Our laboratory studies on control methods of spacecraft such as artificial satellites, deep space probe and develops sensors and actuators for control. Present research topics are shown below. However we are challenging new research themes which are required from space projects, considering student's interest and ability. The laboratory is located in Sagamihara and also belongs to Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency. Therefore, our research is carried out with researchers of Aerospace engineering, Astronomy, High-energy physics, and Planetary science.
In future of lunar and planetary exploration, not only space agencies but also private companies and individuals might develop and operate spacecraft. For such new era, we study on very small and low-cost spacecraft. Research themes are Trajectory design (horizontal landing), Position estimation using optical sensor, Attitude control of nano-spacecraft, Shock absorption mechanism (ex. Airbag), etc. OMOTENASHI nano-spacecraft which will be launched by NASA SLS rocket in 2019 is now under development. Detail information is shown at http://www.isas.jaxa.jp/home/omotenashi/index.html
For touchdown mission on rough but interesting terrain where no space probe has gone before, like “crater central hill”and edge of lunar lava tube hole, an actively controllable landing system is required. This paper proposes an of actively controlled landing leg system by using a variable coefficient damper. We research about the effectiveness of the actively controlled landing leg system. We simulate touchdown based on mathematical models. Further, we made a landing leg experiment system with actuator, and show the effectiveness of actively controlled landing leg system.
Accurate and safe landing is required for future lunar and planetary exploration. Our laboratory studies landmark-based navigation which uses pattern matching between terrain map of the surface and onboard camera images. In Hayabusa project, operator-based landmark navigation system on ground could help the spacecraft to land on the safe area of asteroid Itokawa. In near future lunar exploration, the system will be installed in onboard computer and spacecraft performs landmark navigation autonomously. Moreover, we study autonomous hazard detection and avoidance for safe landing.
At present, astronomical satellites require the pointing accuracy of less than a few arc seconds, namely about 0.001 degree and pointing stability of less than 0.0001degree. To meet such severe requirements, development of fine attitude sensors, precise attitude control algorithm, and development of low induced-vibration actuators are needed. The study results sometimes carried out by students are used in scientific satellite projects after several years.
Though Space is suitable environment for experiments of micro-gravity science, it takes large cost and needs long preparation time. In case of basic research, sometimes drop tower or parabolic flight of airplanes are used for low-cost micro-gravity environment, however, their duration time of micro-gravity is a few seconds or 20 seconds, respectively. We are developing medium-cost and more than 30 seconds high-quality micro-gravity experiment system. That is, the system is lifted by high-altitude balloon and is dropped at 40 km altitude. While free-falling, the system compensate air-drag with drag-free control of double shell structure.
Links: JAXA Balloon Center, Sawai Lab.
Attitude sensors for satellites, especially for scientific satellites, have been studied and developed with companies and researchers in JAXA. Ultra fine sun sensors, star trackers, navigation cameras are developed.The photo is a Star Scanner used for a spin-stabilized spacecraft which was developed in 2014.
Attitude actuators for satellites, especially for scientific satellites, have been studied and developed with companies and researchers in JAXA. The photo is a magnetically-suspended momentum wheel which was developed a few years ago.
We also research about attitude control, navigation and guidance of the lunar lander and rover. Students find theme from those topics.