Receding Horizon-based Fault-tolerant Control of QuadPlus: an Over-actuated Quadrotor

Highly maneuverable, over-actuated aerial robots have gained increasing interest in various inspection applications. However, since these systems carry expensive equipment and must operate in the vicinity of humans, their fail-safe operation is paramount. Hence, we propose a centralized nonlinear model predictive control (NMPC) method to facilitate fault-tolerant control (FTC) of an over-actuated quadrotor against a propeller failure. Thanks to the novel mechanical design, the hyperdynamic quadrotor can independently command and control all 6-degrees-of-freedom (DoFs). Additionally, the underlying reconfigurability of the designed NMPC makes it appropriate for both nominal and faulty operations. Moreover, the centralized nature of the control framework fully exploits the actuator redundancy, thereby ensuring complete system control without losing any DoF. The efficacy of the proposed FTC framework is elaborated via intensive simulations utilizing a realistic model over two different trajectories. From the considered sequential failure cases, it is shown that - even with fault detection delay up to 1s - the aerial robot satisfactorily tracks the reference trajectory.