Command filter sliding mode robust tracking control of underactuated surface vessels

In order to realize tracking control for underactuated surface vessels with parameter uncertainties and external disturbances, a command filter feedback combined with sliding mode method is proposed. The tracking error equations are established based on CFB, which puts tracking control into stabilize surge speed and course angle error using transformation equation. Then, a nonlinear sliding mode controller is designed based on integration ideas. The problem of analytical and numerical differentiation of the virtual control laws is overcome, chattering of control input is circumvented, and the static error and overshoot are decreased. The results of simulation experiments indicate that the controller is robust against the systemic variations and time-varying external disturbances. Moreover, the tracking control with high tracking precision can be achieved by the proposed control method.