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Carson’s Status Report for March 16th, 2024

Progress

This week I helped write some of the asynchronous backend code for the firmware (along with Gary) and did some preliminary energy harvesting tests with the solar panel. For the energy harvesting, I did some measurements of the solar panel to see if it would be viable. We purchased a solar panel small enough to fit on the band of the watch (23mm x 25mm) and tested it outside with a variety of resistances to find the optimal range for power output. Unfortunately, the weather was changing too quickly to do a complete test, but all measurements showed at least 5mW of power output, and one showed above 15mW. These numbers are incredibly high, and give us a considerable margin for losses should we decide to use a panel. To further test this idea, I built the ADP5090-based boost converter circuit and used it to power an LED. Simply pointing my phone’s flashlight at the solar panel from ~10cm away was enough to power the LED intermittently. This was very impressive. Again, I will need to do more thorough tests in the future, but this is a promising power source.

Pacing

This week I would’ve liked to get some more quantitative measurements of more sources, but I was very busy with other obligations. Next week I don’t have much to be working on, so I should be able to catch up on the testing.

Planning

Next week, I will:

  • Finish the measurements of the motor system
  • Finish the measurements of the piezoelectric system
  • Determine how efficiently the ADP5090 can charge the battery
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Gary’s Progress Report for 16 Mar 2024

Progress

This week, I mainly focused on improving and refactoring our existing firmware code. The core of this was additional improvements to the serial handler: as it’s the only communication channel with the GPS, I want to make sure that channel is as simple reliable as possible. I had several frustrations with the implementation of the channels implementation we previously used for the UART communication… the most severe of these was the fact that it provided no way of “pending” (triggering) the UART interrupt handler while writing a buffer, which is necessary in order to actually get the chip’s UART to transmit from the buffer. To solve this, I worked with Carson to totally re-implement the ring buffer-based channels that are used to communicate between the UART handler and the GPS task. The new implementation provides a clean asynchronous interface to the channel which allows me to move more of my lower-level boilerplate logic out of the main code.

Pacing

I’m a little behind now, since I was planning to start on the mapping this week. However, with the overall codebase improvements I made this week I think that task should go smoother now.

Planning

Next week I plan to finally take my first stab at the map interface, and also to work on improving the firmware’s date/time handling.

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Team Status Report for 16 March 2024

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.

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Twain’s Status Report for 16 March 2024

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.

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Gary’s Status Report for 9 March 2024

Progress

Over the past 2 weeks, I’ve made a huge amount of progress on the firmware. I created a proper watch UI which displays the time and location, and I did a very rough preliminary test to see how quickly the device acquires a GPS fix after a cold start: in my testing, it was around 10-20 seconds, which is even better than the datasheet claims. After doing that, I implemented a proper buffering solution for the serial data, and expanded the capabilities of the GPS configuration system by rewriting the packet generator.

Pacing

I’m around on schedule for my tasks. Our original schedule had me not really working on the firmware for a little while after getting it to the state it’s at, but I enjoy adding features so I will probably work ahead while also working on the originally planned tasks.

Planning

This upcoming week, I plan to work with Carson and Twain to ensure that our PCB design is finalized and ordered, and then to start on the minimal street map that we plan to have displayed.

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Carson’s Status Update for March 9th, 2024

Progress

This week, I finalized the layout for the prototype version of our PCB, and made a more functional prototype of the gearbox for the kinetic energy harvesting. The gearbox does spin and has minimal friction. However, the gear ratio is too high, so too much force is required to get the motor to start spinning. This means that even after attaching external weights, the motor would not spin when swung. Fortunately, the design is parametric, so I can experiment with less aggressive gear ratios, which will make it easier for the weight to turn the motor. Just spinning it a quarter-rotation by hand fairly slowly, I could already get 2 volts, so there is plenty of margin to make the gear ratio lower. We only need about 600mV for the energy harvesting to work.

