Rideable animatronic robot uses self-balancing wheels for quadruped gait

Researchers Tadashi Sumioka and colleagues have developed a rideable two-wheeled robot with a quadruped form, aiming to rekindle motorcycle interest among younger generations. The robot is designed as a futuristic partner mobility concept, carrying a rider on its back while exhibiting dynamic quadruped-like behavior. To maximize realism, the team matched the robot's weight and size to a specific character from pop culture, while ensuring rider safety and enabling expressive limb, wrist, ankle, and facial movements. However, pure limb-based locomotion required excessive motor output and resulted in an impractically slow gait, compromising character fidelity.

To solve this, the robot relies on a self-balancing two-wheeled base for primary movement, with limbs providing auxiliary support during mounting and dismounting and coordinating with wheel speed for natural quadruped motion. The control system uses intuitive weight-shift input for free and natural riding. The paper details a robust self-balancing control method that maintains stability during rapid limb movements, alongside a motion control strategy that generates realistic quadruped-like behavior. This approach allows a relatively lightweight, expressive animatronic robot that can be ridden safely.