Nonlinear Discrete-Time Disturbance Attenuation for Robotic Manipulators with Immersion and Invariance Approach

In this paper, attenuation of constant input disturbances in the control of robotic manipulators is considered in discrete-time setting. Firstly, a disturbance estimator design with Immersion and Invariance approach is presented for n-DOF mechanical systems that comprises n-DOF robotic manipulators. Then, a discrete-time backstepping controller established that uses the estimated disturbance information and locally stability using Lyapunov's stability theorem, in an arbitrarily large compact set, of closed loop system is shown. The method applied to 2-DOF robotic manipulator and tested by simulations.