I am trying to make a large scale resistive touch sensor with 4 FSRs, one for each corner of the rectangular sensor. The pressure that I'm going to be applying will be a moderately pressured finger press. I have heard that FSRs are mostly inaccurate as far as precise pressure goes.
For example, the Interlink 402 says in its datasheet that its accuracy is within 2% of its resistive value, and changes with time at a rate of 5% * log10( days ).
As far as tap sensitivity goes, the FSR seems decent, at 10% change after 10 million taps.
I'm wondering if with a passive load of 2kg, and a dynamic load of 1kg, would the 4 FSRs be sensitive enough to make a decent (512×512 (9-bit accuracy)), reliable resistive touch screen, or are other materials better for the cost? If I were to make this, what would my theoretical accuracy be?
Best Answer
simulate this circuit – Schematic created using CircuitLab
300mV deflection at 2/3 FSR rating for load from 2/3 to 1 x FSR rating ?
Static load is probably quasi static, so dynamic touch will be problematic so DC tracking by AC amplification
Some problems with OEM specs at 10k expecting 2.5V at 50% FSR but only seeing 20% on left.
Conclusion
possible if static load is true static.
undefined problems with this approach.