Reconfigurable rocker-bogie robot climbs 40cm steps, turns 5x faster with 83% less torque

A team of Japanese researchers led by Kento Koizumi has proposed a reconfigurable rocker-bogie mechanism that solves a long-standing trade-off in mobile robotics: high step-climbing capability versus agile turning. Traditional rocker-bogie designs (like NASA's Mars rovers) excel at climbing obstacles but struggle with tight turns because their non-steerable wheels require high torque and large radii. The new design adds motors at the bogie joints, allowing each bogie to swing up or down actively. This lets the robot reconfigure between a four-wheel mode (with omnidirectional rear wheels for differential drive) and a six-wheel mode (for maximum climbing traction). The prototype demonstrated zero-radius turning at over five times the speed of a conventional six-wheeled rocker-bogie, while consuming only about 17% of the average wheel torque.

Beyond turning efficiency, the robot maintained impressive climbing performance: it successfully scaled a 40 cm vertical step in an average of 6.4 seconds. The reconfiguration itself takes advantage of the active bogie joints to lift wheels off the ground when not needed, reducing drag and wear. The work was accepted for publication at the IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 2026). This combination of high mobility and maneuverability makes the design promising for applications in disaster response, planetary exploration, and industrial inspection where robots must navigate both rugged terrain and confined spaces.