Vehicle control device, vehicle control method, and vehicle control system

Abstract

According to a vehicle control device, a vehicle control method, and a vehicle control system according to the present invention, in one aspect, a trajectory that includes a portion of a first target trajectory obtained at a first time of calculating the target trajectory that a vehicle is to travel on, in which portion the vehicle advances in the period from the first time to a second time that is the next target trajectory calculation cycle, and a first target position set for the first target trajectory, is retained to obtain a second target trajectory at the second time. This makes it possible to suppress the occurrence of unexpected vehicle behavior while ensuring tracking control performance to the target trajectory.

Description

Technical Field

[0001] The present invention relates to a vehicle control device, a vehicle control method, and a vehicle control system.

Background Art

[0002] The vehicle travel control method of Patent Document 1 is a vehicle travel control method for detecting a target trajectory along which the host vehicle should travel and automatically traveling the host vehicle along the detected target trajectory. At least according to the travel lane information, a forward viewing point distance from the host vehicle to a forward viewing point is temporarily set. When it is assumed that the host vehicle has traveled the temporarily set forward viewing point distance, a travel trajectory of the host vehicle that coincides with the target trajectory at the forward viewing point is estimated. A maximum value of a lateral displacement between the estimated travel trajectory of the host vehicle and the target trajectory between the current position of the host vehicle and the forward viewing point is detected. After setting the forward viewing point distance when the maximum value of the lateral displacement is equal to or less than a predetermined value as the forward viewing point distance, the host vehicle is automatically traveled based on the set forward viewing point distance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, as trajectory tracking control for traveling a vehicle along a target trajectory, for example, there is control for generating a control command of the vehicle with a forward viewing point set on the target trajectory in front of the host vehicle as a tracking target point. In such trajectory tracking control, if the shape of the target trajectory changes greatly between the previous and current calculation cycles, the tracking target point may be displaced suddenly, and there is a risk of causing an unexpected vehicle behavior by trying to make the vehicle follow the tracking target point. Here, in order to prevent the following target point from being displaced in a large step, if the deviation amount between the running trajectory of the vehicle with respect to the target trajectory is set to be equal to or less than a predetermined value, the following target point will be set at a position closer to the host vehicle. Therefore, there is a risk that the following control performance with respect to the target trajectory may deteriorate due to a response delay in vehicle control or the like.

[0005] The present invention has been made in view of the conventional situation, and an object thereof is to provide a vehicle control device, a vehicle control method, and a vehicle control system that can suppress the occurrence of unexpected vehicle behavior while ensuring the following control performance with respect to a target trajectory.

Means for Solving the Problems

[0006] According to the present invention, in one aspect thereof, among the first target trajectories obtained at a first time for calculating a target trajectory for running a vehicle, the distance traveled by the vehicle between the first time and a second time which is a calculation period of the next target trajectory, and a first target position set in the first target trajectory are included to hold a trajectory, and a second target trajectory at the second time is obtained.

Effects of the Invention

[0007] According to the present invention, it is possible to suppress the occurrence of unexpected vehicle behavior while ensuring the following control performance with respect to a target trajectory.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of a vehicle control device, a vehicle control method, and a vehicle control system according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing one aspect of a vehicle control system 200 mounted on a vehicle 100. The vehicle 100 is an automobile having a pair of left and right front wheels 101, 102 and a pair of left and right rear wheels 103, 104.

[0010] The vehicle control system 200 is a driving support system or an autonomous driving system that plans a target orbit of the vehicle 100 and controls the steering angle, driving force, braking force, etc. of the vehicle 100 so that the vehicle 100 travels along the target orbit. The vehicle control system 200 includes an external environment recognition unit 300, a vehicle motion state acquisition unit 400, an automatic driving control device 500, a vehicle motion control device 600, and an actuator unit 700.

[0011] The external environment recognition unit 300 is a device for acquiring information on the driving environment of the road on which the vehicle 100 travels. The external environment recognition unit 300 includes, for example, a GPS (Global Positioning System) receiver 310, a map database 320, a vehicle-road communication device 330, a camera 340, a radar 350, a LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) 360, and the like.

[0012] The GPS receiver 310 measures the latitude and longitude of the position of the vehicle 100 by receiving signals from GPS satellites. The map database 320 is formed in a storage device mounted on the vehicle 100. Note that the map information in the map database 320 includes information such as road positions, road shapes, and intersection positions.

[0013] The vehicle-road communication device 330 transmits information on the vehicle 100 to the roadside unit and receives road traffic information such as curves and intersections from the roadside unit. Note that the external environment recognition unit 300 can be provided with a communication device for performing vehicle-to-vehicle communication for acquiring road traffic information and the behavior information of other companies from other vehicles.

[0014] The camera 340 is a stereo camera, a monocular camera, a surround camera, or the like, and photographs the surroundings of the vehicle 100 to acquire image information on the surroundings of the vehicle 100. The radar 350 and the LiDAR 360 detect objects around the vehicle 100 and output information on the detected objects.

[0015] The vehicle motion state acquisition unit 400 is a device for acquiring information on the motion state of the vehicle 100. The vehicle motion state acquisition unit 400 includes, for example, a wheel speed sensor 410, an acceleration sensor 420, and the like.

