Model reference adaptive control for a hydraulic underwater manipulator

Abstract

This work is focused on an underwater manipulator. To solve its nonlinear dynamics and hydrodynamics when it operates underwater, model reference adaptive control (MRAC) is applied. The output of the reference model represents the expected transient response. Adaptive controller parameters are adjusted on-line in real time according to the error between the reference model output and the system output and the outputs of the state filters, using an adaptive parameter regulator. The system control input is thus achieved such that the system output can track the reference model output. Simulation results demonstrate that the proposed control scheme has accurate tracking ability and can greatly improve the dynamic and static properties of the system. The MRAC for the underwater manipulator is also fairly robust to load disturbance and system parameter variation.