Robust approximate constraint following control for SCARA robots system with uncertainty and experimental validation

Abstract

In the context of mechanical systems characterized by nonlinearity, uncertainty, and unknown external disturbances, this paper presents a novel and practical robust control algorithm based on the Udwadia–Kalaba (UK) equation that incorporates the ideal system trajectory as a servo constraint. Firstly, the constraint force of the system under servo constraints can be written in analytic form, which is the first part of the proposed control algorithm. The remaining parts deal with the initial condition incompatibility and the uncertainty within the system, respectively. Secondly, it is proved that the controlled system with uniform boundedness (UB) and uniform ultimate boundedness (UUB) by using the Lyapunov method. Finally, based on the SCARA robot platform, numerical simulations and experiments are performed using the rapid control prototype CSPACE. The results indicate that the proposed robust control method provides excellent dynamic performance under the constraints of the ideal trajectory. The effectiveness and practicality of the control method are further demonstrated.