Soft Robot Actuator Using Granular Jamming and Resistance Sensing
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Solution Overview
Problem
Conventional robots made of hard components face challenges in shape change and compliance, leading to increased complexity and limited degree of freedom, which is addressed by the development of soft robotics utilizing granular jamming phenomena.
Innovation Solution
An actuator comprising conductive grains within a chamber, with electrodes on its surface, and a controller that adjusts the load based on changes in the electric signal caused by resistance changes in the electrical path formed by the grains, allowing for precise control of the actuator's shape and compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If robots are made of hard components, then structural strength is improved, but shape change capability and compliance deteriorate
Solution Approach 1:
The patent changes the physical state and parameters of the granular medium inside the chamber. By adjusting the volume fraction of grains, applying vibrations, or changing pressure, the medium transitions between jammed (rigid) and unjammed (compliant) states, enabling the actuator to switch between structural strength and shape change capability as needed
Solution Approach 2:
The actuator employs a composite structure combining a flexible chamber wall material with an internal granular medium. This composite design allows the outer structure to provide flexibility while the internal grains provide adjustable rigidity through jamming transitions, resolving the contradiction between strength and compliance
2Measurement precision
If a greater number of connecting portions and control devices are used, then precise movements are improved, but device complexity increases
Solution Approach 1:
The granular jamming mechanism serves multiple functions simultaneously: it provides structural support, enables shape change, and acts as a sensing element through resistance changes. This multi-functionality reduces the need for separate components for each function, thereby reducing overall device complexity while maintaining control precision
Solution Approach 2:
The patent implements feedback control by using the electrical resistance changes of the granular medium as sensing information. The controller monitors resistance variations and adjusts actuation accordingly, enabling precise movement control with minimal components through closed-loop feedback
3Adaptability or versatility
If granular jamming phenomenon is used, then rigidity change capability is improved, but measurement precision deteriorates
Solution Approach 1:
The patent introduces electrical resistance as an intermediary parameter to measure load on the granular medium. Instead of directly measuring mechanical load, the system uses the change in electrical resistance caused by grain rearrangement under load as a proxy measurement, enabling precise load detection while maintaining rigidity change capability
Solution Approach 2:
The patent replaces direct mechanical load measurement with an electrical measurement system. By substituting mechanical sensors with electrical resistance measurements, the system achieves precise load detection without adding complex mechanical measurement components, thus maintaining measurement precision while preserving rigidity adaptability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables precise control of the actuator's shape and compliance, reducing the number of components and control devices needed, enhancing stability, wearability, and versatility, particularly in soft robots.
Implementation Method 1
The change in the electric signal may be based on a change of a resistance in an electrical path provided by the plurality of conductive grains in the chamber
Implementation Method 2
The driving source may apply the load to the plurality of conductive grains in the chamber by using at least one from among pneumatic pressure, magnetism, and a motor
Data Source
AI summary
An actuator according to an aspect of the present invention includes: a driving body including a plurality of conductive grains, a chamber configured to confine the plurality of conductive grains, and two or more electrodes disposed on a surface of the chamber; and a controller configured to obtain, through the two or more electrodes, a change in an electric signal, in response to a load applied to the chamber, and to adjust the load applied to the chamber based on the change in the electric signal.