IROS 2025 Keynotes - Mechanisms and Controls: Kenjiro Tadakuma

Why It Matters

The mechanisms could dramatically reduce complexity and increase resilience of robots operating in extreme or disposable contexts, accelerating adoption in fields from emergency rescue to space missions.

Key Takeaways

• Omni‑ball design enables high step‑climbing for mobile robots.
• Omni‑roller derives directly from omni‑ball geometry principles for mobility.
• New screw‑type differential achieves compact two‑axis motion in robots.
• Bio‑inspired soft actuators provide fire‑ and cut‑resistance for hazardous applications.
• Self‑healing, degradable mechanisms aim toward sustainable robotics solutions.

Summary

Kenjiro Tadakuma’s IROS 2025 keynote centered on a sweeping portfolio of novel mechanisms and control concepts, ranging from omni‑directional locomotion modules to bio‑inspired soft actuators. He framed the discussion around the invention process, showcasing dozens of prototype models that illustrate both functional performance and topological insight.

The talk highlighted the omni‑ball—a spherical wheel with enlarged diameter that delivers superior step‑climbing—and its direct derivative, the omni‑roller, which inherits the same geometry to enable sideways motion with a single motor pair. He introduced a compact screw‑type differential gear that provides two‑degree‑of‑freedom motion in a minimal footprint, and a line‑contact configuration that extends wheel concepts to crawlers and planar gears. Beyond hard mechanisms, Tadakuma presented fire‑ and cut‑resistant soft actuators, three‑layer membranes filled with powder for large deformation, and edible or biodegradable actuation materials.

Memorable examples included a drone‑landing gear prototype that lands without sensors, a tungsten‑wire gripper that resists fire, and a self‑healing chemical system that restores motion within minutes. He emphasized that the omni‑roller’s principle mirrors the omni‑ball’s, and that the reflexive drive concept, developed since 2015, integrates density‑based material selection for passive recovery.

Collectively, these innovations promise simpler, more robust locomotion for harsh‑environment robots, while the biodegradable and self‑repairing designs point toward sustainable, low‑maintenance platforms for disaster response, exploration, and beyond.

Original Description

"Keynote Title: ""Topological Robotic Mechanisms""

Speaker Biography

Kenjiro Tadakuma is currently a tenured Professor at The University of Osaka, where he has been leading the TADAKUMA Mechanisms Group since 2024, and a Visiting Professor at Tohoku University’s Tough Cyberphysical AI Research Center. Throughout his career, he has made outstanding contributions to the design of novel robotic mechanisms. As a Ph.D. student at Tokyo Tech (2004 – 2007), he invented the first omnidirectional mechanism, known as “Omni-Ball”. This brought him to MIT’s Field and Space Robotics laboratory as a post-doctoral researcher (2007), where he went on to contribute to the Mars hopper project and developed a polymer-based mechanical device for medical applications. Back in Japan, he held positions at Tohoku University, the University of Electro-Communications, and Osaka University (2008 – 2015), where he expanded on the concept of omnidirectional mechanisms with successful applications in mobile robotics and gripping mechanisms, such as the “Omni-Crawler” and “Omni-Gripper”. During his time as Associate Professor at Tohoku University (2015 – 2024), his team won numerous national and international awards, including the IEEE ICRA Best Paper Award on Mechanisms and Design in 2019. Now at The University of Osaka, his work aims to achieve “Bio-Extraction Robotics”, to extract the essence of biological mechanisms and expand them as robotic mechanisms that not only surpass the biological function but are also reminiscent of the convergent evolution sometimes observed in nature. The nature of his inventions illustrates his deep focus in pioneering the field of robotics mechanisms as a fundamental science.

Abstract

Conventional omnidirectional wheel mechanisms are limited in their ability to climb steps and cross gaps. The Omni-Ball, consisting of two connected hemispherical wheels, overcomes these limitations by enabling the crossing of higher obstacles and larger gaps than previously. By elongating the Omni-Ball longitudinally into a cylinder shape, we obtained the Omni-Crawler, which enables omnidirectional mobility on rough terrain. In addition, transforming the cylinder shape into a torus with inner-outer membrane motion not only enables robotic mobility in murky water, but makes it possible to further transition from Omni-Crawler to Omni-Gripper. Conventional soft grippers are not suitable for objects with sharp sections such as broken valves and glass shards, but the torus shape solves this problem by using a three-layered variable stiffness skin-bag made of cut-resistant cloth. A similar function could also be achieved using a string of beads made of titanium which can grip objects of almost any shape, even when they are on fire. To build on these gripper mechanisms from the viewpoint of bioinspired robotics, we also developed a structure inspired from the proboscis (mouthpart) of Nemertea, also known as the ribbon worm, and combined it with self-healing materials to realize a robotic blood vessel with active self-healing properties. Through the addition of repair mechanisms, we expect it to be possible to achieve the active transformation of one’s own body, thereby creating the ultimate robotic mechanism. Thus, the perspective of topology can be harnessed in the design of robotic mechanisms, culminating in the establishment of a new academic discipline—Topological Mechanism Science—as a counterpart to topological geometry."