一种具有工具重力补偿功能的机械臂力控牵引方法

摘要

Objective To develop a traction force control method for manipulator with tool's gravity compensation according to the need of force-position interaction in real time with operators in surgery and rehabilitation training.Methods We firstly use six-degree force transducer mounted on the end of the manipulator to detect traction force,then translate it to the displacement of the manipulator's nominal position and update the motion velocity by force-displacement and force-velocity transfer algorithm,finally,drive the manipulator towards the direction of the traction force.A gravity compensation algorithm is implemented in this method in order to eliminate the deviations of the tool's gravity.Results Experiments simulate the registration process of the stereotactic frameless surgery,and the data set suggests that the tool's gravity compensates within ±0.2 N at the steady state.Maximum force control loop frequency is 30 Hz and maximum system latency is 52 ms.Conclusions The manipulator can be driven and avoid the obstacle by traction force easily and smoothly,and the outcome of the gravity compensation is significant.%目的 本文根据多自由度机械臂在外科手术、康复训练中与操作人员进行实时力位交互的需求,设计了一种具有工具重力补偿功能的机械臂力控牵引方法.方法 首先通过安装在机械臂末端的六自由度力传感器检测作用在末端工具上的牵引力,然后应用上位机中的力-位与力-速控制算法将力信息转化为机械臂末端预期位姿偏移量并更新机械臂末端运动速度,进而控制机械臂沿受力方向运动.本文进一步提出一种末端工具重力补偿算法,能够有效补偿机械臂末端工具重力在力传感器上的偏差值.结果 实验模拟无框架立体定向手术的患者注册环节,在无牵引力作用时上位机补偿后的外力值控制在±0.2N以内,最大力控循环采样率30Hz,最大系统延迟52ms.结论 通过牵引力控制能够方便地对机械臂实现力控牵引摆位及运动过程中的紧急避障,重力补偿效果明显.