Vehicle control system and vehicle control method

Abstract

This disclosure relates to a vehicle control system and a vehicle control method. The vehicle control system of a vehicle with steer-by-wire capability performs a linkage reaction force control that, in conjunction with vehicle steering input via driver assistance control, applies a steering reaction force component to the steering wheel. The driver's steering angle is a target steering angle corresponding to the steering angle of the steering wheel. A first system steering angle is the target steering angle requested by the driver assistance control. The linkage reaction force control obtains a second system steering angle by adjusting the first system steering angle according to the driver's steering intention. At this time, the adjustment is performed in a manner that makes the difference between the second system steering angle and the driver's steering angle smaller than the difference between the first system steering angle and the driver's steering angle. Then, the linkage reaction force control applies a steering reaction force component in the direction that reduces the difference between the driver's steering angle and the second system steering angle to the steering wheel.

Description

Technical Field

[0001] This disclosure relates to techniques for controlling vehicles using a steer-by-wire system. In particular, this disclosure relates to techniques for controlling steer-by-wire vehicles equipped with driver assistance controls that assist in driving the vehicle. Background Technology

[0002] Patent Document 1 discloses a driving assistance device for assisting in driving a vehicle. When an obstacle is detected around the vehicle, the driving assistance device determines the amount of braking control to avoid a collision based on the probability of a collision with the obstacle. At this time, if the driver of the vehicle performs a steering operation to move away from the obstacle, the driving assistance device corrects by reducing the amount of braking control.

[0003] Existing technical documents

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 5781791

[0006] Consider vehicles with steer-by-wire systems that also possess driver assistance controls to aid in driving. For example, the driver assistance controls could automatically steer the vehicle independently of driver-operated steering. On the other hand, in vehicles with steer-by-wire systems, reaction force control could be implemented, applying steering reaction force to the steering wheel. Cases where reaction force control is linked to vehicle steering via driver assistance control are also considered. Depending on the situation, the driver might experience discomfort with reaction force control linked to vehicle steering via driver assistance control. Summary of the Invention

[0007] One object of this disclosure is to provide a technique for reducing driver discomfort in vehicles with a steering-by-wire system, which involves reaction force control in conjunction with vehicle steering via driver assistance control.

[0008] The first point is related to the vehicle control system of vehicles that control steer-by-wire.

[0009] The vehicle control system has one or more processors.

[0010] One or more processors are configured to perform: driver assistance control, assisting in driving the vehicle; and linked reaction force control, which, in conjunction with the vehicle's steering input via driver assistance control, applies a steering reaction force component to the steering wheel.

[0011] The linkage reaction force control includes: processing to acquire the driver steering angle as a target steering angle corresponding to the steering angle of the steering wheel; processing to acquire a first system steering angle as a target steering angle requested by driver assistance control; processing to acquire a second system steering angle by adjusting the first system steering angle according to the driver's steering intention; and processing to apply a steering reaction force component in the direction that reduces the difference between the driver steering angle and the second system steering angle to the steering wheel.

[0012] The first system steering angle is adjusted in such a way that the difference between the second system steering angle and the driver steering angle is smaller than the difference between the first system steering angle and the driver steering angle, thereby obtaining the second system steering angle.

[0013] The second point is related to vehicle control methods for vehicles using steer-by-wire systems.

[0014] Vehicle control methods include: driver assistance control, which assists in driving the vehicle; and linkage reaction force control, which, in conjunction with the vehicle's steering input via driver assistance control, applies a steering reaction force component to the steering wheel.

[0015] The linkage reaction force control includes: processing to acquire the driver steering angle as a target steering angle corresponding to the steering angle of the steering wheel; processing to acquire a first system steering angle as a target steering angle requested by driver assistance control; processing to acquire a second system steering angle by adjusting the first system steering angle according to the driver's steering intention; and processing to apply a steering reaction force component in the direction that reduces the difference between the driver steering angle and the second system steering angle to the steering wheel.

[0016] The first system steering angle is adjusted in such a way that the difference between the second system steering angle and the driver steering angle is smaller than the difference between the first system steering angle and the driver steering angle, thereby obtaining the second system steering angle.

