Research on vibration suppression and trajectory tracking control strategy of a flexible link manipulator

Residual vibrations caused by point-to-point motions reduce the positioning accuracy and dynamic performance of flexible link manipulators, and the trajectory planning method, a well-known open-loop control strategy, has been proven to effectively suppress the residual vibration in point-to-point motion. However, this open-loop control method has limitations in dealing with model uncertainty and disturbance problems. In this paper, a control strategy based on dynamics-based trajectory planning and fuzzy self-tuning PD (FST PD) controller is proposed, and applied to achieve residual vibration suppression and trajectory tracking of a flexible link manipulator. To improve the trajectory tracking performance under external disturbances, this control strategy is combined with a linear extended state observer (LESO). Firstly, the dynamic model of the system is deduced using the floating reference frame and Lagrange equation. On this basis, the objective function to minimize the lateral deformation of the tip is constructed, and then the optimal trajectory is obtained by using the Crossbreeding PSO (CBPSO) algorithm. Secondly, the optimal trajectory is used as the desired trajectory to suppress residual vibration, and the FST PD controller combined with the LESO is used to achieve high-precision trajectory tracking control of the flexible link manipulator. Finally, the effectiveness and feasibility of the composite control strategy is verified through multiple simulations. The proposed method can provide support for vibration suppression of flexible link manipulators; meanwhile, the controller structure of this method is simple and easy to implement, and the use of sensors/actuators and other equipment in the system is reduced, which effectively reduces the economic cost.