Effects of Variable Arm Length on UAV Control Systems

Quadrotor is a type of unmanned aerial vehicle that has been widely used in many applications, such as, policing, surveillance, aerial photography and agriculture. Conventionally, the control of quadrotor flight direction is accomplished by varying speeds of rotors or manipulating torques. In this paper, a novel mechanism is proposed. The mechanism uses stepper rotors to control the arm length for changing flight directions, while maintaining rotors' speed at constant. This can be achieved using a mathematical analysis of relation between quadrotor arm length and moment of bending of various position of rotor. Analysis and simulation results have shown the change in arm length required to produce moment of bending for hovering, roll and pitch motion. Experimental results have shown that the new mechanism is able to carry more payloads which the rotor speed can be utilized fully at 100% while the flight direction is been controlled by changing of the arm length compared to conventional flight control mechanisms. (C) 2020 The Authors. Published by Atlantis Press SARL.