Vehicle control method and vehicle control device

Abstract

To provide a vehicle control method and a vehicle control device capable of shortening a braking distance when executing braking control in a state where a vehicle deviates from a traveling road.SOLUTION: Based on a current position of the vehicle and a boundary of the travel road, it is determined whether the vehicle has deviated from the travel road, and when it is determined that the vehicle has deviated from the travel road, steering control is executed such that the vehicle follows an emergency target trajectory along a direction of a current speed vector of the vehicle, and braking control of the vehicle is executed with a predetermined maximum braking force.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle control method and a vehicle control device. [Background technology]

[0002] A technology is known in which, when it is determined that the vehicle is in a deviation state from the target trajectory, the maximum value of the suppression amount for reducing the target vehicle speed is maintained, and when the vehicle returns from the deviation state to the target trajectory and a release condition is met, the maintained value of the suppression amount is reduced at a predetermined speed (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-175257 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology disclosed in Patent Document 1 has the problem that when braking control is performed in a deviation state, braking control is performed while steering control is performed to return to the target trajectory, so that braking force is distributed to the left and right of the vehicle, reducing braking force in the forward and backward directions, making it impossible to shorten the braking distance.

[0005] The problem to be solved by the present invention is to provide a vehicle control method and a vehicle control device that can shorten the braking distance when braking control is executed while the vehicle is deviating from the road. [Means for solving the problem]

[0006] The present invention solves the above problem by determining whether the vehicle has deviated from the lane based on the vehicle's current position and the boundary of the lane, and if it is determined that the vehicle has deviated from the lane, performing steering control so that the vehicle follows an emergency target trajectory along the direction of the vehicle's current velocity vector, and performing vehicle braking control with a predetermined maximum braking force. [Effects of the Invention]

[0007] According to the present invention, when braking control is executed in a state where the vehicle has deviated from the road, the braking distance can be shortened. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a vehicle control system including a vehicle control device according to the present invention. [Figure 2] FIG. 2 is a diagram showing a scene in which lane departure determination and target trajectory correction according to this embodiment are performed. [Figure 3] FIG. 3 is a diagram showing a scene in which lane departure determination and target trajectory correction according to this embodiment are performed. [Figure 4] FIG. 4 is a diagram showing a scene in which lane departure determination and target trajectory correction according to this embodiment are performed. [Figure 5] FIG. 5 is a block diagram showing an example of a functional unit included in the target trajectory correction unit according to this embodiment. [Figure 6] FIG. 6 is an example of a flowchart showing the procedure of the vehicle control method according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] FIG. 1 is a block diagram showing a vehicle control system including a vehicle control device according to the present invention. The vehicle control system 100 is an in-vehicle system that drives a vehicle using autonomous driving control. Autonomous driving control refers to autonomously controlling the driving behavior of a vehicle using a vehicle control device 1, and the driving behavior includes all driving behaviors such as acceleration, deceleration, starting, stopping, steering to the right or left, changing lanes, and pulling over. Furthermore, autonomously controlling driving behavior refers to the vehicle control device 1 controlling the driving behavior using a device in the vehicle. In other words, the vehicle control device 1 intervenes in and controls these driving behaviors within a predetermined range. Driving behaviors that are not intervened in are manually operated by the driver.

[0011] Vehicle control system 100 can be applied not only to vehicle driving under autonomous driving control, but also to assisting vehicle driving under manual driving by a driver. When vehicle control system 100 is applied to autonomous vehicle driving control, it can be applied to cases where both speed control and steering control are autonomously controlled, or where one of speed control and steering control is autonomously controlled and the other is manually controlled.

[0012] 1, the vehicle control system 100 includes a vehicle control device 1, a vehicle position detection device 2, a map DB 3, a detection device 4, and a drive mechanism 5. These devices included in the vehicle control system 100 are in-vehicle devices, are connected by a CAN or other in-vehicle LAN, and can exchange information with each other.

[0013] The vehicle position detection device 2 acquires the current position of the vehicle. The vehicle position detection device 2 is composed of, for example, a GPS unit, a gyro sensor, etc. The vehicle position detection device 2 detects radio waves transmitted from multiple satellite communications using the GPS unit to periodically acquire vehicle position information, and detects the current position of the vehicle based on the acquired vehicle position information, angle change information acquired from the gyro sensor, and vehicle speed acquired from the vehicle speed sensor. The vehicle position detection device 2 also acquires, for example, the position of the vehicle within the road (the lateral position of the vehicle in the left-right direction) as the current position of the vehicle. For example, the vehicle position detection device 2 recognizes the road surface around the vehicle from a camera image and estimates the lateral position of the vehicle within the road. The lateral position of the vehicle within the road is determined, for example, based on the position of the center of gravity of the vehicle. The lateral position of the vehicle may also be determined based on the positions of the left and right sides of the vehicle. The detection information of the vehicle position detection device 2 is acquired by the vehicle control device 1 at predetermined time intervals.

[0014] The map DB3 is a high-precision three-dimensional map that describes road structures, including road surface markings that indicate lanes and destinations. The map DB3 is a database containing information used for generating a target trajectory and / or controlling vehicle travel. The map DB3 includes two-dimensional and / or three-dimensional position information for each map coordinate, road information for each map coordinate, lane boundary information, road attribute information, lane incline / descent information, lane identification information, destination lane information, facility information, and attribute information thereof. The road information includes information such as road width, curvature radius, road shoulder structures, road traffic regulations (speed limits, lane change permission / prohibition), road merging points, branching points, and locations where the number of lanes increases or decreases. The map DB3 may be stored in a readable state on a recording medium provided in the vehicle control device 1 or a server device, as well as in an on-board device.

