Modelling and PID controller design for a quadrotor unmanned air vehicle

This paper delves into the intricate modeling of a quadrotor aircraft, a four-rotor vertical take-off and landing (VTOL) unmanned vehicle. It introduces a novel approach to designing a model specifically tailored for autonomous flight control of this quadrotor, detailing the underlying controller architecture. Emphasis is placed on elucidating the dynamic model of this aircraft—an inherently underactuated system featuring fixed four-pitch-angle rotors—a challenge owing to its complex structure. Developing a realistic model of the quadrotor stands as the primary goal, with a key focus on crafting a model that ensures stability and accuracy. To achieve this, the paper explores the application of a PID (proportional-integral-derivative) control method, a pivotal aspect in establishing stability during the quadrotor's flight.

The model incorporates four input forces, essentially the thrust generated by each propeller linked to a fixed-angle rotor. Manipulating these forces facilitates specific movements: adjustments in front or rear rotor speed govern forward or backward motion, concurrently altering the pitch angle. Similarly, lateral motion (left or right) is executed by modulating the roll angle in a corresponding manner. For precision in controlling yaw—rotational motion around a vertical axis—the front and rear motors rotate counter-clockwise, while the others operate in a clockwise direction. Steering commands involve strategic alterations in motor speeds: increasing or decreasing counter-clockwise motor speeds while inversely adjusting clockwise motor speeds. This detailed study endeavors to comprehensively illustrate the complex dynamics and control mechanisms governing the quadrotor's flight, serving as a robust foundation for the advancement of autonomous aerial systems.