Subsystem Build & Test
Table of Contents
Team Vision for Subsystem Level Build & Test PhaseSummarize:
- What did your team plan to do during this phase?
- What did your team actually accomplish during this phase?
Manufacturing and Assembly:
- Machining and CubeSat frame
- Electronics and sensors
- Solar sail folding
- Graphical User Interface (GUI for Imagine RIT)
- Ice Rink
Tests and Results:
- Boom tests (including experimental booms)
- Deployment tests
- Ice rink deployment tests (including videos and sensor data)
Test Results Summary
Summarize test results and assess effectiveness of test plans to unambiguously demonstrate satisfaction of the engineering requirements
Boom TestsIn the Detailed Design phase last semester, we discussed problems found with the stiffness of the deployment booms. There were two possible shapes that could be used to strengthen the booms - two booms face to face, or two booms joined along one edge.
In the beginning of this phase, we tried to create stronger booms by taping them together in these two configurations. We tried both taping in 4' intervals and continuously taping the booms together with electrical tape. Both shapes were stronger than a single boom, but kinked when we tried to roll them. Because one boom is being rolled at a slightly smaller radius than the other, an 'inchworming' effect happens where the boom on the inside slowly starts to inch forward. With tape every few inches to keep the booms together, the inner boom folds over on itself and kinks. This phenomenon happened with both configurations and in all of our trials.
Other solar sailing cubesats use similar booms for deployment, so we reached out to our contacts at NASA to find out more about the booms they use. We were put in contact with Nexolve who makes the booms for NEA Scout and they sent us a 6' sample to work with for testing and examination. The boom is the same shape that we tested earlier - two long curved sections bound together along one edge. The TRAC boom section rolls easily and is much stronger than our current booms. They were manufactured by laser welding the two pieces together and then heat treating them.
After some welding tests performed by Gary, we have determined that manufacturing our own version of these booms is outside of our capability. We will be getting a quote for the length that we would need and speccing them out for SPEX to purchase in the future.
GUI TestRaspberry pi can be connnected to RIT network. Displays deployment status, has start and stop options. Can add values for PID controller and displays control system output.
Ice Rink Test
In order to test in conditions as close to space as possible, we moved our test from the MSD floor to a home-made ice rink in Jarett's backyard. The ice rink has plywood walls and a large plastic sheet to keep water in place. A 6" PVC tube was frozen into the center of the rink for us to place the cubesat into. This allowed the booms to be level with the ice and slide smoothly out.
ICE RINK CONSTRUCTION PICS?
Our first attempt at testing was on the morning of Saturday 2/15. The ice was perfect for testing, but the wind was too strong and tore a few of the sails when we tried to unroll them.
A second attempt was made a week later on the night of Thursday 2/20 when the wind was calm and the ice was still good. We set up two floodlights and a ladder to hold a phone recording a timelapse of the test.
PIC OF SETUP
In the first test, the sail was packed too tightly in some places, so the sail spindle had a large amount of friction holding it back from freely spinning. This caused the booms to 'bloom' in the reel instead of deploying. A wind of gust halfway through the test also pick up two of the sails and threw them over the cubesat.
In the next test, we kept 1/4" clear of sails on each end of the spindle and it was able to spin freely. In this test, we experienced problems with the sail catching on the corners of the rails while unwinding. The booms were not strong enough to pull the sails past this, so they began to bloom in the reel again. We were able to stop the wind from blowing the sails around by weighing them down with light wooden blocks. Once we helped the cubesat through the first part of deployment, there was a good middle section of smooth deployment with good sensor readings.
We ran one last test without the sail to get good sensor data and prove that the booms work. This test ran smoothly until about 4" from the end where the booms were badly kinked from the previous test.
Risk and Problem Tracking
Functional Demo MaterialsPresentation Slides
Plans for next phaseGantt Chart:
Individual Team Member 3-week plans:
- Amber 3-week plan document
- James 3-week plan document
- Sarah 3-week plan document
- Charlie 3-week plan document
- Jarrett 3-week plan document
Plans for what will be demonstrated at the next phase, Integrated Systems Demo:
- ADACS single axis reaction wheel within CubeSat
- Raspberry Pi GUI with PID control of reaction wheel
- Redesigned sail deployment compartment
- Completed Imagine RIT prototype (includes the electronics and structure)