Command Filtering-Based Adaptive Fuzzy Control of Flexible-Joint Robots With Time-Varying Full-State Constraints

This brief is concerned with trajectory tracking control for n-link flexible-joint robots (FJR) with time-varying full-state constraints and uncertain dynamics. The barrier Lyapunov functions are constructed to avoid the violation of time-varying constraints. The fuzzy logic systems are used to deal with unknown nonlinearities in FJR systems. The "explosion of complexity" problem in the traditional backstepping method is overcomed by introducing command filtered control with error compensation, and an adaptive fuzzy command filtered control scheme based on time-varying barrier Lyapunov function is designed. The stability of the closed-loop system is analyzed using Lyapunov theory. Simulation results show that the proposed method can guarantee the full-state constraints and position tracking accuracy of the system.