The Flying Squirrels team is composed of five French students. Three team members are PhD students academically affiliated with ISAE SUPAERO, France, and with ONERA Toulouse. Two team members are Master students. One is studying at ISEA SUPAERO, while the other is studying at the EI.CESI engineering school (France) and is an apprentice at ONERA.
Nano Control Moment Gyro cluster in microgravity
|University||ISAE SUPAERO, France; ONERA Toulouse, France; EI.CESI, France|
ISAE SUPAERO, France
Adrien Dias Ribeiro
The Flying Squirrels team aims to test a new promising technological system used for controlling the attitude (i.e. the orientation) of cubesats. This system is composed of a cluster of six Single-Gimbal Control Moment Gyros and a new steering law for these actuators. Control Moment Gyros, already used in some satellites and space stations, have proven to be very power-efficient and have more torque capabilities than other actuators of the same mass. For micro-satellites or cubesats, their use is not common because of their mechanical complexity, the difficulty of steering them, and because few systems are commonly available on the market. Nevertheless, the need for more agility and accurate pointing is growing in cubesat missions. For instance, more efficient and performing attitude control systems are needed for observation or debris removal missions. Moreover, cubesats are becoming larger and larger, and in the near future they could become as large as 27 U (1U=10cm*10cm*10cm), thus requiring more powerful attitude control systems than the current ones. The system that the team wants to test meets the new requirements for these missions.
Single-Gimbal Control Moment Gyros are composed of a flywheel that spins at a constant rate, and a torque that is created by gyroscopic effect by rotating the rotation axis of the flywheel. Each actuator therefore instantaneously creates a torque around an axis. To control all three axes of a satellite, clusters of four actuators are usually mounted. Steering a cluster commonly requires an internal singularity avoidance strategy to avoid positions where a torque cannot be created along an axis while the cluster has not reached its maximum capabilities, thus increasing the complexity of controlling the system.
The Flying Squirrels team will test a cluster of six Control Moment Gyros. This cluster has the advantage of being more reliable, having more momentum capabilities, and having nearly no internal singularities. They will also test a new in-house steering law that can handle failures of Control Moment Gyros in the cluster, singularities, and saturations, and that can be calculated in real-time onboard satellites.