[0017] Invention Effects

[0018] According to this disclosure, a linkage reaction force control is performed that applies a steering reaction force component to the steering wheel in conjunction with vehicle steering via driver assistance control. The steering reaction force component for linkage reaction force control is generated based on the difference between the driver's steering angle and the system steering angle. At this time, the system steering angle is adjusted according to the driver's steering intention. Then, the steering reaction force component for linkage reaction force control is generated using an adjusted second system steering angle instead of the original first system steering angle. The difference between the adjusted second system steering angle and the driver's steering angle is smaller than the difference between the original first system steering angle and the driver's steering angle. Therefore, in the presence of the driver's steering intention, the steering reaction force component for linkage reaction force control is suppressed. As a result, the driver's discomfort with linkage reaction force control is reduced. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating an example of the configuration of a vehicle and a vehicle control system according to an implementation method.

[0020] Figure 2 This is a block diagram illustrating the functional configuration of the control device in the vehicle control system of the implementation method.

[0021] Figure 3 This is a concept diagram used to illustrate risk avoidance control as an example of driver assistance control.

[0022] Figure 4 This is a concept diagram used to illustrate lane keeping assist control as another example of driver assistance control.

[0023] Figure 5 This is a concept diagram used to illustrate lane departure suppression control as another example of driver assistance control.

[0024] Figure 6 This is a block diagram representing the linkage reaction force control unit of the comparative example.

[0025] Figure 7 This is a block diagram illustrating the linkage reaction force control unit of the implementation method.

[0026] Figure 8 This is a block diagram illustrating an example of the configuration of the adjustment unit of the linkage reaction force control unit in the implementation method.

[0027] Figure 9 This is a block diagram showing a first configuration example of the gain setting unit in an implementation method.

[0028] Figure 10 This is a block diagram illustrating a second configuration example of the gain setting unit in an implementation method.

[0029] Figure 11 This is a block diagram illustrating a third configuration example of the gain setting unit in an implementation method.

[0030] Figure 12 This is a block diagram showing a modified example of the adjustment section of the linkage reaction force control unit in the implementation method.

[0031] Figure 13 This is a diagram illustrating an example of the change in the gain of the linkage reaction force in the implementation method.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1 vehicle

[0034] 2 wheels

[0035] 3. Steering wheel

[0036] 10 Vehicle Control System

[0037] 20. Steering mechanism

[0038] 30. Reaction force device

[0039] 40 Driving Environment Information Acquisition Device

[0040] 50 Vehicle Status Sensors

[0041] 60 Identification Sensors

[0042] 100 Control device

[0043] 110 processor

[0044] 120 storage devices

[0045] 200 Steering Control Unit

[0046] 300 Reaction Force Control Unit

[0047] 310 Linkage Reaction Force Control Unit

[0048] 320 Pilot's rudder angle acquisition unit

[0049] 330 Adjustment Department

[0050] 340 Gain Setting Section

[0051] 350 Protection Department

[0052] 360 Multiplication Section

[0053] 370 Differential Calculation Unit

[0054] 380 Control Quantity Calculation Department

[0055] 400 Driver Assistance Control Unit

[0056] Gc linkage reaction force gain

[0057] δx (Driver's steering angle)

[0058] δy1 First system rudder angle

[0059] δy2 Second system rudder angle. Detailed Implementation

[0060] The embodiments of this disclosure will be described with reference to the accompanying drawings.

[0061] 1. Vehicle control system

[0062] Figure 1 This is a schematic diagram illustrating an example configuration of the vehicle 1 and the vehicle control system 10 according to this embodiment. The vehicle 1 includes wheels 2 and a steering wheel 3. The steering wheel 3 is an operating component used by the driver of the vehicle 1 for steering operations. A 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 are mechanically separated from the steering wheel 3 (steering shaft 4).

[0063] The vehicle control system 10 controls the vehicle 1, which uses a steer-by-wire system. The vehicle control system 10 includes a steering wheel 20, a reaction force device 30, a driving environment information acquisition device 40, and a control device 100.

[0064] 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 reducer 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. That is, 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.

[0065] 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 reducer 32. By operating the reaction force motor, a steering reaction force can be applied to the steering shaft 4, thereby applying a steering reaction force to the steering wheel 3. The operation of the reaction force actuator 31 is controlled by the control device 100.

[0066] The driving environment information acquisition device 40 acquires driving environment information ENV, which represents the driving environment of vehicle 1. The driving environment information acquisition device 40 includes a vehicle status sensor 50, a recognition sensor 60, etc.

