Adaptive backstepping control for flexible-joint manipulator using interval type-2 fuzzy neural network approximator

In this paper, an adaptive backstepping controller based on interval type-2 fuzzy neural network (IT2FNN) approximator is proposed for flexible-joint manipulator with mismatched uncertainties. Backstepping control has the ability to deal with the mismatched problem, and IT2FNN approximator can be utilized to approximate unknown nonlinear functions. Through the Lyapunov stability analysis, all the signals in the closed-loop system are guaranteed to be ultimately bounded. Simulation results show that the tracking error of the proposed controller can be reduced to arbitrarily small values, and the tracking performance is better than the adaptive backstepping controllers based on type-1 fuzzy neural network approximator and neural network approximator.