Variable structure controller design of a two-link rigid-flexible robotic manipulator

In this paper, a variable structure controller for the joint trajectory tracking of flexible manipulators is proposed. The nonlinear dynamic model of a two-link rigid-flexible robotic manipulator is established by using the clamped-free coordinate references. Based on the technique of input-output linearization, the dynamic equations of flexible manipulators are partially linearized. In order to avoid an unstable internal dynamics, a joint trajectory tracking control law is designed by using a variable structure control in which the stability of elastic modes is considered. In order to eliminate the chattering caused by the switching, a kind of reaching law similar to the power rate one is designed and the damping factor is introduced in this control law. Lyapnov stability is proven to the joint trajectory and the elastic vibration. Simulation results show the efficiency of this control law.