Vehicle control system and vehicle control method

Abstract

The present disclosure relates to a vehicle control system and a vehicle control method. In a vehicle of a steer-by-wire system, a turning direction of the vehicle obtained by a drive assist control is transmitted to a driver. A vehicle control system that controls the vehicle of the steer-by-wire system executes the drive assist control that assists driving of the vehicle. Further, the vehicle control system executes a linkage reaction force control that imparts a steering reaction force component to a steering wheel in linkage with a turning of the vehicle by the drive assist control. The drive assist direction is the turning direction of the vehicle obtained by the drive assist control. The linkage reaction force control includes a feedforward reaction force control that turns the steering wheel in the same direction as the drive assist direction independently of a steering angle of 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 steering control device for a vehicle with steer-by-wire. The steering control device calculates the steering reaction force based on feedback axial force and feedforward axial force, and applies the steering reaction force to the steering wheel. The feedback axial force is equivalent to the road surface reaction force and is calculated based on the steering current of a steering actuator that turns the steering wheel according to the amount of steering wheel input. On the other hand, the feedforward axial force is equivalent to a damping component, etc., and is calculated based on the steering angle of the steering wheel. In lane keeping assist operation to prevent the vehicle from leaving its lane, the steering reaction force is calculated based on the feedforward axial force instead of the feedback axial force.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 5994868

[0006] Consider vehicles with steer-by-wire systems that also possess driver assistance controls to aid in driving. For example, the driver assistance controls automatically steer the vehicle without driver input. In this case, the driver may experience discomfort due to unexpected vehicle behavior. Summary of the Invention

[0007] One object of this disclosure is to provide a technology that can transmit the vehicle steering direction obtained through driver assistance control to the driver in a vehicle with a steering-by-wire system.

[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] Driving assistance steering is the direction of vehicle steering obtained through driving assistance control.

[0012] Linkage reaction force control includes feedforward reaction force control that rotates the steering wheel in the same direction as the driving assistance direction, independent of the steering wheel's 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] Driving assistance steering is the direction of vehicle steering obtained through driving assistance control.

[0016] Linkage reaction force control includes feedforward reaction force control that rotates the steering wheel in the same direction as the driving assistance direction, independent of the steering wheel's steering angle.

[0017] Invention Effects

[0018] According to this disclosure, a linkage reaction force control is implemented that applies a steering reaction force component to the steering wheel in conjunction with vehicle steering control via driver assistance control. The linkage reaction force control includes feedforward reaction force control that rotates the steering wheel in the same direction as the driver assistance direction (the vehicle steering direction obtained through driver assistance control) regardless of the steering angle of the steering wheel. This feedforward reaction force control effectively transmits the driver assistance direction to the driver, thereby reducing discomfort experienced by the driver. 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 illustrating an example of linkage reaction force control in implementing the method.

[0025] Figure 7 This is a block diagram illustrating another example of linkage reaction force control for implementing the method.

[0026] Figure 8 This is a block diagram illustrating a first example of a driving assistance direction acquisition unit according to an embodiment.

[0027] Figure 9 This is a time diagram illustrating an example of feedforward reaction force control for the linkage reaction force control implementation method.

[0028] Figure 10 This is a block diagram illustrating a second example of a driving assistance direction acquisition unit according to an embodiment.

[0029] Figure 11 This is a conceptual diagram used to illustrate a variation of the implementation method.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1 vehicle

[0032] 2 wheels

[0033] 3. Steering wheel

[0034] 10 Vehicle Control System

[0035] 20. Steering mechanism

[0036] 30. Reaction force device

[0037] 40 Driving Environment Information Acquisition Device

[0038] 50 Vehicle Status Sensors

[0039] 60 Identification Sensors

[0040] 100 Control device

[0041] 110 processor

[0042] 120 storage devices

[0043] 200 Steering Control Unit

[0044] 300 Reaction Force Control Unit

[0045] 310 Linkage Reaction Force Control Unit

[0046] 310_FB Feedback Reaction Force Control Unit

[0047] 310_FF Feedforward Reaction Force Control Unit

[0048] 320 Pilot's rudder angle acquisition unit

[0049] 330 Differential Calculation Unit

[0050] 340 Control Quantity Calculation Department

[0051] 350 Driving Assistance Direction Acquisition Unit

[0052] 360° Control Quantity Calculation Department

[0053] 370 Addition Department

[0054] 400 Driver Assistance Control Unit

[0055] Da Driving Assistance Direction

[0056] δx (Driver's steering angle)

[0057] δy is the system's rudder angle. Detailed Implementation

[0058] The embodiments of this disclosure will be described with reference to the accompanying drawings.

