SMA Hinge Apparatus for CubeSat Deployable Structure Actuation
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Solution Overview
Problem
CubeSats face challenges in actively managing their orientation and deployable structures due to resource constraints, limiting their ability to support multi-use actuators, which affects power generation, communication efficiency, and orbital management.
Innovation Solution
A shape memory alloy (SMA) hinge apparatus that uses SMA elements to provide bidirectional rotary motion, allowing for adjustable angles and orientations of deployable structures without the need for complex actuators, by exploiting the reversible transition between austenite and martensite phases through Joule heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional actuators (electric motors, reaction wheels) are used to adjust deployable structures on CubeSats, then the ability to actively manage orientation and power generation is improved, but the size, weight, and complexity of the system increases beyond what CubeSats can support
Solution Approach 1:
The patent replaces complex mechanical actuation systems (electric motors, reaction wheels, bearings) with a shape memory alloy (SMA) based system that uses thermal-mechanical coupling. The SMA elements directly convert electrical energy to mechanical motion through resistive heating and phase transformation, eliminating the need for traditional mechanical actuators and their supporting structures.
Solution Approach 2:
The SMA hinge apparatus serves multiple functions: it acts as both the actuation mechanism and the hinge joint, providing rotary motion while also serving as the structural connection between the deployable structure and the CubeSat body. This multi-functionality reduces the number of separate components needed.
2Device complexity
If single-use actuation mechanisms (spring-loaded latch, burn-through wire) are used on CubeSats, then the size and complexity are reduced, but the ability to adjust position or orientation of deployable structures is lost
Solution Approach 1:
The patent utilizes changes in physical parameters (temperature, phase state) of the shape memory alloy to enable reversible actuation. By controlling the temperature through electrical heating, the SMA elements can transition between martensite and austenite phases, allowing the deployable structure to be positioned at different angles repeatedly rather than being a single-use mechanism.
Solution Approach 2:
The system transitions from static, single-use actuation to dynamic, multi-use actuation. The SMA hinge apparatus can be actively controlled to adjust the position and orientation of deployable structures during the CubeSat's operational lifetime, enabling active management of solar panel orientation and drag surface positioning.
3Adaptability or versatility
If SMA actuators are used in combination with bearing systems to produce various axes of motion, then the range of motion is improved, but the size, weight, and complexity of the motor increases
Solution Approach 1:
The patent extracts and removes the bearing system from the actuator assembly. The SMA elements are configured to provide rotary motion through their inherent elastic recovery and phase transformation properties without requiring external bearing support structures, thereby significantly reducing the weight and complexity of the actuator system.
Solution Approach 2:
The SMA elements function as flexible, thin-walled structures that can undergo large deformations and recover their shape through phase transformation. This flexibility allows the SMA elements to serve as both the actuator and the mechanical linkage, eliminating the need for rigid bearing supports.
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 efficient and multi-use actuation of deployable structures on CubeSats, improving power generation, communication rates, and orbital management while reducing complexity and weight, thereby enhancing the operational lifetime and reliability of CubeSat systems.
Implementation Method 1
uses SMA elements to provide bidirectional rotary motion, allowing for adjustable angles and orientations of deployable structures without the need for complex actuators, by exploiting the reversible transition between austenite and martensite phases through Joule heating
Implementation Method 2
by exploiting the reversible transition between austenite and martensite phases through Joule heating
Data Source
AI summary
A controllable shape memory alloy (SMA) hinge apparatus comprises multiple SMA elements to effect a first angle of rotation and a second angle of rotation between a first object and a second object. In one example, respective SMA elements are independently activated by Joule heating to rotate the first object and/or the second object. SMA elements undergo a three-dimensional transformation, and a pair of elements may undergo antagonistic transformations so as to provide for a multiple-use bidirectional non-continuous rotary actuator. SMA elements may be trained to achieve different angles of rotations between the objects (e.g., zero degrees and 90 degrees). In some examples, the first object may be a spacecraft (e.g., a satellite) and the second object may be a deployable structure (e.g., a robotic appendage, a deployable solar panel, a deployable aperture, a deployable mirror, a deployable radiator, and at least one actuator to steer an antenna dish).