Hierarchical perturbation compensation system with ERL sliding mode controller in a quadrotor

This article addresses the problem of perturbation in Unmanned Air Vehicle (UAV) quadrotors. Three subsystems are designed to provide a continuous and precise estimation of perturbation and residual perturbation. The three subsystems form a Hierarchical Perturbation Compensator (HPC), which is built to compensate for system dynamics uncertainties, non-modeled dynamics, and external disturbances. The nonlinear control Exponential Reaching Law Sliding Mode (ERLSM) is utilized with the HPC. Lyapunov stability analysis proves the stability of the entire compensator-controller system. This system has the ability to decrease unknown perturbation either external or internal. It also has the ability to maintain full control of the six-degree-of-freedom quadrotor. The system performance for position, altitude, and attitude control is demonstrated by analysis, simulation, and experiments.