Characteristic model-based path following controller design for the unmanned surface vessel

Abstract

This paper proposed a path following controller for the unmanned surface vessel (USV) by taking advantage of the vector field (VF) guidance method and the characteristic model-based heading angle and speed tracking approach. Considering the fact that the motions of USVs without professional design were difficult to be accurately modeled due to the high complexity in terms of nonlinearity and coupling, the second-order characteristic model was determined to be the investigated plant which was regarded as the control model. The parameters involved in the model were estimated using forgetting factor recursive least square (FFRLS). Based on the characteristic model of the USV, the intelligent adaptive control method was applied to design the controller for tracking the heading angle and speed. Then, the path following controller was designed for the USV based on the vector field guidance law and the characteristic model-based heading angle and speed controller. Finally, experimental results with comparisons indicate the developed path following controller can simultaneously ensure accuracy in the expected range and defend negative effects induced by slight environmental disturbances, which implied the robustness and preciousness of the proposed controller. The attractive merits of the proposed path following controller mainly thanks to the flexibility and simplicity of the investigated plant (i.e. the second-order characteristic model) and the outperformance of the characteristic model-based controller.