Capstone Week 7 - The beginning of the project

At this point in the class there are no updates to make to the report or other deliverables. I think I am going to pass. That would be great. After this class I have three more to take at a community college online. They should not be very much trouble.

With this class wrapping up it is really the beginning of my colorimeter project. There is a lot of work to do to continue iterating and have a core device that is useful to more people. Right now it is only really useful to engineers that want to take the pieces. 

Overall I feel pretty good about this Computer Science program and that I balanced meeting the criteria with doing something I enjoy. I hope to continue my project and deploy it to more users while using it for my own farming systems.

Capstone Week 6 - Sometimes Things Work Out

The official topic for this weeks learning journal is about the ETS test. I did not take this test. To be honest when I got invited to take this test I thought it was on a hidden camera show or being tested because of the software you are required to install to take the test. In order to have a proctor tell if you are cheating you need to give them control over your computer to see what you are doing, what programs are running, etc. That makes sense if you are using a virtual machine and locking the proctor in a small container or are using a disposable computer that has no personal information or access to your home network. I did not have to do either of these and did not have to take the test, so that was really nice and got rid of a lot of stress. In the end I would not have installed this software and would have worked hard to get a low passing grade instead if it was a big problem.

Instead for this week I focused on assembling, debugging, and trying out my circuit boards for the colorimeter. That involved a trip to "Smart and Final" to get a hot plate and cooking the circuit boards like pancakes. The tools I have at home aren't great for this, so I did have some problems. Those problems put me in a great position to select and buy equipment for companies that need to move very quickly. With this personal experience I can continue to push for reflow ovens, high quality soldering tools, high quality solder paste, etc without any doubt.

In the end I had a short circuit on my light board which caused one of the data lines and the light output lines to short to 3.3V. This prevented communication with the color chip. Fixing this problem was nice though because it showed me that if you follow the data sheets for sensors and other microchips then sometimes things work out great. Read the fine print, do a good job, and things just work!

Capstone Week 5 - Presenting Prints Ahoy!

This weeks capstone material presented good points about presenting. It is easy to try to make content super impressive and technical. That doesn't do the presenter a lot of good though. A presentation should be understandable. For me this is important because there will be people outside of my target audience that can help with a project. There are large gaps in my knowledge relating to business and profitability. So if I am giving a presentation about a device that I am working on it would be good to also make it understandable by people with a different field of interests.

Also discussed was making a presentation memorable and emotional. When I give a presentation I try to focus on having very little that needs to be remembered other than a few words that link the structure together. Making a presentation connect emotionally is about honesty.

Outside the reading this week was about designing and printing parts. Although on accident, there was a good lesson in material saving this week. By stopping my print accidently after the first key features were built I was able to make a few small alignment and fit changes. In the example image below the test tube is loose in the holder, so a tighter section was added to the top. The light sensor board on the right was offset slightly by around 1.5mm. So that component was shifted as well. This kind of partial print technique would be good for many applications, including making a close fit around an odd shape.  

 

Cutaway view of print for test fit check of sensor board, light board, and test tube.

Capstone Week 4 - Open Source Hardware Workflow

This week had a bunch of good reading about interview questions, getting your foot in the door at a new job, etc. I enjoyed that reading but didn't really get much out of it. I am starting a new job soon, if I lost that job I have a few good backup options with great people. Being in between jobs this week does mean one thing: no access to SolidWorks. So what should I do? Well I have been thinking this day would come, and don't really like expensive software or "cloud CAD" like fusion 360. These options are good for high end design and manufacturing. A lot of what I have made over the years is pretty simple though. That is where FreeCAD comes in.

FreeCAD is the mechanical counter part to KiCAD (which is for circuit board design). They are made by different people, but combine you can design electrical and mechanical components. I have messed around with FreeCAD a little bit but this was my first week really using it to try to design something. It went OK so far, but I will really commit to using FreeCAD for all of my open source projects moving forward. The overall open source software work flow for my projects will include all three of the following:

KiCAD - Circuit Boards

FreeCAD - Mechanical Design

Cura - 3d printing, I will use the lulzbot edition, which combines an open source 3d printer with open source software. 