[0059] 1. Vehicle control system

[0060] 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).

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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).

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 2. Steering control

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 3. Reaction force control

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 4. Driver Assistance Control

[0083] 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).

[0084] 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 and 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).

[0085] 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.

[0086] Figure 3 This 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.

[0087] 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.

[0088] Figure 5This 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 in the direction of lane center LC. Steering control is performed via the aforementioned steering control unit 200.

[0089] 5. Coordination between driver assistance control and reaction force control

[0090] 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".

[0091] 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 driver assistance system during operation. To this end, the linkage reaction force control applies a steering reaction force component to the steering wheel 3 to make it follow the steering of the vehicle 1 controlled by the driver assistance system. By rotating the steering wheel 3, the driver can know the steering direction of the target obtained through the driver assistance system. In other words, the linkage reaction force control can transmit (notify) the steering direction of the vehicle 1 obtained through the driver assistance system to the driver.

[0092] The following is a more detailed explanation of the linkage reaction force control in this embodiment.

[0093] 5-1. Feedback Reaction Force Control

[0094] Figure 6 This is a block diagram illustrating an example of the linkage reaction force control in this embodiment. 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.

[0095] exist Figure 6In the example shown, the linkage reaction force control unit 310 includes a feedback reaction force control unit 310_FB. The feedback reaction force control unit 310_FB includes a driver steering angle acquisition unit 320, a differential calculation unit 330, and a control quantity calculation unit 340.

[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 330 calculates the difference (deviation) between the driver's steering angle δx and the system steering angle δy.

[0099] The control quantity calculation unit 340 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 340 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] in this way, Figure 6 The illustrated linkage reaction force control (feedback reaction force control) will cause the steering wheel 3 to follow the steering reaction force component of the vehicle 1's steering wheel movement controlled by the driver assistance system. By rotating the steering wheel 3, the driver can know the steering direction of the target obtained through the driver assistance control.

[0102] However, it is also necessary to consider the situation where even if the driver assistance control performs a turn on vehicle 1, this turn is not reflected in the rotation of steering wheel 3. For example, consider the case where the change in the system steering angle δy requested by the driver assistance control is small. When the steering wheel 3 is to be rotated, static friction acts on the steering shaft 4 connected to the steering wheel 3. Such static friction is generated, for example, by components such as gears in the steering column. If the change in the system steering angle δy is small, and the target control quantity CON_C obtained through the linkage reaction force control is small, it is possible that the steering reaction force applied to steering wheel 3 does not exceed the static friction force, and thus steering wheel 3 will not rotate. Suppose that the gain is set high when calculating the target control quantity CON_C in the control quantity calculation unit 340, then when the driver intends to turn the steering wheel 3, a stronger steering reaction force will be applied in the direction that hinders the driver's steering. The driver will feel uncomfortable with such steering reaction force control that hinders the driver's steering, therefore there is a limit in the gain setting. Furthermore, in vehicle 1 with a steering-by-wire system, there is a tendency for the steering angle θs of the steering wheel 3 to be smaller relative to the steering angle of the wheel 2 in order to achieve a sensitive gear ratio setting. Therefore, even if the actual steering angle δa of the wheel 2 follows the system steering angle δy, the steering wheel 3 may not rotate if the system steering angle δy changes only slightly. When the steering wheel 3 does not rotate and only vehicle behavior occurs, the driver may experience discomfort due to a lack of integration between the steering wheel 3 and the vehicle's behavior.

[0103] Therefore, the linkage reaction force control in this embodiment can also include "feedforward reaction force control" as described below.

[0104] 5-2. Feedforward reaction force control

[0105] Figure 7 This is a block diagram illustrating another example of the linkage reaction force control in this embodiment. In addition to the feedback reaction force control unit 310_FB described above, the linkage reaction force control unit 310 also includes a feedforward reaction force control unit 310_FF and an adder unit 370.

[0106] As described above, the feedback reaction force control unit 310_FB calculates the driver's steering angle δx corresponding to the steering angle θs of the steering wheel 3, and calculates the target control quantity CON_C for linkage reaction force control based on the difference between the driver's steering angle δx and the system steering angle δy. For convenience, the target control quantity CON_C calculated by this feedback reaction force control unit 310_FB is referred to as "FB target control quantity CON_FB".

