An Angular Momentum Allocation Strategy to Extend the Available Time of GEO Navigation Satellites

Abstract

In order to maintain the orbit accuracy of the GEO (geostationary orbit) navigation satellite, the thruster is not allowed to use during long-term orbital operation. The disturbance torque is absorbed by the reaction wheel system to maintain the three-axis nominal attitude. Because the reaction wheel absorbs the angular momentum accumulated by the disturbance torque, the rotation speed continues to increase. When the reaction wheel speed exceeds the safety threshold, it is necessary to switch to other working modes and use the thruster to perform angular momentum unloading. At this time satellite services were unavailable due to the effects of thruster on orbit. In order to maintain a certain degree of redundancy, usually 4 or more reaction wheels are installed on the satellite to form a redundant system. An angular momentum allocation strategy based on a pseudo-inverse solution is adopted. This allocation strategy is an energy minimization strategy. This paper proposes a distribution strategy based on the minimization of the infinite norm of the angular momentum vector. Using this distribution strategy, the maximum capacity of the reaction wheel system can be exerted, under the condition that the angular momentum accumulated by the reaction wheel system is the same, the maximum speed of the reaction wheel is the lowest. This extends the time for the reaction wheel to reach the safe threshold speed, and extends service time for GEO navigation satellites. In this paper, the reaction wheel system with a pyramid configuration is taken as an example for analysis. The angular momentum of the reaction wheel system is decomposed into a linear combination of pseudo-inverse solution and zero space vector, and it is solved under the criterion of infinite norm minimization. At the same time, this paper compares two allocation strategies for 4π space. Analysis and simulation show that the use of infinite norm minimization allocation strategy can significantly increase the available time of navigation satellites.