I'm totally new to this type of thing so I wanted to put up this idea to see if anyone can offer some feedback or criticism.
I am going to be running some vibration tests on some sporting equipment and need to measure the force of impact as it passes through layers of foam. I have an Arduino UNO board and some simple piezo element sensors. I really just need a program than can convert the voltage output by the sensor into the amount of force that it is experiencing.
That's just math.
Convert analog reading from 0 to 1023 into some meaningful # to the user.
May have to use resistor divider from the piezo into the analog input if the piezo output exceeds 5V.
Do you have an oscilloscope to see what the sensor output looks like? Other preconditioning of the signal may also be required.
Done it ,pre than a year ago and the circuit matters not just in how you read it but to protect Arduino pins from overvoltage and negative voltage.
I was able to to detect from a very light touch to a hard smack with a screwdriver handle.
I can't say what I got was super precise but my numbers indicated press, more press and release.
My method involves loading up a wire between transistor and digital pin then seeing how many digital reads it takes to empty the pin which can take a fraction of the time an analog read takes to more than 2 millis.
The values of the components determine just how long to read but that can be calibrated for, my pins stayed safe is my biggest concern. Hit a piezo real hard and you are dealing with a spike. When you let up, there's a reverse spike.
It's not just force that affects what you get. The speed of the hit, the delta-time, also has effect.
What I haven't done but might be good is to put the disk into or onto a bendable piece as a stress gauge and incorporate that as what gets touched.
Hope any of that helps. It worked for what I wanted and I was able to sense press from release and some characteristic of both.
I was able to pick up 13mm piezos, 100 for $10.30 from DX.com. They can't take the beating that better discs can but they're plenty good enough for embedded buttons and can take heavier use than ordinary microswitch buttons. I wouldn't want my PC keyboard hit as hard as they can take.