Design of integrated Guidance and control system in the pitch channel using observer based chattering free sliding mode theory

The design of integrated guidance and control system for flying objects is one of the research fields in the aerospace that is considered by researchers in recent years. Due to the nonlinearity of the kinematic and dynamic equations of the homing interceptors in the terminal phase and also existence of uncertainties such as target maneuvers, external disturbances and variations in aerodynamic coefficients, siding mode control theory is a suitable method for designing integrated guidance and control system. One of the most problem of sliding mode is the presence of high frequency oscillations in the control signal that is called chattering, which makes it impossible to implement this controller. A method for smoothing the control signal in a sliding mode is to use a disturbance observer. In this paper, the control signal is completely smooth, with having the disturbances estimation and using a different scheme compared with standard sliding mode. Also the finite time convergence is guaranteed in the presence of uncertainty. The proposed guidance and control system is evaluated in computer simulation.