Guidance and robust generalized inversion based attitude control of Satellite Launch Vehicle

This paper presents the robustified form of generalized dynamic inversion control and its application to attitude control for satellite launch vehicle. In proposed control law, dynamic constraint is prescribed in the form of asymptotically stable differential equation that encapsulate the control objectives. The constraint differential equation is evaluated along the vehicle's attitude trajectories and is inverted to solve for the control variables using the Moore-Penrose generalized inverse based Greville formula for under determined algebraic systems. For singularity avoidance and stable attitude tracking, a dynamic scale factor is augmented in the involved Moore-Penrose generalized inverse. An additional sliding mode control loop is augmented to make generalized dynamic inversion control robust against model uncertainties and external disturbances. The stability of the control system is ensured by using positive definite lyapunov energy function, for stable attitude tracking. An external guidance loop is applied which reshapes the reference pitch and yaw attitude profiles online based on the normal and lateral positional errors respectively, to achieve desired orbital parameters. To analyse ascent flight trajectory, a detail six degree of freedom mathematical model of four stage satellite launch vehicle is developed in Simulink/Matlab. The effectiveness of the proposed control and guidance scheme is evaluated on satellite launch vehicle simulator, in the presence of parametric variations and external disturbances.