This paper presents an unconventional tri-rotor unmanned aerial vehicle (UAV) design that only employs three brushless motors with three fixed pitch propellers for propulsion and flight control. No additional mechanics for dynamically tilting motor(s), found on existing tricopters, are used. The dynamic model of the proposed system is developed. Then a control strategy to control the stability and manoeuvring of the UAV is presented. The control strategy is achieved by only manipulating the rotational speeds of the propellers at each rotor. Two of the rotors rotate in the same direction while the third rotates in the opposite direction. The control methodology is novel compared to other systems that require either coaxial rotors or an extra servo motor to control the yaw of the UAV. Results show that the proposed design achieved stable flight with minimal position-attitude cross control effect. The fixed nature of the rotors in the proposed design, reduced mechanical requirements and cost compared to exis...
['Belal H. Sababha', "Hamzeh M. Al Zu'bi", 'Osamah Rawashdeh']
A rotor-tilt-free tricopter UAV: design, modelling, and stability control