一种具有重力补偿的串联弹性执行器接触力控制方法

Contact force control method for series elastic actuators with gravity compensation

摘要:

针对机械臂末端安装串联弹性执行器(Series Elastic Actuator，SEA)与环境或工件接触作业工况，考虑SEA端部负载对接触面压力随机械臂运动姿态变化的问题，研究一种具有重力补偿的SEA接触力控制方法。首先分析了一种基于滚珠丝杆模组的SEA与Staubli TX90 组合的力控制实验装置结构，建立了SEA与工件接触过程的动力学模型，提出了一种具有输入重力补偿的PD型SEA弹簧力控制方法，该方法在没有接触力传感器的情况下，依据机械臂关节角对SEA端部负载进行重力输入补偿，通过检测弹簧压缩变形量，计算并反馈弹簧力实现对接触力的控制。最后通过SEA与正弦面工件接触力控制实验，并对力传感器采集的接触力信号进行频谱分析，验证了所提出控制方法的有效性。

Abstract:

For the working scenarios of the interaction between the manipulator end mounted a series elastic actuator(SEA) and its environment or workpieces, a SEA contact force control strategy with gravity compensation is studied to solve the problem which the pressure of the SEA end load on the contact surface changes with the movement posture of the manipulator. Firstly, the force control experimental device based on Staubli TX90 and a SEA combined with the ball screw module is analyzed. A dynamic model of the interaction process between the SEA and its workpieces is established. Then, a PD-type SEA contact force control method with input gravity compensation is proposed without contact force sensors. The SEA end load is compensated by the gravity input according to the joint angles of the manipulator. The contact force is controlled by measuring the spring compression deformation, calculating and feeding back the spring force. Finally, the contact force control experiment between the SEA and a sinusoidal surface workpiece is carried out. And the contact force signal collected by the force sensor is analyzed in the frequency spectrum to verify the effectiveness of the proposed control method.