[0067] Vehicle status sensor 50 detects the status of vehicle 1. Vehicle status sensor 50 includes steering angle sensor 51, steering torque sensor 52, rotation angle sensor 53, rotation angle sensor 54, steering current sensor 55, and vehicle speed sensor 56. Steering angle sensor 51 detects the steering angle θs (steering wheel angle) of steering wheel 3. Steering torque sensor 52 detects the steering torque Ts applied to steering shaft 4. Rotation angle sensor 53 detects the 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 steering motor is equivalent to the steering angle (actual steering angle δa) of wheel 2. Therefore, it can also be said that rotation angle sensor 54 detects the actual steering angle δa of wheel 2. Steering current sensor 55 detects the steering current Im that drives steering actuator 21. Vehicle speed sensor 56 detects the vehicle speed V, which is the speed of vehicle 1. In addition, the vehicle status sensor 50 may also include a yaw rate sensor and an acceleration sensor.

[0068] The identification sensor 60 identifies (detects) the conditions around the vehicle 1. Examples of identification sensors 60 include cameras, LIDAR (Laser Imaging Detection and Ranging), and radar.

[0069] The driving environment information acquisition device 40 may also include a position sensor for acquiring the position of the vehicle 1. An example of a position sensor is a GPS (Global Positioning System) sensor. The driving environment information acquisition device 40 may also acquire map information.

[0070] The driving environment information (ENV) includes vehicle status information and surrounding condition information. Vehicle status information represents the vehicle status detected by vehicle status sensor 50. Surrounding condition information represents the recognition results obtained by recognition sensor 60. For example, surrounding condition information includes images captured by a camera. Surrounding condition information may also include object information related to objects surrounding vehicle 1. Examples of objects surrounding vehicle 1 include pedestrians, other vehicles (vehicles in the lead, parked vehicles, etc.), signs, white lines, roadside structures, etc. Object information represents the relative position and relative speed of the object relative to vehicle 1. The driving environment information (ENV) may also include vehicle 1's location information, map information, etc.

[0071] Control device 100 controls vehicle 1. 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 device 120). Processor 110 performs various processes. For example, processor 110 includes a CPU (Central Processing Unit). Storage device 120 stores various information required for the processes performed by processor 110. Examples of storage devices 120 include volatile memory, non-volatile memory, HDD (Hard Disk Drive), SSD (Solid State Drive), etc. Control device 100 may also include one or more ECUs (Electronic Control Units).

[0072] The control program, which is a computer program, is executed by the processor 110 to perform various processes via 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.

[0073] The control device 100 (processor 110) acquires driving environment information ENV from the driving environment information acquisition device 40. The driving environment information ENV is stored in the storage device 120.

[0074] Figure 2 This is a block diagram illustrating 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 assistance control unit 400 as functional blocks. These functional blocks are implemented through the cooperation of a processor 110 that executes the control program and a storage device 120. It should be noted that the steering control unit 200, the reaction force control unit 300, and the driving assistance control unit 400 can also be implemented using different control devices. In this case, the control devices are connected in a manner that allows them to communicate with each other and exchange necessary information.

[0075] The following is a detailed description of each of the steering control unit 200, the reaction force control unit 300, and the driving assistance control unit 400.

[0076] 2. Steering control

[0077] The steering control unit 200 performs "steering control" to turn the wheel 2. More specifically, the steering control unit 200 turns the wheel 2 by controlling the steering actuator 21 of the steering device 20.

[0078] The steering control unit 200 performs steering control in response to steering operations of the steering wheel 3 performed by the driver. 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 can also be calculated based on 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 wheel 2 according to the target steering angle δt. The actual steering angle δa of the wheel 2 is detected by the rotation angle sensor 54. The steering control unit 200 controls the steering actuator 21 in such a way that the actual steering angle δa follows the target steering angle δt. More specifically, the steering control unit 200 generates a control signal for driving the steering actuator 21 based on the deviation between the target steering angle δt and the actual steering angle δa of the wheel 2. The steering actuator 21 is driven according to the control signal, thereby steering the wheel 2. It should be noted that the current driving the rudder actuator 21 at this time is the rudder current Im.

[0079] Furthermore, the steering control unit 200 performs steering control upon request from the driver assistance control unit 400, as described later. In this case, the steering control unit 200 obtains the target control quantity from the driver assistance control unit 400 and performs steering control according to the target control quantity.

[0080] 3. Reaction force control

[0081] 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 a steering reaction force to the steering wheel 3 by controlling the reaction force actuator 31 of the reaction force device 30.

[0082] The reaction force control unit 300 performs reaction force control in response to 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 the self-aligning torque applied to the wheel 2 based on the steering angle θs and vehicle speed V. The target steering reaction force may also include a damping component corresponding to the steering speed (dθs / dt). The reaction force control unit 300 then controls the reaction force actuator 31 in a manner that generates 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 the steering reaction force.

