Nonsigular fast terminal sliding mode control based on Extended state observer for trajectory tracking of USV

As to the trajectory tracking control problem of unmanned surface vessel(USV) under environment disturbance, this study proposes a nonsingular fast terminal sliding mode controller which is based on an extended state observer(ESO). Firstly, an auxiliary velocity vector is proposed to further simplify the USV models. Secondly, this study adopts an ESO to estimate the total unknown environment disturbance, where the observed value should be compensated into the controller. Thirdly, based ESO, a novel nonsingular fast terminal sliding mode(NFTSM) controller is introduced to guarantee the good tracking performance of the system. Finally, the convergence stability is verified by Lyapunov function and a simulation experiment is introduced to prove the effectiveness and reliability of the developed scheme.