Programmable Locking Cells (PLC) for Modular Robots with High Stiffness Tunability and Morphological Adaptability

Fuente: arXiv
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Main Authors: Zhou, Jianshu, Chen, Wei, Huang, Junda, Liang, Boyuan, Liu, Yunhui, Tomizuka, Masayoshi
Format: Preprint
Published: 2025
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author Zhou, Jianshu
Chen, Wei
Huang, Junda
Liang, Boyuan
Liu, Yunhui
Tomizuka, Masayoshi
author_facet Zhou, Jianshu
Chen, Wei
Huang, Junda
Liang, Boyuan
Liu, Yunhui
Tomizuka, Masayoshi
contents Robotic systems operating in unstructured environments require the ability to switch between compliant and rigid states to perform diverse tasks such as adaptive grasping, high-force manipulation, shape holding, and navigation in constrained spaces, among others. However, many existing variable stiffness solutions rely on complex actuation schemes, continuous input power, or monolithic designs, limiting their modularity and scalability. This paper presents the Programmable Locking Cell (PLC)-a modular, tendon-driven unit that achieves discrete stiffness modulation through mechanically interlocked joints actuated by cable tension. Each unit transitions between compliant and firm states via structural engagement, and the assembled system exhibits high stiffness variation-up to 950% per unit-without susceptibility to damage under high payload in the firm state. Multiple PLC units can be assembled into reconfigurable robotic structures with spatially programmable stiffness. We validate the design through two functional prototypes: (1) a variable-stiffness gripper capable of adaptive grasping, firm holding, and in-hand manipulation; and (2) a pipe-traversing robot composed of serial PLC units that achieves shape adaptability and stiffness control in confined environments. These results demonstrate the PLC as a scalable, structure-centric mechanism for programmable stiffness and motion, enabling robotic systems with reconfigurable morphology and task-adaptive interaction.
format Preprint
id arxiv_https___arxiv_org_abs_2509_07916
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Programmable Locking Cells (PLC) for Modular Robots with High Stiffness Tunability and Morphological Adaptability
Zhou, Jianshu
Chen, Wei
Huang, Junda
Liang, Boyuan
Liu, Yunhui
Tomizuka, Masayoshi
Robotics
Robotic systems operating in unstructured environments require the ability to switch between compliant and rigid states to perform diverse tasks such as adaptive grasping, high-force manipulation, shape holding, and navigation in constrained spaces, among others. However, many existing variable stiffness solutions rely on complex actuation schemes, continuous input power, or monolithic designs, limiting their modularity and scalability. This paper presents the Programmable Locking Cell (PLC)-a modular, tendon-driven unit that achieves discrete stiffness modulation through mechanically interlocked joints actuated by cable tension. Each unit transitions between compliant and firm states via structural engagement, and the assembled system exhibits high stiffness variation-up to 950% per unit-without susceptibility to damage under high payload in the firm state. Multiple PLC units can be assembled into reconfigurable robotic structures with spatially programmable stiffness. We validate the design through two functional prototypes: (1) a variable-stiffness gripper capable of adaptive grasping, firm holding, and in-hand manipulation; and (2) a pipe-traversing robot composed of serial PLC units that achieves shape adaptability and stiffness control in confined environments. These results demonstrate the PLC as a scalable, structure-centric mechanism for programmable stiffness and motion, enabling robotic systems with reconfigurable morphology and task-adaptive interaction.
title Programmable Locking Cells (PLC) for Modular Robots with High Stiffness Tunability and Morphological Adaptability
topic Robotics
url https://arxiv.org/abs/2509.07916