[0083] Furthermore, the reaction force control unit 300 can also perform reaction force control upon request from the driver assistance control unit 400, as described later. Moreover, the reaction force control unit 300 can also perform reaction force control in conjunction with driver assistance control via the driver assistance control unit 400. The reaction force control in conjunction with driver assistance control will be explained in detail later.

[0084] 4. Driver Assistance Control

[0085] The driver assistance control unit 400 performs "driver assistance control" to assist the driving of the vehicle 1. The driver assistance control automatically controls the driving of the vehicle 1 regardless of driving operations performed by the driver. In this embodiment, driver assistance control related to steering is particularly considered. Examples of such driver assistance controls include automatic driving control, risk avoidance control, lane keeping assist (LTA), and lane departure prevention control (LDA).

[0086] The autonomous driving control unit controls the autonomous driving of vehicle 1. Specifically, the driver assistance control unit 400 generates a driving plan for vehicle 1 based on the driving environment information (ENV). Examples of driving plans include maintaining the current driving lane, changing lanes, making left or right turns, and avoiding obstacles. Furthermore, the driver assistance control unit 400 generates a target trajectory (TRJ) required 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. Then, the driver assistance control unit 400 controls vehicle driving by having vehicle 1 follow the target trajectory (TRJ).

[0087] More specifically, the driver assistance control unit 400 calculates the deviation (lateral deviation, yaw rate deviation, and speed deviation) between the vehicle 1 and the target trajectory TRJ, and calculates the target control quantity required to reduce this deviation. 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 quantity. Vehicle driving control includes steering control, acceleration control, and deceleration control. Steering control is performed by the aforementioned steering control unit 200. Acceleration and deceleration control are performed by controlling the drive and braking systems (not shown) of the vehicle 1.

[0088] Figure 3This is a conceptual diagram illustrating risk avoidance control. Risk avoidance control is a driver assistance control used to reduce the risk of collision between vehicle 1 and objects in front. Examples of objects to be avoided include pedestrians, bicycles, two-wheeled vehicles, animals, and other vehicles. The driver assistance control unit 400 identifies objects in front of vehicle 1 based on surrounding condition information (object information) included in the driving environment information ENV. For example, if the risk of collision with the identified 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 to ensure a lateral distance from the object. Then, the driver assistance control unit 400 performs vehicle driving control by having vehicle 1 follow the target trajectory TRJ. The vehicle driving control here includes at least one of steering control and deceleration control. Steering control is performed via the steering control unit 200 described above.

[0089] Figure 4 This is a conceptual diagram illustrating lane keeping assist control. Lane keeping assist control is a driver assistance control that assists vehicle 1 in traveling along the center line LC of a lane. A lane is the area between the left and right lane boundaries LB. Examples of lane boundaries LB include white lines (dividing lines) and curbs. The center line LC is the center line of the lane. The driver assistance control unit 400 identifies the lane boundaries LB and the center line LC based on the surrounding condition information included in the driving environment information ENV. When vehicle 1 deviates from the center line 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 center line LC. Steering control is performed by the aforementioned steering control unit 200.

[0090] Figure 5 This is a conceptual diagram illustrating lane departure suppression control. Lane departure suppression control is a driver assistance control used to prevent vehicle 1 from leaving its driving lane. The driver assistance control unit 400 identifies the lane boundary LB based on the surrounding condition information included in the driving environment information ENV. When the distance between vehicle 1 and the lane boundary LB is less than a predetermined threshold, the driver assistance control unit 400 performs lane departure suppression control. Specifically, the driver assistance control unit 400 communicates the possibility of lane departure to the driver. 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 can also output a warning via display and / or sound. Furthermore, the driver assistance control unit 400 can also perform steering control by moving vehicle 1 towards the center LC of the lane. Steering control is performed via the aforementioned steering control unit 200.

[0091] 5. Coordination between driver assistance control and reaction force control

[0092] Next, we consider the coordination between driver assistance control and reaction force control. For example, we consider the case where reaction force control is performed in conjunction with the steering of vehicle 1 controlled by driver assistance control. Hereinafter, the reaction force control performed in conjunction with the steering of vehicle 1 controlled by driver assistance control will be referred to as "joint reaction force control".

