AAU-11 Overcomes Various
Constraints to Support
the Future of High-Speed Rail


High-precision sensors mounted in a limited space - - The hardware and software technology capabilities of Sumitomo Precision Products have been fully utilized to reduce the cost of Shinkansen line maintenance and improve the work efficiency.

Performing line maintenance work on a service train. High accuracy, low cost, and compact--exactly what is required.

In the past, unevenness measurements on Shinkansen lines were carried out with a laser displacement meter mounted on Doctor Yellow, the dedicated diagnostic Shinkansen train. This product was developed as part of a project in which measurements were carried out using commercial vehicles carrying customers to improve the efficiency of railway maintenance. A highly accurate and very expensive ring laser gyroscope (RLG) was used as an inertial sensor to measure the attitude of a vehicle using a laser emitted from the moving vehicle to a rail. If using a dedicated train car, there would be enough space to load equipment. However, it was difficult to secure space on commercial trains. A high-precision sensor that can be mounted on multiple commercial trains at a low cost and that takes up limited space was therefore required. Our company has a track record of developing high-precision systems using MEMS gyroscope sensors, and we were therefore consulted to solve the problem. During the actual development, there were various restrictions in the practical operation test. In order to obtain test data, it is necessary to travel on actual train tracks. However, the test vehicles run in the gaps in the Shinkansen timetables, so the opportunities to perform testing are limited. This makes it necessary to prepare carefully for each individual test. It was a challenge to deal with all unexpected situations as quickly as possible, and to perform the development while adjusting the schedule so that the project could be advanced smoothly.

High-precision sensors with outstanding stability achieved with the technological capabilities of Sumitomo Precision Products

After testing and improving, we completed the AAU-11 high-precision attitude angle detection gyroscope. This MEMS gyro sensor achieves the same precision as a ring laser gyroscope, at around 1/5 the cost. With MEMS gyroscope sensors, there were problems with measurement errors as the time of use increased. But we developed our own algorithm and optimized it by analyzing actual operation data and data provided by the client. This is a field where even minute errors could have an impact on human life, so precision and stability are extremely important. It was possible to develop this excellent product by working in close cooperation with the client and by repeating trial and error.

Research for system development using MEMS gyro sensors will continue in order to realize the major goals of the client

We are currently preparing for testing on actual service trains by collecting further data and updating the development based on the results. The component produced is extremely small. However, for the client, it is something very important that has the potential to bring significant benefits in the future. In this project, we were able to focus on product development specifically for the single sector of railways, through the collaboration between the two parties. We firmly believe that this was the first major step to expanding the potential of MEMS gyro sensors. In addition to railways, it is also expected to be applied to robot attitude measurement and mobile vehicles such as automobiles. The AAU-11 boasts extremely high performance compared to the products of other companies. This was made possible by the MEMS gyro sensor research accumulated in research continuing since the 1990s, and because of our high level of technological capabilities. We will continue further research to improve performance and to enable the application of the product to other fields.