Bi-Stable Shape Memory Alloy Actuator for Low-Power Object Holding
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Solution Overview
Problem
Conventional actuators used in mobile devices and vehicles are often bulky, heavy, and inefficient, consuming excessive power and increasing manufacturing costs, which is particularly problematic for battery-operated systems where size, weight, and energy efficiency are critical.
Innovation Solution
The use of bi-stable actuators incorporating memory alloys (MAs) that can change shape in response to temperature changes, allowing for a compact, lightweight design that can grip and release objects with reduced power consumption by transitioning between coiled and uncoiled states without additional energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional actuators (solenoids, electric motors) are used to operate mechanical loads, then reliable actuation is achieved, but the actuators become bulky and heavy
Solution Approach 1:
The patent replaces conventional electromagnetic actuators (solenoids, motors) with a shape memory alloy-based actuator that uses thermal-mechanical properties of the MA material. The MA wire transforms electrical energy to thermal energy through resistive heating, which then triggers a phase transformation that produces mechanical motion, eliminating the need for bulky electromagnetic components while maintaining actuation reliability
Solution Approach 2:
The patent utilizes the temperature-dependent phase transformation properties of shape memory alloys. By changing the temperature parameter of the MA material through controlled heating, the actuator transitions between different mechanical states (martensite to austenite phase transformation), enabling reliable actuation with significantly reduced weight compared to conventional actuators
2Force
If conventional actuators are used in mobile devices, then sufficient actuation force is provided, but power consumption increases
Solution Approach 1:
The patent employs periodic or pulsed heating of the shape memory alloy wire rather than continuous heating. The actuator is activated by applying electrical current in pulses to trigger phase transformation only when needed, allowing the MA material to maintain its transformed state without continuous energy input, thereby providing sufficient actuation force while dramatically reducing overall power consumption
Solution Approach 2:
The shape memory alloy material inherently maintains its transformed state through its material properties without requiring continuous external energy input. Once the phase transformation is triggered by a heating pulse, the MA wire retains its deformed configuration and can hold loads or maintain actuated positions autonomously, eliminating the need for continuous power consumption to maintain the actuated state
3Reliability
If conventional actuators are used to meet size parameters, then adequate actuation is achieved, but the actuator dimensions increase
Solution Approach 1:
The patent replaces the complex mechanical and electromagnetic structure of conventional actuators with a compact shape memory alloy wire-based system. The MA wire's intrinsic ability to generate large strains through phase transformation enables adequate actuation performance in a significantly more compact form factor, reducing the length and overall dimensions of the actuator while maintaining reliable actuation capability
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 MA-based actuators are significantly lighter and more energy-efficient than traditional solenoid actuators, offering improved performance in size-constrained applications like electric vehicles by maintaining stable shapes without continuous energy use, thus enhancing both power efficiency and manufacturing costs.
Implementation Method 1
A wire and a strip made of a memory alloy (MA) on the body may uncoil and coil to grasp an object
Implementation Method 2
a wire and a strip made of a memory alloy (MA) on the body may uncoil and coil to grasp an object
Data Source
AI summary
Systems and methods relate to a manner of improving an actuator used to hold an object. In one embodiment, an actuator includes a body that is bi-stable with a coiled state and an uncoiled state. The actuator also includes a strip, coupled to the body, that coils the body according to a power source that activates in response to a detected proximity of an object. The actuator also includes a wire coupled to a side of the body opposite from the strip and the wire uncoils the body in response to heat caused by the power source.