Integrated System Build & Test
Table of Contents
Team Vision for Integrated System Build & Test Phase
- Manufacturing (Paul, Anthony, Rob)
- Machining Rails Succeeded!
- Outsourcing Ultem through Free Program and Stratasys Succeeded!
- Building Boilerplate Solar Cells and Test Mass Succeeded!
- Begin Testing(Tristian, Anthony, Rob)
- Fit II
- Bench Deployment II Succeeded!
- Full System Creep
- Time to Remove
- Resolve HAB Flight Opportunity Succeeded!
- Apply to Conferences Succeeded!
- Finish ImagineRIT Application Succeeded!
Prototype IIIIn this phase, a new prototype was built. This prototype represents the most recent 3-D printed design changes. This prototype also, for the first time, includes machined aluminum rails - a requirement for the final CubeSat. This prototype includes a mass analog as well, which will be necessary for later vibration testing. The plastic used in this version is still ABS as the new Ultem parts have not yet arrived. This prototype is useful for new fit and deployment tests that do not require Ultem.
Assembly ProcessThe new prototype was assembled in a more streamlined manner than the previous prototype. The key to assembly was assembling the hot plate - NiChrome - restraining line structure before attaching the subsystem to the rest of the CubeSat. We found this to be much easier than assembling those components while the restraining line was tensioned to the deployable side panels.
Ultem PrintingWe recently reached out to Stratasys to get a status update. According to their distributor, our parts are being processed now, and should arrive over spring break. When we receive the parts, final assembly will begin.
Mass AnalogFor P16103's vibration test to be as informative as possible to us, our CubeSat requires an internal mass analog. This will simulate the mass of all the internal components. We created an analog by 3-D printing a structure that fits within our CubeSat structure. The internal structure had a cylinder drilled out of it and a metal cylinder inserted to increase overall mass. The target mass for an internal of this nature is 950g but due to the relatively unknown mass of the fasteners that we will use, this number has some leeway. The internal we manufactured has a mass of 735g. This discrepancy leaves room for fasteners to come in heavier than expected. If when the design and fasteners are finalized and the internal mass is still too low, more mass can be added by packing the internal with sawdust.
Hot PlateUpon initial testing of our full CubeSat deployment system, we encountered some issues with the design of the wire path. Several deployment failures were caused by the retention line being pinched by tight corners in its path. In response to this issue, we redesigned the wire path to remove all tight corners, and chose a thinner fishing line that was less rigid.
Deployable Backer PanelWhen we attempted to prepare for the deployment testing, we had some difficulty assembling the retention line onto the deployable panels. To improve this aspect of our design, we integrated small indents to accommodate the retention line knot more easily.
Test Results Summary
Table Top Deploy IILast phase, we tested a table top deployment of the CubeSat. In that test, it was revealed that the restraining line became stuck in its routing path and wouldn't always come lose when cut. As a result, design changes to the routing path were made, as detailed in the previous phase's edge page. During the current phase, a new table top deployment rest was run to see if the design changes were effective in allowing reliable deployment. This test involves deploying a prototype CubeSat in a lab ambient setting. The NiChrome hot knife's ability to cut the restraining line, the springs' ability to deploy the panels and the ability of one hot knife cut to free both panels were all tested. ER5 - Time from command to deploy, is tested.
Videos of Test
- Changes made from the last phase loosened the routing path's grip on the restraining line but still did not allow for full deployment with the fishing line we are currently using.
- There was found to be friction between the standoffs on the hot plate and a reinforcing lip on the deployable backer panel.
- A thinner, more flexible fishing line was used in a second test and in that instance, the CubeSat deployed perfectly.
- During assembly with the thinner fishing line, the line broke at one point.
- It was observed to be very difficult to tension the restraining line after it had been tied in place.
- The knot made in the restraining line protrudes too much in its current location.
- The successful deployment when using thinner fishing line leads us to use a line with smaller diameter. As was seen while assembling the thinner fishing line, thinner lines can break more easily. Becuase of this, we will be looking for a fishing line between the weak .23mm diameter line and the thick .71mm diameter line.
- More room should be given in the wire path so that the new fishing line is less likely to get stuck.
- The geometry of the support lip on the deployable backer panel needs to be changed to prevent interference with the standoffs.
- The deployable backer panel should have a notch that the restraining line knot can be pulled into to allow the line to be better tensioned and to give the knot somewhere to go that is out of the way.
Risk and Problem TrackingThe highest priority risk we were addressing this phase was the potential failure of the solar panels to deploy. Table Top Deploy Test II, which was run with minor design changes from Table Top Deploy Test I, showed a deployment mechanism that was improved but still not reliable. As a result, as detailed above, several more design changes were made. A test of this new system will be required before the likelihood of a failed deployment decreases. All other risks have remained at largely the same level over the past phase.
As we have progressed through this phase, our status on several problems has progressed. We have recieved confirmation from Stratasys that we can get free printed Ultem from them. We have machined a pin for use in the deployment sensor. We have also experienced a second semi-failed deployment test. In addition, many ordinary risks have been delt with, as cataloged below.
Bill of MaterialsBelow is our current Bill of Materials. The BOM has been updated to reflect the aquisition of new, thinner fishing line for use with the hot knife. It also reflects Stratasys's assurance that we will receive free Ultem parts from them.
Imagine RITIn order to make sure we were staying on track to complete our final goals, we began to really look ahead to the Imagine RIT presentation this phase. This mainly included beginning to work on a poster.
PosterBelow is our progress on the poster so far. Much of it is template material and even what we put in ourselves is subject to change over the coming weeks. We will work off of this design from now until Imagine.
Plans for next phase
- Finish Fabrication
- Integrate Ultem Parts
- Rebuild Rails
- Rebuild system as necessary
- Fit Test II
- Full System Creep
- Time to Remove
- Finish ImagineRIT
- Order backup parts
- Reorder Ultem as necessary