基于样条理论的自动垂直泊车轨迹规划

分析泊车轨迹曲线设计要求并综合B样条曲线特点,提出基于B样条曲线理论通过对轨迹控制点优化进行自动垂直泊车轨迹规划的方法.分析泊车过程中存在的可能性碰撞点,并建立相应的避撞约束函数.考虑泊车环境障碍约束、车辆自身参数约束、泊车初始点方位约束、泊车终点位置约束,以泊车轨迹的最大曲率值最小化为目标,以轨迹曲线控制点为变量,根据Ackerman转向原理建立车辆运动轨迹多约束方程.分别对一般泊车环境和狭小空间泊车环境进行泊车轨迹规划,利用Matlab软件非线性约束优化函数求得轨迹控制点,得出轨迹曲线.仿真结果表明:对于一般泊车环境该方法能使车辆无碰撞地进入车位,且满足泊车轨迹曲率连续性;对于相对狭小泊车环境,也能求得一组轨迹控制点,通过不断调节前轮转角实现车辆无碰撞地泊车入位并保证了轨迹曲率的连续性.仿真结果表明了基于样条理论的泊车轨迹规划方法可实现车辆无碰撞地泊车入位,并满足轨迹曲率连续性要求,有效地解决了泊车过程中停车转向问题.

Trajectory Planning of Automatic Vertical Parking Based on Spline Theory

Parking trajectory characteristics were analyzed,and an approach for trajectory planning was proposed on the basis of the B spline theory,and the parking path was realized by adjusting the control points.Potential collision points were analyzed,and the constraint equations were established accordingly.The orientation constraints at the start point,the location constraints at the parking point,and the restriction of vehicle were considered,and the constraint equations were established respectively.Parking kinematic function was presented on the basis of Ackerman steering theory,and parking trajectory optimization function was presented to minimize the max trajectory curvature in parking process with the restrictions mentioned above.The approach was used to plan parking path for general parking space and tight parking space,and the trajectory function was solved in Matlab.The simulation results have shown that the car can reverse into parking set safely in general parking space,with the trajectory curvature changing continuously and the car paralleling the parking set at the parking point.The car can reverse into parking set without collision in tight parking space by adjusting steering angle repeatedly,with the trajectory curvature changing continuously.It is proved that the approach proposed can find a collision-free path in different parking spaces and meets the demand of continuous trajectory curvature,so the problem of shutting down to steer the wheel in parking process has been solved.