A high-accuracy tracking control for welding robot
Welding robots with strong robustness and high-precision trajectory tracking control play an important role in performing automatic welding processes under complex dynamic environments. This paper proposes a new variable structure control (VSC) based on multi-sliding-surface for welding robots with parameter uncertainties. The whole sliding-mode surface of VSC is divided into three sub-sliding-mode-surfaces. The first and second sliding-mode surfaces are designed mainly responsible for guaranteeing the finite-time reachability, as well as the finite-time converging to a vicinity around the equilibrium point along the predesigned sliding-mode surface, while the third sliding-mode one acts to further reduce the terminal steady-state error of VSC. Both the dynamic performances during the reaching and sliding-mode moving phases of VSC can be flexibly co-worked. This VSC helps to balance the confliction between higher steady-state precision and stronger robustness. Simulation results are presented to verify the trajectory tracking performance of the proposed control. Compared with the conventional PED control, the proposed VSC can provide welding robots with higher tracking accuracy as well as better tracking robustness.