Distributed Information and Electric Power Network for Panel Extension Satellite (PETSAT)
- Paper number
IAC-05-D1.4.04
- Author
Prof. Shinichi Nakasuka, University of Tokyo, Japan
- Coauthor
Mr. Takashi Eishima, University of Tokyo, Japan
- Coauthor
Dr. Hironori Sahara, University of Tokyo, Japan
- Coauthor
Dr. Yuya Nakamura, University of Tokyo, Japan
- Coauthor
Ms. Chisato Kobayashi, Astro-Technology SOHLA, Japan
- Coauthor
Dr. Yoshiki Sugawara, University of Tokyo, Japan
- Coauthor
Mr. Takanori Okada, Astro-Technology SOHLA, Japan
- Year
2005
- Abstract
A novel concept of satellite design, named "PETSAT," has been proposed and five year projects supported by Japanese national subsidiary started in 2003, whose detail was proposed in IAC2004. In this concept, a satellite is made of several "Functional Panels" such as "CPU panel," "Battery panel," "Communication panel," "Attitude control panel," or "Thruster panel," each of which has a special dedicated function. By connecting these panels by reliable connection mechanism in "plug-in" fashion, the total integrated system as a whole has a satellite function. Various combinations of functional panels, (for example, two CPU panels + one communication panels + three attitude control panels + two battery panels, etc.) provide flexibility to deal with various mission requirements, even though the basic panels are the same for various missions. These panels are stowed during launch into a small volume, and are extended on orbit, realizing a satellite even with a large antenna, large solar cell area or large boom. PETSAT’s challenge is to change the satellite development cycle in the following way, in order to drastically reduce the total development time and cost. 1) Each functional panel can be produced in mass quantity so that the reliability can be improved and cost can be reduced, and the produced panels are to be stocked. 2) When a certain mission is given, the satellite can be configured only by connecting the appropriate panels in appropriate quantity without much effort on ground tests of the total system, which reduce the development time and cost. One of the most important technical issues is the network architecture of information and electric power among panels. The following requirements should be satisfied for realizing the modularity and fault tolerance for PETSAT. (a) Electric (power) Interface In principle, the electric power required in each panel should be generated by solar cells of the same panel, but in many cases power should be transferred from one panel to another panel. PETSAT should have the capability to autonomously transfer power observing the power generation and consumption in each panel. Autonomous power flow control based on FET has been studied. Reliability of power line is another important issue, which should be realized by carefully designed redundancy. (b) Information Interface The information line between panels should be very reliable and should have enough communication capacity to deal with the flow of house keeping data as well as mission data. Each panel should have a certain level microprocessor for controlling this information traffic as well as managing the information flow inside the panel. So the total system becomes a hierarchical multi-processor system and the architecture to manage such large number of CPUs should be carefully designed so that the strength of the distributed system such as fault tolerance or capability of grid-computing can be pursued as much as possible. CAN bus and SH microprocessor network has been adopted as the basic bus system. The hardware and software system to realize these requirements have been studied and the first results including hardware experiments will be presented at the conference.
- Abstract document
- Manuscript document
IAC-05-D1.4.04.pdf (🔒 authorized access only).
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