A New Cooperative Multi-Agent Heater Controller with its Applications
- Paper number
IAC-06-D1.2.05
- Author
Dr. Junichiro Kawaguchi, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan
- Coauthor
Dr. Osamu Mori, Japan Aerospace Exploration Agency (JAXA), Japan
- Year
2006
- Abstract
The heater electronics used in the spacecraft is usually a classical switching controller, which turns the heaters on and off based on the temperature measurements. The problem sometimes faced in such classical control strategy is in the power consumption over-run, when a lot of those switches are turned on at the same time. This threatens the power supply system aboard. It is designated here as the Resource Restriction that the conventional heaters control system suffers from. Similar problems are found for the power line system for such as trains and the information packets flow control other than in space. JAXA’s Hayabusa spacecraft driving ion engines aboard introduced its proprietary unique heater control strategy that guarantees the total power consumption as specified, while the heaters are appropriately turned on in time-sharing manner. What the Hayabusa’s Heater Control Electronics (HCE) uses is a centralized control which processes the temperature information (status and violation) to manage the heaters circuits taking the power resource constraint into account. This Hayabusa HCE worked very successfully and keeps a specified power poured to the ion engines system. This method is quite useful, however, it needs a lot of cables and wires up-and-down between the HCE processor and the instruments whose temperature is controlled. When a new spacecraft system is built, it is hard to configure the system structure while coping those cables. And the system test has to wait for every instrument to be ready and participate in it. This is an obstacle and leads to lingered the verification period. For the purpose of saving the test cist and time, the system shall be built to allow an instrument to join and to leave the test arbitrarily and easily. Here is proposed a new Cooperative Multi-Agent control strategy guaranteeing the power resource but without a central processor. The basic function is simple and it automatically maintains the temperatures within the power resource as allotted. In addition, the strategy adaptively manages and tunes the nominal duty interval, every of which each heater is supposed to be turned on. Besides, the system can be built to optimize the entire power consumption as lowest as possible. This development consists of the hardware building and it is shown in the paper. The size of each circuit board is only about 25mm by 20mm for everything and it replaces the classical heaters excluding extraordinary amount of cables that connect to the central HCE. Each board has only two power lines and one signal line. The signal line, if needed, can be merged into power line easily. The system built here is versatile and is applicable to a wide variety of social and industrial systems; such as the power line system, and the information flow control. For instance, if the trains in a ecrtain district turn on their motors at the same instance, the peak power exceeds the supply capacity and the system goes down. The technique developed here can be incorporated to avoid such catastrophe. And also the strategy here is applicable to the packets flow control, which is sometimes restricted by the central data processing capacity. Contemporary spacecraft adopts the packet telemetry, which each subsystem is supposed to output data at a certain interval. However, when the packets are generated not-cooperatively at the same instance, the system corrupts. The technique here is applicable to and can avoid such catastrophe The paper presents not only the algorithm but also a numerical simulation. And the presentation also shows the actual hardware circuitry built, and it provides the flight experiment results as well. This subsystem was used aboard the ISAS/JAXA’s miniaturized satellite payload launched this September, and the flight results of this system will be presented. The algorithm here was already applied for the patent right.
- Abstract document
- Manuscript document
IAC-06-D1.2.05.pdf (🔒 authorized access only).
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