[0093] 5-1. Overview of Linkage Reaction Force Control

[0094] The purpose of the linkage reaction force control is to rotate the steering wheel 3 in conjunction with the steering of the vehicle 1 (wheels 2) controlled by the driving assistance control when the driving assistance control is in operation. To this end, the linkage reaction force control applies the steering reaction force component used to make the steering wheel 3 follow the steering of the vehicle 1 controlled by the driving assistance control to the steering wheel 3.

[0095] First, refer to Figure 6 A comparative example will be described. The reaction force control unit 300 includes a linkage reaction force control unit 310. The linkage reaction force control unit 310 calculates a target control quantity CON_C for generating the steering reaction force component for linkage reaction force control. The linkage reaction force control unit 310 includes a driver steering angle acquisition unit 320, a differential calculation unit 370, and a control quantity calculation unit 380.

[0096] The driver steering angle acquisition unit 320 acquires the steering angle θs (steering wheel angle) of the steering wheel 3, which is included in the vehicle status information. Furthermore, the driver steering angle acquisition unit 320 calculates a target steering angle δt corresponding to the steering angle θs of the steering wheel 3 based on the variable gear ratio, etc. The calculation of this target steering angle δt is the same as that performed by the steering control unit 200 described above. For convenience, the target steering angle δt corresponding to the steering angle θs of the steering wheel 3 will be referred to below as the "driver steering angle δx".

[0097] On the other hand, the "system steering angle δy" is the target steering angle δt requested by the driver assistance control. The system steering angle δy is determined by the driver assistance control unit 400 as described above. The linkage reaction force control unit 310 acquires the system steering angle δy determined by the driver assistance control unit 400.

[0098] The differential calculation unit 370 calculates the difference (deviation) between the driver's steering angle δx and the system steering angle δy.

[0099] The control quantity calculation unit 380 calculates a target control quantity CON_C for generating a steering reaction force component in the direction that reduces the difference between the driver's steering angle δx and the system steering angle δy. For example, the control quantity calculation unit 380 calculates the target control quantity CON_C in such a way that the steering reaction force component increases as the difference increases.

[0100] It should be noted that the reaction force control unit 300 calculates the final target control quantity by combining the target control quantity CON_C obtained through linkage reaction force control with the target control quantity obtained through 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 to perform reaction force control according to the final target control quantity.

[0101] Thus, the linkage reaction force control calculates the difference between the driver's steering angle δx and the system's steering angle δy, and assigns the steering reaction force component in the direction that reduces this difference to the steering wheel 3. However, depending on the situation, the driver may feel discomfort from such linkage reaction force control. For example, if the driver has an active steering intention, the driver may feel that the steering wheel 3 is very heavy due to the linkage reaction force control. Or, the driver may feel that the steering wheel 3 is being forcefully turned back due to the linkage reaction force control.

[0102] Therefore, this embodiment proposes a technique that can reduce the discomfort felt by the driver in the control of the linkage reaction force.

[0103] Figure 7 This is a block diagram showing the linkage reaction force control unit 310 of this embodiment. Figure 6 Compared to the comparative example shown, the linkage reaction force control unit 310 also includes an adjustment unit 330.

[0104] The adjustment unit 330 performs an "adjustment process" to adjust the system steering angle δy. For convenience, the system steering angle δy requested by the driver assistance control, i.e., the system steering angle δy determined by the driver assistance control unit 400, is referred to as the "first system steering angle δy1". The adjustment unit 330 acquires the first system steering angle δy1 and adjusts it according to the driver's steering intention. Hereinafter, the adjusted system steering angle δy is referred to as the "second system steering angle δy2". That is, the adjustment unit 330 acquires the second system steering angle δy2 by adjusting the first system steering angle δy1 according to the driver's steering intention.

[0105] The driver's steering intention is reflected in the steering parameter Ps. For example, the steering parameter Ps is the driver's steering angle δx. As another example, the steering parameter Ps can also be the difference between the driver's steering angle δx and the first system steering angle δy1. As yet another example, the steering parameter Ps can also be the steering torque Ts detected by the steering torque sensor 52. The adjustment unit 330 obtains the second system steering angle δy2 by adjusting the first system steering angle δy1 according to the steering parameter Ps.

[0106] The relationship between the first system steering angle δy1 and the second system steering angle δy2 is as follows. The first difference d1 is the difference (deviation) between the first system steering angle δy1 before adjustment and the pilot steering angle δx. On the other hand, the second difference d2 is the difference (deviation) between the second system steering angle δy2 after adjustment and the pilot steering angle δx. The adjustment unit 330 adjusts the first system steering angle δy1 in such a way that the absolute value of the second difference d2 is smaller than the absolute value of the first difference d1, thereby obtaining the second system steering angle δy2.

