Trajectory tracking control of an autonomous underwater helicopter with improved prescribed performance

Aiming at the high-precision trajectory tracking problem of an autonomous underwater helicopter (AUH) under conditions of environmental disturbances, thruster loss and floating error, a prescribed performance control method based on a novel performance function is designed and can be applied in ultra-mobility tasks. The com bination of the proposed new performance function and the constraint inequality avoids large overshoot in the initial period of system and allows the expected convergence time to be set artificially. The thruster loss, expressed in thrust distribution matrix, is incorporated into general uncertainty with external disturbances. In addition, the extended state observer (ESO) is used to compensate the unknown states, providing a reference for the estimation of upper bound of general uncertainty. Simulation results show that the proposed control scheme is able to guarantee the pre-defined tracking performance limited by performance functions under general uncertainty.