Category: William Foy’s Status Reports

This week was focused on giving our final presentation. I worked on the slides and practiced the presentation ahead of time in order to best present our project’s results. I think the presentation went well overall.

I wasn’t able to work much on the chair module this week since we had to watch other presentations and I had other class commitments. This week I plan to get everything ready for the demo which includes finishing the sleep configuration for the Xbees so we can save the power needed to extend our battery life. I also need to wire up a final chair module.

I think we are on schedule to be ready by the demo to present a reliable, working system. The data hub is pretty much done and the frontend is looking great. We will start on our video and final report soon this week.

I made a great amount of progress this week that I’m super happy about.

First off, the chair sensor is much more reliable now. We lowered the resistance from 30MΩ to 20MΩ and also attached the module breadboard underneath the chair to avoid changes in wire positions. The values being output from the CapSense library have a large change now when someone sits in the chair and stands up and we can easily detect changes now. I also added a baseline average computation to the code upon startup so that the range of values for emptiness isn’t static, but dynamic upon startup.

We got our other Xbee modules this week so we wired up a second chair module. I was able to configure the other Xbee onto the same network as our original chair module and data hub and we were able to get two chair modules sending updates to the single data hub. This verifies our proof of concept of having multiple chairs send updates to a single data hub.

The 2000 mAh LiPo batteries arrived this week as well. The batteries operate at 3.7V and upon plugging them into the RAW input of the Arduino which feed into a built-in voltage regulator, the Arduino performed as if it was plugged into the wall. The battery supplied enough current for the Arduino and to power the Xbee. We were also worried that the grounding of the capacitive sensor would be messed up by using a battery instead of power from a laptop, but the sensor performed the same. We were happy to get the chair modules running off of battery power, we just now need to see how low we can get the current draw and then estimate how long the batteries will last.

This next week I intend to write more Arduino code to put the Arduino to sleep and cut power consumption wherever we can. Without going into sleep the Arduino draws about 2mA continuously which will result in the 2000 mAh battery being depleted in around 4 days. By cutting the power through going to sleep, I think we can drastically reduce the average current consumption and extend the battery life significantly. I also want to finish up our testing and then get started on our final presentation.

I am definitely on schedule now and am looking forward to grinding out the rest of the project. We have our major components working now and now we just need to test and focus a bit more on the frontend of the website. We should be ready for the final presentation next week.

This week I focused on the internal demo and configuring the Xbee for Zigbee communication. In the beginning of the week I was a bit blocked since the breakout boards for the Xbee did not arrive when we expected. This meant that there was a delay in physically hooking the Xbee up to the Arduino Pro Mini.

For the demo I showed the functionality of the chair sensor. This showcase made me realize how unreliable our current sensor setup is. I think we need to add more aluminum foil and better tune the algorithm to determine when occupancy changes.

After the breakout boards arrived I was able to work with JJ to connect the Xbees to the Arduino Pro Mini. We were able to program the Xbees with XCTU. All we need to do is test the serial communication from the RPi and Arduino to the Xbee and get the communication up and running with the correct data from the Arduino.

I think we got a bit stuck this past week but we should still be able to get back on schedule. This upcoming week I plan to fully flesh out the Xbee communication. We also will order batteries this week for the Arduinos to be powered off of. I think this week is crucial for our project and I am confident we will make a lot of progress.

This week I spent my time on to get the Xbee modules up and running. This was mostly spent configuring hardware to connect an Xbee to the Arduino Pro Mini. In order to program the Xbee with XCTU it has to have a serial interface. We discovered that we could program the Xbee through the Arduino. So if the Arduino is connected to a computer through the serial module and then the Arduino is connected to the Xbee, the Xbee can be programmed as long as the Arduino is running a blank sketch.

We ran into some challenges connecting the Xbee modules due to the non breadboard compatible pins. We had to wire wrap and solder some wires onto the 4 pins we needed on the Xbee. We then connected these pins to the Arduino (power, ground, tx, and rx). By the end of the week we were able to successfully have XCTU discover the Xbee through the Arduino and we can program it. I also worked a bit more on the chair sensor code to be more robust and correctly check occupancy every few seconds. We also ordered some breakout boards that allows the Xbee to be breadboard compatible, so we will use those once they arrive.

Going forwards we need to wire up another Xbee on the Raspberry Pi so that we can correctly configure the two Xbees on the same network and test the communication. We also need to ensure we are prepared for the demo this upcoming week. I think we should be good to show the chair sensor and possibly the RPi to website communication. We might try to get Xbee working by the demo too but that is undetermined.

I think I am making good progress and on schedule. Getting zigbee communication working between the Arduino and RPi is the last big hurdle which we should be able to accomplish this week. We will make a new schedule for the last few weeks based off of our current status. I think we are on track to have a functional product that meets our requirements by the end of the semester.

This week I spent all my time on getting the capacitive sensor working. The first part of the week was spent experimenting with the Arduino Pro Mini and soldering on header pins. I also did research on how the Capacitive Sensor Arduino library works and how to use it. We also struggled to find and bring aluminum foil to the lab but once we did were able to configure the hardware for the sensor. We first tested the sensor with a small piece of foil and different resistor values. We first tried 10MΩ but then upped it to 30MΩ which worked better. We also used a 100pF capacitor to smooth out any noise which worked well.

