SMC-based model-free tracking control of unknown autonomous surface vehicles

This paper investigates the robust tracking control problem of disturbed unknown autonomous surface vehicles (ASVs), and whereby a sliding-mode-control-based model-free tracking control (SMTC) approach by the combination of sliding-mode control and data-driven backstepping techniques is innovatively devised. By deploying a data-driven backstepping sliding-mode surface, a robust model-free adaptive controller is designed to achieve strong adaptability and robustness to unknown couplings, uncertainties and disturbances. Besides, a data-driven adaptive law based on disturbance observer and feedforward control strategies is effectively developed to estimate these unknowns, and thereafter the estimation is served as the compensation within the controller. Rigorous analysis proves that asymptotic tracking performance and strong robustness can be guaranteed theoretically. Lastly, simulation studies for the ASV are explored to demonstrate the validity and superiority of the devised SMTC approach in terms of disturbance attenuation, nonlinearity adaption, and high accurate tracking.

Q-S (complete or anticipated) synchronization backstepping scheme in a class of discrete-time chaotic (hyperchaotic) systems: a symbolic-numeric computation approach

First, a type of Q-S (complete or anticipated) synchronization is defined in discrete-time dynamical systems. Second, based on backstepping design with a scalar controller, a systematic, concrete and automatic scheme is presented to investigate Q-S (complete or anticipated) synchronization between the discrete-time drive system and response system with strict-feedback form. Finally, the proposed scheme is used to illustrate Q-S (complete or anticipated) synchronization between the two-dimensional discrete-time Lorenz system and Fold system, as well as the three-dimensional hyperchaotic discrete-time Rossler system and generalized discrete-time Rossler system. Moreover numerical simulations are used to verify the effectiveness of the proposed scheme. Our scheme can be also extended to investigate Q-S (complete or anticipated) synchronization between other discrete-time dynamical systems with strict-feedback forms. With the aid of symbolic-numeric computation, the scheme can be performed to yield automatically the scalar controller and to verify its effectiveness in computer.