Moving the future with nanometer movements

With an Internet connection, we can enjoy entertainment from all over the world, and if we look up a word we don’t understand, it immediately appears as a search result. Not many people realize that all of this is data exchange, coming to the device at hand from a data center, a physical storage facility. The ever-increasing amount of data that exists in this world and the ever-increasing demand for data centers is creating a major challenge in terms of the enormous amount of energy consumed. Improving the efficiency of the recording medium, the hard disk drive (HDD), is a major key to solving this problem, and Associate Professor Shota Yabui of the Faculty of Science and Technology is leading the research and development of mechatronics products such as HDDs and magnetic bearings.

Associate Professor Yabui describes his research as “a world so fine that even I can’t tell if it’s working properly just by looking at it.” An HDD (hard disk drive) operates by spinning a disk coated with a magnetic material at high speed, while a component called a magnetic head moves across its surface to read and write data. You might recall hearing a “click-click-click” sound from your computer or game console—that’s the sound of an HDD in action. To function, the magnetic head must be moved to a precise position on the disk, requiring an accuracy of about “10 nanometers.” The finer this control, the more data can be written onto an HDD of the same size. At the time of the interview, the maximum capacity of a 3.5-inch HDD available on the market was 24TB (terabytes), but the goal is to achieve capacities of 50TB or even more in the future. “Increasing the storage capacity of a single HDD allows us to handle more data with the same number of devices. This leads to more efficient data centers,” he explained.

HDDs, capable of storing vast amounts of digital data, are indispensable industrial products in today’s information society. To increase storage capacity, it is necessary to enhance the recording density of data on the disk, which requires reducing the physical size of digital data on the disk. Consequently, the magnetic head, which reads and writes digital data, must achieve precise positioning on a nanoscale—on the order of one-billionth of a meter.

Associate Professor Yabui’s research extends into space as well. He works on the design and production of test devices and control systems necessary for pre-testing and performance evaluation of the turbo pump, a component often referred to as the heart of a rocket engine. He is also involved in research on “rocket sleds,” which are used to conduct rocket tests on the ground.

Rocket sleds operate by placing a cart called a “slipper” on rails like those used for bullet trains, accelerating it with a rocket engine to conduct experiments under various high-speed and high-acceleration conditions. However, since the rails and slipper legs are in direct contact, friction generates heat and significant noise, and the maximum speed is inherently limited. To address these challenges, Yabui developed a “fully magnetic levitation slipper.”

Unlike conventional magnetic levitation systems, which require equipment on the rail (or guide) side, increasing complexity and cost, Yabui’s system clamps the rail with four legs of the slipper, each generating magnetic force to achieve levitation. The distance between the rail and the legs is meticulously controlled at intervals of 0.1mm to 0.2mm, maintaining stability. Even a slipper weighing 11 kilograms can be moved smoothly with just a single finger.

“In the future, as private companies become more active in space development, the need to conduct independent tests without relying on specific organizations will grow, increasing the demand for testing equipment. Japan has often been criticized for lagging behind in space development compared to the rest of the world. I believe this situation needs to change, which is why I am advancing this development,” Yabui explained.

Associate Professor Yabui is currently part of the Robotic Life Support Laboratory, where he is advancing the development of robotic prosthetic arms and tactile sensing technology. While robots have traditionally been used primarily as substitutes for humans, they are now expected to work collaboratively with humans in the future, including in scenarios where they directly interact with people. Under no circumstances should a robot’s malfunction harm a human.

“In the world of robotics, precise control of machines and components through electrical power is increasingly required. This has been the focus of my research for many years, and I am determined to apply my expertise to achieve meaningful results,” Yabui explained.

From HDDs to space exploration and even robotics, the scope of Associate Professor Yabui’s research is vast, yet it all connects to the theme of “moving things with precision.” “As I began studying control engineering in university, I realized that mastering the art of precisely moving small components could open up an extraordinary world. Among these, HDDs require some of the most intricate control, so I decided to focus on perfecting this technology first,” he explains.

In recognition of his groundbreaking work, Yabui received the “Young Scientists’ Award” as part of the 2023 Ministry of Education, Culture, Sports, Science, and Technology (MEXT) Science and Technology Awards. When asked about the driving force behind his research, his deep passion for Japan stood out. “I believe Japan is capable of much more. Our presence in global market capitalization rankings has diminished, but if Tokyo—a global center of innovation—can generate breakthroughs, Japan could not only revitalize itself but also lead the world. I hope the younger generation embraces a greater spirit of challenge, and I believe it’s crucial to create an environment that fosters this mindset. If students equipped with both technical skills and confidence can launch their careers from this university and my lab, nothing would make me happier.”

We often focus only on visible movements, but a comfortable and fulfilling life is supported by incredibly precise and diverse electrical and mechanical controls. Whether enjoying entertainment via the internet or uncovering new knowledge through space exploration, behind it all are tiny components that move with incredible accuracy. From the nanometer scale, Associate Professor Yabui is supporting people’s lives, driving space exploration, and shaping the future.