[0107] On the other hand, the feedforward reaction force control unit 310_FF calculates the target control quantity CON_C for linkage reaction force control independently of the steering angle θs of the steering wheel 3. For convenience, the target control quantity CON_C calculated by the feedforward reaction force control unit 310_FF is referred to as "FF target control quantity CON_FF".

[0108] The addition unit 370 calculates the target control quantity CON_C for linkage reaction force control by adding the FB target control quantity CON_FB and the FF target control quantity CON_FF.

[0109] More specifically, the feedforward reaction force control unit 310_FF includes a driving assistance direction acquisition unit 350 and a control quantity calculation unit 360.

[0110] The driving assistance direction acquisition unit 350 processes information to acquire the driving assistance direction Da. The driving assistance direction Da refers to the steering direction of the vehicle 1 (wheel 2) obtained through driving assistance control. That is, the driving assistance direction Da is either left or right. The driving assistance direction Da can also be represented numerically. For example, Da = 1 indicates either left or right, and Da = -1 indicates the other. An example of the driving assistance direction acquisition processing performed by the driving assistance direction acquisition unit 350 will be described later.

[0111] The control quantity calculation unit 360 calculates the target control quantity CON_FF for steering wheel 3 in the direction of driving assistance Da. Specifically, the control quantity calculation unit 360 calculates the target control quantity CON_FF for generating the steering reaction force component that rotates the steering wheel 3 in the same direction as the driving assistance direction Da. Here, the steering reaction force component (absolute value) that rotates the steering wheel 3 in the same direction as the driving assistance direction Da is set to a value greater than the static friction force acting on the steering shaft 4 connected to the steering wheel 3. The static friction force is known in advance by measurement and simulation. The steering reaction force component that is greater than the static friction force can also be a constant value.

[0112] As explained above, the feedforward reaction force control unit 310_FF performs feedforward reaction force control to rotate the steering wheel 3 in the same direction as the driving assistance direction Da, independent of the steering angle θs of the steering wheel 3. This feedforward reaction force control effectively transmits (notifies) the driving assistance direction Da to the driver. Even with minimal changes in the system steering angle δy requested by the driving assistance control, it is easy to rotate the steering wheel 3 in the same direction as the driving assistance direction Da. This reduces discomfort experienced by the driver.

[0113] 5-3. Example of driver assistance direction acquisition processing

[0114] 5-3-1. The first example

[0115] Figure 8 This is a block diagram illustrating a first example of a driver assistance direction acquisition unit 350. The driver assistance direction acquisition unit 350 acquires the system steering angle δy from the driver assistance control unit 400 and determines the driver assistance direction Da based on the system steering angle δy. More specifically, the driver assistance direction acquisition unit 350 includes a differential section 351 and a sign conversion section 352.

[0116] Differential part 351 obtains the system steering angle δy and calculates the system steering angular velocity ωy by differentiating the system steering angle δy.

[0117] If the system steering angular velocity ωy is positive, the sign conversion unit 352 outputs +1; if the system steering angular velocity ωy is negative, the sign conversion unit 352 outputs -1. The output of this sign conversion unit 352 is used as the driving assistance direction Da. Da = 1 indicates either the left or right direction, and Da = -1 indicates the other direction.

[0118] The control quantity calculation unit 360 calculates the target control quantity CON_FF by multiplying the driving assistance direction Da by a specified gain.

[0119] Figure 9 This is a time diagram used to illustrate an example of feedforward reaction force control. Figure 9 The diagram shows the time variations of the system steering angle δy, system steering angular velocity ωy, driver assistance direction Da (or FF target control quantity CON_FF), steering wheel 3 steering angle θs, and system steering angle θy. The system steering angle θy is the value obtained by converting the system steering angle δy into a steering angle. For example... Figure 9 As shown, the steering angle θs also changes in the direction of the system steering angle δy (system steering angle θy). That is, the steering wheel 3 turns in the same direction as the driving assistance direction Da. Therefore, the driver can know the driving assistance direction Da of the target obtained through driving assistance control.

[0120] It should be noted that in determining the driving assistance direction Da, the system steering angle θy, obtained by converting the system steering angle δy into a steering angle, can also be used instead of the system steering angle δy. Even in this case, the driving assistance direction acquisition unit 350 still determines the driving assistance direction Da based on the system steering angle δy.

