Week 16, final project, the overview

Working on the final project, in week 16 it is the plan to get a good overview of all the different parts and processes needed.

Wednesday Global Class

Neil showed a lot of examples of final projects and of possible area's where the project could be about.

Weekly Assignment week 16

In my own words

Individual assignment:

• Answer a lot of questions about the final project and by doing so get grip on all the needs for it.

Propose a final project masterpiece that integrates the range of units covered,

I will make a worm-mood-station that tells the physical situation of the worms in the worm-bin. answering:

here are the questions with the answers:

What will it do?

My Worms live in a worm-bin, where they digest my vegetatie-cuttings and so make worm-compost and worm-tea. The wormbin has a quite vulnerable environment where it is crucial to keep a stable aerobe environment. If the bin is too wet or if there is too much fresh vegetables then an anaerobe situation will take over, the PH-value will change and a massacre will happen with the worms.

Who's done what beforehand?

The bin is already there, the worms live inside, and by checking on them visually and smelling weekly or more often I keep the worms well and alife. So the design will be for a check-up for the worm-mood for my existing worms. What will you design? I will make a electronical Worm-mood-station where you can see the happiness-situation of the worms in a userfriendly way without having to know a lot about the technical situation. So with this checker I can for example let my kids check on the worms and know if there is some worm-needs. For this I need to check on temperature, PH-value and humidity of the compost. As an output, I would like to have a happy worm if everything is okay and a sad worm if things start to go wrong. It is important to show what is wrong so it is possible to change the environment for the better.

What materials and components will be used?

Input

In order to measure the mood of my worms I have to translate that to the values of some environmental variables in my worm-bin. At first I thought that it is important to measure the PH-value of the compost, the humidity/moisture and temperature, next to that the Oxigen-level/air quality of the air above the compost. The different values (temperature, PH-value) could be too high or low, the moisture could be too dry or too wet and the Oxigen-level could be either good or too low. That makes quite a complicated measurement, because there are 4 variables and they all can be good, too high and too low.

Temperature

I realized that the temperature is not really important to measure constantly in the local climate in the Netherlands, in the winter I already put my worm-bin inside, but the moment for that is quite clear. If I am cold outside, so are my worms. The worms will move more to the inside of the bin when it is cold and will ne inactive. only whenthe compost freezes completely the worms won’t survive. In the summer it is never too hot for the worms, My bin stands on the shadow-side of my house and the ideal temperature is between 15 an 25 degrees Celcius then the worms are most active and make a lot of compost. It is very seldom a higher temperature than that. and will be inactive So I can eliminate the temperature-sensor.

PH-value

The PH-value is important, this is really the thing that makes the environment very unhealthy for the worms. I found some great PH-meters online, but they are mostly chemical sets, where you measure the ground with a special strip or fluid. The electronic sensor for measuring PH were either only for fluids or very expensive (around 70 euro’s).

Air quality

After some research on worm-bins I found that in fact what happens is that there is either too much fresh vegetable cuttings or the environment is too wet, then anaerobe bacteria and small animals take over and they make it an unhealthy environment for the aerobe animals (like my worms). The anaerobe animals will exhale ammonia and sulfur gasses. So with the change of the compost-environment there is also a change in the air above the compost. The sensor for measuring those gasses is the MQ135 and is about 4 euros. With a much more simple sensor I can indirectly measure the PH-changes in the compost, because it also causes the change in sulfur and ammonia in the air above it. If the ammonia and sulfur concentration is too high, then the oxygen-level is too low, so with this one measurement I can take in account of the air-quality and the PH-value in the compost. Great! I bought the Arduino-set for this measurement, because it was cheaper then the loose gassensor, I bought two so I can disconnect it and use only the sensor.

Humidity/moisture

In the compost it should not be too wet (changes the environment in an unhealthy situation) nor too dry, because the worms have a moist skin and are sensitive for dry ground. There is a very nice way to measure the moisture of the ground with a sensor that has two conductive pins in the ground and measures the conductivity of the ground in between those pins. in the dry plant it shows a value of about 600 and in the wet plant (with the saucer) it gives a value of about 250. this is very useful for my compost.

Conclusion

My worm-mood-station will need a sensor for ammonia/sulfur and a sensor for measuring the moisture in the ground.

Output

I want my Worm-mood-station really to reflect teh mood of my worms inside, not a direct output of the sulfur-measurement, but a translation of these measurements to the total wellbeing of my worms. Next to that I would like it to show what needs to be changed so I can improve the environment if it is not very good. My first drawings in week 2 are great to reflect the mood of my worms, that will be the base of my output. Now I know that with charlie-plexing I can turn the different LED’s on while using a small amount of pins. So for my happy and sad worm I can work this out. The output on the different measurements I would like to do with coloured LED’s. Green for good/Orange for not so good/ Red for bad. I will need to go lower and Higher with my LED’s because the moisture can either be to wet or too dry. (maybe blue for wet and red for dry) This I could do with some NEO-pixels. Since I only visit my worm-bin maybe once a day, I don’t want it to be on all day, I would like it to only measure when I am there, therefore I will make a button on it that triggers the measurements and gives a reading. This is also good for the moisture-measurement (less oxidation on the pins) and battery-life.

