Table of Contents
Team Vision for Detailed Design PhaseTeam's Vision
- Finalize Bill of Materials
- Finalize Schematics
- Finalize Test Plans
- Create a plan for MSD II
- Start PCB Design
- Finalized Bill of Materials
- Finalized Schematics for Node 1, 2, Main Node
- Finalized test plans
- Created a plan for MSD II
- Tested strain gauge amplifier circuit and proved concept
- Read/write to an SD card
- Simulated voltage regular and proved concept
Since our preliminary detailed design review, we have done more lab testing and analysis. Our primary focus has been on the strain gauge amplifier circuit. Recently, we put together an amplifier circuit using analog discovery OP-27 and used only fixed resistors in the strain gauge bridge. We were able to confirm the measured gain was correct through calculations. In addition to the strain gauge circuit, we received the SD breakout board and successfully were able to read and write to an SD card.
Over Thanksgiving break, we plan to do additional research on amplification circuits for quarter bridge strain gauges and do PSpice simulations. Edge will be updated with any changes to the customer and engineering requirements, function decomposition, and the team’s vision for this phase. Additional research will be done for the enclosure to come up with a solution on what will be able to house all of our components and still meet the size requirements. Lastly, we plan to finalize the schematic for Node 1 so we can proceed with the PCB design.
When we come back from break, we plan to go to the lab to test our amplifier circuit with actual strain gauges to confirm it will work. Once we determine the amplifier circuit will work, the schematic for Node 2 will be finalized and the PCB design can be finished. The bill of material will be updated with all the components needed to make the final prototype, the risk assessment will be updated with any new risks, the test plans will be updated based off of any new engineering requirements and tests that have been executed, and a schedule for MSD II will be made.
Prototyping, Engineering Analysis, Simulation
Quarter Bridge Strain Gauge Amplifier
Beginning stage using a basic Op-amp:
After further analysis and research, an instrumentation amplifier was analyzed and tested:
When testing the strain gauge in the lab, the resistance was measured to be 350.6ohms. After further research, National Instruments said to perform three wire measurements to eliminate the resistance in the wires. New simulations were performed.
To fully utilize the ADC in the MBed, the output of the instrumentation amplifier is fed into a non-inverting op-amp.
SD Card Read/Write
Drawings, Schematics, Flow Charts, Simulations
The live Full System Flowchart document can be found here.
Updated Customer Requirements
The live Customer Requirements document can be found here.
Updated Engineering Requirements
The live Engineering Requirements document can be found here.
Updated Functional Decomposition
Main Node Schematic
Node 1 Schematic
Node 2 Schematic
Bill of Material (BOM)
The live Bill of Materials can be found here.
The live Test Plans document can be found here.
ER1 Test PlanThe goal of this test is to confirm data can be collected from the hall effect sensors at the required sampling rate of 100Hz.
ER2 Test PlanThe goal of this test is to confirm data can be collected from the strain gauges at the required sampling rate of 500Hz.
ER3 Test PlanThe goal of this test is to confirm temperature readings from a thermocouple can be obtained at the desired rate of 1 Hz.
ER5 Test PlanThe goal of this test is to confirm data can be saved onto an SD Card
ER6 Test PlanThe goal of this test is to confirm data can be Transferred via CAN (Controller Area Network)
ER8 Test Plan
The goal of this test is to make sure IP standards will be met for the connectors. A male to female pair will be mated, submerged in a container of water for five minutes. Once the time is up, the connectors will be removed and validated no water is inside.
ER9 Test Plan
The goal of this test is to make sure IP standards will be met for the enclosure. The enclosure will be submerged in water for thirty minutes. Once the time is up, the enclosure will be removed from the water and validate no water got into the enclosure.
ER16 Test PlanThe goal of this test is to ensure data can be pulled from the SD Card using the MBed via a cable to confirm data can be removed from the node without opening the enclosure
Risk AssessmentThe latest risk's for the project.
The live Risk Assessment document can be found here.
Plans for MSD II
The live schedule can be found here.