Adaptive constraint backstepping fault-tolerant control for small carrier-based unmanned aerial vehicle with uncertain parameters

This paper addresses the control scheme of carrier-based unmanned aerial vehicle systems in the presence of control input constraints, external disturbances, and actuator faults. The scheme is used for command tracking of angle of attack α, the sideslip angle β, and the bank angle of the aircraft φ. The control law makes use of command filters to directly accommodate magnitude, rate, and bandwidth constraints on the aircraft states and the actuator signals. The parameter update laws compensate for any uncertainties or changes in the aerodynamics. An appropriate fault controller structure is proposed, and the matching conditions are derived for fault compensation. The considered faults are modeled as both loss-of-effectiveness and lock-in-place. It is proved that the proposed control approach guarantees that all the signals of the resulting closed-loop system are bounded, and the tracking error between the system output and the reference signal converges to a small neighborhood of zero by appropriate choice of the design parameters. Initial simulations verify that the constraint adaptive control law performs well on the undamaged aircraft model. Maneuvers with some actuator faults are also simulated. The results of these simulations show that the proposed control approach is able to provide accurate tracking, even under some unknown aerodynamic parameters, actuator faults, and severe landing environment.