Adaptive Super Twisting Sliding Mode Formation Control of Multiple Quad-rotors with Wind Disturbances

Abstract

In recent times, multiple unmanned aerial vehicles (UAVs) grouped as leader follower configuration have found numerous applications in various areas such as surveillance, industrial automation and disaster management. The accuracy and reliability for performing such crucial tasks in a group is highly dependent on the applied control strategy. The formation and trajectories of multiple UAVs are governed by two separate controllers, namely formation and trajectory tracking controllers respectively. Environmental effects, disturbances due to wind and parametric uncertainties make the controller design process as a challenging task. This article proposes a robust adaptive formation and trajectory tacking control of multiple quad-rotor UAVs using super twisting sliding mode control method. In the proposed design, Lyapunov function based adaptive disturbance estimators are used to compensate the effects of the disturbances due to wind and parametric uncertainties. The stability of the proposed controllers is guaranteed using Lyapunov theorems. Two variants of the control schemes namely fixed gain super twisting SMC (STSMC) and adaptive super twisting SMC (ASTSMC) are tested using numerical simulations performed in MATLAB/Simulink. From the results presented, it is verified that ASTSMC scheme exhibits enhanced robustness as compared to the fixed gain STSMC.