Designing a closed-loop guidance system to increase the accuracy of satellite-carrier boosters' landing point

A novel closed loop guidance method is provided in this paper to increase the accuracy of satellite-carrier boosters' landing point. The proposed method can be used in the first stage of flight vehicles that fly in atmosphere. In this case, solid motor propelled boosters would be able to more accurately land on the desired point. Moreover, in sub-optimal technique, the closed-loop guidance system would produce commands after booster separation, which guide second stage of satellite-carrier from initial conditions to the desired condition of orbit injection. In this method, sub-optimal integrated solution of control and guidance in closed-loop is developed. This sub-optimal technique named as Model Predictive Static Programming (MPSP) that is based on nonlinear optimal control theory and derived from combined philosophies of Model Predictive Control and Approximate Dynamic Programming; solves a class of finite horizon optimal control problems with terminal constraints. Furthermore because sensitivity matrices that are necessary for obtaining this solution can be computed recursively, this technique is computationally efficient and is appropriate for online implementation. In this paper, the dynamic equations of system are modeled in the presence of aerodynamic loading and the servo-mechanism dynamic. Moreover, by considering integrated guidance and control loops, a solution of the guidance and control system is proposed by three-degree of freedom spherical earth simulation model in atmosphere. Result show that proposed closed-loop guidance not only is able to remove aerodynamic and thrust modeling errors in first stage by flight data update that caused to more accurate of boosters' landing point, but also would still be able to guide second stage of satellite-carrier to the desired condition of placement in the orbit.