Robust Adaptive Fuzzy Control Law for Locomotion Control of a Hexapod Robot Actuated by Hydraulic Actuators with Dead Zone

This investigation presents development of a robust adaptive fuzzy controller for the locomotion control of a hydraulically actuated leg mechanism of a six-legged walking robot COMET-III. The hydraulic servo system of the robot is characterised by dead zone and other nonlinearities as well as uncertainties due to parameter variation. Therefore, adaptive fuzzy control system is a good choice for such problem. However, due to approximation errors caused by the fuzzy system we need to ensure the robustness of the adaptive fuzzy controller by some mechanism. The adaptation law is designed based on Lyapunov synthesis approach. The dead zone is compensated by a fuzzy rule based one-step-ahead controller. The experimental results exhibit a very stable locomotion system of the walking robot with tracking error in the small neighbourhood of zero