Vehicle control device

Abstract

To provide a vehicle control device, a vehicle control method, and a vehicle control system that can suppress occurrence of unexpected vehicle behavior while ensuring follow-up control performance to a target track.SOLUTION: According to a vehicle control device, a vehicle control method, and a vehicle control system of the present invention, as one embodiment thereof, a track including a travel amount of a vehicle from a first time to a second time, which is an operation period of a next target track, of a first target track determined at the first time when calculating a target track for traveling the vehicle, and a first target position set onto the first target track is held, and a second target track at the second time is determined.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] The vehicle driving control method of Patent Document 1 is a vehicle driving control method that detects a target trajectory along which the vehicle should travel and automatically drives the vehicle along the detected target trajectory.The method provisionally sets a forward gaze point distance from the vehicle to the forward gaze point based on at least driving lane information, and, assuming that the vehicle has traveled the provisionally set forward gaze point distance, estimates the vehicle's driving trajectory at the forward gaze point that matches the target trajectory.The method detects the maximum value of lateral displacement between the estimated vehicle's driving trajectory and the target trajectory from the vehicle's current position to the forward gaze point.The method finally sets the forward gaze point distance when the maximum value of lateral displacement is less than a predetermined value as the forward gaze point distance, and then automatically drives the vehicle based on the finally set forward gaze point distance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6610799 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, one example of trajectory tracking control that causes a vehicle to travel along a target trajectory is control that generates a vehicle control command using a forward gaze point set on a target trajectory ahead of the vehicle as a tracking target point. In such trajectory tracking control, if the shape of the target trajectory changes significantly between the previous and current calculation cycles, the tracking target point will be displaced in a single step, and attempting to make the vehicle follow the tracking target point could result in unexpected vehicle behavior. Here, in order to prevent the tracking target point from being displaced in a single step, if the tracking target point is set at a distance where the deviation of the vehicle's driving trajectory from the target trajectory is less than a predetermined value, the tracking target point will be set at a position closer to the vehicle, which could result in a deterioration in tracking control performance to the target trajectory due to response delays in vehicle control, etc.

[0005] The present invention has been made in consideration of the current situation, and its purpose 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 control performance for tracking a target trajectory. [Means for solving the problem]

[0006] According to one aspect of the present invention, a first target trajectory calculated at a first time for calculating a target trajectory for a vehicle to travel is retained, which includes the distance traveled by the vehicle from the first time to a second time, which is the calculation cycle for the next target trajectory, and a first target position set in the first target trajectory, and a second target trajectory at the second time is calculated. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress the occurrence of unexpected vehicle behavior while ensuring the control performance of tracking the target trajectory. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a vehicle control system. [Figure 2] FIG. 1 is a diagram outlining a lane keeping function. [Figure 3] FIG. 2 is a diagram outlining a preceding vehicle following function. [Figure 4] FIG. 1 is a diagram outlining a path following function. [Figure 5] FIG. 10 is a diagram illustrating how to determine a left-right deviation. [Figure 6] FIG. 10 is a diagram illustrating the action and function of orbit maintenance processing. [Figure 7]FIG. 10 is a diagram illustrating a required length of a target trajectory. [Figure 8] FIG. 10 is a diagram illustrating a coordinate transformation process in the trajectory maintenance process. [Figure 9] 10 is a flowchart showing a control process when performing a station-keeping process. [Figure 10] 10 is a flowchart showing a control process when orbit maintenance processing is performed when switching application software. [Figure 11] 10 is a flowchart showing a control process when the orbit maintaining process is cancelled during emergency avoidance. [Figure 12] FIG. 2 is a functional block diagram of trajectory tracking control based on a sequence of trajectory points. [Figure 13] FIG. 1 is a block diagram showing a vehicle control system including an integrated control device having two microcomputers. [Figure 14] 1 is a block diagram showing a vehicle control system including an integrated control device having one microcomputer. [Figure 15] FIG. 10 is a block diagram illustrating an example of a pattern for allocating functional units to two microcomputers. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 accompanying drawings. FIG. 1 is a block diagram showing an embodiment of a vehicle control system 200 mounted on a vehicle 100. As shown in FIG. The vehicle 100 is an automobile equipped with 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 assistance system or an automatic driving system that plans a target trajectory for 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 trajectory. 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 about the driving environment of the road on which the vehicle 100 is traveling. The external environment recognition unit 300 includes, for example, a GPS (Global Positioning System) receiving unit 310, a map database 320, a road-to-vehicle 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 receives signals from GPS satellites to measure the latitude and longitude of the vehicle 100 position. The map database 320 is formed in a storage device installed in the vehicle 100 . The map information in the map database 320 includes information such as road locations, road shapes, and intersection locations.

