Table of Contents
MSD I: Readiness to move to Build & Test
Individual plans for the first 3 weeks of MSDII for each team member can be found here
Status ReviewMechanical / System Design Summary Final State:
The prototype design at the end of MSDI remains at 90% CAD completion, minor changes are still required. The overall design of the prototype has been decided on, but work still needs to be done on clamp designs. It was expected that the design portion would not be completed by the end of MSDI, so we are still on track.
For the mechanical system design we planned to have a nearly completed model of our prototype and clamps completed by the end of MSDI. We also wanted to do analysis on different materials in order to choose the best materials for our structure. Additionally, the plan was to ensure the overall design would be user friendly and be simple to set up and run.
At this point, these goals have been met. The current design is robust and satisfies our customer’s requirements. One area still in progress is the clamp design, creating a simple, effective clamp which will be able to hold the coupon secure. The cost of making the parts has not been evaluated but with the current parts purchased for prototype work, we have not exceeded the budget.
Electrical / Controls Summary Final State:
The goal for MSD1 with respect to the electrical/control systems was to prove that magnetic levitation is feasible. We have been able to levitate objects, thus the levitation portion of the project is feasible while staying well within budget. This was done through researching previous projects and trying to replicate results. The more difficult task is to create a stable levitation system. The difficulty and complexity of this task revealed itself once we were able to levitate.
The project has been proposed in such a way that levitation is useless unless the levitation is extremely stable. The current levitation system is unstable, so the use of subject matter experts will be required moving forward for the aid in creating a stable levitation system. This being said, the hardware and control scheme of the system could change drastically. The consultation of subject matter experts will be done as soon as possible in MSDII (Depending on the availability of the SME).
In addition to consulting subject matter experts to create a deployable system model, experimentation with additional sensors integrated into the control system will be conducted. Additional sensors may help to mitigate some of the system error. In particular, the addition of a second hall-effect sensor above the electromagnetic coil may allow for isolation of the magnetic field from the coil. This would greatly reduce the error involved with sensing the position of the target within our test fixture. These tests will be conducted at the beginning of MSDII.
Also for the final state there will have to be some sort of data acquisition module or system embedded within the system controller. This will allow for real time data logging of proximity data obtained from the cap sensor used to measure the CTE. This data logging will allow the customer to view a plot of the cap sensor data, encompassing the entire duration of the test which would effectively display the CTE of the sample material.
MSDI was successful with regards to proving that levitation is feasible, it also was very successful in the sense of, we know what problems we are going to need to tackle for MSDII. We know that there are some fundamental problems between simulations and hardware. We also know we have hardware implementation hurdles that we will want to take care of in MSDII.
Status From Client:
- Update from DDR
- As a group we must consider lead times for
- Solution: Determine essential components needed for purchase during week 1 of MSDII and document specific lead times for those components. For long lead times, alternative vendors will be chosen.
- Evaluate the possibility of performing a
“deflection” based error analysis.
- Solution: Run tests comparing results to total deflection of coupon sample. This can isolate certain sensitivities and allow us to evaluate which sensitivities affect our deflection results most.
- Once final cap sensor is selected, ensure tech sheet information is accurate for error analysis.
- While performing tests, graph out each plot (test
1, test 2 etc..). This will provide a comparison of
each trial and show our progression. Add error bars!
- Note: Harris asked to see “expectation” plots for analysis.
- Check thermal analysis boundary conditions.
- Solution: Our thermal results appear to be inaccurate. This is simply because of the boundary conditions applied to the simulation. New boundary conditions will be implemented and new tests will be performed to fix this problem.
- Continue researching multiple clamp designs that will account for varying coupon thicknesses.
- Harris has asked for a summary of our DDR. They would like 4-5 slides to pass around the group and have other engineers review our progress. This will also provide our team with additional insight and possible solutions to current issues.
- As a group we must consider lead times for essential purchases.
- Overall, Harris was very pleased, even impressed, with our DDR. We had addressed every concern/issue mentioned at each review and made sure to update our client on any missed details. Our DDR was a success and we are satisfied with progress made in MSDI.