[0107] Next, the differential calculation unit 370 calculates the second difference d2 between the driver's steering angle δx and the second system steering angle δy2. Then, the control quantity calculation unit 380 calculates the target control quantity CON_C for generating the steering reaction force component in the direction that reduces the second difference d2. For example, the control quantity calculation unit 380 calculates the target control quantity CON_C in such a way that the steering reaction force component increases as the second difference d2 increases.

[0108] Thus, in the linkage reaction force control of this embodiment, the system steering angle δy is adjusted according to the driver's steering intention. Then, a steering reaction force component for linkage reaction force control is generated by using the adjusted second system steering angle δy2 instead of the original first system steering angle δy1. The second difference d2 between the adjusted second system steering angle δy2 and the driver's steering angle δx is smaller than the first difference d1 between the original first system steering angle δy1 and the driver's steering angle δx. Therefore, when the driver's steering intention is present, the steering reaction force component for linkage reaction force control is suppressed. As a result, the driver's discomfort with linkage reaction force control is reduced.

[0109] It should be noted that the system steering angle δy is adjusted only in the linkage reaction force control that applies steering reaction force to the steering wheel 3. The driver assistance control unit 400 performs driver assistance control, including steering control, based on its own determined system steering angle δy (i.e., the first system steering angle δy1). Therefore, the vehicle steering is adjusted according to the target direction within the driver assistance control. In other words, the performance of the driver assistance control is not compromised.

[0110] 5-2. Example of the structure of the adjustment section

[0111] Figure 8This is a block diagram illustrating an example configuration of the adjustment unit 330 within the linkage reaction force control unit 310. The adjustment unit 330 includes a gain setting unit 340 and a multiplication unit 360. The gain setting unit 340 performs a "gain setting process" to set the linkage reaction force gain Gc. The gain setting unit 340 sets the linkage reaction force gain Gc based on the driver's steering intention, i.e., based on the steering parameter Ps. Then, the multiplication unit 360 calculates the second system steering angle δy2 (δy2 = Gc × δy1) by multiplying the linkage reaction force gain Gc by the first system steering angle δy1.

[0112] The gain setting unit 340 sets the linkage reaction force gain Gc in such a way that the second difference d2 between the second system steering angle δy2 and the pilot steering angle δx is smaller than the first difference d1 between the first system steering angle δy1 and the pilot steering angle δx. Various configuration examples of the gain setting unit 340 will be described below.

[0113] 5-2-1. First example of composition

[0114] Figure 9 This is a block diagram showing a first configuration example of the gain setting unit 340. The gain setting unit 340 includes a differential calculation unit 341 and a gain mapping unit 342.

[0115] The differential calculation unit 341 calculates the first difference d1 between the first system steering angle δy1 and the driver steering angle δx. It should be noted that in the first configuration example, the first difference d1 between the driver steering angle δx or the first system steering angle δy1 and the driver steering angle δx is equivalent to the steering parameter Ps.

[0116] The gain mapping unit 342 sets the linkage reaction force gain Gc based on the first difference d1. For example, when the pilot's steering angle δx is greater than the first system steering angle δy1, the linkage reaction force gain Gc is set to a value greater than 1 in order to make the second system steering angle δy2 closer to the pilot's steering angle δx. On the other hand, when the first system steering angle δy1 is greater than the pilot's steering angle δx, the linkage reaction force gain Gc is set to a value less than 1 in order to make the second system steering angle δy2 closer to the pilot's steering angle δx. Therefore, the second difference d2 between the second system steering angle δy2 and the pilot's steering angle δx is smaller than the first difference d1 between the first system steering angle δy1 and the pilot's steering angle δx.

[0117] The gain mapping unit 342 can also simultaneously consider the first difference d1 and the vehicle speed V to set the linkage reaction force gain Gc.

[0118] 5-2-2. Second example of composition

[0119] Figure 10This is a block diagram showing a second configuration example of the gain setting unit 340. The gain setting unit 340 includes a differential calculation unit 341, a horizontal G conversion unit 343, and a gain mapping unit 344. The differential calculation unit 341 is the same as in the first configuration example.

[0120] The lateral G conversion unit 343 converts the first difference d1 between the first system steering angle δy1 and the driver steering angle δx into the dimension of lateral acceleration based on the vehicle speed V. The vehicle speed V is obtained from the vehicle state information. The result of the conversion is to obtain the lateral acceleration deviation d1' equivalent to the first difference d1.

