Design of efficient thrust management algorithm for variable thrust solid propulsion system with multi-nozzles

Abstract

In this dissertation, a thrust management algorithm that integrates combustion chamber pressure control and thrust distribution is proposed for a Variable Thrust Solid Propulsion System (VTSPS) with multiple nozzles. A Divert and Attitude Control System (DACS) installed with pintle thrusters that can continuously and linearly change the thrust by varying the nozzle throat area with pintle actuators, which is a kind of VTSPS, is considered in this dissertation. The multiple pintle thrusters sharing the combustion chamber has to control the combustion chamber pressure and simultaneously produce the thrust required by the vehicle. A nonlinear combustion chamber pressure controller with application of nonlinear disturbance observers is proposed in order to consider the chamber pressure dynamics, actuator, nozzle geometry, model uncertainty, and disturbances. Also, a thrust distribution algorithm that can efficiently allocate thrust commands to each thruster based on the pressure control is proposed. Finally, a numerical simulation is conducted to verify the performance of the proposed thrust management algorithm. The proposed chamber pressure controller can reduce the fluctuation of chamber pressure due to nonlinearities, uncertainties and disturbances of the system and can minimize the structure mass of VTSPS related with chamber pressure. Furthermore, the proposed thrust distribution algorithm can minimize the consumed power of the actuation system for pintle thrusters and can reduce the mass of the actuation system.