Vehicle motion control apparatus, vehicle motion control method, and vehicle motion control system

1 . An apparatus comprising:

a vehicle motion controller that is configured to:

receive an input of a target position output from an autonomous driving control unit which generates a target trajectory of a vehicle which is the target position of the vehicle after a preview time, use a vehicle coordinate system when the target position is received as a reference coordinate system, and accumulate the target position as previous target positions on the reference coordinate system; and

output an instruction to an actuator of the vehicle for causing the vehicle to follow the closest point closest to the position of the vehicle, or to follow a target point located on a front side in the traveling direction, wherein the closest point and the target point are on the target trajectory connecting target positions obtained by coordinate transformation of each of previous target positions accumulated with reference to a latest vehicle coordinate system by projecting the reference coordinate system on the latest vehicle coordinate system and closer than a preview point, wherein

the closest point and the target point are closer to the vehicle than the preview point, and

the vehicle motion controller is further configured to calculate the closest point, which is a closest target position and which is the point closest to the vehicle on a line connecting each of the trajectory points accumulated in the trajectory buffer portion, determine a yaw angle at the closest point to be a middle point between yaw angles at two trajectory points between which the closest point is set, determine a vehicle speed at the closest point to be an average value of vehicle speeds at the two trajectory points, calculate a relative position of the closest point relative to an estimated position of the vehicle, and output the instruction for causing the vehicle to follow the closest point based on the calculated relative position.

2 . The apparatus according to claim 1 , wherein the vehicle motion controller is also configured to output, as the instruction, an instruction for causing the vehicle to follow a closest target position closest to the vehicle among the target point, which is the point on the line connecting each of the previous target positions.

3 . The apparatus according to claim 2 , wherein the vehicle motion controller is further configured to:

estimate a position of the vehicle; and

calculate a relative position of the closest target position relative to the estimated position of the vehicle,

output, as the instruction, the instruction for causing the vehicle to follow the closest target position based on the calculated relative position.

4 . The apparatus according to claim 1 , wherein the vehicle motion controller is further configured to:

calculate a curvature of the target trajectory from the target point, which is the point on the line connecting each of the accumulated target positions; and

calculate a posture angle required to allow a traveling direction of the vehicle at the target point, which is the point on the line connecting each of the previous target positions and a tangential direction of the target trajectory to match each other, based on the calculated curvature, the posture angle being an angle formed between the traveling direction of the vehicle and a longitudinal axis direction of the vehicle,

output, as the instruction, an instruction for tilting a front-side direction of the vehicle outward in a steering direction with respect to the tangential direction of the target trajectory, based on the calculated posture angle.

5 . The apparatus according to claim 1 , wherein the vehicle motion controller is further configured to select the target position according to a running state of the vehicle among the target point, which is the point on the line connecting each of the previous target positions and outputs, as the instruction, an instruction for causing the vehicle to follow the selected target position.

6 . The apparatus according to claim 1 , wherein the vehicle motion controller is further configured to:

wherein, when the target position cannot be accumulated, output an instruction for causing the vehicle to follow a trajectory based on external world recognition information, or output an instruction for causing the vehicle to follow a trajectory based on the target point, which is the point on the line connecting each of the previously accumulated target positions.

7 . The apparatus according to claim 1 , wherein the vehicle motion controller is further configured to estimate a position of the vehicle,

wherein, when the target trajectory is changed, the vehicle motion controller receives an input of a next target position before the vehicle reaches the target position on the target trajectory after the change.

8 . The apparatus according to claim 1 , wherein the actuator includes a plurality of actuators, and

wherein, when a failure occurs in any of the plurality of actuators, the vehicle motion controller outputs the instruction to an actuator without the failure.

9 . The apparatus according to claim 1 , wherein the target positions are accumulated using multiple target positions received at different times and the vehicle motion controller calculates a posture angle based on a curvature of the target trajectory at the closest point, and corrects a yaw angle that causes a front-side direction of the vehicle to face outward in a steering direction with respect to the tangential direction of the target trajectory at the closest point.

10 . A vehicle motion control method comprising:

receiving an input of a target position output from an autonomous driving control unit which generates a target trajectory of a vehicle which is the target position of the vehicle after a preview time, using a vehicle coordinate system when the target position is received as a reference coordinate system, and accumulating the target position as previous target positions on the reference coordinate system; and

outputting an instruction to an actuator of the vehicle for causing the vehicle to follow the closest point closest to the position of the vehicle, or to follow a target point located on a front side in the traveling direction wherein the closest point and the target point are on the target trajectory connecting target positions obtained by coordinate transformation of each of previous target positions accumulated by the receiving the input and the accumulating the target position with reference to a latest vehicle coordinate system by projecting the reference coordinate system on the latest vehicle coordinate system and closer than a preview point, wherein

the closest point and the target point are closer to the vehicle than the preview point; and calculating the closest point, which is a closest target position and which is the point closest to the vehicle on a line connecting each of the trajectory points accumulated in the trajectory buffer portion, determine a yaw angle at the closest point to be a middle point between yaw angles at two trajectory points between which the closest point is set, determine a vehicle speed at the closest point to be an average value of vehicle speeds at the two trajectory points, calculate a relative position of the closest point relative to an estimated position of the vehicle, and output the instruction for causing the vehicle to follow the closest point based on the calculated relative position.