[0013] The road-to-vehicle communication device 330 transmits information about the vehicle 100 to a roadside device, and receives road traffic information such as curves and intersections from the roadside device. The external environment recognition unit 300 may include a communication device for performing inter-vehicle communication to acquire road traffic information, behavior information of other vehicles, and the like from other vehicles.

[0014] The camera 340 is a stereo camera, a monocular camera, a full-surround camera, or the like, and captures images of the surroundings of the vehicle 100 to obtain image information of the surroundings of the vehicle 100 . The radar 350 and the LiDAR 360 detect objects around the vehicle 100 and output information about the detected objects.

[0015] The vehicle motion state acquisition unit 400 is a device for acquiring information about 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 rotation speed of each wheel of the vehicle 100, and the detection result of the wheel speed sensor 410 is used in an estimation calculation of the speed of the vehicle 100. It should be noted that instead of the wheel speed sensor 410, or together with the wheel speed sensor 410, a vehicle speed sensor that detects the speed of the vehicle 100 may be provided. The acceleration sensor 420 detects the longitudinal acceleration, lateral acceleration, vertical acceleration, yaw rate, pitch rate, roll rate, and the like of the vehicle 100 .

[0017] The automatic driving control device 500 is an electronic control device mainly including a microcomputer 510 as a control unit that performs calculations based on acquired information and outputs the calculation results. The microcomputer 510 includes a microprocessor unit (MPU), a read-only memory (ROM), a random access memory (RAM), and the like, all of which are not shown.

[0018] The microcomputer 510 acquires an external environment recognition signal from the external environment recognition unit 300, which includes position information of the vehicle 100, road shape information, road surface information, object information, and the like. Furthermore, the microcomputer 510 acquires vehicle motion detection signals such as the speed and acceleration of the vehicle 100 from the vehicle motion state acquisition unit 400 .

[0019] Then, the microcomputer 510 calculates a target command for the trajectory tracking control based on the acquired information, 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, an action planning unit 530, and a target command generation unit 540 as functional units for calculating the target command.

[0020] The surrounding situation recognition unit 520 recognizes the situation around the vehicle 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 situation around the vehicle recognized by the surrounding situation recognition unit 520 includes information such as the curvature of the road, the road surface cant, the road surface gradient, the road surface friction coefficient μ, 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 include, for example, pedestrians, bicycles, motorcycles, other vehicles, etc. The above-mentioned stationary objects include, for example, fallen objects on the road, traffic lights, guardrails, curbs, road signs, trees, billboards, etc.

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

[0022] The target command that the target command generation unit 540 issues to the vehicle motion control device 600 includes, for example, a command indicating the driving area ahead of the vehicle 100, road surface information within the driving area such as friction coefficient, slope, unevenness, etc., and object information such as information on other vehicles, pedestrians, obstacles, etc. Here, the target command generating unit 540 specifies the driving area as the target command as the area between the white lines or between the road edges, and if any object exists within the lane, specifies it as an area that does not include that object.

[0023] Furthermore, the target command generating unit 540 can, for example, set the shadow of an object as a collision risk area in order to guard against the vehicle jumping out from behind the object, and can specify the driving area as an area excluding such collision risk area. Furthermore, when there is an area ahead of the vehicle 100 that could not be recognized, the target command generating unit 540 can specify a traveling 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 acquired information (in other words, input information) and outputs the calculation results. The microcomputer 610 includes an MPU, a ROM, a RAM, and the like, which are not shown.

[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 movement 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 travel area, road surface information, object information, etc. from the automatic driving control device 500, more specifically, from the target command generation unit 540 of the microcomputer 510. Then, the trajectory design unit 620 designs a target trajectory of the vehicle 100 in the driving assistance function related to autonomous driving based on the acquired target command, and outputs information related to the target position of the target trajectory to the trajectory tracking control unit 630.

[0027] Here, the trajectory design unit 620 outputs information about a trajectory point that is a target to be reached by the vehicle 100 in the future, as a target position on the target trajectory. Hereinafter, the trajectory point that is the target of the vehicle 100 after the forward gaze time is referred to as the forward gaze point. In addition, the forward gaze time can be made variable according to the speed of the vehicle 100, as follows: forward gaze time = forward gaze distance / vehicle speed. The information regarding the forward gaze point is position information of the forward gaze point or information regarding the relative position between the forward gaze point and the vehicle 100.

