Airspeed control for unmanned aerial vehicles: a nonlinear dynamic inversion approach

This paper presents a nonlinear airspeed controller for an unmanned aerial vehicle (UAV). It is designed using the technique of nonlinear dynamic inversion. The thrust force of the UAV is generated by a propeller. The nonlinear dynamics of the airspeed are appropriately expressed as a function of the thrust force, which is a nonlinear function of the engine speed. The latter variable is the only physical control input of the system. The airspeed control system is constituted of a linear controller responsible for the generation of the desired airspeed dynamics, which are successively converted into a desired thrust command and an engine speed command through two consecutive nonlinear transformations. The proposed architecture is modular, easy to implement, and computationally efficient. Nonlinear simulation results demonstrate the effectiveness of the method.