[0015] The map DB3 also includes information on lane boundaries, which indicate the boundaries between the lane in which the host vehicle is traveling and other lanes. Lane boundaries exist on both the left and right sides of the host vehicle's direction of travel. The form of lane boundaries is not particularly limited, and examples thereof include road markings and road structures. Examples of lane boundaries that are road markings include lane boundary lines and centerlines. Examples of road boundary structures include medians, guardrails, curbs, tunnels, and expressway sidewalls. Note that lane boundaries are preset in the map DB3 for points where lane boundaries cannot be clearly identified (e.g., within intersections). The preset lane boundaries are imaginary road boundaries and are not actually existing road markings or road structures. The map DB3 also includes information on the coordinate positions of drivable areas in which the vehicle can travel without coming into contact with static objects that are obstacles. Obstacles are objects that may affect the vehicle's travel.

[0016] The detection device 4 is a device that detects various types of information. The detection device 4 includes sensors for detecting the driving environment around the vehicle. The driving environment around the vehicle includes objects around the vehicle. The objects include static objects and dynamic objects. Static objects include, for example, lane markings on roads, zebra strips, center lines, road markings, medians, guardrails, curbs, highway sidewalls, road signs, traffic lights, crosswalks, construction sites, accident sites, traffic restrictions, advertising billboards, road signs, road trees, buildings, and road structures. Dynamic objects include automobiles (other vehicles) other than vehicles, motorcycles, bicycles, and pedestrians. Objects also include obstacles. The detection device 4 acquires the position, attitude (orientation), and speed of detected objects.

[0017] The detection device 4 includes, for example, a camera and / or LiDAR. The detection information of the detection device 4 is acquired by the vehicle control device 1 at predetermined time intervals. The vehicle control device 1 acquires information about objects around the vehicle from the detection device 4. The camera recognizes objects around the vehicle using images. LiDAR is an example of a sensor that detects the three-dimensional shape of the road surface around the vehicle. The camera and / or LiDAR detects a drivable area in which the vehicle can travel without coming into contact with obstacles, with static and dynamic objects considered as obstacles. The detection device 4 may also include a ranging device for calculating the relative distance and relative speed between the vehicle and surrounding objects (a preceding vehicle, an obstacle). The ranging device is, for example, a laser radar, a LIDAR, or the like. A plurality of these devices may be provided in one vehicle.

[0018] The detection device 4 includes sensors for detecting the vehicle state of the vehicle. The vehicle state of the vehicle includes, for example, information on the vehicle speed and slip angle of the vehicle. For example, these sensors are a vehicle speed sensor and a slip angle sensor. The vehicle speed sensor measures the rotation speed of the drivetrain, such as the drive shaft, and detects the running speed of the vehicle (hereinafter also referred to as vehicle speed) based on this. The slip angle sensor detects the slip angle based on the difference between the wheel speed and body speed of the vehicle. The detection information of the detection device 4 is acquired by the vehicle control device 1 at predetermined time intervals.

[0019] The vehicle control device 1 is a device that controls the running of a vehicle by controlling and cooperating with devices included in the vehicle control system 100. In this embodiment, the vehicle control device 1 includes a processor 10, which realizes a vehicle control function. The processor 10 is a computer that includes a ROM that stores a program, a CPU that is an operating circuit that functions as the vehicle control device 1 by executing the program stored in the ROM, and a RAM that functions as an accessible storage device.

[0020] The processor 10 electronically controls the drive mechanism 5, which governs the operation of the vehicle. The processor 10 controls the drive mechanism 5 to drive the vehicle so that it follows a target trajectory at a target speed. The target trajectory is the trajectory along which the vehicle travels within a road. The drive mechanism 5 includes an electric motor and / or an internal combustion engine as a driving source, a power transmission device including a drive shaft and an automatic transmission that transmits output from these driving sources to the drive wheels, a drive device that controls the power transmission device, and a braking device that brakes the wheels. The processor 10 calculates the target speed, generates a control signal including a braking / driving force command value so that the vehicle speed becomes the target speed, and sends the control signal to the drive mechanism 5. The drive device and braking device perform braking / driving control of the vehicle based on the control signal obtained from the processor 10.

[0021] The processor 10 controls the steering device included in the drive mechanism 5 so that the vehicle travels while maintaining a predetermined lateral position relative to the target trajectory. The steering device is equipped with a steering actuator. The steering actuator includes a motor attached to the steering column shaft, etc. The processor 10 generates a target trajectory, generates a control signal including a steering angle command value so that the vehicle follows the target trajectory, and sends the control signal to the drive mechanism 5. The steering device performs steering control of the vehicle based on the control signal obtained from the processor 10. Below, details of each functional unit of the processor 10 according to this embodiment will be described.

[0022] The processor 10 includes, as functional blocks, a drivable area information acquisition unit 11, a lane boundary generation unit 12, a lane departure determination unit 13, a target trajectory generation unit 14, a target speed generation unit 15, a target trajectory correction unit 16, a target speed correction unit 17, a trajectory tracking control unit 18, and a speed tracking control unit 19. The processor 10 of this embodiment executes each function through cooperation between the above-mentioned hardware and software for realizing each function or executing each process.

