基于角动量守恒的空间机器人动力学参数辩识

空间机器人由于加工、装配误差以及在轨燃料消耗等因素使其名义公称参数与实际动力学参数相比存在一定的误差。空间机器人路径规划和地面机器人不同,其广义雅克比矩阵包含动力学参数,使计算的轨迹偏离实际要求的路径,引起末端位姿误差。本文根据自由飘浮空间机器人的角动量守恒方程式,对一种两自由度空间机器人的基座以及机械臂的各个关节分别单独做三次多项式轨迹激励,利用基于偏差模型的最小二乘法和遗传算法对动力学参数进行辨识。仿真结果表明,遗传算法的计算稳定性和对动力学参数辩识精度优于最小二乘法。

Dynamic Parameter Identification for a Space Robot Based on Angular Momentum Conservation

For a space robot there are errors between its nominal dynamic parameters and real dynamic ones because of some factors of machining and assembly. However, Path planning for the space robot is different from that on the ground, since the dynamic parameters exist in the generalized Jacobian matrix, the calculated trajectory will deviate from the really desired one, which will cause some pose errors of the end-effector. According to the angular momentum conservation equation for a free-floating space robot, the base and joints of a two DOF space robot are respectively excited with the cubic polynomial trajectory, then its dynamic parameters are identified respectively using the least-square algorithm based on the error model and the GA (genetic algorithm). The simulation results show that the calculated stability and the dynamic parameters' identification accuracy with GA are better than those with the least square.