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

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.

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.