基于二分试探的平面冗余机械臂碰撞检测与避障

Collision Detection and Obstacle Avoidance of Planar Redundant Manipulator based on Dichotomous Heuristic

针对协作机械臂与未知环境安全交互问题,提出基于二分试探的平面冗余机械臂碰撞位置检测与虚拟碰撞空间估计方法,基本思想为碰撞臂杆绕选定二分点旋转微小角位移,期间根据关节电流信息判断是否发生进一步碰撞,从而确定碰撞位置所处二分区间,以此迭代试探缩小碰撞位置估计误差至可接受范围。建立冗余机械臂碰撞臂杆以选定二分点为不动点的逆运动学模型,解决机械臂二分试探运动控制问题;通过简化改进二阶前馈外力观测器,建立基于关节电流的快速碰撞检测算法;根据碰撞位置与碰撞臂杆位姿信息,建立基于包络法的虚拟碰撞空间模型,以近似表征障碍物空间信息。仿真与实验结果表明,所提出的基于二分试探的碰撞位置检测与虚拟碰撞空间估计方法,可为主从任务转化闭环控制避障算法提供有效的障碍物信息,实现平面冗余机械臂安全避障,提高协作机械臂与环境交互安全性。

Focusing on the issue of security interaction between collaborative robot arm and unknown environment,a dichotomous heuristic(DH)based method of collision position(CP)detection and virtual collision space(VCS)estimation for planar redundant robot arm(PRRA)is proposed.Its basic idea is that rotate the the collision lever with a small angular displacement around the selected equinox,during which further collision is judged according to the joint current information,so as to determine the interval of the collision position.Through iterative trials,the CP detection error can be reduced to an acceptable level.In order to solve the PRRA motion control during DH,the inverse kinematics model with the selected equinox as a fixed point is established.A fast collision detection algorithm based on joint current information is developed by simplifying and improving the second-order feed-forward external force observer.According to the CP information and collision lever pose,an envelope-method-based VSC model is established to approximate the obstacle spatial information.Simulational and experimental results show that the proposed DH based method of CP detection and VCS estimation can provide effective obstacle information for the master and slave tasks transformation-based close-loop-control obstacle avoidance algorithm,so as to realize the safety obstacle avoidance of the PRRA and improve the interaction safety between the cooperative robot arm and the environment.