Related Experiment Video
Updated: May 30, 2025
11:06
Design and Fabrication of an Elastomeric Unit for Soft Modular Robots in Minimally Invasive Surgery
Published on: November 14, 2015
8.9K
A hyperelastic torque-reversal mechanism for soft joints with compression-responsive transient bistability
Woo-Young Choi1,2, Woongbae Kim3,4, Jae-Ryeong Choi1
1Biorobotics Laboratory, Soft Robotics Research Center, Institute of Advanced Machines and Design, Department of Mechanical Engineering, Institute of Engineering, Seoul National University, Seoul, Republic of Korea.
Science Robotics
|January 29, 2025
Summary
Researchers developed a novel soft joint using hyperelasticity to create a torque-reversal mechanism. This design enables impulsive motions and energy storage in soft machines, mimicking natural systems.
Area of Science:
- Soft robotics
- Mechanical engineering
- Materials science
Background:
- Snap-through is a rapid transition in bistable systems, useful for soft devices.
- Natural torque-reversal mechanisms offer advantages but are complex to replicate artificially.
Purpose of the Study:
- To implement a torque-reversal mechanism in a soft joint using hyperelasticity.
- To generate repetitive cilia-like beating motions in soft machines.
Main Methods:
- Developed a hyperelastic torque-reversal mechanism (HeTRM) utilizing transient bistability.
- Embedded a tendon within the soft joint to induce snap-through.
- Explored HeTRM functionalities in proof-of-concept soft machines.
Main Results:
- HeTRM exhibits transient bistability and snap-through at a specific threshold.
- Demonstrated functionalities including energy storage/release, dual motion modes, and mechanical fuse.
- Achieved rapid three-dimensional motions and repetitive cilia-like beating.
Conclusions:
- The hyperelastic torque-reversal mechanism provides a simpler approach to incorporating snap-through in soft machines.
- This design principle offers insights into soft machine functionalities and the relationship between torque-reversal and bistability.
Related Concept Videos
01:14Stability of structures
153
In mechanical engineering, the stability of systems under various forces is critical for designing durable and efficient structures. One fundamental way to explore these concepts is by analyzing systems like two rods connected at a pivot point, O, with a torsional spring of spring constant k at the pivot point. This system is similar in appearance to a scissor jack used to change tires on a car. In this case, the arms of the linkage (equivalent to the rods in this system) are entirely vertical,...
153
01:24Circular Shafts - Elastoplastic Materials
92
The study of solid circular shafts under stress shows that within the elastic limit, stress increases directly to the distance from the shaft's center. This relationship holds until the shaft reaches a critical point of stress, beyond which it begins to yield, marking the transition from elastic to plastic deformation. At this crucial juncture, the maximum torque the shaft can endure without permanent deformation is determined, signifying the limit of its elastic behavior.
As torque on the...
As torque on the...
92
01:18Residual Stresses in Bending
151
In the study of elastoplastic members subjected to bending moments, understanding the loading and unloading phases is crucial for assessing material behavior and structural integrity. During the loading phase, as the bending moment increases, the material initially responds elastically, adhering to Hooke's Law, where stress is directly proportional to strain. When the load exceeds the yield strength, plastic deformation occurs, resulting in permanent strain and deformation that remains even...
151
01:21Plastic Behavior
185
A material's elastic behavior is characterized by the disappearance of stress once the load is removed, allowing the material to return to its original state. However, when stress surpasses the yield point, yielding commences, marking the onset of plastic deformation or permanent set. This change from elastic to plastic behavior is influenced by the peak stress value and the duration before the load is removed. An intriguing observation occurs when a specimen is loaded, unloaded, and...
185
01:19Members Made of Elastoplastic Material
93
The behavior of elastoplastic materials under bending stresses, particularly in structural members with rectangular cross-sections, is crucial for predicting material responses and understanding failure modes. Initially, when a bending moment is applied, the stress distribution across the section follows Hooke's Law and is linear and elastic. This distribution means the stress increases from the neutral axis to the maximum at the outer fibers, up to the elastic limit.
As the bending moment...
As the bending moment...
93
01:20Elastic Strain Energy for Shearing Stresses
156
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...
156