Underactuated hovering control of the minitype autonomous underwater helicopter

This work presents the development of the MAUH, a new type of minitype autonomous underwater helicopter capable of autonomous hovering using only four vertical thrusters. A nonlinear dynamic model of the MAUH was derived based on this underactuated hovering mode. The outer loop controller adopts integral sliding mode control (ISMC) to compute the intermediate command signal needed for the inner loop controller, while the inner loop controller, based on non-singular terminal sliding mode control (NTSMC), is utilized to track orientation error. Finally, simulations and experimental results demonstrate the effectiveness of the proposed underactuated hovering mode and control methods.