[0016] The wheel speed sensor 410 is a sensor that detects the rotational speed of each wheel of the vehicle 100, and the detection result of the wheel speed sensor 410 is used for the estimation calculation of the speed of the vehicle 100. Note that instead of the wheel speed sensor 410, or together with the wheel speed sensor 410, a vehicle speed sensor for detecting the speed of the vehicle 100 can be provided. Also, the acceleration sensor 420 detects the longitudinal acceleration, lateral acceleration, vertical acceleration, yaw rate, pitch rate, roll rate, etc. of the vehicle 100.

[0017] The automatic driving control device 500 is an electronic control device mainly composed of a microcomputer 510 as a control unit that performs calculations based on the acquired information and outputs the calculation results. The microcomputer 510 includes an MPU (Microprocessor Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., which are not shown in the figure.

[0018] The microcomputer 510 acquires an external recognition signal including the position information, road shape information, road surface information, object information, etc. of the vehicle 100 from the external recognition unit 300. Also, the microcomputer 510 acquires a vehicle motion detection signal such as the speed and acceleration of the vehicle 100 from the vehicle motion state acquisition unit 400.

[0019] Then, based on the acquired information, the microcomputer 510 calculates a target command in trajectory tracking control and outputs the calculated target command to the vehicle motion control device 600. The microcomputer 510 of the automatic driving control device 500 includes a surrounding situation recognition unit 520, a behavior planning unit 530, and a target command generation unit 540 as functional units for calculating the target command.

[0020] Based on the external environment recognition signal from the external environment recognition unit 300 and the vehicle motion detection signal from the vehicle motion state acquisition unit 400, the surrounding situation recognition unit 520 recognizes the situation around the host vehicle. The situation around the host vehicle recognized by the surrounding situation recognition unit 520 includes information such as, for example, the curvature of the road, the road camber, the road gradient, the friction coefficient μ of the road surface, the positions of the left and right lane markers, the positions of the left and right road edges, moving objects, and stationary objects. The above-mentioned moving objects are, for example, pedestrians, bicycles, motorcycles, other vehicles, etc. The above-mentioned stationary objects are, for example, fallen objects on the road, traffic signals, guardrails, curbstones, road signs, trees, billboards, etc.

[0021] The action plan unit 530 obtains information on the situation around the host vehicle recognized by the surrounding situation recognition unit 520, and creates an action plan for the vehicle 100, including the selection of the driving lane and the selection of the driving direction at intersections and branch points. Then, the target command generation unit 540 generates a target command to be output to the vehicle motion control device 600 based on the information on the situation around the host vehicle recognized by the surrounding situation recognition unit 520 and the action plan planned by the action plan unit 530.

[0022] The target command that the target command generation unit 540 instructs the vehicle motion control device 600 includes, for example, a command indicating the driving area in front of the vehicle 100, information on the road surface in the driving area such as the friction coefficient, inclination, unevenness, etc., and object information such as other vehicles, pedestrians, obstacles, etc. Here, the target command generation unit 540 indicates the driving area as the area between the white lines or between the road edges, and when there are any objects in the lane, it indicates the area excluding the object.

[0023] In addition, the target command generation unit 540 can, for example, be vigilant about jumping out from the shadow of an object, set the shadow of the object as a collision risk area, and indicate the driving area as the area excluding such a collision risk area. Further, when there is an area that cannot be recognized in front of the vehicle 100, the target command generation unit 540 can indicate the traveling area as the area excluding such an area.

[0024] The vehicle motion control device 600 is an electronic control device mainly including a microcomputer 610 as a control unit that performs calculations based on the acquired information (in other words, input information) and outputs a calculation result. The microcomputer 610 includes an MPU, a ROM, a RAM, etc., which are not shown in the figure.

[0025] The microcomputer 610 calculates a control command based on the target command acquired from the microcomputer 510 of the automatic driving control device 500, and outputs the calculated control command to the actuator unit 700, thereby controlling the motion of the vehicle 100. The microcomputer 610 includes a trajectory design unit 620 and a trajectory tracking control unit 630 as functional units for controlling the motion of the vehicle 100.

[0026] The trajectory design unit 620 acquires a target command including a traveling area, road surface information, object information, etc. from the automatic driving control device 500, specifically, the target command generation unit 540 of the microcomputer 510. Then, based on the acquired target command, the trajectory design unit 620 designs the target trajectory of the vehicle 100 in the driving support function related to the automatic driving, and outputs information regarding the target position of the target trajectory to the trajectory tracking control unit 630.

[0027] Here, the trajectory design unit 620 outputs information regarding a trajectory point that is the arrival target of the vehicle 100 later as the target position on the target trajectory. Hereinafter, the trajectory point that is the arrival target of the vehicle 100 after the forward gaze time is referred to as the forward gaze point. Further, the forward gaze time can be made variable according to the speed of the vehicle 100 with the forward gaze time = forward gaze distance / vehicle speed. Note that the information regarding the forward gaze point is the position information of the forward gaze point or the information regarding the relative position between the forward gaze point and the vehicle 100.

[0028] Note that the trajectory design unit 620 sets the forward gaze point according to a plurality of driving support functions. Examples of the plurality of driving support functions include a lane keeping function, a preceding vehicle following function, and an automatic driving function. FIGS. 2-4 are diagrams schematically showing the setting of the forward gaze point in the lane keeping function, the preceding vehicle following function, and the route following function.

