Design and analysis of a quadcopter attitude control system based on disturbance-observer control

Abstract

To address the attitude control problem of quadrotor drones under changing input signal types, we designed an attitude control system based on Active Disturbance Rejection Control (ADRC). It explains in detail the structure of the ADRC controller—the tracking differentiator, extended state observer, and nonlinear state error feedback law. A complete flight control simulation platform was built in the Simulink environment. To verify the controller’s adaptability, sets of input command changes were applied. Simulation results show that the designed control system quickly converges within 0.5 seconds after a square wave jump, without overshoot; sine tracking has minimal phase lag and negligible amplitude attenuation; under multi-channel compound inputs, each channel is fully decoupled with no cross-interference. The extended state observer can estimate and compensate for equivalent disturbances in real-time, keeping the attitude angles highly accurate. This controller has strong adaptability to changes in command waveform, amplitude, and frequency, and performs excellently with the model, providing an effective solution for stable attitude control of UAV platforms.