11 . The vehicle motion control method according to claim 10 , wherein the outputting the actuator instruction includes outputting, as the instruction, an instruction for causing the vehicle to follow a closest target position closest to the vehicle among the target point, which is the point on the line connecting each of the previous target positions.

12 . The vehicle motion control method according to claim 11 , further comprising:

estimating a position of the vehicle; and

calculating a relative position of the closest target position relative to the position of the vehicle estimated by the estimating the position,

wherein the outputting the instruction includes outputting, as the instruction, the instruction for causing the vehicle to follow the closest target position based on the relative position calculated by the calculating the relative position.

13 . The vehicle motion control method according to claim 10 , further comprising:

calculating a curvature of the target trajectory from the target point, which is the point on the line connecting each of the target positions accumulated by the receiving the input and the accumulating the target position; and

calculating a posture angle required to allow a traveling direction of the vehicle at the target point, which is the point on the line connecting each of previous target positions and a tangential direction of the target trajectory to match each other, based on the curvature, calculated by the calculating the curvature the posture angle being an angle formed between the traveling direction of the vehicle and a longitudinal axis direction of the vehicle,

wherein the outputting the instruction includes outputting, as the instruction, an instruction for tilting a front-side direction of the vehicle outward in a steering direction with respect to the tangential direction of the target trajectory, based on the posture angle calculated by the calculating the posture angle.

14 . The vehicle motion control method according to claim 10 , wherein the outputting the instruction includes selecting the target position according to a running state of the vehicle among the target point, which is the point on the line connecting each of the previous target positions and outputting, as the instruction, an instruction for causing the vehicle to follow the selected target position.

15 . The vehicle motion control method according to claim 10 , further comprising outputting a second instruction to the actuator for fail-safe,

wherein the outputting the second instruction includes, when the target position cannot be accumulated by the receiving the input and the accumulating the target position outputting, as the second instruction, an instruction for causing the vehicle to follow a trajectory based on external world recognition information, or outputting, as the second instruction, an instruction for causing the vehicle to follow a trajectory based on the target point, which is the point on the line connecting each of the target positions accumulated by the receiving the input and the accumulating the target position.

16 . The vehicle motion control method according to claim 10 , further comprising estimating a position of the vehicle,

wherein the receiving the input and the accumulating the target position includes, when the target trajectory is changed, receiving an input of a next target position before the vehicle reaches the target position on the target trajectory after the change.

17 . A vehicle motion control system comprising:

an autonomous driving control unit which generates a target trajectory of a vehicle which is the target position of the vehicle after a preview time;

a vehicle motion controller configured to receive an input of a target position output from the autonomous driving control unit, use a vehicle coordinate system when the target position is received as a reference coordinate system, and accumulate the target position as previous target positions on the reference coordinate system, and configured to output an instruction for causing the vehicle to follow the closest point closest to the position of the vehicle, or to follow a target point located on a front side in the traveling direction wherein the closest point and the target point are on the target trajectory connecting target positions obtained by coordinate transformation of each of previous target positions accumulated with reference to a latest vehicle coordinate system by projecting the reference coordinate system on the latest vehicle coordinate system and closer than a preview point; and

an actuator configured to control the vehicle according to the instruction that is output wherein

the closest point and the target point are closer to the vehicle than the preview point, and

the vehicle motion controller is further configured to calculate the closest point, which is a closest target position and which is the point closest to the vehicle on a line connecting each of the trajectory points accumulated in the trajectory buffer portion, determine a yaw angle at the closest point to be a middle point between yaw angles at two trajectory points between which the closest point is set, determine a vehicle speed at the closest point to be an average value of vehicle speeds at the two trajectory points, calculate a relative position of the closest point relative to an estimated position of the vehicle, and output the instruction for causing the vehicle to follow the closest point based on the calculated relative position.

18 . The vehicle motion control system according to claim 17 , wherein the vehicle motion controller outputs, as the instruction, an instruction for causing the vehicle to follow a target position closest to the vehicle among the target point, which is the point on the line connecting each of the previous target positions.