Disturbance observer-based distributed practical prescribed-time formation tracking control for small tandem-rotor UAVs accounting for actuator dynamics

A disturbance observer-based distributed practical prescribed-time formation tracking control strategy is proposed to address the tracking control problem of the formation of small tandem-rotor unmanned aerial vehicles (STR-UAVs) with external disturbances and model uncertainties, while accounting for actuator dynamics. First, a practical prescribed-time disturbance observer (PPTDO) is developed to estimate external disturbances and model uncertainties. Second, a prescribed-time sliding mode surface (PTSMS) is applied to achieve prescribed-time stability for the formation position and velocity loops. Third, a novel practical prescribed-time sliding mode filter (PPTSMF) is designed to eliminate the analytical calculation of the derivative of the force reference input in the actuator loop and avoid high-order differentiation. Finally, a practical prescribed-time formation tracking control strategy is proposed based on PPTDO, PTSMS, and PPTSMF, and its stability is rigorously proved. Moreover, simulations validate the effectiveness and superiority of the proposed formation control strategy under external disturbances and model uncertainties, while also accounting for actuator dynamics.