Redefined Output Model-Free Adaptive Control Method and Unmanned Surface Vehicle Heading Control

Based on the model-free adaptive control (MFAC) theory, the heading control problem of an unmanned surface vehicle (USV) with uncertainties is researched. First, the compact form dynamic-linearization-based MFAC (CFDL-MFAC) method and its inherent failure problem with USV heading control are analyzed. Second, to solve the problem that the distinctive dynamic characteristics of USV heading control subsystem make the CFDL-MFAC unsuitable, the redefined output CFDL-MFAC (RO-CFDL- MFAC) method is proposed by introducing redefined output gain. Then, theoretical analysis shows that the RO-CFDL-MFAC method can be applied to the heading control subsystem, that is, it makes the heading control satisfy the quasi-linear assumption of MFAC. Next, the minimum range of redefined output gain and the main influences are analyzed, and the stability of RO-CFDL-MFAC method is theoretically proved. Finally, the simulation studies and field experiments demonstrate the validity and engineering practicability of the RO-CFDL-MFAC method.