摘要
对空间机械臂的路径规划算法进行了研究。针对一种星体和冗余机械臂(7自由度)的星臂联合系统,采用星臂联合路径规划方法。建立了机械臂末端位置和姿态的运动学方程。用基于多项式的伪逆路径规划算法对路径进行规划。仿真发现用三次多项式规划算法所得系统运行平滑且稳定末端能跟踪上目标,运行初始和结束时刻角速度达到设计要求,但系统运行结束时角加速度未收敛至零,存在软冲击缺陷。增加两个角加速度约束条件,用五次多项式改进了规划算法,仿真发现该系统解决了软冲击问题,且运行更稳定。为避免伪逆算法因奇异而失效的固有问题,设计了一种基于五次多项式的伪逆路径和规避奇异路径的联合规划方法。采用倒数法规避奇异问题,当奇异出现时,采用规避奇异路径规划算法,计算阻尼最小方差广义逆矩阵;当奇异不出现时,采用基于五次多项式的路径规划算法,计算雅可比矩阵的广义逆。最后可规划出机械臂各关节的角速度。仿真表明:用该联合规划方法所得系统在保证运行的精度和稳定度的同时,可避免奇异问题,提供了系统的稳定性和安全性。研究对空间机械臂设计有一定的参考价值。
The path planning method of space redundancy manipulator system was studied in this paper.The satellite and manipulator combined path planning was adopted for a satellite and manipulator system with 7 degree of freedom.The kinematics equations of the position and attitude of the manipulator end were established.The path was planned by pseudo-inverse path planning method based on polynomial.The simulation found that the operation of the system planned by cubic polynomial path planning method was smooth and the manipulator end could track the target.The angular velocity met the design requirement at the initial and finishing time.But the angular acceleration would not converge on zero when the system operation was completed,which meant that there was flexible strike.The path planning method was improved by adding two angular constrained conditions based on quintic polynomial.The simulation found that the flexible strike was eliminated and the system planned by the improved path planning method would operate much smoothly.To avoid the failure of pseudo-inverse path planning because of singularity,a new planning method united pseudo-inverse path planning based on quintic polynomial and singularity avoiding planning was designed.The singularity was avoided by reciprocal method.When the singularity appeared,the singularity avoiding path planning was adopted and calculated damp minimum variance generalized inverse matrices.When the singularity did not appear,the pseudo-inverse path planning based on quintic polynomial was adopted and calculated generalized inverse of Jacobian matrix.At last,the angular velocities of each joint of the manipulator were planned.The simulation showed that the system planned by the new united planning method could avoid singularity when the operation accuracy and smooth were guaranteed,which provided the stability and safety of the redundancy space manipulator system.The study has some valuable for the design of the space manipulator system.
出处
《上海航天》
CSCD
2017年第5期30-39,共10页
Aerospace Shanghai
关键词
空间冗余机械臂
路径规划
动力学耦合
软冲击
奇异
伪逆路径规划算法
规避奇异路径规划算法
五次多项式
space redundancy manipulator sys tem
path planning
dynamic coupling
flexible s tr ik e
s ingularity
pseudo-inverse path planning
singularity avoidance path planning
quintic polynomial
