Category: Steph’s Status Reports

This week, I helped our group try to reach our MVP requirements.

One thing was trying to pick out components for the RC filter which was initially going to be 1.2KOhm resistor and a 2.2microF since this would yield a cutoff frequency of 60.29. However, with further testing, the amplifier fine tuned the signal enough without noise and distortion which allows no need for the filter. I further investigated this and documented the total harmonic distortion graphs that I found in the amplifier chip’s data sheet in the design report. However, it may still be in consideration to be used in the future as testing continues.

Since I was not in Pittsburgh when the robot chassis came in, I was unable to work and help on it. However, I continued to help by documenting the project in the design report, putting in the use case and design requirements, implementation, and such.

This week, I plan to construct the collimator and attach to the working speaker and amplifier apparatus to see if this will put out the fire as intended. I also plan to help on test the robot and integrating the speaker apparatus with the chassis.

This week I continued research on the circuitry part of the design which includes the ESP32, RC filter, amplifier, and the speaker. I picked up the parts that came in and the amplifier specifically needed to be more looked into. The main thing was figuring out all the inputs and outputs of the amplifier board which would take in the signal through a 3 pin connector which would in turn be the breadboard from the filter and that would in turn be connected to the ESP32. From the other end of the amplifier board, it would take in power supply which would be between 36-48V and then the right and left connectors would be connected to the speaker magnet via ground and voltage. I am looking into purchasing the malleable steel sheets soon so that we are able to build the collimator as well with the cardboard being the interior structure.

By next week, since we have the speaker magnet, I want to construct the collimator with the cardboard and the steel sheets and then have that fitted. However, since next week will be the week prior to spring break and I will be leaving relatively early in the week, I hope that we can get more testing done with the amplifier and also get the parts for the filter.

This week I started finalizing the design for the speaker apparatus and purchasing items. The type of amplifier was chosen (TPA3255) to be able to meet the specs of the speaker which would be 100W RMS and 8Ohm load. This chip would be able to meet the requirements with the downside of needing a higher voltage input than we anticipated so therefore we will be increasing the LiPo batteries that are needed. Another thing was adding in a simple low-pass filter before the amplifier part since we are using an ESP32-WROOM to generate the signal. I chose the ESP32 since it is able to generate the lower frequency range of 30-60Hz that we intend to test with while also outputting a sinusoidal wave.

Once I get the parts for the speaker and all the components, I want to start testing the ESP32 first and get the code working for that. I also want to get the specific parts for the filter and build that so it would be simple to connect everything further along.

In the past week, we put together the proposal presentation and I practiced for the presentation on Monday. On the day of the presentation, we received questions that we should take into consideration such as storing the signal into ESP32 for example. Along with that, I have put together a bill of materials spreadsheet that the team can keep track with on what needs to be bought, what has been delivered, and what we already have. While doing this, I have been researching and picking out the best subwoofer magnets to utilize and ones that would be most affordable but also hit our range of frequencies.

I hope to test fires with a standard speaker in the next week to get an approximate idea of the distance the speaker needs to be in relation to the fire. Furthermore, it would help to gauge how big of a fire we expect to put out.