[0023] The drivable area information acquisition unit 11 acquires information on drivable areas outside the roadway where the vehicle can travel, based on obstacle information acquired from the map DB 3 and the detection device 4. Acquisition of drivable area information may be performed, for example, when the vehicle deviates from the roadway, or may be performed periodically before the vehicle deviates from the roadway. A drivable area is an area in which the vehicle can travel without coming into contact with an obstacle. For example, the drivable area information acquisition unit 11 acquires drivable area information from the map DB 3. The map DB 3 includes coordinate positions of the drivable area. The drivable area information acquisition unit 11 may acquire drivable area information from a camera provided in the detection device 4. The drivable area information acquisition unit 11 may acquire drivable area information from a sensor (for example, LiDAR) that detects the three-dimensional shape of the road surface around the vehicle.

[0024] The lane boundary generation unit 12 executes lane boundary generation processing to generate the boundary of the lane along which the vehicle will travel, based on the current position of the vehicle and information from the map DB3. The lane boundary generation unit 12 acquires surrounding lane information, including information ahead of the vehicle, from the map DB3. For example, the lane boundary generation unit 12 acquires lane information including the lane boundary lines of the lane along which the host vehicle is traveling. The lane information includes the position of the lane and the width of the lane. Alternatively, the lane boundary generation unit 12 may acquire lane information including the lane boundary lines of the host lane from an image of the surroundings of the vehicle captured by a camera included in the detection device 4. The lane boundary generation unit 12 generates the boundary of the lane along the acquired lane boundary lines of the host lane. In other words, the lane is the area between the left and right lane boundary lines of the host lane.

[0025] The lane deviation determination unit 13 performs lane deviation determination to determine whether the vehicle has deviated from the lane based on the current position of the vehicle and the lane boundary. Specifically, the lane deviation determination unit 13 acquires the current position of the vehicle from the vehicle position detection device 2 and acquires the boundary of the lane on which the vehicle is traveling from the lane boundary generation unit 12. For example, the current position is the center of gravity of the vehicle. When the center of gravity is located outside either the left or right boundary of the lane, the lane deviation determination unit 13 determines whether the vehicle has deviated from the lane based on the target distance between the center of gravity and the left or right boundary closest to the center of gravity. More specifically, the lane deviation determination unit 13 determines that the vehicle has deviated from the lane when the target distance is equal to or greater than a predetermined distance threshold set based on the vehicle width. The predetermined distance threshold is, for example, a distance equivalent to the vehicle width. Alternatively, the current position may be, for example, a position on the side of the vehicle. When the side position of the vehicle is located outside the boundary of the lane in either the left or right direction of the vehicle, the lane deviation judgment unit 13 judges whether the vehicle has deviated from the lane depending on the target distance between the side position and the boundary on either the left or right side that is closest to the side position.

[0026] An example of lane deviation determination according to this embodiment will now be described with reference to FIGS. 2 to 4. FIG. 2 is a diagram showing a scene in which lane deviation determination and target trajectory correction according to this embodiment are performed. In FIG. 2, a target trajectory T is set within the lane R between the left boundary Bl and the right boundary Br. The vehicle V1 moves away from the target trajectory T and is positioned outside the right boundary Br of the lane R. As shown in FIG. 2, the distance between the center of gravity Pg of the vehicle V1 and the position Pr on the right boundary Br that is closest to the center of gravity Pg is calculated as the target distance Td. The lane deviation determination unit 13 determines whether the vehicle V1 has deviated from the lane R according to the target distance Td.

[0027] FIG. 3 is a diagram showing a scene in which lane deviation determination and target trajectory correction according to this embodiment are performed. In FIG. 3, as in FIG. 2, a target trajectory T is set within the lane R between the left boundary Bl and the right boundary Br. The vehicle V1 moves away from the target trajectory T and is positioned outside the right boundary Br of the lane R. As shown in FIG. 3, the distance between the position Ps of the left side surface of the vehicle V1 and the position Pr on the right boundary Br that is closest to the position Ps of the left side surface of the vehicle V1 is calculated as the target distance Td. The lane deviation determination unit 13 determines whether the vehicle V1 has deviated from the lane R according to the target distance Td.

[0028] FIG. 4 is a diagram illustrating a scenario in which lane deviation determination and target trajectory correction according to this embodiment are performed. In FIG. 4, similar to FIGS. 2 and 3, a target trajectory T is set within the lane R between the left boundary Bl and the right boundary Br. A return area RA and an emergency deceleration area EA are set outside the lane boundaries Bl and Br. The return area RA is an area where a portion of the vehicle V1 is located within the lane R. When the vehicle V1 is in the return area RA, the target trajectory correction unit 16 generates a return target trajectory RT for the vehicle V1 to return to the lane R. The emergency deceleration area EA is an area where the entire vehicle V1 is located outside the lane R. When the vehicle V1 is in the emergency deceleration area EA, the target trajectory correction unit 16 generates an emergency target trajectory ET. In the left diagram of FIG. 4, the center of gravity position Pg of the vehicle V1 is located within the return area RA, and a portion of the vehicle V1 is located within the lane R. In this case, it is determined that the vehicle V1 has not deviated from the lane R, and the target trajectory correction unit 16 generates a return target trajectory RT. 4, the center of gravity position Pg of the vehicle V1 is located outside the return area RA (within the emergency deceleration area EA), and the entire vehicle V1 is located outside the road R. In this case, it is determined that the vehicle has deviated from the road R, and the target trajectory correction unit 16 generates an emergency target trajectory ET.

