Improved active disturbance rejection heading control for unmanned wave glider

Abstract

The Unmanned Wave Glider (UWG) captures wave energy in the ocean and mechanically converts it into propulsion. This unique propulsion mode makes the speed of UWG uncontrollable and changeable, which leads to the unique heading control problem. The large model perturbation brought by the speed change of UWG makes it difficult for traditional controllers to maintain consistent heading control effect. In this paper, the Improved Active Disturbance Rejection Control (IADRC) method was proposed for UWG heading control. The Improved Linear Extended State Observer (ILESO) was proposed to dynamically modify the second-order series integral system transformed from LESO based on similarity principle. Falfunction filter was utilized in ILESO to reduce the influence of speed sensor noise. The Improved S-surface control strategy was proposed as the error feedback of IADRC. Compared with Non-Linear State Error Feedback (NLSEF), the parameters of the controller are greatly reduced and can be adjusted adaptively according to the speed of UWG. Numerical simulation experiments and sea trail were performed. The results showed that the proposed IADRC can significantly improve heading control performance for UWG at both steady and unsteady speeds.