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Open Source Cubesat Platform
for Heliogyro Deployment Testing
Authors: Artur Scholz (1,2), Jer-Nan Juang (1,3) Affiliation: (1) National Cheng Kung University, (2) LibreCube Initiative (3) National Institute of Aerospace Venue: The Fourth International Symposium on Solar Sailing 2017 Location: Kyoto, Japan Date: Tuesday, 17th January 2017, 12:15-12:30
Credits: U.S. Centennial of Flight Commission
Credits: NASA Langley
Solar Sail Concepts
Credits: Wikipedia
NASA HELIOS project
Project lead at NASA Langley Research Center
HELIOS is precursor for future heliogyro missions
Based on a previous MIT study, but uses miniaturized (CubeSat) technologies
Accomplishments: Coupled FEM modal analysis Blade controller design and analysis Modal tests in vacuum chamber Sail fabrication (preliminary)
Sail Deployment
Most recent research on heliogyro focuses on sail control. Need more attention on deployment, it is most vital for mission success. Examples of heliogyro sail deployments:
1967 MacNeal
2013 Janhunen
1990 Blomquist
Deployment Process
Deployment process of Heliogyro is particularly demanding: Sail packaging and fixation
Satellite detumbling
Satellite spin-up
Sail deployment
Sail control
Credits: NASA
Research Topics
Deployment experiment design must focus on: Sail blades
Deployment mechanism
Deployment monitoring
Avionic system
Credits: NASA
Our Proposal
Open Source / Open Research
CubeSat Platform
Open Hardware
LibreCube is a non-profit organization to enable and support:
Community for exchange and collaboration of open
source CubeSat projects
Standardization to ensure compatibility and facilitate collaboration
Reference architecture for a generic CubeSat missions
Open and free tools for mission design and operation
Open Software
Modeling and simulation of all aspects of HelioGyro deployment and control shall make use of freely available and open source software. Makes it possible for anyone to reproduce the results and to contribute The simulation ecosystem is based on the Python programming language and its many scientific libraries:
• Matplotlib – plotting • Numpy – numerical processing • SciPy – scientific computing • SimPy – algebraic computation, incl. Lagrangian/Kane’s method • etc.
Preliminary Research Results
Description of the forces maintaining a gravity gradient stability
https://en.wikipedia.org/wiki/Space_tether
θ
r
Simulation I: Zero Tension
• Zero tension
• Equations of motion
Pelaez, J. (1995). On the Dynamics of the Deployment of a Tether From an Orbiter-Part II. Exponential Deployment. Acta Astronautica, Vol. 36, No.6, Elsevier Science, Ltd
Non-dimensional Angle and Angular Velocity
Non-dimensional time τ
Angular Velocity
Time (sec)
RPM
Angle
Time (sec)
deg
Non-dimensional Deployed Length
Non-dimensional time τ
Deployed Length
Time (sec.)
Initial/ejection velocity: 1 m/sec Initial length: 1 m m
Non-dimensional Tension
Non-dimensional time τ
Conclusion
• Heliogyro has low technological readiness level (TRL)
• Propose research in Open sharing Properly acknowledge contributions
• Rely on open source hardware and software
• Initial research results provide confidence on sail
deployment from spinning CubeSat
Thanks for Your Attention!
Q & A
Position Vector
• The center of mass of the cubesat will be taken as the origin O; the x axis lies in the local vertical and points to the zenith; the y axis lies in the tangent to the trajectory, and the z axis is normal to the orbital plane.
• From the circular motion of the cubesat follows the constant angular velocity of the cubesat frame relative to a geocentric inertial frame:
• Position vector of the end mass in terms of the body polar
coordinates (r, θ) is
Lagrange’s Equations of Motion
• Potential energy with the end mass m
• Kinetic energy with hub + end mass m
• Lagrangian • Lagrange’s equations
Equations of Motion
• Keep up to the second-order terms • Equation of motion for the string
• Equation of motion for the angle
Non-Dimensional Equations of Motion
Non-dimensional parameters Equation of motion for the string Equation of motion for the angle
Deployment Design Process
• Define an equation to describe the deployed length in time:
satisfying the initial condition
• Solve the following equations of motion
• Compute the non-dimensional tension force
• Search for a deployment equation that provides a stable deployment trajectory and minimizes the vibrational motion of string.