Shape-Memory Actuator for Dynamic Stiffness in Flexible Members
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Solution Overview
Problem
Existing flexible members lack the ability to dynamically adjust their stiffness in response to varying external forces and conditions, limiting their adaptability and functionality in applications such as endoscopes and other flexible instruments.
Innovation Solution
A variable-stiffness actuator is integrated into flexible members, comprising hard members, shape-memory alloys, inducing members that generate heat to transition the shape-memory alloy between low and high stiffness phases, and urging members to control the stiffness by altering the phase of the shape-memory alloy between hard members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a coil pipe is compressed by pulling a flexibility adjustment wire, then the stiffness of the soft part is improved, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by utilizing phase transition of shape-memory alloys to alter stiffness. The shape-memory alloy changes its physical state between martensite (low stiffness) and austenite (high stiffness) phases through temperature or stress changes, enabling dynamic stiffness adjustment without complex mechanical structures like coil pipes and adjustment wires.
Solution Approach 2:
The patent replaces the mechanical compression system (coil pipe and flexibility adjustment wire) with a material-based solution using shape-memory alloys. Instead of mechanically compressing a coil pipe to increase stiffness, the shape-memory alloy inherently changes its stiffness through phase transition, substituting a complex mechanical system with a simpler material property change.
2Strength
If the shape-memory member transitions to high stiffness phase, then the stiffness is improved, but the ease of deformation deteriorates
Solution Approach 1:
The patent applies dynamics by making the stiffness property changeable through phase transition. The shape-memory alloy can dynamically switch between low stiffness (martensite phase) for easy deformation and high stiffness (austenite phase) for structural support, allowing the system to adapt its mechanical properties based on operational requirements.
Solution Approach 2:
The patent directly applies phase transitions of shape-memory alloys to control stiffness. The material transitions between martensite and austenite phases through temperature or stress changes, enabling reversible switching between soft and stiff states. This phase transition mechanism allows the same material to provide both ease of deformation and high stiffness at different times.
3Adaptability or versatility
If multiple hard members and shape-memory members are added to enable variable stiffness, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by making the shape-memory alloy perform multiple functions simultaneously. The shape-memory alloy member provides both structural support (acting as a connection element) and active stiffness control (through phase transition), replacing what would traditionally require separate structural and actuation components. This multi-functionality reduces overall device complexity while maintaining adaptability.
Solution Approach 2:
The patent applies composite materials by combining shape-memory alloy with hard members to create a hybrid structure. The shape-memory alloy member connects hard members while providing variable stiffness, creating a composite system that leverages the high strength of hard members and the adaptive properties of shape-memory alloy, achieving both adaptability and structural integrity.
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
Enables flexible members to change stiffness dynamically, providing both high and low stiffness states as needed, enhancing their adaptability and functionality by allowing for easier deformation and return to a memorized shape under external forces.
Implementation Method 1
at least one inducing member configured to cause a portion of the shape-memory member located between the hard members to transition in phase between the first phase and the second phase
Implementation Method 2
The shape-memory member has a property of transitioning in phase between a first phase and a second phase. The shape-memory member is in a low stiffness state when the shape-memory member is in the first phase, and is in a high stiffness state when the shape-memory member is in the second phase
Data Source
AI summary
A variable-stiffness actuator is to be installed into a flexible member and provide different degrees of stiffness to the flexible member. The actuator includes two hard members located apart from each other, and a shape-memory member connecting the hard members. The shape-memory member has a property of transitioning in phase between a first phase and a second phase. The shape-memory member is in a low stiffness state when in the first phase, and is in a high stiffness state when in the second phase. The actuator also includes a inducing member configured to cause a portion of the shape-memory member between the hard members to transition in phase between the first and second phases, and a urging member configured to urge the hard members in directions away from each other.