The Pursuit of Energy-Efficient Prosthetic Legs: CTO Daisuke Kaneishi’s Seven-Year Research Journey
Advances in prosthetic technology have opened new doors for mobility, independence, and quality of life for prosthetic users. But behind every breakthrough device is a story of research, collaboration, and human-centered design. At BionicM , Chief Technology Officer Daisuke Kaneishi plays a pivotal role in shaping the next generation of assistive devices.
With a background in mechanical engineering, robotics, and biomechanics, Daisuke has dedicated his career to exploring the potential of robotic technology to improve/augment human physical capabilities.
His approach bridges scientific inquiry and practical application, addressing the everyday challenges faced by prosthetic users. In this interview, Daisuke shares his journey, insights into prosthetic development, and vision for creating assistive technology that empowers individuals.?
Profile
Exploring Human Augmentation Through Science and Engineering
— Please tell us about your academic and research background.?
At Waseda University, I joined a laboratory focused on medical and welfare robotics. Initially, I intended to research powered suits, which are wearable devices that enhance muscular strength. Around this time, CYBERDYNE’s Robot Suit HAL was gaining attention at the Aichi Expo. However, I soon realized that powered suits might not be suitable for the elderly, who would benefit most by using them. The risk of injury from forced movement outweighed the potential benefits.?
We focused on a major concern for the elderly: stumbling and fall prevention. Small ridges or uneven surfaces can cause stumbles, leading to falls that drastically reduce quality of life. I came up with the idea of a system alerting users to these minor obstacles when analyzing motion capture data. Unfortunately, progress was slow as I worked alone as an undergraduate student.?
Later, following my professor’s advice, I joined a project on tremor suppression robots. While there are a number of methods that can be used to suppress tremors, this project explored the use of external loads given by orthosis. To illustrate, let’s take a hand-cranked rechargeable radio. To charge the radio, you turn the lever. As you do so, you’ll feel some resistance, or a slight load (brake). In the same way, if you put enough load on your body to cancel out tremors, it will act as a brake to make your body stand still. Of course, if the brake is constantly applied, the wearer will find it difficult to move his/her body. So, the users' intentional movements are detected by integrated sensors measuring bio-signals (myoelectric signals) from muscles, the system temporarily releases the brake. Through this research project, I gained foundational knowledge in motion analysis and bio-signal processing.?
Designing Wearable Robots That Adapt to Daily Life
— From very early in your career, you have focused your research on the theme of augmenting the human body with technology. How did you continue this in your doctoral studies in the US?
At UC Berkeley, I built on my earlier work, researching assistive devices for rehabilitation and augmentation. The goal of the project was to investigate the design of mechanism and control strategies for assistive systems assisting only when necessary and avoiding interference otherwise. For example, imagine a wearable elbow-assist robot; on the way to a grocery store, no assistance is needed. However, on the user’s way back, he/she would need assistance and support to carry a heavy bag of purchases. The robot should support the arm, reducing strain by balancing the load.?
We have investigated control methods that could switch usage scenarios based on biometric signals and safely assist users. A senior colleague, who was good at manufacturing, was mainly in charge of designing and developing the assistive devices. My role was to investigate control algorithms of the developed devices to match user’s scenarios. This process requires abstracting developed devices (i.e., physical systems) into mathematical models, considering the control algorithms mathematically with the model, and then translating them back into real-world applications. I found this process of bridging theoretical concepts with tangible devices incredibly fascinating.?
Beyond the research project, I explored another approach of developing assistive devices according to users’ pain points as part of a club activity. One day, I met a student with a disability, and we connected over the idea of creating assistive devices together. The student expressed a desire for an assistive glove that he could improve dexterity and wear independently.
Initially, we designed the glove with a wire-driven mechanism, intending to enhance the dexterity. However, during user testing, we encountered an unexpected issue; the glove shape required the user to bend each finger individually to put it on. This made it impractical for someone with limited hand mobility to use without assistance. It felt counterintuitive to create a device meant to provide independence that still required help to wear.
Determined to address this, we redesigned the device with a mitten-like structure. This new design allowed users to easily slide their fingers (except the thumb) into the device. Seeing that the new design allowed the student to independently wear the device and perform tasks like picking up a book or turning a doorknob brought me immense accomplishment. It remains one of my most cherished memories.
The Passion Behind Human-Machine Fusion
— What originally sparked your interest in the concept of the fusion of humans and technology??
While I can’t pinpoint a specific reason for my interest in the fusion of humans and machines, it likely stems from my scientific mindset, which emphasizes understanding existing phenomena, rather than an engineering mindset focused solely on building practical solutions.?
Generally speaking, science seeks to understand the mechanisms behind nature, whereas engineering, at its core, is about creating functional and useful things based on the acquired knowledge. Robots, for instance, are primarily an engineering endeavor – designing better and more functional robots within certain rules, as seen in Robot Contest (ROBOCON). In parallel with my engineering work, I’ve always been drawn to asking questions like, “What are the limits of current motors?” or “How can we push those boundaries?” Combined with my fascination for humanoid robots and the way professional athletes use their bodies, this scientific curiosity led me to explore the fusion of humans and machines.
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Another factor was my desire to work on things I could personally use or relate to. I believe that if something is enjoyable and meaningful for me, it might also be valuable for others. This belief has guided my research and continues to shape my personal code as an engineer. I strive to create products that are intuitive, effective, and satisfying to use—if I’m not happy with it, I won’t release it.