[0028] The trajectory design unit 620 sets the forward gaze point in accordance with a plurality of driving support functions. Multiple driving assistance functions include lane keeping, following the vehicle ahead, and autonomous driving. Figures 2 to 4 are diagrams outlining 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. In addition, in the preceding vehicle following function, the trajectory design unit 620 sets a forward gaze point at the position of the preceding vehicle. In addition, in the route tracking function, the trajectory design unit 620 sets a forward gaze point on the route to the destination.

[0030] In addition, in the process of setting 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. In other words, the trajectory design unit 620 can design a target trajectory that places emphasis on 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 tracking control unit 630 calculates a control command for making the vehicle 100 follow the target trajectory based on the amount of deviation of the vehicle 100 from the target trajectory. FIG. 5 is a diagram showing how to obtain the lateral deviation ey at the forward gaze point.

[0032] The trajectory tracking control unit 630 calculates, as the lateral deviation ey, the amount of lateral deviation of the vehicle 100 from the target trajectory that is predicted to occur after the forward gaze time, assuming that the vehicle 100 continues to move in the current direction. Then, the trajectory tracking control unit 630 sets a lateral acceleration command based on the lateral deviation ey, for example, and outputs a control command to the actuator unit 700 to realize the lateral acceleration command.

[0033] The actuator section 700 controls the motion of the vehicle 100 based on a control command from the vehicle motion control device 600 (microcomputer 610). The actuator section 700 includes an internal combustion engine 710 and a motor 720 that generate driving force for the vehicle 100, a braking device 730 that applies braking force to the vehicle 100, an electronically controlled power steering device 740 for changing the direction of travel of the vehicle 100, and an electronically controlled suspension (active suspension) 750 that can adjust damping force and vehicle height. It should be noted 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] The trajectory design unit 620 has a function of designing a target trajectory so as to prevent the forward gaze point, which is the target position, from suddenly changing during the calculation cycle of the target trajectory. Specifically, in calculating the target trajectory for each calculation cycle [ms], the trajectory design unit 620 retains a trajectory of a predetermined distance from the vehicle 100 from the first target trajectory calculated at a first time, calculates a second target trajectory at a second time, which is the next calculation cycle after the first time, and has the function of outputting information regarding the second target position (second forward gaze 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 that includes the trajectory design process described above.

[0035] Here, the trajectory design unit 620 sets the predetermined distance for maintaining the trajectory shape as a distance required to keep the displacement of the forward gaze point within an allowable range during the calculation cycle of the target trajectory. Specifically, the trajectory design unit 620 retains a trajectory of the first target trajectory calculated at the first time that includes the distance traveled by the vehicle 100 between the first time and the second time, which is the calculation cycle for the next target trajectory, and the first target position (first forward gaze point) set in the first target trajectory, and calculates a second target trajectory at the second time.

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

[0037] By designing such a target trajectory, sudden changes in the forward gaze point, which is the target position for tracking control, are prevented, thereby preventing unexpected vehicle behavior from occurring by controlling the vehicle 100 toward the forward gaze point. Furthermore, in designing the above-mentioned target trajectory, the trajectory design unit 620 does not perform processing to shorten the forward gaze distance in order to prevent sudden changes in the forward gaze point, thereby preventing deterioration of the tracking control performance to the target trajectory due to response delays in vehicle control, etc.

[0038] The following describes in detail the design of a target trajectory that partially maintains the trajectory shape. The trajectory design unit 620 needs to change the shape of the target trajectory from moment to moment in accordance with the surrounding environment that changes as the vehicle 100 travels. Here, when the trajectory design unit 620 calculates the target trajectory at a fixed calculation period ΔT, the target trajectory that begins to be calculated at time t0 (first time) is not actually used for tracking control until time t0+ΔT (second time) when the target trajectory is updated.

[0039] Furthermore, in controlling the vehicle 100 to follow the target trajectory, the trajectory following control unit 630 controls the actuator unit 700, as described above, with the forward gaze point ahead of the vehicle 100 as the target position. Therefore, if the trajectory shape changes by the distance calculated by adding the distance traveled by vehicle 100 during the calculation period ΔT and the forward gaze distance, which is the distance from vehicle 100 to the forward gaze point, the forward gaze point may shift in a single step between the previous period and the current period, causing a sudden change in the left-right deviation ey (see Figure 5).

