“Cepheus” is a research project aimed to the development, contruction and validation of a pico-satellite based on CubeSat standard from design phase to Flight Model (FM) phase. “Cepheus” pico-satellite embeds various experimental payloads, namely: fuel cell system, star tracker with MEMS (MicroElectroMecanical System) technology and secondary communications link. This way, the project faces some of the main challenges of current micro space vehicles: energy storage, navigation sensor cost, and communication link energy consumption.
As for energy storage, batteries have been traditionally used in the space industry. Albeit, the use of fuel cells have been also extensively validated for about 40 years since the launch of Gemini and Apollo spacecrafts. The underlying idea of the use of fuel cells so far is to use on-board hydrogen and oxygen in order to produce electrical energy and water as a by-product. As an interesting concept, “Cepheus” is aimed to the investigation and validation of an integrated system enabling on-board production of hydrogen via electrolys and subsequent electricity production by fuel cells as a means to store energy collected from the sun.
Regarding navigation systems, main navigation sensors currently used in pico-satellites are solar sensors, magnetometers and terrestrial optical sensors. These three sensor types have the disadvantage of being rather imprecise thus making it difficult to achieve precise Attitude Determination and Control Systems (ADCS). By contrast, solar trackers provide accurate on-line attitute determination, although at a high cost. In this framework, “Cepheus” is aimed to design, develop and validate a micro star tracker based in MEMS technology addressing low weight, small dimensions and low energy consumption so as to allow its use in pico-satellites.
Last but not least, “Cepheus” is also aimed to the design, development and validation of a light, energy-efficient and small communications link as a means to improve off-the-shell COTS communications systems.
Our main contributions to the project are related to ADCS development. Specifically, the following research activities are undertaken:
- Mecanical model development: Mathematical model of the pico-satellite physical structure integrating the effects produced by the different actuators of the system.
- Definition of operational modes: Analysis and selection of the diverse operational modes regarding satellite attitude. As for each mode, definition of sensor feedback use depending on orbital location.
- Control laws design: Mathematical characterization of control laws aimed to govern movement of the pico-satellite in each operational mode.
- Definition of ADCS updates.
- Construction of ADCS system: Control laws implemention in selected embedded controller, computational burden optimization and implemention ofADCS update so as to allow in-line updates during flight.
- Construction of a test bench aimed to validate ADCS system.
The research leading to these results has received funding from CDTI and has been supported by the Spanish Ministry of Economy and Competitiveness – “Fondo de inversión local para el empleo, Gobierno de España”
- Date 29 September, 2013
- Tags Control Engineering, Modeling and Simulation, Other, Public - National, Software Engineering
- Programme FEDER INNTERCONECTA
- Partners ABENGOA HYNERGREEN (Coord.); SOLARMEMS; INABENSA; MESUREX; ALTER TECHNOLOGY; AICIA; UNIVERSITY OF MÁLAGA; IDENER
- Project cost 2.449.165 EUR
- Start date April, 2013
- End date December, 2014