[0029] Furthermore, when it is determined that the vehicle has deviated from the lane, the lane departure determination unit 13 may determine whether or not the deviated vehicle can return to the lane. For example, the lane departure determination unit 13 determines whether or not the vehicle can return to the lane in a drivable area outside the lane based on information about the drivable area. The determination of whether or not the vehicle can return to the lane may be performed before it is determined that the vehicle has deviated from the lane and the target trajectory is changed to the emergency target trajectory, or may be performed while braking control is being executed after the target trajectory is changed to the emergency target trajectory.

[0030] The target trajectory generation unit 14 generates a target trajectory based on the boundary of the road located ahead of the vehicle. More specifically, the target trajectory generation unit 14 generates a target trajectory within the road. For example, the target trajectory generation unit 14 generates a target trajectory along the center line between the left and right boundaries of the road. The target trajectory generated by the target trajectory generation unit is a target trajectory during normal driving before the vehicle deviates from the road, and is a target trajectory for the vehicle to travel within the road. The target trajectory is, for example, a trajectory that has a predetermined trajectory length and curvature, starting from the center of gravity of the vehicle.

[0031] The target speed generation unit 15 generates a target speed based on the target trajectory generated by the target trajectory generation unit 14 and detection information obtained by detecting the driving environment around the vehicle. The driving environment around the vehicle includes, for example, a preceding vehicle, an obstacle, etc. The target speed generated by the target speed generation unit 15 is a target speed during normal driving before the vehicle deviates from the road, and is a target speed for the vehicle to drive on the road.

[0032] When it is determined that the vehicle has deviated from the traveling path, the target trajectory correction unit 16 executes a target trajectory correction process to change the target trajectory to an emergency target trajectory that is aligned with the direction of the vehicle's current velocity vector. That is, the emergency target trajectory is a straight-line trajectory that extends in the direction of the vehicle's current velocity vector. An example of a method for generating an emergency target trajectory will be described with reference to FIG. 2. In the example of FIG. 2, the target trajectory correction unit 16 acquires the direction Vd (dashed line in FIG. 2) of the velocity vector of the vehicle V1 from the detection information of the vehicle state, starting from the center of gravity position Pg of the vehicle V1. The direction of the vehicle's velocity vector is, for example, the angle of the direction of the vehicle's velocity vector with respect to the longitudinal direction of the vehicle. The target trajectory correction unit 16 generates a straight-line trajectory that is aligned with the direction Vd of the velocity vector of the vehicle V1 as the emergency target trajectory ET. At this time, the curvature of the emergency target trajectory is 0. The trajectory length of the emergency target trajectory is set based on the trajectory length of the previous target trajectory.

[0033] Furthermore, the target trajectory correction unit 16 may transition the target trajectory from the target trajectory before change (target trajectory during normal driving) to the emergency target trajectory by gradually changing the curvature of the target trajectory. This is to prevent the trajectory on which the vehicle travels from changing significantly and causing the vehicle to suddenly steer if the target trajectory during normal driving is changed to the emergency target trajectory all at once. Here, a method for changing the curvature of the target trajectory will be explained. The target trajectory correction unit 16 acquires the curvature ρ of the previous target trajectory, and continuously changes the target curvature ρ so that the curvature of the target trajectory gradually becomes 0 from ρ. * The rate of change of the curvature is preset. The previous target trajectory is a target trajectory for normal driving generated by the target trajectory generating unit 14, and is the trajectory that the vehicle was following before it was determined that the vehicle had deviated from the road. The target trajectory correcting unit 16 calculates the target curvature ρ * Each time the target curvature ρ * A new target trajectory is generated based on the target curvature ρ, and the target trajectory is updated to the newly generated target trajectory. * Then, the target trajectory is generated as follows: *becomes 0, the curvature of the target trajectory becomes 0 and coincides with the emergency target trajectory. Furthermore, the target trajectory correction unit 16 may change the curvature of the target trajectory while limiting the rate of change of the curvature of the target trajectory based on the vehicle body yaw resonance and the steering constraint so that the rate of change does not exceed a predetermined limit rate of change. For example, the limit rate of change is a value set so that steering control is performed in a state where the vehicle body yaw resonance frequency of the vehicle is maintained below a predetermined frequency. Furthermore, the limit rate of change may be a value set so that steering control is performed in a state where a predetermined steering constraint is satisfied, for example, the steering angular velocity of the vehicle is maintained below a predetermined steering angular velocity.

[0034] Furthermore, the target trajectory correction unit 16 may change the position of the emergency target trajectory when there is an obstacle in the direction of the current velocity vector of the vehicle. More specifically, the target trajectory correction unit 16 updates the position of the emergency target trajectory so as to avoid the obstacle, and changes the target trajectory to the updated emergency target trajectory. A method of updating the position of the emergency target trajectory so as to avoid the obstacle is, for example, to rotate the trajectory from the center of gravity position of the vehicle as a starting point and set the emergency target trajectory at a position a predetermined distance away from the obstacle. Furthermore, when there is an obstacle in the direction of the current velocity vector of the vehicle, the target trajectory correction unit 16 may relax the limit on the change speed so that the obstacle can be avoided by steering control.

[0035] Furthermore, when it is determined that the vehicle can return to the lane, the target trajectory correction unit 16 may generate a return target trajectory for the vehicle to return to the lane.

[0036] When it is determined that the vehicle has deviated from the road, the target speed correction unit 17 sets the target speed to 0 km / hour in order to stop the vehicle.

