SAMPLED-DATA CONTROL OF QUAD ROTOR UNMANNED AERIAL VEHICLE

Abstract

Technological advancements in the field of computers have urged digital implementation of control techniques. Sampled data control of quadrotor unmanned aerial vehicle (UAV) is presented in this document. Two control techniques, sliding mode control (SMC) and backstepping (BS) have been applied in this regard to stabilize the quadrotor UAV. And for each technique four discrete time (DT) controllers are extracted, two from the discretization of the continuous time (CT) control based on continuous time system model (CSTM) and two controllers are based on approximate discrete time equivalent system model (ADTESM). Full state stabilization of quadrotor UAV has been achieved in a semiglobal practical sense. ADTESM of quadrotor has been obtained via Euler forward difference (EFD) method. In order to establish the robustness of the controllers Monte Carlo simulations have been performed. And these simulations have revealed that DT controllers based on ADTESM are far more robust than the DT controllers based on CTSM. Simulations for different initial conditions have revealed that the controllers designed based on ADTESM have larger regions of attraction as compared to the controllers obtained by discretizing the CT controls based on CTSM. Simulations in the presence of the wind gust have also been carried out and a comparative analysis has been presented as well. The proposed Discrete time sliding mode control (DTSMC) with and without integral action not only addresses the issue of chattering that is inherited in SMC but also achieves full state stabilization of quadrotor UAV in a semiglobal practical sense. Additionally, proposed discrete time backstepping control (DTBSC) with and without integral action based on ADTESM robustly stabilizes the UAV with parameter perturbations of ± 30 percent randomly generated tolerance. While the DTBSC based on CTSM destabilizes even with the parameter perturbations of ± 3 percent tolerance and discrete time integral backstepping control (DTIBSC) based on CTSM can withstand up to ± 5 percent parameter perturbation in random