Relaxed Hover Solution Based Control for a Bi-Copter with Rotor and Servo Stuck Failure

As the usage of bi-copters increases in military and civilian fields, the demand for reliable bi-copters is on the rise. This study focuses on controlling a bi-copter under rotor or servo stuck failure. A relaxed hover solution is derived for the bi-copter, by solving an optimization problem subject to rotor and servo stuck failures. The solution is used for designing a reduced attitude controller based on linear quadratic regulator (LQR). To ensure hover capability, we introduce a position controller based on a cascaded-PID. The numerical simulations are conducted to demonstrate that position control is possible, even with complete rotor or servo stuck failure, by driving the bi-copter into relaxed hover state through the abandonment of the yaw channel. Meanwhile, the FTC scheme is examined under constant wind disturbances and uncertainties in the rotational damping parameters.