[0037] The trajectory tracking control unit 18 executes steering control of the vehicle so that the vehicle follows the target trajectory. The trajectory tracking control unit 18 controls the steering device so that the vehicle travels while maintaining a predetermined lateral position with respect to the target trajectory. Specifically, the trajectory tracking control unit 18 generates a control signal including a steering angle command value so that the vehicle follows the target trajectory, and sends the control signal to the drive mechanism 5.

[0038] Furthermore, when the trajectory tracking control unit 18 determines that the vehicle has deviated from the traveling path, it executes steering control so that the vehicle follows the emergency target trajectory. The trajectory tracking control unit 18 controls the steering device so that the vehicle travels while maintaining a predetermined lateral position with respect to the emergency target trajectory. Furthermore, when the trajectory tracking control unit 18 determines that the vehicle can return to the traveling path, it changes the target trajectory to a return target trajectory and then executes steering control so that the vehicle follows the return target trajectory.

[0039] The speed tracking control unit 19 executes braking / driving control of the vehicle so that the vehicle speed becomes the target speed. The speed tracking control unit 19 generates a control signal including a braking / driving force command value so that the vehicle speed becomes the target speed, and sends the control signal to the drive mechanism 5.

[0040] Furthermore, when it is determined that the vehicle has deviated from the road, the speed tracking control unit 19 changes the target trajectory and then executes braking control of the vehicle with a predetermined maximum braking force. More specifically, the speed tracking control unit 19 generates a control signal including a braking / driving force command value so that the vehicle stops, i.e., so that the vehicle speed becomes 0 km / h.

[0041] Here, the processing procedure for target trajectory correction according to this embodiment will be described with reference to Fig. 5. Fig. 5 is a block diagram showing an example of functional units provided in the target trajectory correction unit according to this embodiment. As shown in Fig. 5, the target trajectory correction unit 16 includes, as functional units, a trajectory length calculation unit 160, a target curvature setting unit 161, an emergency trajectory generation unit 162, and a switching unit 163.

[0042] First, the lane deviation determination unit 13 acquires the current position of the vehicle and the boundary of the lane, and determines whether or not the vehicle has deviated from the lane based on the current position of the vehicle and the boundary of the lane. If the lane deviation determination unit 13 determines that the vehicle has deviated from the lane, it outputs an emergency deceleration request indicating a request for emergency deceleration to the switching unit 163 and the target speed correction unit 17. The target trajectory generation unit 14 generates a target trajectory for the vehicle to travel in the lane under normal circumstances, and outputs it to the trajectory tracking control unit 18. The target trajectory is a coordinate position in the X and Y coordinates (X T * , Y T * ) The trajectory length calculation unit 160 acquires the previous target trajectory, calculates the trajectory length s of the previous target trajectory, and outputs it to the emergency trajectory generation unit 162. The target curvature setting unit 161 acquires the curvature of the previous target trajectory and the current vehicle speed (V) of the vehicle, and sets the target curvature ρ * and output it to the emergency trajectory generation unit 162. At this time, the target curvature ρ * is calculated so as to gradually decrease from the curvature ρ of the previous target trajectory to 0 (ρ(∞)=0). The emergency trajectory generating unit 162 calculates the slip angle β, the target curvature ρ * , and the trajectory length s, an emergency target trajectory is generated and output to the trajectory tracking control unit 18. The emergency target trajectory is defined by the coordinate position (X R * , Y R * )

[0043] The switching unit 163 switches the target trajectory to be output to the trajectory tracking control unit 18 based on the determination result of whether or not the vehicle has deviated from the traveling path. The switching unit 163 is a switch for switching the connection to the trajectory tracking control unit 18, and when an emergency deceleration request is output from the traveling path deviation determination unit 13, the switching unit 163 switches so that the emergency target trajectory is output to the trajectory tracking control unit 18. When an emergency deceleration request is not output from the traveling path deviation determination unit 13, the switching unit 163 switches so that the target trajectory for normal traveling is output to the trajectory tracking control unit 18. Based on the acquired target trajectory (the normal target trajectory or the emergency target trajectory), the trajectory tracking control unit 18 sets the steering angle command value δ so that the vehicle follows the target trajectory. * Generate.

[0044] In this embodiment, as shown in FIG. 5, the target speed generating unit 15 generates a target speed V * and outputs it to speed tracking control unit 19. When an emergency deceleration request is output from lane departure determination unit 13, target speed correction unit 17 generates a speed suppression amount and adds the speed suppression amount to the target speed. More specifically, the target speed is adjusted so that the target speed becomes 0 km / h. Speed ​​tracking control unit 19 generates braking / driving force command values ​​based on the input target speed. The braking / driving force command values ​​include a torque command value T (driving force) and a hydraulic pressure command value P (brake).

[0045] 5, the emergency trajectory generating unit 162 calculates the slip angle β, the target curvature ρ * , and the trajectory length s, the emergency target trajectory generation unit 162 is not limited to this, and may also generate an emergency target trajectory based on the distance between the vehicle and a preceding vehicle traveling in front of the vehicle, the distance between the vehicle and an obstacle positioned around the vehicle, the slip angle β, the target curvature ρ * 5, the target curvature setting unit 161 may generate the emergency target trajectory based on the curvature of the previous target trajectory and the current vehicle speed. * However, the present invention is not limited to this, and the target curvature setting unit 161 may set a rate of change at which the target curvature is changed so as to avoid an obstacle positioned around the vehicle.

[0046] Next, a procedure in which the vehicle control device 1 executes the vehicle control method according to this embodiment will be described with reference to Fig. 6. Fig. 6 is an example of a flowchart showing the procedure of the vehicle control method according to this embodiment.

