I'm trying to DIY an FSR linear softpot.
It is a long thin pressure sensitive resistor that can also detect where you press along the sensor.
Basically it works like a potentiometer and an FSR sensor in one. You take a measurement of the force and then a few microseconds after take a measurement of the potentiometer part to get both pressure and position.
The R-wiper in the picture is the FSR layer that changes resistance depending on how hard you press. The R-fixed is the fixed resistive track that changes resistance depending on where you press.
I have read on how to implement it in arduino but there is a detail that I don't quite understand.
This works like a regular potentiometer but the wiper has resistance that can change depending on how hard you press.
I'm wondering how this can work, won't the position detection be inaccurate if the resistance of the wiper changes?
I'm guessing the pressure sensing part may also be affected depending on where you press.
If I wanted to DIY one of these sensors in a custom shape for example what resistance would I use on the FSR and fixed resistance track to get the least amount of error? I know they use about 1000 Ohm per inch on the fixed resistance so I can just copy that but what I'm wondering is if it's better to use a less resistive FSR layer or more resistive?
So what I'm really wondering is how the resistance ratio of the wiper part vs the fixed resistor affect accuracy? Is it better to have the fixed resistance at say 10k and the FSR at 0-10k or the FSR at 0-300k? Or maybe the fixed resistor at 300k and the fsr at 0-10k?
I've tried to read up on resistance and voltage calculations in parallel and series circuits, voltage dividers etc. but I don't quite understand this.