Purely magnetic spacecraft attitude control by using classical and modified sliding mode algorithms

A modified sliding mode control algorithm for purely magnetic attitude control of small satellites is proposed in this work. It is designed by following the steps characteristic to variable structure control method and magnetic attitude control problem. The asymptotical stability of the control law is proven by using theoretical and intuitive approaches together. The stability of the controller is verified by converging simulation results of the states. The aim is to obtain a controller superior to the sliding mode magnetic controller with continuous law in terms of steady state error under disturbance effect. The time responses of Euler angles indicate that the aim is reached. The necessity of modifying the classical reaching algorithm is made clear by comparing Euler angles´ responses obtained using the classical and the modified sliding mode algorithms.