Position Control of Crazyflie 2.1 Quadrotor UAV Based on Active Disturbance Rejection Control

This paper presents the active disturbance rejection control (ADRC) algorithm applied to control the position of the small flying robot Crazyflie 2.1 in two degrees of freedom (movement in x and y axis). The platform and its functionalities, such as physical attributes and a communication system, were presented. Discrete proportional-integral-derivative (PID) and ADRC controllers were implemented and tuned. Furthermore, comparative tests were performed. Sensory data from the OptiTrack motion capture system was used in real flight experiments, ensuring high precision of measurements and high sampling frequency. Selected time plots and numerical quality indices were compared, especially for different ADRC controller gains. Based on the obtained results, one can conclude about some advantages of the ADRC method for nonlinear system, such as a drone. The presented approach additionally, once tuned, theoretically works fine for any object model.