Microcontroller

I will work on the program in the arduino-IDE to connect the sensors to the right output, my plan is to use an ATtiny, probably I’ll need a slightly bigger ine than the 1614, because the program will have to do some calculation.

Product development

With this small amount of input and output I am probably able to make a nice small product. I will focus on the size of the PCB-first and try to make that very small and then work from that and make a nice and small case around it. I would like the case to be waterproof, because that will lengthen the lifetime of the product

Where will come from?

See above, most components are available at Waag, the sensors I bought at my local electronics-store. the acrylic plates and vinyl is available at Waag and

How much will they cost?

(I added onto this list with the real components of the final project, at the moment of writing in week 16 I did not know all the details of the components and housing yet. )

How I counted the Housing:

• acrylic 2mm thick from the scraps at waag, normally €20 per m2, I use 3 pieces of 5X7cm is about 100cm2 so it would cost about 20 cents.
• scrap multiplex 18mm populier, normally 60 euro's for a 122X250 plate so 0,00197 euro per cm2 I used 2 layers of 5x7 cm and needed to cut that out, so I'll add 0,5 cm cutting-kerf. is 6X8 times 2 is 96cm2 = €0,19

What parts and systems will be made?

I will try and make everything myself, except for the electronic components, and the gas-sensor those I will buy. The moisture-sensor I will make myself.

What processes will be used?

• PCB-milling
• Soldering
• Programming in C
• Lasercutting the acrylic for the screen
• Vinylcutting the vinyl backing for the acrylic
• for the housing: either milling (wood) or 3D-printing (plastic)
• 3D-printing the rubber waterproof-seal (s)

Next spirals:

• Epoxy-coating for waterproofing the electronics
• Solar panel

What questions need to be answered?

Most questions I answered above in the input-section. I did quite some research on worm-life and habitat. the things I have to work on is:

• How it will fit all together? how small can I really go.
• What microchip will fit all my needs but is not extremely big, I hope one of the Attiny's because I am quite happy and familiarized with them.
• How to make a nice housing that has a friendly look and feel and will not look too fab-made. I might use wood, cast plastic, make a 3d-printed version, and when closing it, I might use casted rubber, or lasercut rubber.
• How to replace the moisture-module and gas-sensor-module by my own design?
• what are the right values to change from good (green) to not really good (yellow) not good (orange) bad (red) and really awful (purple) (and what are the two input values for that)
• How do I get everything finished in time?
• How can I make the individual worms light up nicely?
• How can I turn the whole thing off when not in use?
• What do I want to present in my video, what questions do I prepare for.

How will it be evaluated?

Real life test: I will put my worm-moodstation in my worm-bin and see if it helps me to control the wellbeing of my worms. laboratory-tests I will put my wormmoodstation in several situations that mimic the bad conditions of my wormbin in a controlled environment (with high/low moisture and a bit of ammonia form a bottle) and show the results. Due to ethic reasons I do not want my worms to have a bad living area so it will be impossible to see the worst situation with life worms, but I can create an anaerobe situation in a bin of compost and do some measurements there.

Your project should incorporate 2D and 3D design,

electronics design and production:

• It will consist of 2 pcb-boards, one main board with the chip and the outputside and one sensor-board with the different sensors.

additive and subtractive fabrication processes:

Additive:

• 3D-printing for the button.
• 3d printing for the housing Subtractive:
• lasercutting for the different layers of the acrylic screen. and maybe for the housing and for the rubber closing-ring.
• PCB-milling
• vinylcutting for the worms to light up individually
• cnc-milling for the housing.
• Maybe cnc-milling for molding and casting the housing

embedded microcontroller interfacing and programming:

I will use a attiny and program it to read the sensors and show the input through LED's

system integration and packaging:

I will try to make a minimalists design of the housing, with all parts nicely fitting inside. The main board will be the biggest part and I will design the sensorboard in such a way that it will fit nicely on the bottomside of the housing.

Where possible, you should make rather than buy the parts of your project

Of course, if possible:

• I will make the moisture-sensor myself.
• I will only use the gas-sensor, not the whole module. the module is in fact a microprosessor changing the analog values into digital and I will need the analog values.
• my plan is to design and make everything for the housing and product myself

Projects can be separate or joint, but need to show individual mastery of the skills, and be independently operable.

My project will be individual, I chose this project because it is a clear personal need and hopefully it is quite small in size and components. This way I can show the skills and competences I acquired during the fab-academy.

Learnings this week

I really liked making something that you can really hold in your hands and does something, giving the interaction that I want. Meantime I underestimated the time it would take to finish this small and quite simple product, with only two sensors and LED-output.

• I loved thinking out the design, so it would be nice and small and well integrated.
• answering these questions made me think of more things and helped me forward with my design.
• I got a bit nervous with the timing that I was still working out my sketches and everything and I saw all these colleague-students making things already. But on the other hand, I hear that they are fighting against many mistakes, so with my knowledge it is maybe better, to first think things through and then start making. (maybe I do not have to make many trial versions, although I will try prototyping soon)

Links to Design-files

Just sketches this week, no design files, they are all in the final project process-page (I am on my way to work with KiCAD.)