针对具有谐波减速器的柔性关节机器人容易产生振动的问题,设计了一种轮辐式力矩传感器.该力矩传感器安装于谐波减速器输出端和机器人臂杆之间,用于反馈机械臂反作用于关节的扭转力矩,从而能够直接获得关节的振动状态信息.基于该力矩传感器信息和计算的关节名义输出力矩,提出了一种新的振动抑制方法,在传统力矩负反馈PD控制器基础上通过增加名义输出力矩前馈补偿,实现了振动的快速抑制.建立了单关节控制实验平台,并进行了梯形轨迹跟踪振动抑制实验.实验结果表明:本文所提出的控制器不但能够快速抑制关节振动,而且不影响轨迹跟踪精度,从而解决了传统力矩负反馈PD控制器不能同时兼顾振动抑制效果和轨迹跟踪精度的问题.
A spoke-type torque sensor mounted between the output of harmonic reducer and the link of robot is developed to control the vibration of flexible joint with harmonic reducer.The torque sensor is used to feed back the reaction torque exerted on the joint by the robot arm,and thereby obtain the vibration state information of the flexible joint directly.An approach to vibration suppression,which is capable of reducing the vibration quickly by means of adding a feed-forward compensation of nominal output torque to the conventional PD controller plus torque negative feedback,is proposed based on the feedback information from the designed torque sensor and the calculated nominal output torque of the joint.A series of vibration suppression experiments for tracking trapezoidal trajectories are carried out on an experimental platform newly designed for single joint control.The experimental results show that this approach can suppress the joint vibration quickly with a high degree of trajectory tracking precision.Hence,the difficulty that traditional PD controller plus torque negative feedback can't take into account both the effect of vibration suppression and the precision of trajectory tracking will be overcome by using the controller proposed.