[0040] Therefore, the trajectory design unit 620 sets the distance obtained by adding the distance traveled by the vehicle 100 during the calculation period ΔT of the target trajectory and the forward gaze distance as a predetermined distance for maintaining the trajectory shape, so that the trajectory shape for that distance does not change even when recalculated. This prevents the forward gaze point from being displaced in a single step and the left-right deviation ey from changing suddenly during the calculation cycle ΔT of the target trajectory, thereby preventing the occurrence of unexpected vehicle behavior.

[0041] FIG. 6 illustrates an example of changes in the target trajectory and the forward gaze point when the vehicle 100 enters a curve. The left side of Figure 6 shows the displacement of the forward gaze point when the target trajectory is completely redrawn at a second time t0+ΔT after a calculation period ΔT, without retaining 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 approximately straight because it is just before the curve, whereas the shape of the target trajectory newly redrawn at the second time t0+ΔT after the calculation period ΔT is a shape that follows the curve shape in preparation for entering the curve. Therefore, the forward gaze point (second target position) at the second time t0+ΔT changes suddenly in the left-right direction relative to the forward gaze point (first target position) at the first time t0.

[0043] On the other hand, the right side of Figure 6 shows the forward gaze 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 by retaining the trajectory for a distance equal to the sum of the distance traveled by vehicle 100 during the calculation cycle ΔT and the forward gaze point distance, out of the first target trajectory obtained at the first time t0. In this case, the shape of the target trajectory for the distance obtained by adding the distance traveled by the vehicle 100 during the calculation period ΔT and the forward gaze point distance remains the same as that of the previous period, but the target trajectory beyond that point is changed.

[0044] Therefore, the lateral displacement of the forward gaze point (second target position) at the second time t0+ΔT relative to the first forward gaze point (first target position) at the first time t0 is suppressed. In other words, the forward gaze point, which is the target position on the target trajectory, is prevented from being displaced in a single step, and sudden changes in the left-right deviation ey are prevented, thereby preventing unexpected vehicle behavior from occurring due to trajectory tracking control. Furthermore, in the design of the target trajectory described above, the forward gaze distance is kept constant, so that it is possible to prevent the performance of the target trajectory tracking control from deteriorating due to a shortened forward gaze distance.

[0045] FIG. 7 is a diagram for explaining the requirements for the length of a target trajectory in designing a target trajectory that maintains a trajectory for a predetermined distance from the vehicle 100. In FIG. In FIG. 7, Tfwd represents the forward gaze time. When calculation of the target trajectory starts at time t0, the target trajectory shown by the solid line in FIG. 7 is calculated based on information such as the travel area command obtained at time t0. 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, which begins to be calculated at time t0, is used for trajectory tracking control at time t0+ΔT, when a calculation period ΔT has elapsed since time t0. Furthermore, the vehicle 100 travels a distance according to the speed of the vehicle 100 during the calculation period ΔT. Here, in the process of retaining the trajectory shape, the trajectory design unit 620 uses, from the time t0+ΔT, the target trajectory at the time t0 one cycle before as is until the time t0+ΔT+Tfwd.

[0047] Therefore, the target trajectory at time t0+ΔT must overlap with the target trajectory from one cycle ago when viewed in the absolute coordinate system until time t0+ΔT+Tfwd; in other words, it must maintain the shape of the target trajectory from one cycle ago. In other words, if the trajectory shape is to be maintained for a distance equal to the sum of the distance traveled by the vehicle 100 during the calculation period ΔT and the forward gaze point distance, the trajectory design unit 620 must calculate the target trajectory at time t0 up to a distance further forward than the trajectory at time t0+ΔT+Tfwd.

[0048] FIG. 8 is a diagram for explaining the coordinate transformation process in the calculation of a target trajectory that partially maintains the trajectory shape. In Figure 8, the target trajectory shown by the solid line is a target trajectory calculated based on information obtained at time t0, and the target trajectory shown by the dotted line is a target trajectory calculated based on information obtained at time t0 + ΔT. Of the target trajectory calculated based on information obtained at time t0+ΔT, the portion ΔT+Tfwd from vehicle 100 must overlap with the target trajectory calculated based on 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 of the target trajectory calculated at time t0 that is ΔT+Tfwd from vehicle 100 needs to be converted to the vehicle coordinate system at time t0+ΔT. Therefore, at time t0+ΔT, the trajectory design unit 620 converts the portion of the target trajectory calculated at time t0 that is ΔT+Tfwd from the vehicle 100 into the vehicle coordinate system at time t0+ΔT based on the vehicle movement amount in the calculation period ΔT.

