Hello everyone, new to the forum and Arduino (And electronics in general). I have tried to make sense of all the options and choices Arduino offers but after several searches and a bottle of Tylenol, I still have no clue of what I need, which makes it impossible to know what to search for.
I am essentially building a dynamometer for small engines (I.e lawnmowers) and need to collect data, process that data and graph the results.
I found a board to use with an inertia dyno, but no such luck with a brake dyno. The sensors I will use are an S strain gauge, wide band O2, thermal couples (2) and an RPM sensor. So what boards would I need to use to collect the data, process and display on a computer? I know I will need a program to interface with the Arduino, and may need suggestions on that later ( or not), but just trying to determine what I need for the acquisition part at the moment, and if it would be cost effective to build my own or not. I'm not the smartest but can take off with a project out of my comfort zone once I get my head around how it works, I enjoy learning and employing new things that peak my interest.
If I could get a run down of what boards for what sensors and what Arduino model like UNO would work that would be great.
Why do you think that sensors are bound to specific controller boards?
Sensors connect by wires, the number of required pins depends on the number and kind of the connected sensors.
Sensors frequently require some analog circuitry, so that you better buy breakout boards instead of naked sensors.
If a controller needs network access for remote display and control, you have the choice of separate communication modules or shields, or on-board networking. Details depend on wire/less connection, distance, power etc.
The first step you need to take is to determine how each sensor will be coupled to the board, either analog or digital, and how it will be read i.e. what does any interface circuit look like. So here goes my take.
RPM: Digital input to the board. It can be done either using a variable reluctor or Hall sensor. If a variable reluctor you will need to convert the output voltage to a digital friendly format. The Hall sensor does that already.
Wideband oxygen sensor: Analog input to the board. The sensor needs to be interfaced through an appropriate heater and signal conditioning circuit to read the output voltage.
Thermocouples: Analog input to the board. You will need some thermocouple amplifier circuits.
Strain gage: Also analog. Here again you will need an appropriate interface circuit.
Each of the required analog interface circuits should give you an output that does not exceed 5 volts or the Analog Reference voltage of board for the measurements of interest. If you use the Analog Reference you get better resolution than if you use the full scale 5 volts.
So by your description you only need 1 digital input and 4 analog inputs, and any one of the boards will work for that. At that point the long pole in the tent is how much onboard memory you'll need to be able to run your application. That's a crap shoot until you get into it more so I'd choose the largest memory board you can and then downsize later if you are able.
need to collect data, process that data and graph the results... to collect the data, process and display on a computer?
You need to think a little more about this part of the requirements also. Is it ok to store the results as the test is being performed, then process/analyse the data later, "off-line", or do you need to monitor the data in real-time as the test continues? If the latter, how can the data be sent back to the computer? Wires (ethernet or some other serial standard) or wirelessly? If wirelessly, what range are we talking, and in what kind of environment?
The easiest method, I suspect, would be to have the Arduino record the data to an SD card. Then remove the card after the test and read/analyse on the computer. It's easy enough for the Arduino to write the data in CSV format, then it can be read on the computer using Excel, for example.
what Arduino model like UNO
The thing with Uno, Mega and Arduino with that shape, is that they are great if there exists a shield that you can connect on top of the Arduino and that shield contains all the extra circuits your project needs. If there is no suitable shield, then normally you will be creating a prototype circuit on breadboard at first. So it's much easier to use an Arduino that is breadboard compatible, i.e. will plug into a breadboard, along with the other components. Uno/Mega cannot plug into a breadboard. The result is a mess of confusing, error-prone and delicate wiring. So my advice would be to start with a Nano.