I'm new to Arduino and prototyping a pressure sensing glove.
I'm somewhat familiar with mapping analog input. What I need to do is capture analog input from a known accurate force/strain gauge and then calibrate the piezo sensors to it.
The piezo sensors will be pressed on the strain gauge, so the 2 inputs happen simultaneously. For example, as the gauge reads 2kg, 3kg, 4kg... I'll get the piezo voltage 2mv, 5mv, 8mv.
How can I calibrate the piezo to the force gauge?
Thanks, in advance.
Ben
You need to give us a reference to the piezo sensors. Are they linear, exponential, quadratic? You could always just do linear interpolation, but we don't know how much accuracy you need.
In case you mean how to apply the same force to both sensors, mount them vertically (to exclude gravity) with a hard distance piece in between, and apply the force from any/either side (parallel vice...).
Remember that piezos provide almost dynamic signals. Their impedance is very high, so that you'll need a very high impedance amplifier to get (somewhat) static readings. Do you already have an applicable amplifier, or how to you intend to measure the piezo voltage?
Thank you both for your replies.
I'm uncertain of the piezo reference. The link below leads to the sensor data sheets.
This is how I'm thinking about my challenge:
The piezo sensor produces voltage under pressure.
If I can peg that voltage to a known force, I can get a reasonably accurate measure of force from the piezo sensor voltage.
If I press the sensor against the force gauge I get 2 streams of data that are representing the same force.
I can read both the strain gauge and piezo sensor data via my analog inputs on my Arduino Uno (I think).
What sort of code do I need to match them up and correlate the strain gauge data to the piezo sensor?
I appreciate your help. I'm not an engineer. The fact that I roomed with an electrical engineer for 2 years has not benefited me on this project.
Ben
From the data sheet: "used primarily as dynamic strain gages and contact microphones for vibration or impact detection".
You'll get reasonable readings for force changes, but not for a constant force. I.e. when you apply a constant force to the piezo and read its voltage multiple times, the voltage is decreasing with every analogRead.
So your idea of calibration is okay, but you would compare apples and oranges 
Thank you for your help. I think I'll test the force sensing resistor (FSR) products.
Much obliged.
Ben