Soft Actuator Cooling Control for Faster SMA Spring Relaxation
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Solution Overview
Problem
Existing wearable strength aids impede natural body movement, are heavy, and have slow cooling speeds due to reliance on natural temperature changes, leading to reduced efficiency and increased musculoskeletal strain.
Innovation Solution
A soft actuator using a shape memory alloy spring with integrated cooling parts and a controller to manage power supply, allowing for rapid temperature changes and enhanced flexibility, including forced cooling methods to accelerate relaxation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If natural cooling is used for the shape memory alloy spring, then the structure remains simple, but the cooling speed is slow
Solution Approach 1:
The patent introduces a cooling medium (such as water or air) as an intermediary substance to facilitate heat transfer from the shape memory alloy spring. The cooling medium flows through channels or contacts the spring surface, acting as a mediator between the spring and the environment to accelerate cooling without requiring complex active cooling systems.
Solution Approach 2:
The patent employs hydraulic or pneumatic cooling systems where a fluid (water or air) is circulated through channels formed in or around the shape memory alloy spring. This fluid circulation enables rapid heat removal, significantly increasing the cooling speed compared to natural convection while maintaining relatively simple system architecture.
2Force
If a motor and frame are used in wearable strength aids, then driving force is sufficient, but the weight increases and structure becomes rigid
Solution Approach 1:
The patent replaces the traditional motor-driven mechanical system with a shape memory alloy-based actuation system. The shape memory alloy spring generates driving force through thermal actuation, eliminating the need for heavy motors, gearboxes, and rigid frames, thereby significantly reducing the overall weight while maintaining sufficient driving capability.
Solution Approach 2:
The patent utilizes the temperature-dependent properties of shape memory alloy to generate mechanical force. By changing the temperature parameter (through heating or cooling), the alloy undergoes phase transformation that produces large elastic deformation, providing the necessary driving force without mechanical motors or complex transmission mechanisms.
3Productivity
If shape memory alloy spring is used for rapid actuation, then responsiveness improves, but cooling speed becomes the limiting factor
Solution Approach 1:
The patent divides the cooling function into separate, dedicated cooling channels or zones that are specifically designed for rapid heat removal from the shape memory alloy spring. This segmentation allows the cooling system to focus its capacity on the critical cooling requirement, enabling faster relaxation rates that match the rapid actuation capability of the alloy.
Solution Approach 2:
The patent implements a continuous cooling system that maintains constant thermal management during operation. The cooling medium continuously circulates through the system, ensuring that heat is constantly removed from the shape memory alloy spring, thereby enabling rapid and repeated actuation cycles without thermal accumulation limiting the relaxation speed.
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
The solution provides a lightweight, flexible, and responsive wearable robot with increased cooling speed, reducing musculoskeletal strain and enhancing operational efficiency.
Implementation Method 1
The cooling part includes a cooling surface disposed at the heat reaction member
Implementation Method 2
a heating surface disposed opposite to the cooling surface
Implementation Method 3
a shape memory alloy spring is used... the heat reaction member is configured to be contracted or relaxed according to a temperature change
Data Source
AI summary
In a soft actuator having a cooler, a wearable robot having the soft actuator, a massage device having the soft actuator, and a method for controlling the soft actuator, the soft actuator includes a heat reaction member, a cooling part and a controller. The heat reaction member is configured to be contracted or relaxed according to a temperature change. The cooling part includes a cooling surface disposed at the heat reaction member, and a heating surface disposed opposite to the cooling surface. The controller is configured to control a power supply part so that a power is blocked to be supplied to the heat reaction member and the power is supplied to the cooling part, when the heat reaction member is changed to be a relaxation state.