[0029] In the lane keeping function, the trajectory design unit 620 sets the forward gaze point at the center of the lane. Also, in the preceding vehicle following function, the trajectory design unit 620 sets the forward gaze point at the position of the preceding vehicle. Also, in the route following function, the trajectory design unit 620 sets the forward gaze point on a route toward the destination or the like.

[0030] Note that in the setting process of the target trajectory (forward gaze point), the trajectory design unit 620 can generate a target trajectory so that the lateral acceleration or lateral jerk of the vehicle 100 is as small as possible within the driving area instructed by the automatic driving control device 500. That is, the trajectory design unit 620 can design a target trajectory that emphasizes the ride comfort of the vehicle 100 by designing the target trajectory so that the lateral acceleration or lateral jerk of the vehicle 100 is as small as possible.

[0031] On the other hand, the trajectory following control unit 630 calculates a control command for causing the vehicle 100 to follow the target trajectory based on the deviation amount of the vehicle 100 from the target trajectory. FIG. 5 is a diagram showing how to obtain the left-right deviation ey at the forward gaze point.

[0032] The trajectory following control unit 630 obtains, as the left-right deviation ey, the lateral deviation amount of the vehicle 100 with respect to the target trajectory that is predicted to occur after the forward gaze time when it is assumed that the vehicle 100 travels straight in the current direction. Then, the trajectory tracking control unit 630 sets, for example, left and right acceleration commands based on the left and right deviation ey, and outputs a control command for realizing such left and right acceleration commands to the actuator unit 700.

[0033] The actuator unit 700 controls the movement of the vehicle 100 based on a control command from the vehicle motion control device 600 (microcomputer 610). The actuator unit 700 includes an internal combustion engine 710 and a motor 720 that generate a driving force of the vehicle 100, a braking device 730 that applies a braking force to the vehicle 100, an electronic control power steering device 740 for changing the traveling direction of the vehicle 100, an electronic control suspension (active suspension) 750 capable of adjusting damping force and vehicle height, and the like. Note that the motor 720 can be operated as a generator to apply a braking force (in other words, a regenerative braking force) to the vehicle 100.

[0034] By the way, the trajectory design unit 620 has a function of designing a target trajectory so as to prevent a sudden change in the forward fixation point, which is the target position, in the calculation cycle of the target trajectory. Specifically, in the calculation of the target trajectory for each calculation cycle [ms], the trajectory design unit 620 holds a trajectory for a predetermined distance from the vehicle 100 among the first target trajectories obtained at the first time, and calculates the second target trajectory at the second time, which is the calculation cycle next to the first time. The trajectory design unit 620 has a function of outputting information on the second target position (second forward fixation point) set in the second target trajectory to the trajectory tracking control unit 630. In other words, the microcomputer 610 is configured to execute a vehicle control method including the above-described trajectory design process.

[0035] Here, the trajectory design unit 620 sets a predetermined distance for maintaining the trajectory shape as a distance necessary to suppress the displacement of the forward fixation point within the allowable range in the calculation cycle of the target trajectory. Specifically, the trajectory design unit 620 holds a trajectory including the distance traveled by the vehicle 100 from the first time to the second time, which is the calculation period of the next target trajectory, among the first target trajectories obtained at the first time, and the first target position (the first forward viewing point) set in the first target trajectory, and obtains the second target trajectory at the second time.

[0036] In other words, the trajectory design unit 620 variably sets a predetermined distance for maintaining the trajectory shape based on information such as the calculation period of the target trajectory, the forward viewing time, and the speed of the vehicle 100. Then, based on the information regarding the second target position (the second forward viewing point) set in the second target trajectory, the trajectory tracking control unit 630 outputs a control command for driving the vehicle 100 to the actuator unit 700.

[0037] By designing the target trajectory in this way, sudden changes in the forward viewing point, which is the target position of the tracking control, are suppressed, so that unexpected vehicle behavior is suppressed by controlling the vehicle 100 toward the forward viewing point. Further, in the above design of the target trajectory, since the trajectory design unit 620 does not perform a shortening process of the forward viewing distance for suppressing sudden changes in the forward viewing point, it is possible to suppress deterioration of the tracking control performance to the target trajectory due to a response delay in vehicle control or the like.

[0038] Hereinafter, the design of the target trajectory for partially maintaining the trajectory shape will be described in detail. The trajectory design unit 620 needs to change the shape of the target trajectory from moment to moment according to the surrounding environment that changes due to the running of the vehicle 100. Here, when the trajectory design unit 620 calculates the target trajectory every fixed calculation period ΔT, the target trajectory started to be calculated at time t0 (the first time) is actually used for the tracking control only after the time t0 + ΔT (the second time) when the target trajectory is updated.

[0039] Furthermore, in the control for causing the vehicle 100 to follow the target trajectory, as described above, the trajectory tracking control unit 630 controls the actuator unit 700 with the forward fixation point in front of the vehicle 100 as the target position. Therefore, if the trajectory shape changes by a distance obtained by adding the distance that the vehicle 100 travels during the calculation cycle ΔT and the forward fixation distance, which is the distance from the vehicle 100 to the forward fixation point, the forward fixation point may be displaced in a large step between one cycle ago and this time, and the left-right deviation ey (see FIG. 5) may change suddenly.

