Understanding the control characteristics of electric vertical take-off and landing (eVTOL) aircraft for urban air mobility

The aim of the present paper is to present an understanding of the control characteristics for representative eVTOL (Electric Vertical Takeoff and Landing) quadcopters having the same properties of interest as the eVTOL configurations developed presently in Urban Air Mobility. In this context, the paper concentrates on eVTOL quadcopters with pure rpm control, pure propeller pitch control and both rpm and propeller pitch control. Dynamic effects of electric motors can potentially have significant effects on the flight characteristics of these vehicles. The paper will demonstrate for a pitch manoeuvre that while varying purely the rpm of the rotors results in a system that behaves as an acceleration-control system, varying purely the propeller pitch corresponds more to a velocity-control system. The rotor pitch control is more sensitive to the coupling rotor-motor and its transients dynamics. Varying both the rpm and the rotor pitch for controlling the pitch manoeuvre is the best option as this brings the system more towards velocity-control behaviour and dampens the transients due to the motor dynamics.