Disturbance-observer-based Controll of the Underwater Vehicle for Manipulation

Recently, more and more interventional underwater vehicles are widely used in marine industry and marine science. The vehicle-manipulator system is a hybrid vehicle composed of a remotely operated underwater vehicle (ROV) and an autonomous underwater vehicle (AUV). An importance issue for the vehicle-manipulator system is to keep consistent control performance of underwater manipulation. In this paper, a control scheme based on the disturbance observer is proposed to maintain high performance even under lumped disturbance that includes the motion of the manipulator, model uncertainties and currents. The compensation item of the controller is able to achieve quick response to attenuating disturbance, and is also able to decrease in the absence of disturbance. In other words, the proposed control scheme alleviates the restriction of the feedforward control that is regarded as a valid method to relieve the influence of disturbance. The effectiveness of the proposed control scheme is demonstrated by lake experiments.