Angle of Attack and Sideslip Angle Estimation for Load-relief Control of Launch Vehicle System

Abstract

In this thesis, methods to estimate the angle of attack and the sideslip angle of a launch vehicle using GPS/INS navigation data are proposed. Open-loop, closed-loop, and hybrid load-relief control algorithms are designed to reduce an aerodynamic load on the launch vehicle at ascent phase. From dynamics of the launch vehicle, the equations of the angle of attack and sideslip angle are derived. Kalman filter and sliding mode observer are designed to estimate the angle of attack and sideslip angle. Also, extended Kalman filter using the dynamics and kinematics of the launch vehicle is designed. Numerical simulation is conducted to evaluate performance of each estimator. Using the estimated angle of attack and sideslip angle, the closed-loop and hybrid load-relief control algorithms are proposed. A simple angle of attack controller and nonlinear controller are designed as the closed-loop control method. An attitude proportional-derivative controller is chosen as the open-loop load-relief control method for performance comparison. Nonlinear six degree of freedom model is used for Monte Carlo simulation to analyze the load-relief controllers.