Short SMA Wire Actuator Assembly for Compact Precision Control
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Solution Overview
Problem
Existing SMA actuator systems are inefficient for applications requiring short stroke movements with rapid movement cycles and precise positional control, as they often require longer wires for sufficient stroke, leading to larger sizes and higher power consumption.
Innovation Solution
The use of short SMA wires (less than 5 mm in length) with a high spring constant, allowing for high resonant frequencies and reduced power requirements, enabling compact and efficient actuator assemblies suitable for applications like super-resolution cameras and 3D sensing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If longer SMA wires are used to provide sufficient stroke, then the stroke is improved, but the device size and power consumption increase
Solution Approach 1:
The patent employs a flexible suspension system with flexures that dynamically adapts to the short SMA wire contraction, converting the limited linear displacement into effective positional control of the movable part through elastic deformation and geometric transformation
Solution Approach 2:
The suspension system transforms the one-dimensional wire contraction into multi-dimensional movement of the movable part, utilizing flexure bending and geometric relationships to achieve positional control in multiple directions despite the short wire length
2Length of moving object
If longer SMA wires are used to provide sufficient stroke, then the stroke is improved, but the power consumption increases
Solution Approach 1:
The flexible suspension system dynamically converts the limited thermal contraction of short SMA wires into effective mechanical stroke through elastic deformation, reducing the energy required compared to rigid systems that would require longer wires for the same displacement
Solution Approach 2:
The system changes the mechanical parameters through the flexure suspension geometry, transforming the small linear contraction of short wires into effective positional control, thereby reducing the power consumption required for actuation
3Volume of moving object
If shorter SMA wires are used, then the actuator assembly size is reduced, but the stroke is limited
Solution Approach 1:
The flexible suspension system dynamically amplifies the limited contraction of short SMA wires into effective stroke through elastic deformation and geometric transformation, allowing compact actuator assembly while maintaining sufficient movement range
Solution Approach 2:
The suspension system converts the one-dimensional wire contraction into multi-dimensional movement, enabling the movable part to achieve positional control in multiple directions despite the short wire length, thus compensating for the limited stroke
4Speed
If shorter SMA wires are used, then the resonant frequency is increased, but the movement cycle speed must be controlled to avoid resonance
Solution Approach 1:
The flexible suspension system dynamically adapts to the high resonant frequency of short SMA wires by utilizing elastic deformation that naturally filters out resonance, allowing rapid movement cycles without exciting resonant vibrations
Solution Approach 2:
The system converts the potentially harmful high resonant frequency into a beneficial feature by using the flexure suspension to naturally filter out resonance, allowing the short SMA wires to operate at high speeds without causing vibrations or reducing productivity
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 short SMA wires enable rapid movement cycles with precise positional control, reducing power consumption and allowing for smaller, more efficient actuator assemblies that can achieve high-resolution imaging and 3D sensing tasks effectively.
Implementation Method 1
at least one shape memory alloy (SMA) wire connected between the support structure and the movable part via wire attach components and arranged, on contraction, to drive movement of the movable part
Implementation Method 2
The SMA wire may typically have a length of order 10 mm to provide the desired stroke
Data Source
AI summary
An actuator assembly comprises a support structure (6), a movable part (5) movable relative to the support structure, at least one shape memory alloy (SMA) wire (2) connected between the support structure and the movable part via wire attach components and arranged, on contraction, to drive movement of the movable part and a control circuit configured to apply drive signals to the at least one SMA wire so as to drive movement of the movable part relative to the support structure between predetermined positions in a repeated pattern; wherein the length of the at least one SMA wire extending between respective wire attach components is less than 5 mm.