[0047] In step S10, the processor 10 acquires the current position of the vehicle, map information, and vehicle conditions (vehicle speed, yaw rate, and slip angle). At this time, the processor 10 may also acquire the distance between the vehicle and a preceding vehicle and the distance between the vehicle and an obstacle. In step S20, the processor 10 executes a lane boundary generation process. In the lane boundary generation process, for example, the processor 10 first determines whether the current position of the vehicle is located within the lane. If the current position of the vehicle is located within the lane, the processor 10 calculates the vehicle's travel distance L [m] T [s] ahead based on the vehicle's current speed V [m / s]. However, a minimum value for T [s] is set so that T [s] does not become 0. The processor 10 acquires boundary lines, such as lane boundaries, from the map information for the travel distance L [m] ahead from the current position of the vehicle in increments of ΔL, and generates lane boundaries along the boundary lines.

[0048] In step S30, the processor 10 executes lane departure determination. In the lane departure determination, the processor 10 first acquires lane boundaries, information on the drivable area, and the current position of the vehicle. The processor 10 determines whether, of the left and right lane boundaries, the boundary closest to the vehicle's center of gravity is the left boundary (e.g., the left lane boundary line). If the boundary closest to the vehicle's center of gravity is the left boundary, the processor 10 determines whether the shortest distance Lr between the vehicle's center of gravity and the right boundary is smaller than a predetermined distance threshold Lth. If the shortest distance Lr is smaller than the predetermined distance threshold Lth, the processor 10 determines that the vehicle has deviated from the lane. If the shortest distance Lr is not smaller than the predetermined distance threshold Lth, the processor 10 determines that the vehicle has not deviated from the lane. If the boundary closest to the vehicle's center of gravity is not the left boundary, the processor 10 determines whether the shortest distance Ll between the vehicle's center of gravity and the left boundary is smaller than a predetermined distance threshold Lth. If the shortest distance Ll is smaller than the predetermined distance threshold Lth, the processor 10 determines that the vehicle has deviated from the road. If the shortest distance Ll is not smaller than the predetermined distance threshold Lth, the processor 10 determines that the vehicle has not deviated from the road.

[0049] Furthermore, if processor 10 determines that the vehicle has deviated from the lane, it determines whether or not the vehicle can return to the lane. If it determines that the vehicle can return to the lane, processor 10 proceeds to step S40. If it determines that the vehicle cannot return to the lane, processor 10 outputs an emergency deceleration request. If processor 10 determines that the vehicle has not deviated from the lane, it proceeds to step S40.

[0050] In step S40, the processor 10 generates a target trajectory within the lane based on the boundary of the lane acquired in step S20. In step S50, the processor 10 generates a target speed based on the target trajectory generated in step S40 and detection information of obstacles around the vehicle detected by the detection device 4.

[0051] In step S60, the processor 10 executes a target trajectory correction process. In the target trajectory correction process, the processor 10 first acquires the previous target trajectory and the direction of the current velocity vector of the vehicle. The processor 10 calculates the curvature ρ of the previous target trajectory and the trajectory length s of the previous target trajectory. The processor 10 calculates the target curvature ρ * Specifically, the processor 10 calculates the target curvature ρ * The target curvature ρ gradually decreases from the previous target curvature ρ to 0. * The processor 10 calculates the target curvature ρ * An emergency target trajectory is generated based on the trajectory length s and the direction of the velocity vector. The processor 10 determines whether an emergency deceleration request has been output. If an emergency deceleration request has been output, the processor 10 selects the emergency target trajectory as the target trajectory. If an emergency deceleration request has not been output, the processor 10 selects the target trajectory for normal driving.

[0052] In step S70, processor 10 corrects the target speed to an emergency target speed based on the lane departure determination performed in step S30. The emergency target speed is a speed at which the vehicle stops, for example, 0 km / h. In step S80, processor 10 generates a steering angle command value so that the vehicle follows the target trajectory. In step S90, processor 10 generates braking / driving force command values ​​so that the vehicle follows the target speed. After outputting the generated command value to drive mechanism 5, processor 10 ends the control flow. Drive mechanism 5 performs speed control and steering control based on the command value.

[0053] In this embodiment, in automated driving or driving assistance on cold roads, if a vehicle deviates from its roadway due to the effects of a μ jump or the like, braking control is performed along an emergency target trajectory suitable for deceleration in order to quickly stop the vehicle. Because the emergency target trajectory is a trajectory that is straight in the direction of the vehicle's velocity vector, a slip angle [deg] = 0 can be achieved, and the drive mechanism can maximize tire force in the longitudinal direction of the vehicle. This allows the vehicle to stop with maximum braking force and shorten the braking distance. Furthermore, by gradually shifting the target trajectory to follow the direction of the velocity vector, the target trajectory is prevented from becoming one that would require sudden steering, allowing the vehicle to stop stably without disrupting its behavior.

[0054] As described above, in the vehicle control method and vehicle control device according to this embodiment, the processor generates a target trajectory based on the boundary of the road ahead of the vehicle, performs steering control of the vehicle so that the vehicle follows the target trajectory, obtains the current position of the vehicle, determines whether the vehicle has deviated from the road based on the current position and the boundary of the road, and if it determines that the vehicle has deviated from the road, changes the target trajectory to an emergency target trajectory that is aligned with the direction of the vehicle's current velocity vector, performs steering control so that the vehicle follows the emergency target trajectory, and performs braking control of the vehicle with a predetermined maximum braking force. This makes it possible to shorten the braking distance when braking control is performed while the vehicle has deviated from the road.

