Robust control for rigid robotic manipulators using nonlinear disturbance observer

In this paper, the robust control scheme is developed for rigid robotic manipulators with the unknown system uncertainty and the unknown external disturbance. In the robust control design, the unknown system uncertainty and the unknown external disturbance are treated as an unknown compounded disturbance which is estimated using the nonlinear disturbance observer. Utilizing the estimate output of the developed disturbance observer, the robust tracking control is designed for rigid robotic manipulators. The closed-loop system stability is rigorously proved via Lyapunov analysis and the good tracking performance can be guaranteed under the integrated effect of the unknown system uncertainty and the unknown external disturbance. Numerical simulation results are presented to illustrate the effectiveness of the proposed robust control scheme for unknown rigid robotic manipulators.