刚柔耦合空间闭链机器人轨迹跟踪与振动抑制研究

针对含多变量高维度空间刚柔耦合闭链机器人的轨迹跟踪和振动抑制问题,提出了一种基于前馈补偿的PD控制方法。首先,采用有限元法对柔性空间构件进行离散,基于浮动坐标系描述柔性构件位移场矢量,并根据Lagrange方程建立考虑刚性末端执行器微小位移的刚柔耦合空间并联机器人动力学模型;然后,利用前馈控制对预先求出的含耦合效应的控制力矩进行补偿,提高刚柔耦合控制系统的响应速度及跟踪性能,同时通过PD控制律保证空间闭链机器人的轨迹精度,并对不同末端载荷作用下的轨迹跟踪精度进行分析;最后,与位置PID算法进行了比较。结果表明:与位置PID算法相比,基于控制算法作用下的刚性末端执行器轨迹精度得到提高,其中,X方向误差降低了89.7%,Y方向误差降低了4.3%,Z方向误差降低了12.9%,柔性空间构件产生的振动得到了有效抑制。

Trajectory Tracking and Vibration Suppression of Rigid-Flexible Coupling Spatial Closed-chain Robot

To study the trajectory tracking and vibration suppression of a multi-variable high-dimensional spatial rigid-flexible coupling closed-chain robot, a PD control method based on feedforward compensation was proposed. The flexible spatial links were discreted by finite element method, and then the displacement field vector of the flexible links was described based on the floating frame of reference formulation, and the dynamic model of the rigid-flexible coupling spatial parallel robot was established considering the small displacement of the rigid end effector according to the Lagrange equation. The feedforward control was used to compensate the control torque with the coupling effects obtained in advance, which improved the response speed and tracking performance of the rigid-flexible coupling control system. At the same time, the PD control law was used to ensure the trajectory accuracy of the spatial closed-chain robot, and the trajectory tracking accuracy under different end loads was analyzed, and finally it was compared with the position PID algorithm. The results showed that the trajectory accuracy of the rigid end effector under the control algorithm was effectively improved relative to the trajectory accuracy under the position PID algorithm. Among them, the error in the X direction was reduced by 89.7%, the error in the Y direction was reduced by 4.3%, and the error in the Z direction was reduced by 12.9%, the vibration generated by the flexible spatial links was suppressed, and the effectiveness of the controller design was verified.