Line of sight-based MFAC path-following control of underactuated surface vessels with exact sideslip compensation

In this paper, a novel discrete-time reduced-order extended state observer (ESO) sideslip observer-based mode-free adaptive control (ELOS-MFAC) scheme is developed for underactuated unmanned vehicles. The main contributions are as follows: 1) the time-varying sideslip angle is exactly estimated by a reduced-order ESO, thus achieving a high-precision estimation of the sideslip angle and laying the groundwork for sideslip angle compensation; 2) an ESO-based Line of Sight (ELOS) guidance law is proposed to enhance the generalis ability of the LOS guidance law in the case of unknown side slip angles; 3) with estimated surge speed and heading guidance, MFAC technology is adopted in the design of speed controllers. The simulation study conclusively demonstrates the efficacy and superiority of the proposed ELOS-MFAC framework.