机械臂与环境交互的位置/力切换抑制振动方法

Method for Suppressing Vibration During the Position/Force Switching of the Interaction Between a Robotic Arm and the Environment

当机械臂执行位置/力的混合跟踪任务时,位置控制一般用于机械臂的自由运动阶段,力控制一般用于约束运动阶段。这种位置/力切换的控制结构既能实现与环境接触前对机械臂位置的精确控制,也能保证接触后对期望控制力的准确跟踪。由于开关系统本身存在的切换不稳定性,机械臂在以一定的速度与环境接触时,机械臂执行器会在环境表面振动甚至弹跳。针对此问题,提出了一种半主动阻尼阻抗学习方法,该方法主要包含两部分:基于位置/力切换控制的半主动阻尼控制器;基于一种逆秩拟牛顿法(broyden fletcher goldfarb shanno,简称BFGS)的阻抗学习算法,根据学习到的环境参数调节半主动阻尼,实现机械臂在接触面的振动抑制和平稳过渡。在仿真及实验中,应用提出的方法让机械臂与不同环境交互,结果表明:该方法能很好地抑制接触过渡阶段的超调力,并防止机械臂在切换过程中的振动,实现了柔顺接触和平稳过渡。

When a robotic arm performs a mixed tracking task of position/force,position control is generally used for the free motion stage of the robotic arm,while force control is generally used for the constrained motion stage.This control structure of position/force switching can achieve the precise control of the robotic arm's posi-tion before contact with the environment,and ensure the accurate tracking of the desired control force after con-tact.However,due to the switching instability of the switching system itself,the robotic arm's actuators may vi-brate or even bounce on the surface of the environment when the robotic arm contacts with the environment at a certain speed.To address this issue,a semi-active damping impedance learning method is proposed,which mainly consists of two parts:a semi-active damping controller based on the position/force switching control;an impedance learning algorithm based on a broyden-fletcher-goldfarb-shanno(BFGS)method,which adjusts the semi-active damping according to the learned environmental parameters to suppress vibration and ensure a smooth transition of the robotic arm on the contact surface.In simulations and experiments,the proposed meth-od is applied to enable the robotic arm to interact with different environments,and the results show that the method can effectively suppress overshooting force during the contact transition stage,prevent vibration during the switching process,and achieve smooth contact and transition.