[0050] FIG. 9 is a flowchart showing the control process of the microcomputer 610 (the trajectory design unit 620 and the trajectory tracking control unit 630) when partial retention of the trajectory shape is performed. In step S1001, the microcomputer 610 acquires information on the position, speed, etc. of the vehicle 100.

[0051] Next, in step S1002, the microcomputer 610 predicts the sum of the distance traveled by the vehicle 100 during the calculation period ΔT of the target trajectory and the forward gaze distance, which is the distance traveled by the vehicle 100 during the forward gaze time Tfwd, and sets the predicted total distance as the length L [m] of the trajectory to be maintained (see Figure 6).

[0052] Here, the microcomputer 610 calculates the length L [m] of the track to be maintained from equation (1) based on the time T obtained by adding the calculation period ΔT and the forward gaze 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] Furthermore, the microcomputer 610 can calculate the length L of the track to be maintained by taking into consideration the change in speed due to the acceleration of the vehicle 100, using equation (2). L=T×vehicle speed+1 / 2×acceleration×T 2 …(2) Furthermore, the microcomputer 610 can obtain the length L of the track to be maintained based on the calculation period ΔT, the vehicle speed, and the forward gaze distance D from the formula (3). L=ΔT×vehicle speed+forward gaze distance D…(3)

[0054] Furthermore, the microcomputer 610 can obtain the length L of the track to be maintained from the formula (4) based on the calculation period ΔT, the vehicle speed, the forward gaze distance D, and the acceleration. L=ΔT×vehicle speed+1 / 2×acceleration×ΔT 2 +Forward gaze distance D…(4) In addition, when the vehicle 100 is traveling at a low speed, that is, when the speed of the vehicle 100 is lower than a predetermined value, the microcomputer 610 can fix the length L of the track to be maintained at a predetermined constant distance, rather than varying it depending on the vehicle speed.

[0055] After determining the length L of the track to be retained, in step S1003, the microcomputer 610 retains the track of length L from the position of vehicle 100 of the target track from one cycle ago; in other words, it sets the shape of the track of length L from the position of vehicle 100 not to change. Then, in the next step S1004, the microcomputer 610 calculates the target trajectory for the portion farther than the length L.

[0056] Next, in step S1005, the microcomputer 610 designs a target trajectory consisting of a trajectory of length L from the target trajectory of the previous cycle and a newly calculated target trajectory that continues beyond that, and ends the calculation of the target trajectory. The above-described processes in steps S1001 to S1005 are performed by the trajectory design unit 620.

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

[0058] The control process shown in the flowchart of FIG. 9 is basically based on the premise that one application software (in other words, one driving assistance function) is continuously executed and the target trajectory is calculated at every calculation period ΔT. However, the situation in which the microcomputer 610 performs partial retention of the trajectory shape is not limited to when one piece of application software is continuously executed.

[0059] When the microcomputer 610 selectively switches and executes one of a plurality of application software (in other words, a plurality of driving assistance functions) that control the motion state of the vehicle 100 using different indicators depending on the driving conditions of the vehicle 100, it can maintain a trajectory of a predetermined distance from the vehicle 100 before and after switching the application software. The driving assistance functions that can be switched and executed include the lane keeping, preceding vehicle following, and route following, as already mentioned. In other words, when the microcomputer 610 switches from a first control that controls the motion state of the vehicle 100 to a second control that controls the motion state of the vehicle 100 using an index different from that of the first control depending on the driving conditions of the vehicle 100, the microcomputer 610 can maintain the trajectory and determine a second target trajectory using the second control.

[0060] FIG. 10 is a flowchart showing a control process when a target trajectory for a predetermined distance from the vehicle 100 is maintained before and after switching of application software (in other words, driving assistance functions). The microcomputer 610 acquires information on the position and speed of the vehicle 100 in step S1101. Next, in step S1102, the microcomputer 610 predicts the total value of the distance traveled by the vehicle 100 during the calculation 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 a change in the driving target or conditions, such as a change in application software, has occurred. Specifically, in step S1103, the microcomputer 610 determines whether it is necessary to redraw the target trajectory due to a change in the way the target trajectory is created, a change in the index used in creating the target trajectory, a change in the surrounding environment, or the like.