Interestingly, many of my colleagues at BionicM share a love for science fiction, particularly themes of humans and robots coexisting. Sci-fi doesn’t just inspire us; it often predicts or even drives real-world research. For example, ideas from sci-fi can inspire new research themes, and breakthroughs in research can, in turn, be reflected in imaginative stories.
A fitting anecdote is how the world’s first bipedal robot WABOT, which inspired me to apply to Waseda University in high school, was developed by Prof. Kato in the 1970s, who drew inspiration from Astro Boy. It’s a powerful reminder of how sci-fi and scientific discovery often go hand in hand.
From Academia to Industry: Choosing BionicM
— You could have continued on in academia after earning your doctorate. Why did you decide to join BionicM instead??
From the time I received my master's degree in Japan, I had not considered remaining in academia. My advisor at Waseda University came from a corporate background, and his philosophy of “creating usable products” became a cornerstone of my own approach. I thought that, especially in the field of assistive devices, even groundbreaking research would have limited impact unless it could be translated into products. For assistive devices—the focus of my work—practicality is key. They only make a difference when they are used, so I recognized the importance of gaining the skills and experience to put research results into practical use.
Academia, by its nature, often requires researchers to work independently, handling everything from conducting research to securing funding. In contrast, I felt that joining a company whose mission aligned with my goals would allow me to focus on the aspect I was most passionate about—developing control systems of assistive devices—while contributing to a larger team effort.
That said, I wasn’t drawn to large corporations. Smaller companies, with their flexibility and opportunities for hands-on involvement, seemed like a much better fit for my aspirations than the structured, hierarchical systems of large corporations. My experience as an intern in Germany influenced this preference. Through the Vulcanus in Europe program, I spent about a year at Continental Automotive GmbH, one of the world’s leading manufacturers of automotive parts and tires. I was assigned to a department focused on the design and development of automotive components. While I gained valuable insights, I realized that research was more enjoyable for me. I now understand that it’s impractical to assign significant responsibilities to a student or intern—especially one from overseas—at the time, however, I found myself disinterested in the design tasks. The designs were largely predetermined, leaving little room for input. I often thought, “It would be more interesting to explore different shapes or challenge existing design conventions.” This experience solidified my preference for a more dynamic environment. I realized I would thrive in a setting where I could take initiative, work across different roles, and learn a broad range of skills.?
— So you were looking to work for a small organization, not academia or a big company...how did you end up at BionicM?
As I approached graduation, I began attending international conferences to explore career opportunities. At one such conference in the summer of 2018, I came across Dr. Sun’s poster presentation on his research. It focused on robotic prosthetic legs, which are a relatively niche area at the University of Tokyo’s Jouhou System Kougaku (JSK) Laboratory. Since it was closely aligned with my own field of research, it left a lasting impression.
A few months later, I stumbled upon news that Dr. Sun was planning to start his own company. Intrigued, I reached out to him via social media, expressing my interest and asking to visit him. Dr. Sun agreed, and we reconnected in April 2019 when I returned to Japan for a short visit.
The development of prosthetic legs at BionicM is strongly related to the research I had been conducting. I was also immediately drawn to the team, as the members’ diverse expertise was impressive; and Dr. Sun himself, a prosthetic leg user, knows the limits of the current prosthetic legs and can convey the advantages of our product. . The combination of these talents convinced me that we could create something truly groundbreaking together.
I also felt that I could seamlessly integrate into this team and contribute meaningfully. By October 2019, shortly after completing my doctoral program, I officially joined BionicM as part of their team.
The Challenge of Energy-Efficient Prosthetic Legs
— What excites you most about developing prosthetic legs?
I find it fascinating that energy consumption can be minimized by incorporating a hybrid approach that combines active and passive components. This idea closely aligns with my doctoral research and the concepts envisioned by Dr. Sun.
Take wearable robots, for example. A military-grade powered suit may be equipped with a large battery and provide continuous, power-intensive assistance. However, for devices intended for daily life, the design must prioritize being lightweight and compact, including the battery. To ensure long operating hours in such cases, energy efficiency becomes crucial. One strategy to achieve this efficiency is by adopting hybrid mechanisms. For instance, a prosthetic leg can provide active assistance when power is needed, such as climbing stairs, while relying on passive mechanisms for tasks like walking on flat ground.? Biomechanical studies reveal that the human knee functions passively as a brake during walking. When you step forward with your foot, you’ll land from the heel. The Achilles tendon in that leg stores energy as it stretches gradually when the other leg is swinging. This stored energy is utilized to produce the force that propels your leg forward when pushing off the ground with your foot. However, to prevent the leg from swinging too far, the muscles around the knee engage to brake the motion. In terms of a prosthetic knee, this braking action may be utilized to conserve energy with appropriate mechanisms. Similar to the hand-cranked rechargeable radio mentioned earlier, applying a controlled load using a motor can act as a brake while simultaneously generating energy to recharge the prosthesis. In this way, the prosthetic knee conserves power during walking while consuming energy only in high-demand scenarios like stair climbing.
While there has been significant research in this area, the concepts are not yet fully established as a unified theory. For me, the ability to extend users' mobility while optimizing energy consumption through the hybrid prosthesis is one of the most exciting challenges we face at BionicM.
CTO Daisuke Kaneishi’s journey is a testament to the power of innovation driven by compassion and a deep understanding of user needs. At BionicM, his work is not just about engineering better prosthetics but about using science to foster independence and enhance mobility for people worldwide.
If Daisuke’s story resonates with you or aligns with your mission as a clinician or Certified Prosthetist Orthotist (CPO), we invite you to visit the BionicM homepage to learn more about how we are shaping the future of mobility together.