基于最小Snap的UUV轨迹优化方法

Trajectory Optimization Method for a UUV Based on Minimum Snap

为了解决无人水下航行器(UUV)多项式轨迹大幅偏移原直线路径的问题,保证其能平稳且安全地通过障碍物区域,提出了一种基于7阶最小Snap的UUV多项式轨迹优化方法。首先在A*算法生成的初始路径基础上,根据预瞄线原理选取轨迹优化的参考点,然后拟合2种不同等式约束下的最小Snap轨迹,并且在具有连续约束的轨迹中增加中间平衡点进行偏移优化,同时设定评估指标来评价优化前后的偏移程度,最后在构建的障碍物环境中进行仿真试验,得到在时间一致约束下的3种不同轨迹。仿真结果表明,0约束下的轨迹虽然具有无碰撞保证,但是依然为折线轨迹,具有连续约束的轨迹虽然较平滑,但存在较大偏移,优化后的方法可以生成一条平滑且偏移量更小的轨迹。

To solve the problem of polynomial trajectory deviation from the original straight path and to allow an unmanned undersea vehicle(UUV)to pass an obstacle area smoothly and safely,a polynomial trajectory optimization method for a UUV based on the seventh-order minimum Snap method is proposed.First,based on the initial path generated by the A*algorithm,reference points for trajectory optimization are selected according to the principle of the preview line.Next,the minimum Snap trajectory is fitted under the constraints of two different equations,and the intermediate balance point is added to the trajectory according to the continuity constraint for offset optimization.Indicators are set to evaluate the degree of offset before and after the optimization.Finally,a simulation experiment is performed in a constructed obstacle environment to obtain three different trajectories under the constraint of time consistency.The simulation results show that obstacles are avoided by the vehicle when it follows a trajectory under the zero constraint;however,this trajectory is a polyline.Furthermore,the trajectory in which the continuity constraint is considered is smoother;however,its offset is larger.The optimization method can generate a smoother trajectory with a smaller offset.