[0062] Here, a change in the way the target trajectory is created is, for example, when the control mode is switched from lane keeping (first control) to following the preceding vehicle (second control). Furthermore, a change in the index for generating the target trajectory may occur, for example, when the generation of a target trajectory that prioritizes ride comfort is changed to the generation of a target trajectory that maintains the vehicle closer to the center of the lane. Furthermore, changes in the surrounding environment are changes in the surrounding environment that require the target trajectory to be redrawn, such as when the friction coefficient of the road surface changes, or when a new obstacle, preceding vehicle, pedestrian, etc. is detected.

[0063] If the microcomputer 610 determines in step S1103 that no change in driving targets or conditions, such as a change in application software, has occurred, for example, if one application software is to be continuously executed, the microcomputer 610 proceeds from step S1103 to step S1104. In step S1104, similar to step S1003 described above, the microcomputer 610 performs setting to hold a trajectory of length L from the position of the vehicle 100 among the target trajectory calculated one cycle before. Then, in the next step S1105, the microcomputer 610 calculates the target trajectory for the portion farther than the length L.

[0064] On the other hand, if the microcomputer 610 determines in step S1103 that a change in the driving target or conditions, such as a change in application software, has occurred, the process proceeds from step S1103 to step S1106. In step S1106, the microcomputer 610 calculates a target trajectory under new travel targets and conditions (for example, application software after switching) so that the trajectory of length L from the position of the vehicle 100 remains unchanged from before the switching.

[0065] After the microcomputer 610 has performed the calculation of the target trajectory in step S1105 or step S1106, the process proceeds to step S1107, where the calculation of the target trajectory is completed. The above-described processes in steps S1101 to S1107 are performed by the trajectory design unit 620. The microcomputer 610 performs the processing as the trajectory tracking control unit 630 in steps S1108 and S1109.

[0066] In step S1108, the microcomputer 610 acquires information on the position of the vehicle 100, and in step S1109, performs trajectory tracking control by outputting a control command to the actuator unit 700 based on the amount of trajectory deviation at the forward gaze point after the forward gaze time Tfwd (in other words, forward by the forward gaze distance D). According to this control process, even if a change in driving target or conditions occurs that requires the target trajectory to be redrawn, the forward gaze point, which is the target position for tracking control, is prevented from suddenly changing as a result of the redrawing, thereby preventing unexpected vehicle behavior from occurring due to a sudden change in the forward gaze point.

[0067] In addition, the microcomputer 610 can include in the conditions for switching application software that the forward gaze point (target position) before and after the switch is within a specified range, that is, that the forward gaze point before and after the switch is the same or close to each other. When such switching conditions are applied, the microcomputer 610 calculates the target trajectory for each of the two application software before switching the application software, and if it determines that the forward gaze point is the same or close before and after the switch, it switches the application software (in other words, switches the target trajectory used for trajectory tracking control).

[0068] This prevents the forward gaze point (target position) from suddenly changing when switching application software, and prevents unexpected vehicle behavior from occurring due to a sudden change in the forward gaze point. After switching the application software, the microcomputer 610 maintains a trajectory of length L from the position of the vehicle 100 among the target trajectories calculated one cycle ago, thereby preventing a sudden change in the forward gaze point (target position).

[0069] In addition, when the vehicle 100 needs to make an emergency avoidance, the microcomputer 610 can cancel the process of retaining the trajectory of length L from the position of the vehicle 100 among the target trajectory calculated one cycle ago, and design a new target trajectory from the position of the vehicle 100. If the microcomputer 610 cancels orbit keeping when emergency avoidance becomes necessary, the performance of emergency avoidance is prevented from being degraded. Emergency avoidance refers to a situation in which, for example, an obstacle or pedestrian cuts into the driving path of vehicle 100 and it becomes necessary to avoid the obstacle, etc., and driving assistance for emergency avoidance is switched on.

[0070] FIG. 11 is a flowchart showing the control process for canceling stationkeeping when an emergency avoidance becomes necessary. In step S1201, the microcomputer 610 determines whether or not emergency avoidance is necessary based on an emergency avoidance determination flag, which serves as a trigger for implementing driving assistance for emergency avoidance.

[0071] Then, the microcomputer 610 cancels the retention of the trajectory shape by bypassing the trajectory design process for retaining the trajectory shape performed in steps S1202 to S1206. In other words, when emergency avoidance becomes necessary, the microcomputer 610 prioritizes emergency avoidance, such as avoiding an obstacle, over preventing a sudden change in the forward gaze point (target position), and designs a new target trajectory for emergency avoidance without being restricted by the history of target trajectories up to that point.

