キューブサットバスシステムのための標準化・適応性インターフェース設計

Since the 2000s, small satellite launches have increased rapidly each year and the number of players in this field is strongly linked to the popularity of the CubeSat standard around the globe. Highlights of its achievements are often the compatibility of launches via a standardized deployer (i.e. POD), shorter development times and lower costs than conventional large satellites. CubeSats are not just popular instruments for educating students in space research and engineering, but also enable us to demonstrate challenging technologies in a cheaper and quicker way and carry out scientific research in the field. But the success of CubeSat\u27s mission often fails. Improvements in reliability and prevent poor workmanship are necessary. The CubeSat standard enabled the small satellite market to expand enormously. In fact, a modular spacecraft deployer which can be attached to many different launch vehicles as a secondary payload was the key technology for the CubeSat Standard. To date, only external CubeSat interfaces, especially the mechanical interface, have been standardized. CubeSat needs a standardized internal interface to take advantage of the modularity. It will contribute to cost reduction and development time. One key to cutting costs and delivery time is a standardized internal interface for different CubeSat missions. In three CubeSat projects at the Kyushu Institute of Technology in Kyutech, a backplane interface approach, proposed as UWE-3 by the University of Würzburg in Germany, has been implemented to reduce the time for development and assembly. The backplane approach also helped to reduce the risk of harnessing faults. In order to satisfy the mission requirements, however, modifications to the proposed standard interface board were necessary for each CubeSat project. The thesis proposes a new idea of a Software-Configurable Bus Interface (SoftCIB) with a backplane board to obtain more flexibility, particularly for data connections. Instead of hardware routing, a Complex Programmable Logical Device (CPLD) was used to reprogram the bus interface on the PCB. The following advantages will be offered by the standardized backplane interface board: (1) less harness, (2) ease of assembly and disassembly (3) compatible with different CubeSat projects and (4) flexible for routings. We can use the SoftCIB again to reduce the cost and development of the interface boards, rather than designing and making new interface boards for new CubeSat projects. Various projects have various payloads for missions and interface requirements. The high flexibility of SoftCIB\u27s interface allows one to select either the same or a different subsystem board such as an OBC or EPS. A functional test with a breadboard module validated the concept. A radiation test has shown that the selected CPLD is strong enough to maintain total ionization doses in low Earth orbit of more than 2 years. The system level verification has been carried out in the engineering model of the BIRDS-3 project at Kyutech.九州工業大学博士学位論文 学位記番号：工博甲第485号 学位授与年月日：令和元年9月20日1. Introduction|2. Background|3. Implementation of Backplane approach for CubeSats|4. Purposed interface – The SoftCIB|5. Testing campaign|6. On-orbit demonstration|7. Conclusions九州工業大学令和元年

キューブサットバスシステムのための標準化・適応性インターフェース設計

九州工業大学博士学位論文（要旨）学位記番号：工博甲第485号 学位授与年月日：令和元年9月20

Programmable CubeSat Interface Board to Reduce Costs and Delivery Time

A standardized interface for different CubeSat missions is one of the keys to reduce costs and delivery time. A backplane interface approach, proposed by the University of Wuerzburg in Germany as UWE-3, was implemented in three CubeSat projects at the Kyushu Institute of Technology (Kyutech) in Japan to shorten the development and assembly times. The backplane approach also helped to reduce the risk of workmanship errors associated with the harness. The proposed standard interface board, however, needed changes in every CubeSat project to comply with the mission requirements. To obtain more flexibility especially for data connections, this work introduces a novel idea of a software-configurable bus interface with the backplane board. A Complex Programmable Logic Device (CPLD) was used instead of the hardware routing so that we can reconfigure the bus interface by reprogramming the CPLD. The concept was validated by a functional test with a breadboard module. A radiation test verified that the selected CPLD has enough strength to survive total ionization dozes of more than 2 years in low Earth orbit. A new backplane board with CPLD have been integrated with Engineering Model and Flight Model of the fourth CubeSat project at Kyutech, BIRDS-3 project, and system level verification was conducted. The flight model is now ready for delivery to JAXA in February 2019 for a planned launch to International Space Station in April 2019. The initial on-orbit data will be obtained by the time of the conference in August 2019 and will be presented to the audience

CubeSat bus interface with Complex Programmable Logic Device

A standardized interface for different CubeSat missions is one of the keys to reducing costs and delivery time. A backplane interface approach, proposed by the University of Würzburg in Germany as UWE-3, was implemented in three CubeSat projects at the Kyushu Institute of Technology (Kyutech) to shorten the development and assembly times. The backplane approach also helped to reduce the risk of workmanship errors associated with the harness. However, changes to the proposed standard interface board were necessary in every CubeSat project, to comply with the mission requirements. To obtain more flexibility, especially for data connections, this work introduces a novel idea of a software-configurable bus interface with a backplane board. A Complex Programmable Logic Device (CPLD) was used instead of hardware routing so that we can reconfigure the bus interface by reprogramming the CPLD. The concept was validated by a functional test with a breadboard module. A radiation test verified that the selected CPLD has enough strength to survive total ionization doses of more than 2 years in low Earth orbit. A new backplane board with CPLD has been integrated into the engineering model of the fourth CubeSat project at Kyutech, the BIRDS-3 project, and system level verification has been conducted