[0040] Therefore, the trajectory design unit 620 sets the distance obtained by adding the distance that the vehicle 100 travels during the calculation cycle ΔT of the target trajectory and the forward fixation distance as a predetermined distance for maintaining the trajectory shape, and ensures that the trajectory shape for such a distance does not change even by recalculation. As a result, during the calculation cycle ΔT of the target trajectory, the forward fixation point is prevented from being displaced in a large step and the left-right deviation ey from changing suddenly, so that the occurrence of unexpected vehicle behavior is suppressed.

[0041] FIG. 6 illustrates the changes in the target trajectory and the forward fixation point when the vehicle 100 enters a curve. The left side of FIG. 6 shows the displacement of the forward fixation point when the entire target trajectory is redrawn at the second time t0 + ΔT after the calculation cycle ΔT without holding a part of the target trajectory calculated at the first time t0.

[0042] Here, the shape of the target trajectory calculated at the first time t0 is substantially linear because it is in front of the curve, whereas the shape of the target trajectory newly redrawn at the second time t0 + ΔT after the calculation cycle ΔT is a shape along the curve shape in preparation for entering the curve. For this reason, the forward fixation point (the first target position) at the first time t0 and the forward fixation point (the second target position) at the second time t0 + ΔT will change suddenly in the left-right direction.

[0043] On one hand, on the right side of FIG. 6, among the first target trajectories obtained at the first time t0, the trajectory corresponding to the distance obtained by adding the distance that the vehicle 100 travels during the calculation cycle ΔT and the forward viewing point distance is held, and the forward viewing point when the second target trajectory at the second time t0+ΔT, which is the next calculation cycle after the first time t0, is obtained is shown. In this case, the shape of the target trajectory corresponding to the distance obtained by adding the distance that the vehicle 100 travels during the calculation cycle ΔT and the forward viewing point distance remains unchanged from one cycle before, and the subsequent target trajectory is changed.

[0044] Therefore, the lateral displacement of the forward viewing point (the second target position) at the second time t0+ΔT with respect to the first forward viewing point (the first target position) at the first time t0 is suppressed. That is, the forward viewing point, which is the target position on the target trajectory, is prevented from displacing suddenly, and the sudden change in the left-right deviation ey is suppressed. Therefore, the occurrence of unexpected vehicle behavior due to trajectory following control is suppressed. Also, in the design of the above-mentioned target trajectory, since the forward viewing distance is kept constant, it is possible to prevent the deterioration of the following control performance for the target trajectory due to the shortening of the forward viewing distance.

[0045] FIG. 7 is a diagram for explaining the requirements for the length of the target trajectory in the design of the target trajectory that holds the trajectory for a predetermined distance from the vehicle 100. Note that Tfwd in FIG. 7 represents the forward viewing time. When the calculation of the target trajectory starts at time t0, based on information such as the command of the driving area obtained at time t0, the target trajectory shown by the solid line in FIG. 7 is calculated. Note that the target trajectory shown by the solid line in FIG. 7 is shown in the vehicle coordinate system at time t0.

[0046] The target trajectory whose calculation starts at time t0 will be used for trajectory following control at the time t0+ΔT when the calculation cycle ΔT has elapsed from time t0. Also, the vehicle 100 will travel a distance corresponding to the speed of the vehicle 100 during the calculation cycle ΔT. Here, in the process of maintaining the track shape, at time t0 + ΔT, the trajectory design unit 620 uses the target trajectory at time t0 one cycle ago as it is until time t0 + ΔT + Tfwd.

[0047] Therefore, the target trajectory at time t0 + ΔT must overlap with the target trajectory one cycle ago when viewed in the absolute coordinate system until time t0 + ΔT + Tfwd. In other words, it is necessary to maintain the shape of the target trajectory one cycle ago. That is, when maintaining the track shape for the distance obtained by adding the distance traveled by the vehicle 100 during the operation cycle ΔT and the forward viewing point distance, the trajectory design unit 620 needs to calculate the target trajectory at time t0 to a position further ahead than the trajectory at time t0 + ΔT + Tfwd.

[0048] FIG. 8 is a diagram for explaining the coordinate conversion process in the calculation of the target trajectory that partially maintains the track shape. In FIG. 8, the target trajectory indicated by the solid line is the target trajectory calculated based on the information obtained at time t0, and the target trajectory indicated by the dotted line is the target trajectory calculated based on the information obtained at time t0 + ΔT. Among the target trajectories calculated based on the information obtained at time t0 + ΔT, the portion from the vehicle 100 by ΔT + Tfwd needs to overlap with the target trajectory calculated based on the information obtained at time t0.

[0049] Here, since the target trajectory calculated at time t0 is based on the vehicle coordinate system at time t0, the portion from the vehicle 100 by ΔT + Tfwd in the target trajectory calculated at time t0 needs to be converted to the vehicle coordinate system at time t0 + ΔT. For this reason, at time t0 + ΔT, the trajectory design unit 620 converts the portion from the vehicle 100 by ΔT + Tfwd in the target trajectory calculated at time t0 to the vehicle coordinate system at time t0 + ΔT based on the vehicle movement amount during the operation cycle ΔT.

[0050] FIG. 9 is a flowchart showing the control process of the microcomputer 610 (the orbit design unit 620 and the orbit tracking control unit 630) when performing partial holding of the orbit shape. In step S1001, the microcomputer 610 acquires information such as the position and speed of the vehicle 100.

[0051] Next, in step S1002, the microcomputer 610 predicts the total value of the distance traveled by the vehicle 100 during the operation cycle ΔT of the target orbit and the forward viewing distance, which is the distance traveled by the vehicle 100 during the forward viewing time Tfwd, and sets the predicted total distance as the length L [m] of the orbit to be held (see FIG. 6).

