Humanoid robot with flexible legs improves balance and motion control
Modeling and Control of a Rigid-soft Hybrid-link Humanoid Robot
Robotics
Summary
Humans move smoothly partly because their bodies can flex and absorb shocks. The authors studied robots that combine stiff parts with flexible parts, like springy legs, which can help with energy use and reduce impact. They created a new way to calculate and control how these robots move using a model that breaks the flexible parts into smaller segments. They tested their approach in computer simulations and with a real robot that has springy prosthetic legs, showing it can keep balance while standing and walking.
What this means in practice
- •For robotic system designers: Design control algorithms for humanoid robots featuring flexible components to improve energy efficiency and impact absorption during dynamic motions.
- •For rehabilitation device manufacturers: Develop prosthetic legs with flexible elements and control methods to enhance standing balance and locomotion stability.$Commercial implications: Enables sales of bipedal prosthetic devices with improved adaptive control for better user balance and comfort.
Authors
Zewen He, Taiki Ishigaki, Ko Yamamoto
Abstract
Physical flexibility plays a significant role not only in human motions but also in robot motions. For example, a humanoid robot with passive and flexible elements, which can be regarded as a rigid--soft hybrid-link system, has the advantages of storing energy and mitigating impact in a dynamic motion. However, the motion design and control of a hybrid-link system are challenging to achieve and have only been discussed in the literature. In this study, we propose the framework of inverse kinematics and compliance optimization-based control for a hybrid-link humanoid system that represents the continuous deformation of a flexible structure using the piece-wise constant strain (PCS) model. The proposed method was validated using forward dynamics simulations for standing, jumping, and walking motions. Then, we built an experimental setup using a biped humanoid robot with leaf-spring type prosthesis leg, in which the prosthesis deformation was measured by a motion capture system. Using this setup, we experimentally validated the proposed method for standing balance control in both double- and single-support cases.