Control-Oriented Physical Input Modelling for a Helicopter UAV

It has become standard in the helicopter UAV control literature to use the main and tail rotor thrusts, and the main rotor flapping angles as inputs. However, the physically-controllable inputs are servomotors which actuate the main rotor cyclic and collective pitch, and the tail rotor collective pitch. Precise treatments of the helicopter model exist which study the physical inputs. However, these models remain intractable for practical implementation motivating researchers to use rough approximations such as simple gain relationships between thrust and collective. We propose and identify a physical input model which retains the accuracy of a general model but is algebraically simple enough for its use in control design. As a result of experimental validation, the vehicle's velocity is incorporated into the model to improve its accuracy.