[0052] Here, the microcomputer 610 obtains the length L [m] of the orbit to be held from Equation (1) based on the time T obtained by adding the operation cycle ΔT and the forward viewing time Tfwd, and the speed [m / s] of the vehicle 100 (hereinafter referred to as the vehicle speed). L = (ΔT + Tfwd) × vehicle speed = T × vehicle speed... (1)

[0053] Further, the microcomputer 610 can obtain the length L of the orbit to be held from Equation (2) in consideration of the speed change due to the acceleration of the vehicle 100. L = T × vehicle speed + 1 / 2 × acceleration × T 2 ... (2) Also, the microcomputer 610 can obtain the length L of the orbit to be held from Equation (3) based on the operation cycle ΔT, the vehicle speed, and the forward viewing distance D. L = ΔT × vehicle speed + forward viewing distance D... (3)

[0054] Also, the microcomputer 610 can obtain the length L of the orbit to be held from Equation (4) based on the operation cycle ΔT, the vehicle speed, the forward viewing distance D, and the acceleration. L = ΔT × vehicle speed + 1 / 2 × acceleration × ΔT 2 + forward viewing distance D... (4) Further, when the vehicle 100 is in a low-speed driving state where the speed of the vehicle 100 is lower than a predetermined value, the microcomputer 610 can fix the length L of the trajectory to be held at a preset constant distance without variably setting it according to the vehicle speed.

[0055] After obtaining the length L of the trajectory to be held, in step S1003, the microcomputer 610 holds a trajectory of length L from the position of the vehicle 100 in the target trajectory of the previous cycle. In other words, a setting is made not to change the shape of the trajectory of length L from the position of the vehicle 100. Then, in the next step S1004, the microcomputer 610 calculates the target trajectory of the portion farther than the length L.

[0056] Next, in step S1005, the microcomputer 610 designs a target trajectory composed of the trajectory of length L in the target trajectory of the previous cycle and the newly calculated target trajectory following it, and ends the calculation of the target trajectory. Each process in the above steps S1001 - S1005 is the processing content in the trajectory design unit 620.

[0057] In steps S1006 - S1007, the microcomputer 610 performs processing as the trajectory tracking control unit 630. In step S1006, the microcomputer 610 acquires information on the position of the vehicle 100. Next, in step S1007, the microcomputer 610 outputs a control command to the actuator unit 700 based on the amount of trajectory deviation at the forward fixation point.

[0058] By the way, the control process shown in the flowchart of FIG. 9 is basically premised on the case where one application software (in other words, one driving support function) is continuously executed and the target trajectory is calculated every calculation cycle ΔT. However, the situation where the microcomputer 610 executes partial holding of the trajectory shape is not limited to the case where one application software is continuously executed.

[0059] When the microcomputer 610 selectively switches and executes one of a plurality of application softwares (in other words, a plurality of driving assistance functions) that control the motion state of the vehicle 100 with different indexes according to the driving conditions of the vehicle 100, it can maintain the trajectory for a predetermined distance from the vehicle 100 before and after the switching of the application software. Note that the driving assistance functions to be switched and executed include those described above, such as lane keeping, following the preceding vehicle, and following the route. In other words, when the microcomputer 610 switches from the first control that controls the motion state of the vehicle 100 according to the driving conditions of the vehicle 100 to the second control that controls the motion state of the vehicle 100 with an index different from the first control, it can maintain the trajectory and obtain the second target trajectory according to the second control.

[0060] FIG. 10 is a flowchart showing a control process when maintaining the target trajectory for a predetermined distance from the vehicle 100 before and after the switching of the application software (in other words, the driving assistance function). In step S1101, the microcomputer 610 acquires the information on the position and speed of the vehicle 100. Next, in step S1102, the microcomputer 610 predicts the total value of the distance traveled by the vehicle 100 during the operation period ΔT of the target trajectory and the distance traveled by the vehicle 100 during the forward gaze time Tfwd.

[0061] In step S1103, the microcomputer 610 determines whether there has been a change in the driving target or conditions, such as the switching of the application software. Specifically, in step S1103, the microcomputer 610 determines whether it is necessary to rectify the target trajectory due to a change in the way of creating the target trajectory, a change in the index in creating the target trajectory, a change in the surrounding environment, etc.

[0062] Here, a change in the method of creating the target trajectory is, for example, when switching from lane keeping (first control) to following a preceding vehicle (second control). In addition, a change in the index in creating the target trajectory is, for example, when changing from generating a target trajectory that emphasizes riding comfort to generating a target trajectory that maintains a position closer to the center of the lane. Furthermore, a change in the surrounding environment is, for example, a change in the surrounding environment such that the target trajectory needs to be corrected, such as when the coefficient of friction of the road surface changes or when obstacles, preceding vehicles, pedestrians, etc. are newly detected.

[0063] When the microcomputer 610 determines in step S1103 that there is no change in the driving target or conditions represented by, for example, a change in the application software, such as when continuing to execute one application software, it proceeds from step S1103 to step S1104. In step S1104, the microcomputer 610 makes a setting to hold a trajectory of length L from the position of the vehicle 100 among the target trajectories calculated one cycle earlier, similar to step S1003 described above. Then, in the next step S1105, the microcomputer 610 calculates the target trajectory of the part farther than the length L.

