Model Reference Adaptive Sliding Mode Control Of A Hexacopter Drones For Delivery Application

Abstract

Unmanned Aerial Vehicles (UAVs) are rapidly evolving due to technology improvement andlow costs, with a wide range of applications. Its nonparametric uncertainty inputs, close coordination of subsystems, external disruptions, and unknown physical features make it favourable location for control systems research as well. The hex copter is a six-rotor UAVthat is a nonlinear, under actuated, multivariable, and unstable system. To design a suitable controller, system modeling is required. In this regard, in this thesis the Newton-Euler-based mathematical modelling of hex copter UAVs is developed. In order to enhance the altitudeand attitude stabilization performance of hex copter drones for delivery applications, amodel reference adaptive sliding mode control (MRA-SMC) was implemented. To have specific path of the drone, a minimum jerk trajectory generation was developed. The developed controller achieves asymptotic stability by applying the Lyapunov stability analysis. The PID controller generates sliding surfaces for the SMC controller, and also the reference model for the hex copter is generated by using the LQR technique. The MRAC scheme adaptively adjusts the Sliding Mode Controller parameters to compensate for uncertainties and disturbances in the system dynamics. The developed controller's performance is tested for a given trajectory with varying loads and wind disturbances in aMATLAB/Simulink environment. The simulation results indicated that the proposed controller tracks the specified trajectory with a small tracking error of 0.01. Besides, the system was tested on different masses, considering from 2.5kg to 12kg efficiently with and without external disturbance. Accordingly, the proposed controller for a 12kg mass results in 0.15 error with 0.5 disturbance error. In general, due to the adaptation of the reference model, the result of the proposed SMC controller results in small errors under variable payloads and disturbances with minimum chattering effect.