Ringbot Quad: A Monocycle Robot with Four Legs for Versatile Wheel-Leg Transformable Locomotion
Kevin Gim, Joohyung Kim
AI summary
Problem
Wheeled robots lack obstacle-crossing capability while legged robots suffer from energy inefficiency and limited speed. This work addresses the need for a compact, single-platform robot that seamlessly integrates both locomotion modes to navigate complex urban terrains.
Approach
The design replaces a traditional monocycle drivetrain with four independently actuated driving modules, each topped with an articulated leg. By shifting internal mass and coordinating leg movements, the robot toggles between gyroscopic-stabilized rolling and quadrupedal walking using decoupled controllers and optimized link lengths.
Key results
- Compact-scale prototype demonstrates seamless wheel-leg mode switching
- Decoupled control enables stable gyroscopic driving and quadrupedal gaits
- Grid-search optimization minimizes leg motor torque while preserving balance
- Proof-of-concept validates unified platform feasibility for complex terrains
Why it matters
Provides a compact, energy-efficient mobile robot platform capable of navigating both smooth roads and complex obstacles, with direct applications in urban delivery and inspection tasks.
Abstract
Integrating multiple locomotion modes on a single platform has become an active focus in pursuit of versatile and efficient movement. This paper introduces a novel mono- cycle robot with four legs, named Ringbot Quad, combining the wheeled and legged mechanisms. The Ringbot Quad is developed as a unique monocycle mechanism that replaces the traditional monocycle drivetrain with four individually actuated driving modules, each topped with an articulated leg. The four legs can be used for balance and steering in driving mode and for quadruped walking that fully supports the body with the legs. By switching between two distinct locomotion modes, it can navigate various terrains and overcome obstacles typically challenging for either mechanism alone. In this work, we present a compact-scale Ringbot Quad prototype as a proof of concept for the proposed mechanism, demonstrating the feasibility of a new type of mobile robot.