Practical stabilization in attitude thruster control

The attitude stabilization of a spacecraft using thrusters is considered from a practical point of view, i.e., when actuator constraints, uncertainties and failures, measurement noise, fuel consumption, and inertia matrix uncertainty are considered. A variable structure controller based on sliding modes is obtained first, which guarantees global exponential stability under actuator constraints, uncertainties, and failures. The design is based on a continuous average-proportional torque selection function and a set of feasible sliding surfaces, which may be adapted to improve performance. Exponential convergence towards ultimate bounds is guaranteed when all other practical issues arise.     

Thruster design for position/attitude control of spacecraft

The objective of this work is to design the configuration of thrusters and valves of a propulsion system which should reject external and internal perturbations to control position and attitude of a spacecraft. As has been proved in a previous paper by Pena et al. (see ibid., vol. 36, no. 3, 2000), there exist configurations of 6 thrusters which can achieve this task, even under the failure of any one of them. Nevertheless, that previous result only presents analysis conditions and furthermore its implementation would demand also 6 valves, one for each thruster. Here we propose a design method that can solve the aforementioned problem with 6 thrusters/3 valves.