Global Fuzzy Sliding Mode Control for Multi-joint Robot Manipulators Based on Backstepping

In this paper, a new method of backstepping sliding mode control for tracking control of multi-joint robot manipulators is introduced. Multi-joint robot manipulators system is a nonlinear and strong coupling system. According to sliding mode control theory, backstepping is used to design global sliding mode controller. The backstepping control algorithm decomposes the complex nonlinear system into the subsystems that do not exceed the order of the system and then designed the Lyapunov functions and virtual control signal for each subsystem in which backstepping to the entire subsystem until the control law is finished. We focused on the chattering problem of sliding mode controller and designed the global fuzzy sliding mode controller which reduced the chattering issue. Based on the Lyapunov principle, sufficient conditions for system stability are given. Simulation results show that compared with the global sliding mode control method, the proposed method can effectively reduce chattering and improve the accuracy of trajectory tracking.