- Our Main Goals for MSDI:
- Evaluate and test magnetic levitation - COMPLETE
- Quantify error sensitivities - COMPLETE
- Create a structured housing for our system design - COMPLETE
- Evaluate materials for our structure - COMPLETE
- Run thermal analysis - COMPLETE
- We have left MSDI with great progress. Our plans and path forward into MSDII are clear and laid out within our edge page. We hope to have an easy transition once the Fall semester begins.
Overall System Design:
At the end of MSD I, the prototype design remains at 90% completion. The final 10% will come from updated clamp designs and finalizing dimensions of components.
Next steps to reach design completion:
- Design a more secure clamp
- Finalize dimensions of final design
- Verify material selection
- Create box to store electrical components (i.e Arduino)
Steps for final prototype:
- Machine prototype parts (Top plate, base plate, slot, shroud, rods, clamp)
- Test fitment of parts
- Begin testing
- Optimize design - see if overall design can be made smaller
- Upgrade components (sensors) to the best our budget can buy
Steps for Clamps:
- Print 3D prototype
- Scale to full size and make out of metal
- Make corrections as necessary
Electrical DesignSystem Architecture
- Control System
- Key Components- Arduino, Matlab/Simulink
- Key Focus Area- Creating a stable control system
- Control system can levitate an object but it is not stable
- Control system currently drives a PWM signal, which doesn’t correspond well with simulations
- Reasonable gain values are difficult to determine
- Creating a control system that will be stable enough for our needs.
- Will our max sample rate using the Arduino be fast enough
- Is creating a stable system feasible when it’s driven by PWM?
- Electrical hardware implementation
- Key Components- Hall sensor, Electromagnet, MOSFET, Power source
- Key Focus Area- Movement away from a PWM driven system
- The hardware is currently set up to vary current, while the simulations vary voltage
- Will the current hardware design change significantly if the control structure is changed?
Electrical System Design
- Control system, the Arduino implements the control system created in Simulink
- Electrical Hardware, the MOSFET is what drives current to the magnet
- Power input, The system requires power supplies for the MOSTFET as well as power supplies for the sensors
- Electromagnet, this drives the whole levitation system
Top level pseudocode:
- At the highest level the control system tries to keep the levitating object at a fixed position
- If the object falls too far from the magnet, the PWM increases
- If the object gets too close to the magnet, the PWM decreases
Bill of Material (BOM)here.
Problem Solving Process
Link to the live document here.
Team Shared End State VisionBest Case Scenario:
Team will demonstrate our fully working prototype with results fully backed by an in depth error analysis. The prototype will be able to measure CTE of 1 high expansion and 1 low expansion material. A BOM will be handed off telling Harris what components are needed to reach the specified accuracy they desire. Instructions for using the system, how to build and test will also be provided. Overall, this best case scenario will leave Harris pleased with the end result with all our goals and requirements met. Harris will be able to buy the high end components, file the patent and begin utilizing their new CTE tester.
Moderate Case Scenario:
Working prototype is demonstrated but error analysis has not quantified every source of error. This means that our prototype demonstrates the MagLev feasibility and is able to obtain measurements for CTE however, we can only speculate the complete error within our measurement. A plan of action for how error analysis can be carried out can still be provided. Supporting documentation such as usage instructions may or may not be provided. Suggestions for upgraded components would still be provided to Harris, but the final error analysis may not be useful to Harris due to the high degree of uncertainty. In this case, Harris would most likely be displeased and lack of effort from our team would be apparent. Since this moderate case leaves Harris with an incomplete project, there is potential for another MSD team to finish this project as a continuation.
Worse Case Scenario:
No working prototype is produced, no error analysis or it is not near completion and we do not list suggestions for upgraded components. Overall, Harris is disappointed, we make our guide look bad, and we look bad as engineers. Our reputation as well as the reputation of RIT is negatively impacted. If project is continued by another MSD team, they may need to start over completely due to a lack of useful documentation from our part.
Review of MSD II schedule
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