Design of a 3-DOF Hopping Robot with an Optimized Gearbox: An Intermediate Platform Toward Bipedal Robots

Fuente: arXiv
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Autores principales: Choe, JongHun, Kim, Gijeong, Kim, Hajun, Kang, Dongyun, Kim, Min-Su, Park, Hae-Won
Formato: Preprint
Publicado: 2025
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author Choe, JongHun
Kim, Gijeong
Kim, Hajun
Kang, Dongyun
Kim, Min-Su
Park, Hae-Won
author_facet Choe, JongHun
Kim, Gijeong
Kim, Hajun
Kang, Dongyun
Kim, Min-Su
Park, Hae-Won
contents This paper presents a 3-DOF hopping robot with a human-like lower-limb joint configuration and a flat foot, capable of performing dynamic and repetitive jumping motions. To achieve both high torque output and a large hollow shaft diameter for efficient cable routing, a compact 3K compound planetary gearbox was designed using mixed-integer nonlinear programming for gear tooth optimization. To meet performance requirements within the constrained joint geometry, all major components-including the actuator, motor driver, and communication interface-were custom-designed. The robot weighs 12.45 kg, including a dummy mass, and measures 840 mm in length when the knee joint is fully extended. A reinforcement learning-based controller was employed, and robot's performance was validated through hardware experiments, demonstrating stable and repetitive hopping motions in response to user inputs. These experimental results indicate that the platform serves as a solid foundation for future bipedal robot development.
format Preprint
id arxiv_https___arxiv_org_abs_2505_12231
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Design of a 3-DOF Hopping Robot with an Optimized Gearbox: An Intermediate Platform Toward Bipedal Robots
Choe, JongHun
Kim, Gijeong
Kim, Hajun
Kang, Dongyun
Kim, Min-Su
Park, Hae-Won
Robotics
This paper presents a 3-DOF hopping robot with a human-like lower-limb joint configuration and a flat foot, capable of performing dynamic and repetitive jumping motions. To achieve both high torque output and a large hollow shaft diameter for efficient cable routing, a compact 3K compound planetary gearbox was designed using mixed-integer nonlinear programming for gear tooth optimization. To meet performance requirements within the constrained joint geometry, all major components-including the actuator, motor driver, and communication interface-were custom-designed. The robot weighs 12.45 kg, including a dummy mass, and measures 840 mm in length when the knee joint is fully extended. A reinforcement learning-based controller was employed, and robot's performance was validated through hardware experiments, demonstrating stable and repetitive hopping motions in response to user inputs. These experimental results indicate that the platform serves as a solid foundation for future bipedal robot development.
title Design of a 3-DOF Hopping Robot with an Optimized Gearbox: An Intermediate Platform Toward Bipedal Robots
topic Robotics
url https://arxiv.org/abs/2505.12231