Airbus Defence and Space

PLATFORM

Control moment gyro actuator

A Compact, Cost-effective, High Performance Solution for Enhanced Agility on Small Satellites

Airbus Defence and Space and Teldix now offer the CMG 15-45S (15 Nms, 45 Nm Standard), a compact, high performance CMG optimized for small satellites.

  • Rigid preload in the bearings to withstand launch loads (no locking device)
  • Precise balancing of the wheel and very low friction in the gimbal bearings for very low disturbances
  • Highly accurate pointing performances (high frequency controller using a high resolution optical encoder)
  • One electronic channel per CMG (optional full redundancy), with 1553 bus interface (optional RS422)
  • Mass : 15 kg

Features / technical details

A cost-effective solution for new-generation observation and science missions : the demand for agile satellites has increased considerably over the last few years, be it for commercial or military applications, Earth observation, astronomy, optical instruments or radar payloads. Even for small satellites, when it comes to providing a high output torque (above 0.5 Nm typically) at reasonable cost (mass and power consumption), reaction wheels are no match for small Control Moment Gyroscopes (CMGs).

A high-performance product optimized for small, agile satellites : CMGs have been known for decades, but used to be considered difficult to operate, owing to singularities during satellite manoeuvres (except by over-sizing the momentum capacity). Recent developments in guidance algorithms to suppress singularities now means that the full capacity of the CMG cluster can be exploited, minimizing the momentum demand for each CMG. With four CMGs of only 15 Nms, it is now possible to repoint a 1 ton class satellite at more than three degrees per second in less than two seconds. Such a low momentum demand offers many system advantages compared to an oversized solution: the equipment is more compact and performances are improved.

A product based on proven technologies : both the equipment and its electronics have been designed for series productions to minimize recurring costs. The wheel is based on Teldix core technologies and the gimbal mechanism uses standard components from European manufacturers qualified by CNES and ESA. The electronics is based on an ASIC running at high frequency, and on a 1553 data bus interface (optional RS422).

A compact product with simple interfaces : the components are assembled in an optimized architecture that minimizes the volume and the mass. The CMG can be mounted on a single base plate with a minimal footprint and no additional hardware is required to install the equipment.

The CMG 15-45S integrates easily into small satellites of one tonne or even less. This compact architecture, which has been patented by Airbus Defence and Space, has been retained for our mini and medium CMGs.

Applications

Agile satellites for Earth observation and science missions