Stabilization of Asymmetric Underactuated Ships With Full-State Constraints: From Underactuated to Nonholonomic Configuration

Dear Editor, This letter addresses the stabilization control of an asymmetric underactuated surface ship with full-state constraints. To simplify the design of controller, the original ship model is transformed into a nonlinear cascade system with a minimum phase. Then, the stabilization of the cascade system is further processed into an equivalent stabilization of a reduced-order nonholonomic-like system. A discontinuous stabilization control method is proposed through a combination of state-scaling and state-dependent function transformations, nonlin-ear filters, and switching technologies. Stability analysis demon-strates that under the newly designed stabilization controller, the closed-loop system states are bounded and the desired state constraints are not violated.