Since 1997, Astro- und Feinwerktechnik Adlershof GmbH has developed a family of reaction wheels for small satellites. The objective of this activity is to develop a High Momentum Wheel for telecommunication satellites. It provides a 100 Nms momentum capacity and an output torque of 0.2 Nm. Furthermore, it offers a digital interface with an embedded closed loop controller for higher accuracy and torque stability.
- Design to cost, using radiation tolerant automotive grade EEE parts
- Development and qualification within 2 years
- Equipment mass below 12 kg
- Extended bearing life time for more than 15 years in GEO
- Full ground testability
Astrofein’s reaction wheels are so called “smart reaction wheels”. These devices relieve the attitude control data processing unit and the satellite’s attitude control engineering team. Hence, they are performing tasks which were hitherto part of the attitude control system of satellites, tasks which are related to controlling and monitoring the reaction wheel.
Astrofein’s Smart RWs (Reaction Wheels) are characterized by the following attributes:
- Digital interface
- Internal monitoring and protective mechanism
- Model based controller
Monitoring and protective mechanism will provide early indication of possible wheel issues and automatically react on it. These mechanisms make Astrofein’s Smart RWs very robust and reliable. The Smart RWs contain the following monitoring and protection mechanisms:
- Monitoring of internal voltage lines (voltage and current)
- Inrush current limitation
- Temperature monitoring
- Protection against overheating
- Redundant wheel parameter, including parameter verification
- Rate and torque limitation
- Processor and command watchdog
- In-orbit patch capability, including software verification
With model-based controllers, Astrofein’s Smart RWs will reach higher accuracies and stabilities. They use internal friction estimation results in an improvement of reaction torque stability and repeatability. Moreover, Smart RWs operating very accurate in the zero-speed area. Furthermore, they compensate automatically effects resulting from time delay, instabilities or violating physical boundaries.
Due to design-to-cost approaches and utilization of AEC-Q qualified EEE parts, the reaction wheel is more cost efficient than comparable reaction wheels. Radiation assurance is guaranteed by radiation qualification and additional testing.
RW6000 provides a 100 Nms momentum capacity and an output torque of 0.2 Nm. With model-based controllers Astrofein’s Smart RWs will reach higher accuracies and stabilities. Using internal friction estimation results in an improvement of reaction torque stability and repeatability. Moreover, Smart RWs operating very accurate in the zero-speed area. Furthermore, they compensate automatically effects resulting from time delay, instabilities or violating physical boundaries.
The reaction wheel is a fully integrated device, consisting of the reaction wheel assembly (including flywheel, chassis and housing) and the wheel drive electronics (including motor, sensors).
The project plan comprises a Development Phase to be completed by Mid 2021. By the end of 2021, Qualification is to be completed. In early 2022 the first flight sets are planned to be delivered.
The design is almost frozen. A structural mock-up (SM) has been manufactured and mechanical and thermally tested. Critical EEE parts have been radiation tested and a electronics breadboard (EBB) has been built. The SM and EBB have been combined to a engineering model (EM) for further functional an performance testing. The PDR has been considered to be successful. The CDR is scheduled beginning of 2021.