[0064] On the other hand, when the microcomputer 610 determines in step S1103 that there is a change in the driving target or conditions represented by, for example, a change in the application software, it proceeds from step S1103 to step S1106. In step S1106, the microcomputer 610 calculates the target trajectory under the new driving target or conditions (for example, the application software after switching) so that the trajectory of length L from the position of the vehicle 100 does not change from before the switching.

[0065] When the microcomputer 610 performs the calculation of the target trajectory in step S1105 or step S1106, it proceeds to step S1107 and ends the calculation of the target trajectory. Each process in the above steps S1101 - S1107 is the processing content in the trajectory design unit 620. The microcomputer 610 performs processing as the trajectory tracking control unit 630 in steps S1108 - S1109.

[0066] The microcomputer 610 acquires information on the position of the vehicle 100 in step S1108, and in step S1109, based on the amount of trajectory deviation at the forward viewing point after the forward viewing time Tfwd (in other words, D ahead), outputs a control command to the actuator unit 700 to perform trajectory tracking control. According to such a control process, even if there is a change in the driving target or conditions that require the correction of the target trajectory, the sudden change of the forward viewing point, which is the target position of the tracking control, can be suppressed along with the correction, and the occurrence of unexpected vehicle behavior due to the sudden change of the forward viewing point can be suppressed.

[0067] Note that the microcomputer 610 can include, in the conditions for executing the switching of the application software, that the forward viewing points (target positions) before and after the switching are within a predetermined range, that is, the forward viewing points before and after the switching coincide or are close to each other. When applying such switching conditions, the microcomputer 610 calculates the target trajectory with each of the two application softwares prior to the switching of the application software, and when it is determined that the forward viewing points coincide or are close to each other before and after the switching, performs the switching of the application software (in other words, the switching of the target trajectory used for the trajectory tracking control).

[0068] Thereby, the sudden change of the forward viewing point (target position) along with the switching of the application software can be suppressed, and the occurrence of unexpected vehicle behavior due to the sudden change of the forward viewing point can be suppressed. Then, after switching the application software, the microcomputer 610 holds a track of length L from the position of the vehicle 100 in the target track calculated one cycle before, so as to prevent a sudden change in the forward viewing point (target position).

[0069] Also, when an emergency avoidance is required for the vehicle 100, the microcomputer 610 cancels the process of holding the track of length L from the position of the vehicle 100 in the target track calculated one cycle before, and can newly design the target track from the position of the vehicle 100. If the microcomputer 610 cancels the track holding when an emergency avoidance is required, it is possible to prevent a decrease in the performance of the emergency avoidance. Note that the emergency avoidance is, for example, a situation where an obstacle or a pedestrian interrupts the traveling path of the vehicle 100 and it is necessary to avoid such an obstacle, and the driving support is switched to the emergency avoidance.

[0070] FIG. 11 is a flowchart showing a control process when canceling the track holding when an emergency avoidance is required. In step S1201, the microcomputer 610 determines whether an emergency avoidance is necessary based on an emergency avoidance determination flag or the like that is a trigger for performing driving support for the emergency avoidance.

[0071] Then, the microcomputer 610 cancels the holding of the track shape by bypassing the process of designing the track for holding the track shape performed in steps S1202 - S1206. That is, when an emergency avoidance is required, the microcomputer 610 gives priority to the emergency avoidance such as avoiding an obstacle rather than suppressing a sudden change in the forward viewing point (target position), and newly designs the target track for the emergency avoidance without being restricted by the history of the target track until then.

[0072] On the one hand, if the microcomputer 610 determines in step S1201 that the situation does not require emergency avoidance, it designs the target trajectory by implementing the processes of steps S1202 - S1206 to hold the trajectory of a predetermined distance from the vehicle 100 among the target trajectories of one cycle before. Since the processes of steps S1202 - S1206 described above are the same as the processes of steps S1001 - 1005 described above, detailed descriptions are omitted.

[0073] Then, the microcomputer 610 acquires the information of the position of the vehicle 100 in step S1207, and in step S1208, based on the amount of trajectory deviation at the forward viewing point after the forward viewing time Tfwd (in other words, a distance D forward), it outputs a control command to the actuator unit 700 to perform trajectory tracking control. According to such a control process, in a situation where emergency avoidance is not required, the sudden change of the forward viewing point (target position) is suppressed, so that the occurrence of unexpected vehicle behavior can be suppressed. Also, when emergency avoidance becomes necessary, the emergency avoidance performance can be maximally exerted.

[0074] By the way, the trajectory tracking control by the microcomputer 610 is not limited to the control with the forward viewing point as the target position. For example, the microcomputer 610 can perform control to make the vehicle 100 follow the closest contact point (closest contact target position), which is the point on the line connecting the accumulated trajectory points on the target trajectory and closest to the vehicle 100 among the trajectory points accumulated on the target trajectory, as disclosed in Japanese Patent No. 6837196.

[0075] FIG. 12 is a functional block diagram when the trajectory tracking control unit 630 performs control to make the vehicle 100 follow the above - mentioned closest contact point. The trajectory tracking control unit 630 shown in FIG. 12 acquires, as information regarding the target position, the information of a trajectory point sequence having a length of a predetermined distance or more corresponding to the forward viewing distance from the trajectory design unit 620.

