High-Level Project Summary
In this project "Let it go - without a bang" we have developed an electric gear-driven threaded coupler. We have developed a repeatable coupling/uncoupling process, through the use of an externally threaded gear driven by a planetary gear system. This solves the challenge through the use of mechatronics over explosive charges and ensures the process can be repeated with consistency. This is important because it will allow for an easier reset of the coupler and does not require the replacement of a charge after each use. This will reduce costs, space debris, lead-time, and reduce safety concerns.
Link to Project "Demo"
Link to Final Project
Detailed Project Description
What does it do?
Our coupler has a self-contained externally threaded gear. The threaded gear is driven by a planetary gear arrangement located internally in the shaft. This arrangement is powered using a low-wattage motor. The threaded gear shaft will thread into the opposite housing of the coupler when spun in one direction and unthread when spun in the other. An internal spring will help to push the coupler apart for complete separation when unthreaded. The gear and shaft system will be fixed within the housing of the coupler to prevent direct contact with the system. The estimated system weight is less than 0.420 kg (solid cylinder of tungsten), the maximum system dimensions when coupled are shown in the figure below.
How does it work?
This system is powered through a small motor. The motor turns the internal sun gear of the planetary gear arrangement. By locking the planetary gears they act as idlers and spin the external ring gear. The external ring gear is threaded to mate with the male housing as shown in the figure below.
Using torque to drive the gear system both sides of the couple are pulled together or pushed apart. Once unthreaded the compressed spring will expand and push on the male housing for a smooth release.
The power screw was design to withstand the 4000lbs launch load. A preliminary heating system was also included to deal with the vast range of temperature difference. More details can be found in the linked report.
What benefits does it have?
The benefits of this coupler include: re-testable, re-settable, reduction in shock to the spacecraft, reduction in space debris, and can be calibrated to work with multiple couplers for a timed release.
What do you hope to achieve?
We hope to achieve the successful design and mechanical function of our coupler while meeting the specifications required by this challenge. We have achieved "without a bang" in this design and have provided a system that can easily be set and reset for each flight. This system can be assembled with medium difficulty and is easy to interpret its mechanical functionality.
In this project we have used many tools to achieve a successful design, namely SolidWorks for the 3D design of the mechanical system, this has allowed us to visualize and refine physical properties and mechanical specifications. A number of data resources (spec. charts) and quantitative research have been valuable tools used to give us clear theory into concepts and ideas involving interspace mechanics and systems. Education in Mechanical Engineering and Engineering Technologies has provided the knowledge to deal with complex theory, problem-solving, mathematics, and many other engineering aspects faced in this challenge.
Space Agency Data
Throughout this project, we have gathered info regarding NASA spacecraft couplers and release mechanisms. During the space apps presentations, some information was given to teams to base their projects on. This data and info was noted and used to ensure mechanical and physical specifications were met.
Hackathon Journey
Our Space Apps experience has been excellent overall. Diving into a space-related problem posed many fun and interesting challenges for our team, alongside the great resources from Space Apps and NASA we have learned that there is a multitude of solutions for any given problem, and viewing them from different perspectives will allow for more efficient and effective problem-solving. We have also learned to consider the complexity of space travel upon mechanical systems and components, adapting equations and specifications to ensure proper functionality within extreme temperatures, forces, and the vacuum of space.
Our team Space Cats was inspired to choose this challenge by our personal interest in developing interesting, unique, and functional mechanical systems. Our team is also inspired to challenge our own field of knowledge in Engineering and Mechanics through higher level problems and problem specific applications. NASA has been an inspiration to all of our team members throughout our lives by showing the world what we can achieve through science and technology as well as the many programs, clubs, and events funded by NASA to stimulate and developed young Engineers and Scientists.
When approaching this challenge our team chose to develop a piece of hardware (Coupler) based on our extensive knowledge of Mechatronics, Mechanical System Design, and Material Properties. We first decided to theorize a mechanical coupler able to be set and reset easily while being able to withstand the launch forces specified without releasing. Once theorized, 3D design and revision began to determine size and weight constraints.
During the project many calculations were made and reworked based on many factors, many things such as the shear force of the gear teeth and the required torque to turn the threaded shaft were calculated and used to revise specifications and design aspects Once our mechanical design was complete and calculations confirmed, the functionality of the system was scrutinized for potential issues and failures to ensure the reliability of the Gear-Driven Threaded Coupler.
References
[1] A. Sexton, C. Dayton, R. Wendland & J. Pellicciotti, Design Development and Testing of the GMI Launch Locks, NASA. Available:
https://ntrs.nasa.gov/api/citations/20110016488/downloads/20110016488.pdf
[2] M.H.Lucy, R.C.Hardy, E.H.Kist, Jr., J.J.Watson & Dr. S.A.Wise, Report on Alternatives to Pyrotechnics on Spacecraft, NASA, 1996. Available:
https://ntrs.nasa.gov/api/citations/19960054342/downloads/19960054342.pdf
[3] R. Budynas, J. Nisbett, Shigley’s Mechanical Engineering Design, 9th edition, 2011.
[4] Tungsten material properties, MatWEB, 2019. Available: http://www.matweb.com/
[5] Gear Systems (Planetary Gears), KHK Stock Gears, 2021. Available:
https://khkgears.net/new/gear_knowledge/gear_technical_reference/gear_systems.html
[6] Nickel Chromium Alloy Material Properties, MatWEB, 2019. Available: http://www.matweb.com/search/datasheet.aspx?matguid=5bdf5ed4c6a44b1ca35416de78af6eef
[7] PG15S-J20-HHF3 (Stepper motor datasheet), digikey, 2021. Available:
https://media.digikey.com/pdf/Data%20Sheets/NMB-MAT/PG15S-J20-HHF3.pdf
[8] D. Randell, Controlling Precision Stepper motors in Flight using (Almost) no Parts, NASA, 2016. Available:
https://trs.jpl.nasa.gov/bitstream/handle/2014/45312/09-4848_A1b.pdf?sequence=1
[9] Wire Heating Element Materials, Heating Element Alloy’s, 2015. Available: https://www.heating-element-alloy.com/article/wire-heating-element-materials.html
[10] Thermal Systems - Mars Reconnaissance Orbiter, NASA. Available: https://mars.nasa.gov/mro/mission/spacecraft/parts/thermal/
Tags
#coupler, #mechanical, #blastoff, #spaceapps, #pyrotechnics, #withoutAbang, #spaceDebris, #spring, #gear, #planetaryGear
Global Judging
This project has been submitted for consideration during the Judging process.