[0055] In the vehicle control method and vehicle control device according to this embodiment, the processor transitions the target trajectory from the pre-change target trajectory to the emergency target trajectory by gradually changing the curvature of the target trajectory, thereby preventing sudden steering of the vehicle due to the change in the target trajectory.

[0056] Furthermore, in the vehicle control method and vehicle control device according to this embodiment, the processor changes the curvature of the target trajectory while limiting the rate of change of the curvature of the target trajectory so that the rate of change does not exceed a predetermined limit rate of change, and the predetermined limit rate of change is a value set so that steering control is performed while the vehicle body yaw resonance frequency of the vehicle is maintained below a predetermined frequency. This makes it possible to prevent unstable vehicle behavior caused by vehicle body yaw resonance.

[0057] In the vehicle control method and vehicle control device according to this embodiment, the processor changes the curvature of the target trajectory while limiting the rate of change of the curvature of the target trajectory so that the rate of change does not exceed a predetermined limit rate of change, and the predetermined limit rate of change is a value set so that steering control is performed while the steering angular velocity of the vehicle is maintained below a predetermined steering angular velocity. This makes it possible to prevent unstable vehicle behavior caused by the steering angular velocity.

[0058] Furthermore, in the vehicle control method and vehicle control device according to this embodiment, if an obstacle is present in the direction of the vehicle's current velocity vector, the processor updates the position of the emergency target trajectory so as to avoid the obstacle, and changes the target trajectory to the updated emergency target trajectory, thereby enabling vehicle braking control to be performed with maximum deceleration while avoiding the obstacle.

[0059] Furthermore, in the vehicle control method and vehicle control device according to this embodiment, if an obstacle is present in the direction of the vehicle's current velocity vector, the processor relaxes the limit on the rate of change so that the obstacle can be avoided by steering control. This makes it possible to execute braking control of the vehicle with maximum deceleration while avoiding the obstacle during transition of the target trajectory.

[0060] In the vehicle control method and vehicle control device according to this embodiment, the processor acquires the position of the center of gravity of the vehicle as the current position, and when the position of the center of gravity is located outside either the left or right boundary of the road, determines whether the vehicle has deviated from the road based on the target distance between the position of the center of gravity and the left or right boundary of the road that is closest to the position of the center of gravity. As a result, when the position of the center of gravity of the vehicle deviates, braking control is executed, and the braking distance can be shortened.

[0061] Furthermore, in the vehicle control method and vehicle control device according to this embodiment, the processor acquires the position of the side of the vehicle as the current position, and when the position of the side is located outside the boundary of the lane in either the left or right direction of the vehicle, determines whether the vehicle has deviated from the lane according to the target distance between the position of the side and the boundary of the lane that is closest to the position of the side. This makes it possible to detect the point where the vehicle has deviated significantly and determine whether the vehicle has deviated from the lane, thereby shortening the braking distance.

[0062] In the vehicle control method and vehicle control device according to this embodiment, the processor determines that the vehicle has deviated from the road when the target distance is equal to or greater than a predetermined distance threshold set based on the vehicle width. This makes it possible to adjust the determination that the vehicle has deviated from the road and change the timing of executing braking control.

[0063] Furthermore, in the vehicle control method and vehicle control device according to this embodiment, when the vehicle deviates from the lane, the processor acquires information about a drivable area outside the lane in which the vehicle can drive, determines whether the vehicle can return to the lane in the drivable area based on the information about the drivable area, and if it determines that the vehicle can return to the lane, generates a return target trajectory for the vehicle to return to the lane, changes the target trajectory to the return target trajectory, and then executes steering control so that the vehicle follows the return target trajectory. As a result, if the vehicle can return to the lane, it can return to the lane by following the target trajectory for return.

[0064] Furthermore, in the vehicle control method and vehicle control device according to this embodiment, when the vehicle deviates from the lane, the processor acquires information about a drivable area outside the lane in which the vehicle can travel, and during braking control, determines whether the vehicle can return to the lane in the drivable area based on the information about the drivable area, and if it determines that the vehicle can return to the lane, generates a return target trajectory for the vehicle to return to the lane, changes the target trajectory from the emergency target trajectory to the return target trajectory, and then executes steering control so that the vehicle follows the return target trajectory. As a result, if it becomes possible to return to the lane during braking control, the vehicle can return to the lane by following the target trajectory for return.

[0065] In the vehicle control method and vehicle control device according to this embodiment, the processor acquires information about the drivable area from map information including the coordinate positions of the drivable area, thereby determining the positions of static objects around the vehicle as non-drivable areas and acquiring information about the drivable area.

[0066] In the vehicle control method and vehicle control device according to this embodiment, the processor acquires information about the drivable area from a camera that captures images of the driving environment around the vehicle, thereby determining the positions of dynamic objects around the vehicle as areas where the vehicle cannot be driven and acquiring information about areas where the vehicle can be driven.

[0067] In the vehicle control method and vehicle control device according to this embodiment, the processor acquires information about the drivable area from a sensor that detects the three-dimensional shape of the road surface around the vehicle, thereby determining the positions of dynamic objects around the vehicle as non-drivable areas and acquiring information about the drivable area of ​​the vehicle.