[0076] The trajectory tracking control unit 630 includes a self-position estimation unit 631, a curvature calculation unit 632, a closest point calculation unit 633, an attitude angle calculation unit 634, a relative position calculation unit 635, and an actuator command unit 636. The self-position estimation unit 631 obtains the position of the vehicle 100 by measuring the latitude and longitude of the vehicle 100 by the GPS reception unit 310 or by dead reckoning or the like.

[0077] The curvature calculation unit 632 calculates the curvature and the change in curvature of the line connecting each trajectory point acquired from the trajectory design unit 620. The closest point calculation unit 633 obtains the closest point (in other words, the closest target position) on the line connecting each trajectory point that is closest to the position of the vehicle 100.

[0078] The attitude angle calculation unit 634 calculates the attitude angle of the vehicle 100 necessary to make the traveling direction of the vehicle 100 coincide with the yaw angle of the closest point, that is, the tangent direction of the target trajectory, at the closest point obtained by the closest point calculation unit 633 based on the curvature and the change in curvature of the target trajectory obtained by the curvature calculation unit 632. The attitude angle is the angle formed by the traveling direction of the vehicle 100 and the longitudinal axis direction of the vehicle 100.

[0079] The relative position calculation unit 635 calculates the relative position of the closest point obtained by the closest point calculation unit 633 with respect to the position of the host vehicle estimated by the self-position estimation unit 631, that is, the amount of track deviation. Then, the actuator command unit 636 corrects the yaw angle of the closest point based on the attitude angle calculated by the attitude angle calculation unit 634, generates a steering command and an acceleration or deceleration command to pass through the closest point at the target vehicle speed and the corrected yaw angle, and outputs the generated commands to the actuator unit 700. The steering commands output by the actuator command unit 636 include, for example, a yaw rate command, a left-right position command, and a yaw angle command.

[0080] Here, the trajectory design unit 620 may change the target trajectory in the case of a lane change or the like. At this time, if the trajectory design unit 620 is not configured to perform processing for maintaining the trajectory for a predetermined distance, the trajectory design unit 620 discards the information on the trajectory point sequence before the change (in other words, the target position), and among the trajectory points after the change, starting from the trajectory point closest to the position of the vehicle, it outputs the information on the trajectory point sequence up to the trajectory points within the forward viewing distance to the trajectory tracking control unit 630 in order. In this case, similar to the case of causing the vehicle 100 to follow the forward viewing point, the trajectory point sequence may be displaced suddenly, which may cause unexpected vehicle behavior.

[0081] On the other hand, if the trajectory design unit 620 is not configured to perform processing for maintaining the trajectory for a predetermined distance, the trajectory design unit 620 holds the trajectory including the distance traveled by the vehicle during the calculation period of the target trajectory and the trajectory point sequence (the first target position) in the previous period, and obtains the trajectory point sequence (the second target position) in this period. In this case, it is possible to suppress a sudden change in the trajectory point sequence that is the target position, and while ensuring the tracking control performance for the target trajectory, it is possible to suppress the occurrence of unexpected vehicle behavior.

[0082] Incidentally, in the vehicle control system 200 shown in FIG. 1, the upper unit, the automatic driving control device 500, and the vehicle motion control device 600 are configured as individual units, but the present invention is not limited to such a configuration. FIG. 13 shows a vehicle control system in which an integrated control device (in other words, one unit) 800 includes a microcomputer 810 that generates a target command and a microcomputer 820 that performs trajectory tracking control.

[0083] That is, the integrated control device 800 includes a microcomputer 810 having functional units such as the surrounding situation recognition unit 520, the action plan unit 530, and the target command generation unit 540, and a microcomputer 810 having functional units such as the trajectory design unit 620 and the trajectory tracking control unit 630. The microcomputer 810 and the microcomputer 820 are connected by circuits and wiring and are configured to be able to exchange signals with each other, and exhibit the same operating functions as the vehicle control system of FIG. 1.

[0084] Further, the vehicle control system 200 is not limited to a system that separately includes a first microcomputer having each functional unit of a surrounding situation recognition unit 520, an action plan unit 530, and a target command generation unit 540, and a second microcomputer having each functional unit of a trajectory design unit 620 and a trajectory following control unit 630. FIG. 14 shows a vehicle control system in which an integrated control device 830 includes one microcomputer 840, and the microcomputer 840 includes each functional unit of a surrounding situation recognition unit 520, an action plan unit 530, and a target command generation unit 540 as a host unit logic 840A, and further includes each functional unit of a trajectory design unit 620 and a trajectory following control unit 630 as a vehicle motion control logic 840B.

[0085] Also, the distribution pattern when distributing each functional unit of the surrounding situation recognition unit, the action plan unit, the target command generation unit, the trajectory design unit, and the trajectory following control unit to a plurality of microcomputers is not limited to the pattern of FIG. 1 or FIG. 13. For example, FIG. 15 shows a vehicle control system in which an integrated control device 850 includes a first microcomputer 851 and a second microcomputer 852, the first microcomputer 851 includes a surrounding situation recognition unit 520 as a functional unit, and the second microcomputer 852 includes each functional unit of an action plan unit 530, a target command generation unit 540, a trajectory design unit 620, and a trajectory following control unit 630.

[0086] Each technical idea described in the above embodiment can be used in appropriate combination as long as there is no contradiction. In addition, although the content of the present invention has been specifically described with reference to the preferred embodiment, it is obvious that those skilled in the art can adopt various modified forms based on the basic technical idea and teaching of the present invention.

