Inner-outer loop control with constraints for rotary-wing UAVs

Motion control of UAVs is an interesting problem due to the nonlinear and underactuacted nature of their dynamics. This paper focuses on position and yaw control of a rotary-wing UAV with state and input constraints using an inner-outer loop control structure. The outer loop generates saturated thrust and reference roll and pitch angles, while the inner loop is designed to follow the reference angles based on a Proportional-Derivative (PD) controller. In the outer loop, a smooth nested saturation controller is designed and proven to be asymptotically stable. A simulation based on the indoor ANCL (Applied Nonlinear Control Lab) quadrotor platform at University of Alberta is used to demonstrate the performance of the proposed controller.