[0068] It should be noted that the above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above-described embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. [Explanation of symbols]

[0069] 100...Vehicle control system 1...Vehicle control device 2...Vehicle position detection device 3. Map database 4. Detection device 5...Drive mechanism 10...Processor 11...Drivable area information acquisition unit 12...Run boundary generation section 13...Lane departure detection unit 14…Target trajectory generation unit 15...Target speed generation section 16...Target trajectory correction section 17…Target speed correction section 18...Trajectory tracking control unit 19...Speed ​​tracking control section

Claims

1. 1. A vehicle control method executed by a processor, comprising: The processor: generating a target trajectory based on a boundary of a road located ahead of the vehicle; performing steering control of the vehicle so that the vehicle follows the target trajectory; Obtaining the current location of the vehicle; determining whether the vehicle has deviated from the road based on the current position and the road boundary; When it is determined that the vehicle has deviated from the road, the target trajectory is changed to an emergency target trajectory along a direction of a current velocity vector of the vehicle; A vehicle control method that executes the steering control so that the vehicle follows the emergency target trajectory, and executes braking control of the vehicle with a predetermined maximum braking force.

2. 2. The vehicle control method according to claim 1, The processor: A vehicle control method for transitioning the target trajectory from the target trajectory before change to the emergency target trajectory by gradually changing the curvature of the target trajectory.

3. 3. The vehicle control method according to claim 2, The processor: changing the curvature of the target trajectory in a state in which the rate of change of the curvature of the target trajectory is limited so that the rate of change does not exceed a predetermined limit rate of change; The vehicle control method, wherein the predetermined limit change rate is a value set so that the steering control is executed in a state where a vehicle body yaw resonance frequency of the vehicle is maintained below a predetermined frequency.

4. 3. The vehicle control method according to claim 2, The processor: changing the curvature of the target trajectory in a state in which the rate of change of the curvature of the target trajectory is limited so that the rate of change does not exceed a predetermined limit rate of change; The vehicle control method, wherein the predetermined limited change speed is a value set so that the steering control is performed in a state where the steering angular speed of the vehicle is maintained below a predetermined steering angular speed.

5. 3. A vehicle control method according to claim 1 or 2, The processor: If there is an obstacle in the direction of the current velocity vector of the vehicle, the position of the emergency target trajectory is updated so as to avoid the obstacle; A vehicle control method for changing the target trajectory to the updated emergency target trajectory.

6. 5. A vehicle control method according to claim 3 or 4, The processor: A vehicle control method that, when an obstacle is present in the direction of the current velocity vector of the vehicle, relaxes the limit on the rate of change so that the obstacle can be avoided by the steering control.

7. 2. The vehicle control method according to claim 1, The processor: acquiring a center of gravity position of the vehicle as the current position; A vehicle control method for determining whether the vehicle has deviated from the lane when the center of gravity position is located outside either the left or right boundary of the lane, based on the target distance between the center of gravity position and either the left or right boundary of the lane that is closest to the center of gravity position.

8. 2. The vehicle control method according to claim 1, The processor: acquiring a position of a side of the vehicle as the current position; A vehicle control method that determines whether the vehicle has deviated from the lane when the side position is located outside the boundary of the lane in either the left or right direction of the vehicle, depending on the target distance between the side position and the left or right boundary of the lane that is closest to the side position.

9. 9. A vehicle control method according to claim 7 or 8, The processor: A vehicle control method that determines that the vehicle has deviated from the road when the target distance is equal to or greater than a predetermined distance threshold set based on the vehicle width of the vehicle.

10. 2. The vehicle control method according to claim 1, The processor: When the vehicle deviates from the road, information on a drivable area outside the road in which the vehicle can travel is acquired; determining whether the vehicle can return to the road in the drivable area based on the information on the drivable area; If it is determined that the vehicle can return to the lane, a return target trajectory for the vehicle to return to the lane is generated; a vehicle control method for changing the target trajectory to the return target trajectory, and then executing the steering control so that the vehicle follows the return target trajectory;

11. 2. The vehicle control method according to claim 1, The processor: When the vehicle deviates from the road, information on a drivable area outside the road in which the vehicle can travel is acquired; During the braking control, based on the information on the drivable area, it is determined whether or not the vehicle can return to the road in the drivable area; If it is determined that the vehicle can return to the lane, a return target trajectory for the vehicle to return to the lane is generated; a vehicle control method for changing the target trajectory from the emergency target trajectory to the return target trajectory, and then performing the steering control so that the vehicle follows the return target trajectory;

12. 12. A vehicle control method according to claim 10 or 11, The processor: A vehicle control method that acquires information about the drivable area from map information including coordinate positions of the drivable area.

13. 12. A vehicle control method according to claim 10 or 11, The processor: A vehicle control method that acquires information about the drivable area from a camera that captures an image of the driving environment around the vehicle.

14. 12. A vehicle control method according to claim 10 or 11, The processor: A vehicle control method that acquires information about the drivable area from a sensor that detects the three-dimensional shape of the road surface around the vehicle.

15. A vehicle control device including a processor, The processor: generating a target trajectory based on a boundary of a road located ahead of the vehicle; performing steering control of the vehicle so that the vehicle follows the target trajectory; Obtaining the current location of the vehicle; determining whether the vehicle has deviated from the road based on the current position and the road boundary; When it is determined that the vehicle has deviated from the road, the target trajectory is changed to an emergency target trajectory along a direction of a current velocity vector of the vehicle; a vehicle control device that executes the steering control so that the vehicle follows the emergency target trajectory, and executes braking control of the vehicle with a predetermined maximum braking force;

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