[0087] For example, when the trajectory design unit 620 recognizes a curve ahead while the vehicle 100 is traveling on a straight road, it can switch from a mode of newly calculating the target trajectory from the position of the vehicle 100 every calculation cycle to a mode of holding a predetermined distance of the target trajectory. That is, the entry from a straight road to a curve is a condition where a sudden change in the target position such as the forward fixation point is likely to occur. When a sudden change in the target position is predicted, the trajectory design unit 620 can perform a process of holding a predetermined distance of the target trajectory.

[0088] In addition, when the friction coefficient of the road surface is smaller than a predetermined value, which makes it easier for unexpected vehicle behavior to occur due to a sudden change in the target position such as the forward fixation point, the trajectory design unit 620 can perform a process of holding a predetermined distance of the target trajectory.

Explanation of Signs

[0089] 100... vehicle, 200... vehicle control system, 300... external recognition unit, 400... vehicle motion state acquisition unit, 500... automatic driving control device, 510... microcomputer, 520... surrounding situation recognition unit, 530... action planning unit, 540... target command generation unit, 600... vehicle motion control device, 610... microcomputer (control unit, control unit), 620... trajectory design unit, 630... trajectory tracking control unit, 700... actuator unit

Claims

1. A vehicle control device including a control unit that outputs a result obtained by performing an operation based on input information, wherein the control unit, holds a trajectory including the distance the vehicle travels from the first time to the second time, which is the calculation period of the next target trajectory, among the first target trajectories obtained at the first time when calculating the target trajectory for driving the vehicle, and the first target position set in the first target trajectory, and obtains the second target trajectory at the second time, and outputs a control command for driving the vehicle based on information regarding the second target position set in the second target trajectory. Vehicle control device.

2. The vehicle control device according to claim 1, wherein the control unit, obtains the trajectory to be held based on the sum of the calculation period and the forward gaze time of the first forward gaze point, which is the first target position, and the speed of the vehicle. Vehicle control device.

3. The vehicle control device according to claim 1, wherein the control unit, a value obtained based on the sum of the calculation period and the forward gaze time of the first forward gaze point, which is the first target position, and the speed of the vehicle, a value obtained based on the acceleration of the vehicle and the forward gaze time of the first forward gaze point, which is the first target position, and obtains the trajectory to be held by adding them together. Vehicle control device.

4. The vehicle control device according to claim 1, wherein the control unit, a value obtained based on the calculation period and the speed of the vehicle, the forward gaze distance of the first forward gaze point, which is the first target position, and obtains the trajectory to be held by adding them together. Vehicle control device.

5. The vehicle control device according to claim 1, wherein the control unit, a value obtained based on the calculation period and the speed of the vehicle, a value obtained based on the acceleration of the vehicle and the calculation period, the forward gaze distance of the first forward gaze point, which is the first target position, and obtains the trajectory to be held by adding them together. Vehicle control device.

6. The vehicle control device according to claim 1, wherein the control unit, when the speed of the vehicle is lower than a predetermined value, holds the trajectory at a predetermined distance set in advance. Vehicle control device.

7. The vehicle control device according to claim 1, wherein the control unit, When emergency avoidance becomes necessary for the vehicle, the second target trajectory is obtained without maintaining the trajectory. Vehicle control device.

8. The vehicle control device according to claim 1, wherein the control unit, when switching from the first control for controlling the motion state of the vehicle according to the driving conditions of the vehicle to the second control for controlling the motion state of the vehicle with an index different from the first control, maintains the trajectory and obtains the second target trajectory by the second control. Vehicle control device.

9. The vehicle control device according to claim 8, wherein the control unit, when the first target position in the first control and the first target position in the second control are within a predetermined range, switches from the first control to the second control. Vehicle control device.

10. A vehicle control device including a control unit that outputs a result calculated based on input information, wherein the control unit, among the first target trajectories obtained at a first time for calculating a target trajectory for driving the vehicle, holds a trajectory corresponding to a predetermined distance from the vehicle and obtains a second target trajectory at a second time that is the next calculation cycle after the first time, and outputs a control command for driving the vehicle based on information regarding a target position set in the second target trajectory. Vehicle control device.

11. A vehicle control method executed by a control unit mounted on a vehicle, wherein the control unit, among the first target trajectories obtained at a first time for calculating a target trajectory for driving the vehicle, holds a trajectory including the distance traveled by the vehicle from the first time to a second time that is the next calculation cycle after the first time and the first target position set in the first target trajectory, and obtains a second target trajectory at the second time, and outputs a control command for driving the vehicle based on information regarding a second target position set in the second target trajectory. Vehicle control method.

12. An external recognition unit that acquires information regarding a driving environment of a driving route on which the vehicle travels, a vehicle motion state acquisition unit that acquires information regarding the motion state of the vehicle, a control unit that outputs a result calculated based on input information, Among the first target trajectories obtained at the first time for calculating the target trajectory for running the vehicle, hold a trajectory including the distance that the vehicle travels from the first time to the second time which is the next calculation cycle, and the first target position set in the first target trajectory, and obtain a second target trajectory at the second time. Output a control command for running the vehicle based on information regarding the second target position set in the second target trajectory. The control unit; An actuator unit that controls the motion state of the vehicle based on the control command; A vehicle control system comprising the above.

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