[0121] The gain mapping unit 344 sets the linkage reaction force gain Gc based on the lateral acceleration deviation d1' instead of the first difference d1. The strategy for setting the linkage reaction force gain Gc is the same as that for the gain mapping unit 342 in the first embodiment described above. However, the gain mapping unit 344 does not depend on the vehicle speed V, and is therefore simpler than the gain mapping unit 342 in the first embodiment.

[0122] 5-2-3. Third example

[0123] Figure 11 This is a block diagram illustrating a third configuration example of the gain setting unit 340. The gain setting unit 340 includes a driver steering determination unit 345 and a gain switching unit 346.

[0124] The driver steering determination unit 345 determines whether the driver intends to turn. To do this, the driver steering determination unit 345 determines whether the steering parameter Ps, which reflects the driver's steering intention, exceeds a threshold. For example, the steering parameter Ps is the steering torque Ts detected by the steering torque sensor 52. As another example, the steering parameter Ps can also be the first difference d1 between the driver's steering angle δx and the first system steering angle δy1. As yet another example, the steering parameter Ps can also be the lateral acceleration deviation d1' obtained by converting the first difference d1 into the dimension of lateral acceleration. If the steering parameter Ps exceeds the threshold, the driver steering determination unit 345 determines that the driver intends to turn.

[0125] The gain switching unit 346 switches the linkage reaction force gain Gc based on the determination result obtained by the driver steering determination unit 345. Specifically, when it is determined that the driver has no steering intention, the gain switching unit 346 sets the linkage reaction force gain Gc to "1". On the other hand, when it is determined that the driver has a steering intention, the gain switching unit 346 sets the linkage reaction force gain Gc to a value α, which is different from 1.

[0126] For example, the third configuration example is applied to a situation where the steering direction generated by the driver is opposite to the steering direction generated by the driver assistance control. In the case of opposite phase, the value α is less than 1. By using a linkage reaction force gain Gc less than 1, the second difference d2 between the second system steering angle δy2 and the driver steering angle δx is smaller than the first difference d1 between the first system steering angle δy1 and the driver steering angle δx.

[0127] When the steering direction generated by the driver and the steering direction generated by the driver assistance control are in phase, the value α changes according to the relationship between the driver's steering angle δx and the first system steering angle δy1. When the driver's steering angle δx is greater than the first system steering angle δy1, the value α is set to a value greater than 1. On the other hand, when the first system steering angle δy1 is greater than the driver's steering angle δx, the value α is set to a value less than 1. Therefore, the second difference d2 between the second system steering angle δy2 and the driver's steering angle δx is smaller than the first difference d1 between the first system steering angle δy1 and the driver's steering angle δx.

[0128] 5-3. Variations

[0129] Figure 12 This is a block diagram showing a modified example of the adjustment unit 330 of the linkage reaction force control unit 310. (And...) Figures 8-11 Compared to the example shown, the adjustment unit 330 also includes a protection unit 350. The protection unit 350 gradually changes the linkage reaction force gain Gc to suppress abrupt changes in the steering reaction force.

[0130] Figure 13 This is a graph used to illustrate an example of the change in the gain Gc of the linkage reaction force. In Figure 13 In the example shown, the reaction force gain Gc gradually changes from "1" to "α". For instance, the change time of the reaction force gain Gc is set to "the reciprocal of the main frequency component of the first system steering angle δy1" × 1 / 2. Therefore, the gradient of the second system steering angle δy2 is smaller than the original gradient of the first system steering angle δy1. This suppresses abrupt changes in the steering reaction force.

[0131] 5-4. Effects

[0132] As explained above, according to this embodiment, a linkage reaction force control is performed that applies a steering reaction force component to the steering wheel 3 in conjunction with the steering of the vehicle 1 via driver assistance control. The steering reaction force component for linkage reaction force control is generated based on the difference between the driver's steering angle δx and the system steering angle δy. At this time, the system steering angle δy is adjusted according to the driver's steering intention. Then, the steering reaction force component for linkage reaction force control is generated by using the adjusted second system steering angle δy2 instead of the unadjusted first system steering angle δy1. The second difference d2 between the adjusted second system steering angle δy2 and the driver's steering angle δx is smaller than the first difference d1 between the unadjusted first system steering angle δy1 and the driver's steering angle δx. Therefore, when the driver's steering intention is present, the steering reaction force component for linkage reaction force control is suppressed. As a result, the driver's discomfort with linkage reaction force control is reduced.

