Real-time on line tuning of fuzzy controller for two-link rigid–flexible robot manipulators

Abstract

In this paper, an online time self-tuning multi-input–multi-output (MIMO) fuzzy bang-bang controller (FBBC) is proposed for the control of two-link rigid and flexible robot manipulators. Two-link rigid and flexible robot manipulators are highly non-linear plants. The fuzzy control is based on the Takagi–Sugeno-type architecture fuzzy model combined with online self-tuning so that both the desired transient and steady-state responses can be achieved. The proposed FBBC is different from a fuzzy logic controller (FLC) in that it has a bi-level output like a relay but with fuzzy inputs. The online self-tuning is based on the gradient of steepest descent tuning method, which tunes the FBBC’s input and output gains. The controller operation is demonstrated and compared with a classic FLC and sliding mode controller (SMC) by simulation to highlight its tracking ability and the manipulator’s positioning control with rigid and flexible robot types. Based on the simulation results, the proposed controller with this tuning strategy was found to be superior at different operating conditions.