[0072] On the other hand, if the microcomputer 610 determines in step S1201 that the situation does not require emergency avoidance, it carries out the processing of steps S1202 to S1206 to design a target trajectory by retaining the trajectory of the previous cycle for a predetermined distance from the vehicle 100. The processing in steps S1202 to S1206 is similar to the processing in steps S1001 to S1005 described above, and therefore a detailed description thereof will be omitted.

[0073] Then, in step S1207, the microcomputer 610 acquires information on the position of the vehicle 100, and in step S1208, performs trajectory tracking control by outputting a control command to the actuator unit 700 based on the amount of trajectory deviation at the forward gaze point after the forward gaze time Tfwd (in other words, forward by the forward gaze distance D). According to this control process, in situations where emergency avoidance is not required, sudden changes in the forward gaze point (target position) are prevented, thereby suppressing the occurrence of unexpected vehicle behavior, and when emergency avoidance becomes necessary, emergency avoidance performance can be maximized.

[0074] Incidentally, the trajectory tracking control by the microcomputer 610 is not limited to control in which the forward gaze point is set as the target position. For example, the microcomputer 610 can accumulate trajectory points on a target trajectory, as disclosed in Japanese Patent Publication No. 6837196, and perform control to cause the vehicle 100 to follow the closest point of contact (closest target position), which is the point closest to the vehicle 100 on the line connecting the accumulated trajectory points.

[0075] FIG. 12 is a functional block diagram when the trajectory tracking control unit 630 performs control to make the vehicle 100 follow the closest point. The trajectory tracking control unit 630 shown in FIG. 12 acquires, from the trajectory design unit 620, information on a sequence of trajectory points having a length equal to or greater than a predetermined distance equivalent to the forward gaze distance, as information on the target position.

[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 determines the position of the vehicle 100 by measuring the latitude and longitude of the vehicle 100 using the GPS receiving unit 310, or by dead reckoning.

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

[0078] Based on the curvature and curvature change of the target trajectory calculated by the curvature calculation unit 632, the attitude angle calculation unit 634 calculates the attitude angle of the vehicle 100 required to align the traveling direction of the vehicle 100 at the closest point calculated by the closest point calculation unit 633 with the yaw angle of the closest point, i.e., the tangent direction of the target trajectory. The attitude angle is the angle between 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 calculated by the closest point calculation unit 633 with respect to the position of the vehicle estimated by the self-position estimation unit 631, that is, the amount of trajectory 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 for passing 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 command output by the actuator command unit 636 includes, 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 due to a lane change or the like. At this time, if the trajectory design unit 620 is configured not to perform processing to maintain the trajectory for a predetermined distance, the trajectory design unit 620 will discard the information on the trajectory point sequence before the change (in other words, the target position), and output to the trajectory tracking control unit 630 the information on the trajectory point sequence after the change, starting from the trajectory point closest to the vehicle position to the trajectory point at the forward gaze distance. In this case, as in the case where the vehicle 100 is made to follow the forward gaze point, the sequence of trajectory points may be displaced in a single step, which may cause unexpected vehicle behavior.

[0081] On the other hand, if the trajectory design unit 620 is not configured to perform the process of retaining a trajectory for a predetermined distance, the trajectory design unit 620 retains a trajectory including the distance traveled by the vehicle during the target trajectory calculation cycle and the trajectory point sequence (first target position) in the previous cycle, and calculates the trajectory point sequence (second target position) in the current cycle. In this case, sudden changes in the sequence of trajectory points, which are the target positions, can be prevented, and the occurrence of unexpected vehicle behavior can be suppressed while ensuring the performance of tracking control to the target trajectory.

[0082] In the vehicle control system 200 shown in FIG. 1, the automatic driving control device 500, which is a higher-level unit, and the vehicle motion control device 600 are configured as separate units, but the system is not limited to this configuration. FIG. 13 shows a vehicle control system in which one 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] In other words, the integrated control device 800 includes a microcomputer 810 having the functional units of a surrounding situation recognition unit 520, an action planning unit 530, and a target command generation unit 540, and a microcomputer 810 having the functional units of a trajectory design unit 620, and a trajectory tracking control unit 630. Microcomputer 810 and microcomputer 820 are connected by circuits and wiring, and are configured to be able to send and receive signals to and from each other, and perform the same functions as the vehicle control system of FIG.

