Tilt-Ropter: A Fully Actuated Hybrid Aerial-Terrestrial Vehicle with Tilt Rotors and Passive Wheels
This work addresses the need for energy-efficient multi-modal robots for long-duration missions in constrained environments, offering a fully actuated design that improves maneuverability and efficiency over conventional underactuated HATVs.
Tilt-Ropter is a fully actuated hybrid aerial-terrestrial vehicle that uses tilt rotors and passive wheels for efficient multi-modal locomotion. Experiments show a 92.8% reduction in power consumption during ground locomotion compared to flight, enabling long-duration missions.
In this work, we present Tilt-Ropter, a fully actuated hybrid aerial-terrestrial vehicle (HATV) that integrates tilt rotors with passive wheels to enable efficient multi-modal locomotion. Unlike conventional underactuated HATVs, the fully actuated design of Tilt-Ropter allows decoupled force and torque control, improving maneuverability and ground locomotion efficiency. A unified nonlinear model predictive controller (NMPC) is developed to track reference trajectories, enforce non-holonomic constraints, and accommodate contact effects across locomotion modes, while ensuring actuator feasibility through dedicated control allocation. To address complex wheel-ground dynamics, an external wrench estimator is incorporated to provide real-time interaction wrench estimates. The system is validated through simulation and real-world experiments, including seamless air-ground transitions and trajectory tracking tasks. Experimental results demonstrate low tracking errors in both modes and reveal a 92.8% reduction in power consumption during ground locomotion compared to flight, highlighting the platform's suitability for long-duration missions in energy-constrained environments.