Attitude control of a satellite system is an attractive research area. This is due to its versatility and applicability in a broad range of applications. In this paper, a new mathematical model is presented which provide more comprehensive mathematical representation of a model attitude control system by using characteristics data of RazakSAT. The focus of this project is on applying the sliding mode control (SMC) as it is robust against parameter of uncertainties and external disturbances. However, its control signal exhibits high frequency oscillations called chattering after the system state reaches the sliding surface. In order to reduce the chattering effect, the width of the boundary layer is adjusted based on the state norm for the uncertain linear system. Additionally, a suitable boundary layer in sliding mode control is also developed in order to eliminate and reduce the chattering effect. Hence, the state dependent boundary layer method has been proposed for attitude control to deal with two critical issues that is the chattering effect and control signal accuracy. The developed control system was tested for attitude control of satellite. The state dependent boundary layer technique will manipulated the state variables to determine the boundary layer width which depends on its current state value. Such a design will automatically adjusts the boundary layer width based on the system condition, and will be robust in dealing with unexpected situations. The performance of the control system was verified by comparing its performance with PID controller. Our experimental results the development control system is capable in handling the disturbance and reduce the chattering affect inside the boundary layer.
