一种零空间避障的机械臂末端轨迹跟踪算法  

A Trajectory Tracking Algorithm of Null Space Obstacle Avoidance for End-effector of Manipulators

作　　者：刘雪飞 徐向荣[1] 查文斌 江杨林 朱佐君 LIU Xuefei;XU Xiangrong;ZHA Wenbin;JIANG Yanglin;ZHU Zuojun(School of Mechanical Engineering,Anhui University of Technology,Maanshan 243032,Anhui,China)

机构地区：[1]安徽工业大学机械工程学院,安徽马鞍山243032

出　　处：《机械科学与技术》2021年第7期1009-1015,共7页Mechanical Science and Technology for Aerospace Engineering

基　　金：国家重点研发计划项目(2017YFE0113200)。

摘　　要：针对传统的零空间避障方法无法根据障碍物距离提前采取避障行为同时保证末端跟踪精度的问题,提出一种零空间避障的机械臂末端轨迹跟踪算法。该方法采用伪距离代替欧氏距离作为距离接近度指标解决零空间避障问题,同时设计一种自适应正定系数矩阵K和速度误差饱和函数sat(e),将实时轨迹运行结果反馈给冗余机械臂运动学反解,根据反馈结果自适应调节关节角速度以减小末端轨迹跟踪误差。采用iiwa14机械臂进行仿真实验,仿真的结果表明,所提出的算法能够在完成冗余机械臂零空间避障的同时保证末端轨迹跟踪误差在1 cm以下,验证了所提算法的有效性和优越性。Aiming at the problem that the traditional null space obstacle avoidance methods cannot take the obstacle avoidance behavior in advance according to the obstacle distance,while ensure the end-effector tracking accuracy,a trajectory tracking algorithm of null space obstacle avoidance for end-effector of manipulators is proposed in this paper.In this algorithm,the pseudo-distance instead of Euclidean distance is first used as the proximity for distance to complete null space obstacle avoidance for manipulators.Then,an adaptive positive definite matrix K and velocity error saturation function sat(e)are designed to feedback the results of the real-time trajectory tracking to the inverse kinematics of redundant manipulators;next,according to the results of feedback,the joint angular velocity is adaptively adjusted to minimize the trajectory tracking error of end-effector.The iiwa14 manipulator was employed for the simulation experiment,and the simulation results showed that the proposed algorithm can accomplish the null space obstacle avoidance for redundant manipulator while ensuring the end-effector trajectory tracking error below 1 cm,which verifies the effectiveness and superiority of the proposed algorithm.

关 键 词：冗余机械臂 零空间避障 轨迹跟踪 伪距离 

分 类 号：TP242.2[自动化与计算机技术—检测技术与自动化装置]