[0121] Based on the first example, the switching of the driving assistance direction Da can be quickly determined based on the system steering angle δy.

[0122] 5-3-2. Second example

[0123] Figure 10This is a block diagram illustrating a second example of the driver assistance direction acquisition unit 350. In this second example, the driver assistance direction Da is notified to the driver assistance direction acquisition unit 350 from the driver assistance control unit 400. That is, the driver assistance direction acquisition unit 350 directly acquires the information of the driver assistance direction Da from the driver assistance control unit 400. The driver assistance control unit 400 can then determine the target trajectory TRJ (refer to...) based on its own determined trajectory. Figure 3 To identify the driving assistance direction Da in the near future.

[0124] 5-4. Variations

[0125] like Figure 11 As shown, when switching the driving assistance direction Da, the control quantity calculation unit 360 can also gradually change the target control quantity CON_FF. This prevents abrupt changes in steering reaction force when switching the driving assistance direction Da.

[0126] The linkage reaction force control unit 310 may also exclude the feedback reaction force control unit 310_FB and only include the feedforward reaction force control unit 310_FF.

[0127] 5-5. Effects

[0128] 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 linkage reaction force control includes feedforward reaction force control that rotates the steering wheel 3 in the same direction as the driver assistance direction Da, independent of the steering angle θs of the steering wheel 3. This feedforward reaction force control effectively transmits (notifies) the driver of the driver assistance direction Da. Even when the change in the system steering angle δy requested by the driver assistance control is small, it is easy to rotate the steering wheel 3 in the same direction as the driver assistance direction Da. By rotating the steering wheel 3, the driver can know the driver assistance direction Da, that is, the driver can know the steering direction of the target obtained through driver assistance control. This reduces discomfort experienced by the driver.

Claims

1. A vehicle control system that controls a vehicle of a steer-by-wire type, the vehicle control system includes one or more processors, the one or more processors are configured to execute: a drive assist control that assists driving of the vehicle; and a linked reaction force control that imparts a steering reaction force component to a steering wheel in linkage with turning of the vehicle by the drive assist control, a system turning angle is a target turning angle requested by the drive assist control, a drive assist direction is a turning direction of the vehicle by the drive assist control, the linked reaction force control includes a feedforward reaction force control that turns the steering wheel in the same direction as the drive assist direction regardless of magnitudes of a steering angle of the steering wheel and the system turning angle.

2. The vehicle control system according to claim 1, wherein the feedforward reaction force control includes: a drive assist direction acquisition process that acquires information of the drive assist direction; and a process that imparts the steering reaction force component that turns the steering wheel in the same direction as the drive assist direction to the steering wheel.

3. The vehicle control system according to claim 2, wherein the drive assist direction acquisition process includes: a process that acquires the system turning angle that is the target turning angle requested by the drive assist control; and a process that determines the drive assist direction based on the system turning angle.

4. The vehicle control system according to claim 3, wherein the drive assist direction acquisition process includes a process that calculates a system turning angular velocity by differentiating the system turning angle, and determines the drive assist direction based on the system turning angular velocity.

5. The vehicle control system according to any one of claims 1 to 4, wherein the steering reaction force component by the feedforward reaction force control is set to a value larger than a static friction force that acts on a steering shaft that is connected to the steering wheel.

6. The vehicle control system according to any one of claims 1 to 4, wherein the linked reaction force control further includes a feedback reaction force control, the feedback reaction force control includes: a process that acquires a driver turning angle that is a target turning angle corresponding to the steering angle of the steering wheel; a process that acquires the system turning angle that is the target turning angle requested by the drive assist control; and a process that imparts a steering reaction force component in a direction that reduces a difference between the driver turning angle and the system turning angle to the steering wheel.

7. A vehicle control method that controls a vehicle of a steer-by-wire type, including: a drive assist control that assists driving of the vehicle; and a linked reaction force control that imparts a steering reaction force component to a steering wheel in linkage with turning of the vehicle by the drive assist control, a system turning angle is a target turning angle requested by the drive assist control, a drive assist direction is a turning direction of the vehicle by the drive assist control, ​ The linkage reaction force control includes a feedforward reaction force control that turns the steering wheel in the same direction as the driving assist direction regardless of the magnitude of the steering angle of the steering wheel and the system turning angle. The linkage reaction force control includes a feedforward reaction force control that turns the steering wheel in the same direction as the driving assist direction regardless of the magnitude of the steering angle of the steering wheel and the system turning angle.

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