Carnegie Mellon ECE Capstone, Spring 2024: Twain Byrnes, Gary Bailey, Carson Swoveland
Between last and this status report, I helped with the comfortability survey. I also started to work on the final presentation poster and the final report.
My progress is on schedule. Next week, I will finish the final design report and poster before they are due.
This week, we acquired the final PCB, soldered all of the parts onto the board, and created the case for the watch so that it is wearable. We did more work on the firmware as well, adding the ability to load map data from the SD card on the fly. Aside from our design tasks, we also created our final presentation for next week.
We have no new risks that we are worried about, nor are there any changes we have made to the design of the system.
Between last and this status report, we got our final PCB layout, and I put solder paste onto the board and then used the pick and place machine to put all of the small pieces onto the board, as seen in the last attached picture. Additionally, I worked on the final presentation.
My progress is on schedule. Next week, I hope to finalize the watch and work on the final design report and poster.
Through this project, I have found myself needing to learn how to program in Rust better than I could before, and I used the Rust documentation and my friends who know Rust to learn it better. I learned more about designing hardware systems, which was mostly through my teammates, as well as some online resources. I also learned how to use the pick and place machine just this past week, which I figured out through the help of my teammates and a bit of experimentation. Throughout this project, I made much use of my human resources, ie friends of mine who had more experience than I did with the various aspects of my project, as well as online resources such as forums and videos online.
We have no new risks that we are worried about, nor are there any changes we have made to the design of the system.
We have run some tests on GPS location accuracy, walking around CMU campus in various conditions and testing to see how long it takes to get a lock and how accurate this lock is. For accuracy, we will compare Landhopper’s location fix against a known-good and known accurate position source, a U-Blox ZED-F9P (which we will borrow from Roboclub). The ZED provides very high-accuracy and high-precision RTK-GPS position fixes, accurate down to a few centimeters, so it is an ideal “ground truth” for comparison.
As for actual cases we will test, we want to experiment with various positions for the antenna on the wearer’s wrist to determine which results in the most accurate fix. Simultaneously, we hope to test the amount of battery taken to get a fix, as well as the amount used in typical usage by logging the battery levels along with each location store. We hope to be able to analyze both of these results in order to meet our use case requirements of a week-long hiking trip with high-fidelity tracking, by synthesizing the position data from Landhopper with the power consumption data and visualizing it with QGIS.
Through the course of the project, we have done much analysis to see what energy harvesting source we should use. Though we tried several times to figure out the best way to attach the piezo tiles to a metal band, they always popped off of the band when it was bent to the necessary curvature. We’ve gone through a few versions of the gearbox for the motor generator option, but all of them have either. At the current stage, we’re thinking of cutting our losses on the piezo option, but we’re still going to give the motor option one or two more iterations. If we get it to the point of generating any amount of useful power, we’ll definitely give it a proper comparison against the solar option by determining which harvests the most energy in both indoor and outdoor scenarios.
Solar harvesting is showing to be very fruitful so far: the 15mA we have achieved from full sunlight far outpaces the maximum power generation given in our referenced papers for the piezo and motor techniques (the most given was around 9mA). We will further test with different orientations and positions of the solar panel on the watch case (like with the antenna) to determine which results in the most power generation outdoors. We’ll visualize this data alongside the position and other parameters to make sure we’re meeting our planned requirements.
Between last and this status report, I helped with attaching more pieces to the circuit board, and I also soldered together resistors to be fine tuned for our energy harvesting purposes.
My progress is on schedule.
Next week, I hope to help with the firmware more.
This week was mostly all about firmware changes: we implemented the ability to switch between a watch face and a map on the screen using the buttons, and made more progress toward getting the SD card up and running.
We have no new risks that we are worried about, nor are there any changes we have made to the design of the system.
Between last and this status report, I helped with the firmware for the display.
My progress is on schedule.
Next week, I hope to finish up more of the integration between various parts so that the demo will be more impressive.
Between last and this status report, I worked on the PCB and attached all of the parts that we had that were needed for the PCB.
My progress is on schedule.
Next week, I hope to put in orders for more parts and start to work on more of the mechanical aspects of the watch.
This week we made the major step of finally ordering the first revision of our PCB, and we also made incremental progress on the firmware and energy harvesting components of our project. Firmware changes include a refactoring to improve communication with the GPS. On the energy harvesting front, we received our solar cells so began working to characterize them and compare them to to the piezoelectric and generator-based options.
We have no new risks which have arisen. There have been no changes made to the design of the system or to the schedule.
Between last and this status report, I ordered our PCB and have managed issues arising with the order. I also worked on some of the energy harvesting to see how best to create usable electricity from our sources.
My progress is on schedule.
Next week, I hope to put in orders for more parts and continue working on the energy harvesting.