Pacing

This PCB should have been ordered over Spring Break, but unfortunately there were several difficulties with part selection, having to create custom symbols and footprints, and having to learn how to do impedance control on a trace. Fortunately we can still do our testing on a breadboard; I will focus on getting efficiency from the energy harvesting while the board is being manufactured.

Planning

Next week, I need to:

  • Get a gearbox that spins under its own weight
  • Measure performance numbers for the energy harvesting strategies
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Team Status Report for 09 March 2024

The main risk that we see right now is the PCB not working well for our project, which is being managed by putting in this order early enough that we can edit the design and get another PCB when we see what we don’t like about this design.

There have been no changes made to the design of the system or to the schedule.

A was written by Carson Swoveland, B was written by Twain Byrnes, and C was written by Gary Bailey.

Part A: Our product can work in a variety of environments around the globe. It can track location anywhere around the world with an open sky by using satellites from several different countries (GPS, GLONASS, Galileo, and BeiDou). In addition, the lack of any emitted signals means that it can still be used even in countries with more stringent requirements on radio spectrum use. Areas with limited or unreliable power infrastructure can still be served using the energy harvesting functionality.

Part B: Our product solution meets cultural needs surrounding privacy and data control. In cultures such as American culture, where a strong emphasis is placed on individual autonomy, the watch becomes a valuable tool that aligns with these cultural values. Our watch meets these needs by storing all data locally on the device. This feature directly caters to cultural preferences that prioritize autonomy and control over one’s information. Users from such cultural backgrounds may be more inclined to adopt a tracking device that respects and aligns with their cultural values of safeguarding personal data.

Furthermore, this local storage prevents real-time tracking and cloud-based sharing, aligning with cultural norms that prioritize the privacy. Landhopper meets this cultural need by offering a tracking solution that is not only functional, but also respects and aligns with the cultural values of privacy, autonomy, and control over personal information.

Part C: Due to the fact that Landhopper has an on-board energy harvesting system, the environmental impact of continuously using it is minimal: no external power input is needed to keep it operational for long stretches of time. In terms of the manufacturing process, Landhopper is as environmentally-friendly as electronics can be. In our prototypes, we have taken care to use the least toxic resources possible, such as lead-free solder for the circuitry and PLA for the case. While it is inevitable that there are negative environmental impacts from the manufacture of electronics, the manufacturers of several of the core components used in Landhopper (STMicroelectronics and U-blox) have made commitments to minimize their carbon emissions.

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Twain’s Status Report for 09 March 2024

Between last and this status report, I helped create the design report, writing several sections and editing others to reach the correct length requirements and for clarity. Additionally, I entered more items into the order form for the parts we have yet to make.

My progress is on schedule.

Next week, I hope to put in the order for the PCB and continue working on the energy harvesting.

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Team Status Report for 24 February 2024

This week, we had some major successes with prototyping the motor-based energy harvesting scheme and finishing the breadboard prototype of the digital hardware.

We have no new risks that we are worried about, nor are there any changes we have made to the design of the system.

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Carson’s Status Update for February 24th, 2024

Progress

My primary accomplishment this week was designing the gearbox that will be used for the motor-based energy harvesting scheme. The gear ratio and general structure was based on the design by Cai, Liao, et. al, but I had to determine the exact dimensions, optimal gear profile, mounting strategy, etc. myself.

I printed using the “Extra Fine” slicer settings and standard print speed on the Robotics Club Bambu X1 Carbon printer in PLA. The result worked astonishingly well, spinning smoothly enough to keep going off of inertia alone for about a second. Even with the small amount of weight provided by three M6 nuts and minimal balancing, the gearbox would spin in my hand as I swung my arm. We were unfortunately unable to attach the motor for real power measurements, as we discovered that we needed M1.6 size screws, but even so this is very promising.

Pacing

Working on the gearbox put me somewhat behind on the PCB design; I will need to work on that some more next week. Fortunately, the gearbox testing is doing much better than expected, so I should be able to catch up.

Planning

Next week, I will:

  • Attach the gearbox to the motor and get real numbers on power output
  • Do the layout for the PCB so it can be ordered over Spring Break