Origami-Inspired Foldable Solar Arrays
Georgia Tech Masters Thesis Project, 2020
Advisor: Lisa Marks
Thesis Committee: Glaucio Paulino, Athanos Economou
Solar is the most abundant power source on the planet and the future of sustainable energy.
Populated areas have the highest energy demand, but these areas are already developed and divided into small privately-owned pieces, making it difficult to implement solar energy collection at scale.
Origami offers many solutions to elegantly stowing materials into small volume, and one origami pattern in particular,
the Iso- Area Flasher, is especially attractive in this regard.
In practice, the thickness of real-world materials brings many complexities and obstacles that often prevent these products from coming about.
The Project: Redesigning Solar Panels to be anywhere we need them.
To research, identify, and remove the obstacles that prevent the Flasher origami pattern from being employed in solar arrays and other thick-material product applications.
Crease pattern of a hexagonal origami flasher
Paper prototypes of origami Flasher, able to store a large surface areas by rotating it around a central polygon
Why focus on the Flasher pattern?
The mechanism by which a flasher opens and closes bears close resemblance to a natural botanical movement exhibited by flowers called nyctinasty.
Our solar panels have the same exact needs and use case as flowers:
open configuration, to maximize exposure to pollinators/sunlight
closed configuration, to protect vulnerable material from forces
efficient maneuverability between these two configurations
This structure is the result of natural selection, meaning it is highly
efficient at what it does, and worthy of emulating in human designs.
Flasher Pattern Varieties
A thin-material origami Flasher can be made out of any flat surface. This is done by determining a central polygon, then subdividing the surrounding area into panels of the correct geometries that allow rotational folding.
While any regular polygon can be used as the Flasher center, I chose to focus my research on hexagon-based Flashers.
This is because hexagons are the best shape.
Rotational nyctinasty in the Datura Flower.
other opinions are wrong
These are some of the benefits of using hexagons in this application:
Hexagons have the most efficient packing density of the regular polygons. This has a large potential for opening mechanisms and multi-panel assemblies.
Hexagon have the least sharp corners
of the regular tiling polygons. Sharp corners place high amounts of stress on hinge mechanisms and panel structures.
Hexagon sides perfectly align to an isometric grid system, which provides an accessible framework for building models.
In a system with many variables, choosing one single shape-center helped define and focus the project scope.
Previous Work and State of Knowledge
of the Flasher Pattern
The first Iso-Area folding pattern first appeared in 1987 in Origami for the Connoissuer by Toshikazu Kawasaki, who introduced it in a square rose pattern known as the Kawasaki rose. The original design did not feature any thickness-accommodation elements.
In 2013, a team at Brigham Young University's Compliant Mechanism Research Lab used the Flasher pattern in a concept for an orbital solar array.
Origami expert Robert Lang authored the paper "Single Degree-of-Freedom Rigidly Foldable Cut Origami Flashers" in Journal of Mechanisms and Robotics with researchers from BYU in 2016.
This publication describes the parametric relationships which determine the angles of crease lines on the Flasher crease pattern, including variables for thickness-accommodation elements, most-notably ε.
Thickness accommodation was achieved by using a hinge-thickening method called Flexible Membrane Technique, which allowed for the creation of a high-fidelity physical model.
ε = 0°
ε = 4°
ε = 9°
The Flexible Membrane Technique widens gaps between panels, which reduces rigidity in the overall system and requires an additional ring structure to surround the model and apply forces from all sides.
The original origami model has single degree-of-freedom movement, so the thick-material solution for this model should not require this type of ring structure.
The geometry produced is a 2D crease pattern, and is somewhat limited to materials which behave like paper; taking creases and folding from a single large sheet.
To use thick and rigid materials such as wood or metal, the interactions of thick-material hinges and vertices must integrated into the same model.
Project Success Criteria
The Prototype Goal of the project is to make a physical model of a rigid thick-material origami Flasher that preserves the advantages of the thin paper model. Things like:
This Methodology Goal of the project is to make a process that determines geometry for functional models of the Flasher, so that this pattern could be used for a variety of applications with different parameter requirements. This process should be:
Compact face-to-face stowage & economy of space
Portability for remote energy collection
Single Degree-of-Freedom maneuverability between configurations
Center of mass for strong mountability
Energy collection on par with existing solar array models by area
Fully parametric process, taking material thickness and number of panel layers as input variables
Approachable process, enabling users without full understand of all origami engineering principles
I built physical models at every stage of the process. This helped me:
understand the existing research
build an intuition for panel interactions
make tangible examples of parameter changes
Digital Design & Parametric Modeling
I used digital modeling tools to specify, highlight, and track individual features of the Flasher pattern. The hexagonal rotational symmetry was utilized to divide the pattern into identical subgroups representative of the whole.
Integrating Thick-Material Hinge Geometry
I integrated Lang's model of 2D parametric Flasher crease pattern generation with thick hinge geometry models, treating the panels as 3D volumes instead of 2D flat shapes.
Algorithmic Modeling Software
I used Fusion 360 and Rhino/Grasshopper for 3D-modeling and ideation.
Large Scale Thick-Material Prototype
To show that all aspects of thickness accommodation have been addressed, I built a model from a completely thick-rigid material. This model is made from 1/4" (6.3mm) basswood, and opens and closes smoothly. Due to exclusively using the hinge-shift technique and using inherent parameters to calculate panel geometries, the model both retains effective single degree-of-freedom movement (openable by articulating a single hinge), and also optimally compact during stowage. This model also retained planarity of bottom hinges, as shown by the flat bottom on the right. There are 4 panel layers on this model, but this was only due to the limitations of feasibility of building the physical prototype: my thickness accommodation framework allows for an arbitrary number of panels to be stowed around the central polygon.
This is an ongoing project: I am currently developing the next iteration of digitally-fabricated high-fidelity prototype.
Future phases of the project will see the incorporation of real photovoltaic solar materials into the thick-material Flasher.