Assignment 18: Applications and Implications
- Propose a final project that integrates the range of units covered,
What will it do?
My final project is to automate pH control and fertilizer balance in a hydroponic system. A pH meter is used to measure pH level in the hydroponic nutrient solution and a peristaltic pump is used to apply phosphoric acid into solution to get the pH level in desired range. Mass of the hydroponic nutrient solution is measured to estimate the need of the phosphoric acid and nutrients. Nutrients are pumped into the solution as well with peristaltic pump. Then electrical conductivity (EC) is measured to get the amount of total salts dissolved in the hydroponic nutrient solution. In closed systems, some elements tend to accumulate in the hydroponic nutrient solution, because plants doesn't absorb them in high quantities. It can be used to help in the timing of the nutrient solution replacement or dilution with fresh water. Solenoid valve is used to control fresh water flow from reservoir tank.
Who's done what beforehand?
There are huge amount of projects related to hydroponic systems. In the Fab academy, Guillaume Teyssie made an impressive aquaponics system. It measures pH, water and air temperature and air humidity, but these values are not used for automation. Sachin Salim made a hydroponic system with automated pumping. Marcel Kellner made a small hydroponic system where the pumping is automated and temperature and humidity are measured. Typically in all of the systems that I found online, automatic systems mean that the pumping is automated. In Youtube can be found plenty of different systems, but with rather limited documentation. Edwin Martin has made a similar system to what I'm planning to do, but the video doesn't really show much. Same problem is with Johann Cover, who has made interesting hydroponic nutrient solution measurement system based on store bought measurement devices. One project in Instructables by BLT Robotics did almost everything I want to do, but it does also something extra.
What will you design?
I will design:
- the storage systems with included measurements and all the structures,
- the peristaltic pumps based on some diy pumps,
- also boards for the main control, controller board for RepRap sterpper driver modules, pH measuring and EC measuring.
What materials and components will be used?
Materials for the:
- hydroponic nutrient solution tank, I will use acrylic,
- hydroponic nutrient solution tank base, I will use OSB,
- pH storage solution holder, polystyrene
- pump structures, ABS or PLA,
- pump tubing, Pharmed BPT NSF-51,
- pH sensor,
- EC sensor,
- temperature sensor,
- stepper motors x4,
- RepRap stepper driver module x4,
- load cell x4,
- weighing sensor AD module,
- solenoid valve,
- ball bearings,
- 2x16MHz resonators,
- resistors (Ohm), 0 , 10k, 100k, 51k, 2k, 4.7k, 36k, 820, 4.7M.
- pin headers, FTDI, 2x2, 2x3 and 2x5
- capacitors, 10 µF, 100µF
- IC OPAMP, TL34CD, CA3140AMZ, TL081BCD
- Charge pump LM2660M x2
- BNC connectors x2
- IC binary counter, CD4060BM
Where will come from?
- the non-Fab inventory components from Digikey,
- pH and EC sensors, solenoid valve, load cells and pump tubing from China,
- weighing sensor AD module, RepRap stepper driver modules, ball bearings, from EU area in Ebay,
- acrylic plastic from Stark Oulu.
How much will they cost?
- acrylic 35 €/m2,
- components digikey 10 €, Fab inventory 10 €,
- pH sensor 17 €,
- EC sensor 32 €,
- weighing sensor AD module 1.5 €,
- RepRap stepper driver modules 9 €,
- stepper motors 43.3 €,
- ball bearings 24.2 €,
- load cells 3.75 €,
- solenoid valve 8 €,
- tubing 20 €,
- total 213.75 €
What parts and systems will be made?
I will make:
- hydroponic nutrient solution tank,
- hydroponic nutrient solution tank base,
- pH storage solution holder,
- pump structures,
- main board,
- controller board for RepRap sterpper driver modules,
- pH meter board,
- EC meter board,
- temperature meter.
What processes will be used?
I will use:
- 2D and 3D design, for the whole machine,
- laser cutting, for the hydroponic nutrient solution tank,
- CNC (Rensi), for the hydroponic nutrient solution tank base,
- vacuum forming, for the pH storage solution holder,
- 3D printing, for the pump structures,
- electronics design, milling (SRM-20), soldering, programming, for the boards,
- inputs: pH measurement, EC measurement, temperature measurement, weight measurement,
- outputs: stepper motors, solenoid valve.
What questions need to be answered?
- How to make peristaltic pumps tight and well performing?
- How to implement everything in a single unit and to control the whole machine?
- Does all of my sensors work when I put them together?
How will it be evaluated?
Minimum requirement is to control hydroponic nutrient solution pH level and nutrients using peristaltic pumps and weight information from load cells. Additional benefits for the project offers EC measurement, which can be used to monitor salininity of the solution and to control solenoid valve to let fresh water in or to tell the user to replace solution.
What is the schedule?
I aim to finish everything by the 20.6 with all the necessary documentation. First I'm going to finish peristaltic pump (before 3.6) and pH meter (done), because nothing works without those. Load sensor with the whole structure is the second task (before 5.6). Finally I will move to EC measuring (if there is some extra time). All the steps include boards and code.
What tasks need to be completed?
- I have completed pH meter and calibrated it. I need to complete everything else.
- I'm close to getting peristaltic pump to work. The rotating part needs more work. Boards are designed and mostly done. Controller board for RepRap stepper driver modules needs to be remade.
- The structure is designed, but the joints have to be made before I can CNC mill and laser cut the parts.
- Load sensors and the boards exists, but I have not had the chance to test them yet.
- EC meter board is not designed yet.
Your project should incorporate 2D and 3D design,
additive and subtractive fabrication processes,
electronics design and production,
microcontroller interfacing and programming,
system integration and packaging
It does contain all of those processes.
Where possible, you should make rather than buy
the parts of your project
Due to lack of time, I bought some parts, which I could have made like solenoid valve, RepRap sterpper driver modules and weighing sensor AD module.
Projects can be separate or joint, but need to show individual
mastery of the skills, and be independently operable
Mine is an individual project, but I think the project would have benefitted from co-operation.