RAIPAL: A Powerful and Agile Humanoid Arm for Human Tasks

Abstract:This paper presents humanoid manipulator hardware designed specifically for human-level performance throughout its broad domain of tasks, from heavy payloads to highly dynamic motions. Unlike conventional designs targeting uniform workspace capability, the proposed approach derives force, speed, and endurance targets from published measurements of task-relevant human upper-limb performance. These targets guide the actuator, mechanism, and thermal design toward torque transparency and sustained operation. The platform integrates force-oriented upper-arm components, speed-oriented forearm components, and a posture-dependent elbow mechanism that shifts its torque-speed behavior. These components are driven by planetary actuators and compact actuator-embedded electronics. Experimental results validate broad task capability, demonstrating a peak payload of 20 kg (2.25x its own mass), an endpoint speed of 20.6 m/s, and continued operation under repeated hammering impacts. Thermal analysis further confirms that the robot's sustained operation capability exceeds the published human load--duration boundary across nearly the entire load spectrum. These findings show that hardware targets derived from human-task measurements narrow the human-to-humanoid capability gap. A supplementary video is available at this https URL

Published in IEEE Robotics and Automation Letters (RA-L), 2026. Supplementary video: this https URL

Robotics (cs.RO)

arXiv:2611.04334 [cs.RO]

(or arXiv:2611.04334v1 [cs.RO] for this version)

https://doi.org/10.48550/arXiv.2611.04334 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

https://doi.org/10.1109/LRA.2026.3741787 Focus to learn more DOI(s) linking to related resources

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