After getting the small piece of foil to pick up a human hand we wanted to try using foil underneath a chair. We used a chair from the common space outside the lab and taped some aluminum foil to the bottom of the chair. A wire was run from the foil to the Arduino. We used the same setup with 30MΩ resistance and 100pF capacitance which worked very well. The capacitance that the library output with this setup resulted in the capacitance at least doubling when someone sat in the chair. This large difference was detected by the foil underneath the chair. We were very pleased with the performance and the solution since we can hide the aluminum foil underneath chairs without the user even noticing.

A video of the sensor working can be seen here: https://18500f21.slack.com/files/U02B5N4M0AH/F02KFNDMF9Q/image_from_ios.mov

I think my progress is on track after getting the sensor to work. I will work on the Arduino code a bit more to start building a module that will continually detect changes in occupancy and using some sort of hysteresis method to stop changes from being reported when they shouldn’t be.

This next week I plan to work on the Xbee configuration to get Zigbee communication working. This will entail wiring the hardware together and using XCTU to program the Xbee modules. I hope to get Xbee communication working on the Arduino side by the end of the week and hopefully get communication with the Raspberry Pi functional.

Last week (10/10 – 10/16) I spent most of my time contributing to the design review doc. We split up the doc between the three of us and I was responsible for the system overview section and the tradeoff section.

This week (10/17-10/23), I spent the first couple of days on the Ethics assignment, in preparation for Wednesday’s guest lecture. I enjoyed Wednesday’s lecture and it was nice to get an outside perspective on the ethics of our project.

In addition to the ethics assignment, I spent this week making sure all necessary components were ordered. We had to pivot to using a different type of battery, a 3.7V LiPo with a large capacity close to 5000 mAh. I think all of our components are set to go right now.

I also started setting up an Arduino to test our capacitive sensor. We haven’t yet received our Arduino Pro Minis so I used an Uno which was available. I started getting familiar with the CapSense library and figuring out how to connect the aluminum foil to the board.

I think I am slightly behind on schedule. I need to pick up the pace in terms of getting the proof-of-concept for the capacitive sensor working since that is a vital part of our project. Next week I hope to fully test the sensor and tune it with appropriate resistors in order to pick up human presence. If I can get the capacitive sensor to a good state next week I will be back on pace.

Overall our team is moving ahead nicely and we are collaborating as a team. JJ and Nathan have both made great progress on their respective parts of the project as well. After we get all components delivered and the capacitive sensor working we’ll be in good shape going forwards.

This week was mostly spent listening to other groups’ design review presentations and giving feedback. I also helped JJ prepare for our presentation and he did a fantastic job. For our project, I continued to do some research for the chair module regarding the Arduino code that will interface with the capacitive sensor and the Xbee. I have been exploring XCTU and how we need to set up the Xbee modules. We also need to start ordering components, specifically Xbee modules. The ECE department should have RPis and Arduino Nanos that we can use. I also put in a request to get AWS credits for our cloud-based web app.

I think we are on schedule still. We will finish up our design review this week and then can dive right into implementation. Everything on the preliminary research end should be wrapping up soon.

Next week I plan to work on our design review document for submission Wednesday. I also want to get all of our components figured out, whether ECE already has them or we need to order them. Finally, I want to start testing the capacitive sensor with an Arduino as soon as we get on.

This week was spent doing further research in order to find a viable solution for the chair module that meets our requirements. At the beginning of the week, we thought we would switch to using a NodeMCU since it’s cheaper than an Arduino Nano, but then we switched back to the Nano since it consumes less power and we don’t need the WiFi capabilities of the NodeMCU.

I also found a new idea for the chair sensor, which involves the Arduino Capacitive Sensing Library. With some tuned resistors and pieces of aluminum foil, I think we can detect human presence on the chair using this library. More info can be found here https://playground.arduino.cc/Main/CapacitiveSensor/.

I helped our team prepare for the design review as well, which involved making 4 of the slides for our slide deck and working with JJ to prepare for his presentation. I think we are prepared to give a great presentation next week.

I think we are on track according to our schedule. After presentations next week we should be all good to start our implementation. We have a solid design in place with good requirements and a valid testing plan.

As we had proposal presentations this week I personally did not make much progress on our project this week. I helped Nathan prepare to give our proposal presentation at the beginning of the week, and I think we did well but also received a lot of good constructive feedback regarding areas we could have done better in.

I did a little research on my own regarding other embedded systems to use than an Arduino since we got some feedback on that. I think there are other solutions that are cheaper and smaller and can connect with an Xbee and chair sensor for our purposes.

I think we are on schedule, we need to wrap up our research this next week and set on what components we want to use so we can start ordering items if need be. We could have done a bit more this week since we mainly just listened to other presentations and gave feedback, so I think we need to get a lot done this next week in order to have a strong start on our project.

This week I focused on researching potential chair sensors to use to detect occupancy and also which microcontrollers and Zigbee modules to potentially use. During lab, I worked with the team to coordinate the development of our proposal slides and to narrow down which sensor would be the most feasible for our project. I personally made 4 of the slides in our slide deck and contributed to the Gantt chart for our schedule.

We seem to be on schedule since we will have our proposal ready to go by Sunday night. We’ve been doing significant research and I think we are at a good place in regard to narrowing down how we will implement a solution and meet our requirements.

Next week, in addition to hearing other presentations and giving feedback, I plan to help my team research more and further our design, specifically for the chair sensor component which I will be working on. We need to figure out exactly what sensor we want to use, and how to connect a Zigbee module to the sensor through a microcontroller.