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

[0085] Furthermore, when the functional units of the surrounding situation recognition unit, the action planning unit, the target command generation unit, the trajectory design unit, and the trajectory tracking control unit are allocated to multiple microcomputers, the allocation pattern is not limited to the patterns shown in FIG. 1 or FIG. 13. For example, Figure 15 shows a vehicle control system in which one integrated control device 850 has a first microcomputer 851 and a second microcomputer 852, the first microcomputer 851 has a surrounding situation recognition unit 520 as a functional unit, and the second microcomputer 852 has the functional units of a behavior planning unit 530, a target command generation unit 540, a trajectory design unit 620, and a trajectory tracking control unit 630.

[0086] The technical ideas explained in the above embodiments can be used in appropriate combinations as long as no contradiction occurs. Furthermore, although the contents of the present invention have been specifically described with reference to preferred embodiments, it is obvious that a person skilled in the art can adopt various modified embodiments based on the basic technical idea and teachings of the present invention.

[0087] For example, when the vehicle 100 is traveling on a straight road and recognizes a curve ahead, the trajectory design unit 620 can switch from a mode in which the target trajectory is newly calculated from the position of the vehicle 100 at each calculation cycle to a mode in which a predetermined distance of the target trajectory is retained. In other words, entering a curve from a straight road is a condition in which a sudden change in target position, such as the forward gaze point, is likely to occur, and the trajectory design unit 620 can perform processing to maintain a predetermined distance of the target trajectory when a sudden change in target position is predicted.

[0088] In addition, the trajectory design unit 620 can perform processing to maintain a predetermined distance of the target trajectory when the friction coefficient of the road surface is smaller than a predetermined value, making unexpected vehicle behavior more likely to occur due to a sudden change in the target position, such as the forward gaze point. [Explanation of symbols]

[0089] 100...vehicle, 200...vehicle control system, 300...external environment 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), 620...trajectory design unit, 630...trajectory tracking control unit, 700...actuator unit

Claims

1. A vehicle control device comprising an external environment recognition unit that acquires information about the driving environment of a road on which a vehicle is traveling, and a control unit that outputs a result of calculation based on the input information, The control unit calculating a predetermined distance for maintaining a target trajectory including a first target trajectory determined at a first time when a target trajectory for traveling the vehicle is calculated and a first target position set on the first target trajectory; When it is determined that the trajectory should be changed due to a change in the running environment, a second target trajectory is calculated so that the shape of the trajectory does not change for the predetermined distance; outputting a control command for causing the vehicle to travel based on information relating to a second target position set on the second target trajectory; Vehicle control device.

2. A vehicle control device according to claim 1, The control unit The trajectory to be maintained is determined based on a time obtained by adding a calculation cycle of the next target trajectory from the first time to a forward gaze time of the first forward gaze point, which is the first target position, and a speed of the vehicle. Vehicle control device.

3. A vehicle control device according to claim 1, The control unit a value calculated based on a time obtained by adding a calculation cycle of the next target trajectory from the first time to a forward gaze time of the first forward gaze point, which is the first target position, and a speed of the vehicle; a value calculated based on the acceleration of the vehicle and a forward gaze time of the first forward gaze point, which is the first target position; The trajectory to be retained is obtained by adding Vehicle control device.

4. A vehicle control device according to claim 1, The control unit a value calculated based on a calculation period of the next target trajectory from the first time point and the speed of the vehicle; a forward gaze distance of a first forward gaze point, which is the first target position; The trajectory to be retained is obtained by adding Vehicle control device.

5. A vehicle control device according to claim 1, The control unit a value calculated based on a calculation period of the next target trajectory from the first time point and the speed of the vehicle; a value calculated based on the acceleration of the vehicle and the calculation period of the next target trajectory from the first time; a forward gaze distance of a first forward gaze point, which is the first target position; The trajectory to be retained is obtained by adding Vehicle control device.

6. A vehicle control device according to claim 1, The control unit If the speed of the vehicle is lower than a predetermined value, the trajectory is maintained at a predetermined distance. Vehicle control device.

7. A vehicle control device according to claim 1, The control unit When an emergency avoidance becomes necessary for the vehicle, the trajectory is not maintained, and the second target trajectory is obtained. Vehicle control device.

8. A vehicle control device according to claim 1, The control unit When switching from a first control that controls a motion state of the vehicle to a second control that controls the motion state of the vehicle using an index different from that of the first control depending on a running condition of the vehicle, maintaining the trajectory and determining the second target trajectory under the second control; Vehicle control device.

9. A vehicle control device according to claim 8, 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, Switching from the first control to the second control; Vehicle control device.

10. A vehicle control device according to claim 1, The control unit The external environment recognition unit determines to change the trajectory when information is acquired that a moving object or a stationary object is newly detected in front of the vehicle. Vehicle control device.

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