[0133] It should be noted that the system steering angle δy is adjusted only in the linkage reaction force control that applies steering reaction force to steering wheel 3. The steering control in the driver assistance control is based on the original first system steering angle δy1. Therefore, the vehicle steering will be adjusted according to the target direction in the driver assistance control. In other words, it will not compromise the performance of the driver assistance control.

[0134] Furthermore, according to this embodiment, the linkage reaction force gain Gc is multiplied by the system steering angle δy, rather than by the driver steering angle δx. Therefore, the driver steering angle δx, which reflects the driver's steering intention, remains unaffected. This achieves reaction force control corresponding to the driver's steering intention without compromising the influence of the driver steering angle δx in the reaction force control.

[0135] Furthermore, the adjustment of the system steering angle δy is performed by the reaction force control unit 300 (linkage reaction force control unit 310) instead of the driver assistance control unit 400. This eliminates the need to send the steering parameter Ps, which reflects the driver's steering intention, to the driver assistance control unit 400. This reduces the amount of data communication between ECUs.

Claims

1. A vehicle control system for controlling a vehicle with steer-by-wire capability. The vehicle control system has one or more processors. The one or more processors are configured to execute: Driving assistance control assists in driving the vehicle and automatically controls the vehicle's movement independently of driving operations performed by the driver; as well as The linkage reaction force control, in conjunction with the vehicle's steering input via the aforementioned driver assistance control, applies a steering reaction force component to the steering wheel. The linkage reaction force control includes: Processing to obtain the driver's steering angle as a target steering angle corresponding to the steering angle of the steering wheel; Processing to obtain the first system steering angle as the target steering angle requested by the driving assistance control; The adjustment process of obtaining the second system steering angle by adjusting the first system steering angle according to the driver's steering intention of the vehicle; and The process of applying a steering reaction force component in the direction that reduces the difference between the driver's steering angle and the second system's steering angle to the steering wheel. The adjustment process adjusts the first system steering angle in such a way that the difference between the second system steering angle and the driver steering angle is smaller than the difference between the first system steering angle and the driver steering angle, thereby obtaining the second system steering angle.

2. The vehicle control system according to claim 1, wherein, The adjustment process includes: Gain setting processing for setting the linkage reaction force gain based on the driver's steering intention; and The process of calculating the steering angle of the second system by multiplying the gain of the linkage reaction force by the steering angle of the first system is as follows: The gain setting process sets the linkage reaction force gain in such a way that the difference between the second system steering angle and the driver steering angle is smaller than the difference between the first system steering angle and the driver steering angle.

3. The vehicle control system according to claim 2, wherein, The gain setting process sets the linkage reaction force gain based on the difference between the driver's steering angle and the first system steering angle.

4. The vehicle control system according to claim 3, wherein, The gain setting process includes: The process of converting the difference between the driver's steering angle and the first system's steering angle into the dimension of lateral acceleration to obtain the lateral acceleration deviation; and The processing of setting the gain of the linkage reaction force based on the lateral acceleration deviation.

5. The vehicle control system according to claim 2, wherein, The gain setting process includes: The process of determining whether the steering parameters reflecting the driver's steering intention exceed a threshold; and If the steering parameter exceeds the threshold, the linkage reaction force gain is set to a value different from 1 in such a way that the difference between the second system steering angle and the driver steering angle is smaller than the difference between the first system steering angle and the driver steering angle.

6. The vehicle control system according to any one of claims 1 to 5, wherein, The driving assistance control is based on the steering angle of the first system, not the steering angle of the second system, to steer the vehicle.

7. A vehicle control method for controlling a vehicle with steer-by-wire capability, comprising: Driving assistance control assists in driving the vehicle and automatically controls the vehicle's movement independently of driving operations performed by the driver; as well as The linkage reaction force control, in conjunction with the vehicle's steering input via the aforementioned driver assistance control, applies a steering reaction force component to the steering wheel. The linkage reaction force control includes: Processing to obtain the driver's steering angle as a target steering angle corresponding to the steering angle of the steering wheel; Processing to obtain the first system steering angle as the target steering angle requested by the driving assistance control; The adjustment process of obtaining the second system steering angle by adjusting the first system steering angle according to the driver's steering intention of the vehicle; and The process of applying a steering reaction force component in the direction that reduces the difference between the driver's steering angle and the second system's steering angle to the steering wheel. The adjustment process adjusts the first system steering angle in such a way that the difference between the second system steering angle and the driver steering angle is smaller than the difference between the first system steering angle and the driver steering angle, thereby obtaining the second system steering angle.

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