetermined value when changing from the second state to the first state. Vehicle control system.

6. A vehicle control system for controlling a steer-by-wire vehicle, Equipped with one or more processors, The one or more processors described above are: Road surface information transmission control that applies a steering reaction force component corresponding to vibrations caused by road surface irregularities to the steering wheel of the vehicle, Lane departure prevention control that vibrates the steering wheel to inform the driver of the possibility of the vehicle deviating from its lane, It is configured to perform, The one or more processors further include: By multiplying the target control amount required by the aforementioned road surface information transmission control by a gain, the final target control amount related to the aforementioned road surface information transmission control is calculated. In the first state where the lane departure prevention control is not activated, the gain is set to a predetermined value greater than zero. In the second state in which the lane departure prevention control is in operation, the gain is set to zero. When changing from the second state to the first state, the gain is gradually changed from zero to the predetermined value. Vehicle control system.

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