Attitude Tracking Control for Quadrotors Under Unknown Disturbances Based on Dual-Loop Nonlinear Command Filters

Attitude tracking of quadrotors under external disturbances is a challenging problem. This brief presents a backstepping method that integrates a function-adaptive rule designed as an attitude controller for quadrotors. The adaptive law based on command filters is capable of achieving an online adaptive approximation of the unknown function of the system without requiring any additional function-fitting technology. The command filter is designed as a unique double-loop nonlinear structure that can estimate the derivative of unknown signals. The system’s stability is proven using the Lyapunov criteria. The experiments are carried out for the Hover system. The results verify the effectiveness of the designed controller.