Distributed liquid crystal reflectivity control device network for momentum wheel unloading

Abstract

Momentum wheels are widely used in spacecraft attitude control. However, in the space far‐away from the Earth, it is difficult for the wheels to realize unloading to maintain their control ability because of the dependance of fuel. Reflectivity control devices (RCDs) become a possible solution for fuel‐free space attitude control by generating controllable solar radiation pressure (SRP) torque. However, the control ability of RCDs is limited because the torques they produce are rather small. To combine the advantages of both the momentum wheels and the RCDs, in this paper, an attitude control scheme utilizing momentum wheels as actuators and an RCD network for unloading is proposed. Firstly, the physical composition, force model, torque model, and principles of the distributed RCD network are given. After that, a stable and reliable unloading control method based on the envelope analysis is provided. Also, a three‐axis stabilized solar sail is utilized as an example to show to control system design. Numerical simulation proved that the momentum unloading for wheels can be realized safely and efficiently.