Sliding mode control-based limit cycle oscillation suppression for UAVs using synthetic jet actuators

A sliding mode control (SMC) method is presented in this paper, which is proven to achieve asymptotic SJA-based LCO suppression without the use of adaptive laws or function approximators. In addition, the SMC-based control strategy presented here is shown to achieve suppression of both pitching and plunging displacements for a class of so-called dual-parallel underactuated systems, where a single scalar control signal simultaneously affects both states. The dual-parallel underactuated system cannot be expressed in a cascade or normal form, and hence, standard backstepping-based control approaches cannot be applied. In this paper, this difficulty is mitigated through novel algebraic manipulation in the error system development, along with innovative design of the sliding surface. A detailed model of the UAV dynamics is utilized along with a rigorous analysis to prove asymptotic regulation of the plunging displacement, and numerical simulation results are provided to demonstrate asymptotic suppression of the pitching and plunging displacements.