Six-dimensional thruster actuation and configuration design for spacecraft

The design of spacecraft for scientific missions includes the layout of a propulsion subsystem. The science goal usually limits the acceptable disturbances and thus the possible types of AOC actuators/thrusters. An ongoing investigation have been started to identify and develop suitable methods and algorithms. to actuate these thrusters, regarding to six-dimensional controller commands (forces and torques). The algorithms should be capable to deal with complex thruster configurations and even engine failures. During the work, a software test-bed for the different types of thruster actuation algorithms was implemented. It provides the opportunity to simulate various types of state of the art electrical thrusters with different configurations. So appropriate control methods can be analyzed and chosen for different thrusters and science missions. Additionally this tool is capable to support the design process of a spacecraft. It can calculate the exact control authority of the propulsion subsystem, depending on different types of thrusters, configurations and control algorithms. This is applicable for many near term science missions. This paper will give an overview of current six-dimensional thruster control methods. It also outlines the advances that have been developed with respect to requirements of micro propulsion thrusters as well as onboard real-time restrictions. These new methods provide the opportunity to reduce the fuel consumption, extend the engine- and mission-lifetime and increase the failure tolerance for truster failures.