EMC2 - CNC machine control, milling metal and plastics

Each of these programs is free and has their source code available online. The more people that use this kind of workflow the more money we can all save and the more we can collaborate. If you are going to sink a ton of time into a project, why not give it a long life by having it be open source? That seems to be the way to go to me. 

Capstone Week 3 - Integration time, averaging, and repeatability

This weeks learning came in form of a series of graphs as the embedded and control panel software were modified simultaneously. This path began with  erratic values given from a high intensity flashing light source with low sensor integration time.

 

Poor target illumination(intense short flash) and sensor timing yield erratic values with wide range. Low integration time also gave a narrow range of values from maximum to minimum light intensities. Increasing the integration time of the light sensors gave a wider value range and higher resolution.

Illuminating the target before sensing, averaging multiple samples, and receiving stable values from the 18 light channels.

 

 Running two rounds of calibration using six sample concentrations with stable and repeatable values 

 Final result with one invalid value, possible swap or mixing error. 

 

Modifying the NodeRed display panel software and embedded software simultaneously appears to be a good way to quickly experiment with a device and close in on a desired result. I would recommend this route to others doing similar development efforts. 

Capstone Week 2 - project planning as an explorer with a funny hat on a 3d surface

    This week came with an important decision to make. The sensor I had selected was not performing at the level that I would like to see for this kind of device. So the sensor was immediately abandoned and a new sensor was connected to take its place. One quarter of the way through a project it is critical to have the basic functionality established so that a full evaluation can take place. If that means using cardboard and hot glue with some development kits then that can work. The important part is to be able to have full project visibility by knowing the components and how data travels between them as a connected graph.
   Another aspect of this weeks development cycle was prototyping material selection. I choose to use hot glue and cardboard with scissors. At first that seemed a little odd to me, selecting from processes like laser cutting and 3d printing. In reality this does exactly what I need: hold a test tube, light source, and light sensor in a repeatable position. It also has the benefit of reducing the impact of the high brightness LED flash on people around the device.
   By pivoting as necessary and not wasting effort and material with unnecessary prototypes this project can hit it's objectives.
   This is the strategy I try to follow for any project: There are hills and valleys in the problem space for any new development. If you can't get up on top of the hills to see into the valleys you're not sure what you will find. Climbing a few of the key mountains early on, even imperfectly, gives you visibility and functionality. Each of the valleys you see could take years to fully explore. It is critical not to get trapped in these valleys though. So get up on the hills, build graphs showing their relations, and map the surface to project completion.

Capstone Week 1 - prototyping

Nitrate solutions of varying concentration

   This week was all about MQTT, Mosquitto, NodeRed, and the ESP8266. At the start of a new project it is important to hit all areas and find your risk items. For my colorimeter capstone that meant setting up the server, building and programming an embedded device, running first dashboard trials and taking real measurements.The results of each step in this first week prototyping process will determine the direction of the project for the remainder of the course. 

   The first risk item identified was the lighting source. Initially the LED was run off a 9V battery and resistor but an unstable spiking and then dropping off light level was measured. To accommodate this spike and drop an AMLD-6070Z LED power supply was added. This device was configured to have a constant but adjustable current output to stabilize the lighting source.

NodeRed flow for receiving colorimeter data and estimating nitrate

Dashboard for basic nitrate display & debug

  With only three data points and a preliminary sensor device the results are not completely solid. Averaging of 20 samples was used to remove noise in the sensor data. This will be combined with more data points on the calibration curve. No housing has been built, so there are other lighting consistency concerns to address moving forward. These concerns revolve around the repeatability of the light path going through the test tubes, and exterior lighting. Adding a housing which gives repeatable positioning between the light source, sample, and detector should also help improve these results. In addition it will block ambient light which will remove another variable from the lighting equation. 

 

First known sample results

    Overall the strategy for this project has been to hit the key targets, then improve each of those targets as time allows. That strategy will result in a functioning device with a full scope of improvements and risk items for device success. Moving across targets like this on a project is a critical skill to have in a career within technology development. Collecting user feedback involves rapid iteration and review. If a long time passes between the availability of functional software then the user can't provide feedback. By operating my projects in this fashion I can continually integrate user feedback by showing demonstration sections that operate.