挖掘机自主挖掘分段可变阶多项式轨迹规划

Piecewise Polynomial with Variable Order in Trajectory Planning for Autonomous Mining

为保证挖掘机在自主挖掘作业中轨迹平稳连续,降低振动冲击,提出了一种轨迹规划方法,即将作业空间中路径进行合理分段,使其在保证轨迹规划结果中路径偏差较小不影响完成工作任务的前提下计算量尽量减小,并对每一段路径进行可变阶多项式插值轨迹规划。以某型单斗液压挖掘机实现自主挖掘为例,采用3-3-5-3-3多项式插值法进行轨迹规划,通过Matlab平台仿真,结果显示挖掘机各关节角位移、角速度、角加速度曲线平滑连续,但部分轨迹段角加速度超出加速度约束值。为进一步提高其动力学特性,对角加速度不满足要求的轨迹段,根据加速度约束,修正多项式最高阶次数,并利用修正后的高阶多项式进行轨迹规划。通过仿真结果对比,该分段可变阶多项式轨迹规划方法能够实现更加平稳连续的自主挖掘。

A new path planning method was proposed for an excavator to finish the autonomous mining,which was aimed to make the trajectory smooth and continuous,and decrease vibration impact strength.According to the proposed method,the path in working space will be reasonably segmented,so that the calculation of the amount of calculation will be reduced as far as possible in order to ensure that the path deviation of the path planning result is not affected by the task completion,and the trajectory planning of each segment was computed respectively by using interpolation polynomial with variable order. A certain type of single bucket hydraulic excavator was taken as the research object. First of all,the mining path was separated into five segments which employed interpolation polynomial with high order of 3-3-5-3-3successively in trajectory planning. The simulation was achieved by Matlab software. The result showed that the three curves for joint angle, angular velocity and angular acceleration were smooth and continuous,but some acceleration values in some segments exceeded the acceleration constraint. In order to improve the dynamics performance of the excavator＇s working mechanism,the segments having odd values were computed afresh with modified trajectory polynomial of which the highest order was calculated in terms of the acceleration constraint. New curve which figured by the piecewise polynomial with variable order showed that the new trajectory planning could be of use for the stable and continuous operation in autonomous mining.