Optimized Integral-Backstepping Controller Design for Quadcopter Attitude and Position Control Using Wolf Search Algorithm

Abstract

A Quadcopter is an unmanned aerial vehicle (UAV), a small rotary-wing aircraft equipped with four identical motors and fixed-end propellers. These vehicles are characterized by multivariable, unstable, under-actuated, nonlinear, and strongly coupled, presenting significant control challenges due to wind effects and parameter uncertainties. This study proposes a novel Grey Wolf Optimization-based Integral Backstepping (GWO-IBS) controller to address these challenges effectively. A nonlinear mathematical model is developed using the Newton-Euler mechanism and transformed into a state-space representation. The integral and backstepping gains are optimized through the Grey Wolf Optimization algorithm. Lyapunov stability analysis ensures asymptotic stability. Extensive simulations using MATLAB 2021a/Simulink demonstrate the controller's capability to track a helical trajectory and maintain stability under wind disturbances over 25 seconds. Comparative analysis reveals that the GWO-IBS controller significantly outperforms the Integral Backstepping (IBS) and Sliding Mode Control (SMC) controllers, achieving lower Root Mean Square Error (RMSE) values with improvements of 81.68% for the position x-trajectory, 93.65% for the position y-trajectory, 99.86% for altitude, and substantial enhancements 48.38% for roll, 41.29% for yaw, and 88.75% for pitch angles. The results highlight the GWO-IBS controller's superior robustness and stability in handling unknown disturbances, making it a promising solution for the effective control of quad copters.