Design and Control of a Small Humanoid Equipped with Flight Unit and Wheels for Multimodal Locomotion

TL;DR

This work presents a small humanoid that integrates a fully actuated three-rotor flight unit with passive wheels to achieve rapid terrestrial and aerial locomotion, including aerial manipulation. An optimized clutch-based reconfiguration and an integrated control framework unify aerial, legged, and wheeled modes, enabling seamless transitions and manipulation across domains. The authors validate the approach on a prototype by demonstrating hover stability, thrust-assisted walking, wheel-based locomotion, and object handling in the air and on the ground. The results show the feasibility of simultaneous multimodal locomotion in a single humanoid platform and point to future directions for autonomous mode selection and advanced manipulation tasks.

Abstract

Humanoids are versatile robotic platforms owing to their limbs with multiple degrees of freedom. Although humanoids can walk like humans, they are relatively slow, and cannot run over large barriers. To address these limitations, we aim to achieve rapid terrestrial locomotion ability and simultaneously expand the locomotion domain to the air by utilizing thrust for propulsion. In this paper, we first describe an optimized construction method for a humanoid robot equipped with wheels and a flight unit to achieve these abilities. Then, we describe the integrated control framework of the proposed flying humanoid for each locomotion mode: aerial, legged, and wheeled locomotion. Finally, we achieved multimodal locomotion and aerial manipulation experiments using the proposed robot platform. To the best of our knowledge, this is the first time that a single humanoid has simultaneously achieved three different types of locomotion, including flight.

Figures (17)

• Figure 1: Proposed flying humanoid. It equipped with wheels on foot and a fully-actuated trirotor flight unit. Multimodal locomotion is achieved with this robot platform. Lower left: aerial locomotion using thrust. Lower center: legged locomotion. Lower right: wheeled locomotion using thrust and wheels deployed on the foot.
• Figure 2: Dynamics model of fully-actuated trirotor flight unit. Each rotor has vectoring freedom so each rotor can exert force in two directions.
• Figure 3: Joint configuration and modules of flying humanoid. (A): Joint configuration and arrangement of each module. Flight unit is deployed above the humanoid and clutch module is employed to achieve reconfigurable connection. Passive wheels are deployed on foot. (B): Foot with passive wheels. (C): Clutch module used to combine humanoid and flight unit.
• Figure 4: Desired wrench described in \ref{['optimization wrench']}. Gravity compensation term is divided into x and z directions, and torque $\tau_y$ is exerted.
• Figure 5: Plot of feasible torque around pitch axis when tilting by pitch angle. Blue line: $\text{max}\qty(\tau_y)$ in \ref{['opt']}. Orange line: $\text{min}\qty(\tau_y)$ in \ref{['opt']}. The range of feasible torque is maximized when the pitch angle of the body is 0 rad