考虑任务优先级的超冗余机械臂避障轨迹优化

Obstacle Avoidance Trajectory Optimization of Super Redundant Manipulator Considering Task Priority

针对冗余机械臂末端轨迹跟踪与避障运动冲突情况,提出一种考虑任务优先级的超冗余机械臂避障轨迹优化方法。采用雅克比矩阵对不同的任务约束实施优先级排序划分,能够保证任务的精度。构建出7自由度机械臂结构模型,利用超冗余自由度避开障碍物,发挥其运动特性,并引入臂平面和避障面,通过虚拟排斥力推导零空间运动方程。将避障空间缩小至一维空间内,运算超冗余机器臂的运动学逆解。依据逆动力学控制方法获得障碍与机械臂间最小距离值的变化,采用任务优先级转化的避障算法实现超冗余机械臂避障轨迹优化。对比实验结果表明:所提方法能够防止冲突现象发生,关节变化角度的实际值与期望值基本重合,机器人手臂与障碍物之间的平均距离维持在(0.2~0.3)m之间,完成机械臂避障轨迹优化。

In view of the conflict between the end track tracking and obstacle avoidance motion of redundant manipulator,an obstacle avoidance trajectory optimization of super redundant manipulator considering task priority is proposed.First of all,considering the task priority,we use Jacobian matrix to rank different task constraints,which can ensure the accuracy of the task.Then,a 7-DOF mechanical arm structure model is constructed,which uses the super redundant DOF to avoid obstacles and give full play to its motion characteristics.Then,the arm plane and obstacle avoidance surface are introduced to deduce the zero space motion equation through the virtual repulsion force.Reducing obstacle avoidance space to one-dimensional space,the inverse kinematics solution of super redundant manipulator is calculated.According to the change of the minimum distance between the obstacle and the manipulator,the obstacle avoidance algorithm of task priority conversion is used to optimize the obstacle avoidance trajectory of the super redundant manipulator.The experimental results show that the proposed method can prevent the occurrence of collision,the actual value of the joint change angle basically coincides with the expected value,the average distance between the robot arm and the obstacle is maintained between 0.2 and 0.3 m,and the robot arm obstacle avoidance trajectory is optimized.