Constrained Control Allocation Approaches in Trajectory Control of a Quadrotor Under Actuator Saturation

Quadrotors are highly maneuverable vehicles that can be used to perform extremely aggressive maneuvers. Commanding a quadrotor to perform a maneuver that is beyond the physical capabilities of its actuators leads to actuator saturation. A prolonged state of saturated actuators can cause the vehicle to behave unpredictably. This work investigates the use of constrained control allocation methods in a cascaded control structure to mitigate the adverse effects of actuator saturation. More specifically, a weighted least squares approach is used in the position controller and mixer to prioritize certain control efforts while considering constraints on the actuators and, optionally, vehicle attitude. Additionally, a yaw-decoupled attitude controller is adopted to complement the control allocation method employed in the mixer. The proposed strategy offers a more comprehensive approach to addressing actuator saturation and was found to enhance the stability and tracking performance of the vehicle when compared to conventional approaches in simulation.