Hello, for a project I plan to measure force with moderate accuracy using the RP-S40-ST force sensor; however, its response is not linear and has a rather steep curve that does not allow for precise readings. Besides using code to transform the reading to the exerted pressure, is there any circuit that can transform its non-linear response to a linear one?
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There is no need to linearize the response. If you fit a curve to a table of response versus force applied, the curve can be accurately interpolated.
However, you will probably find that the response curve is not very repeatable, which is a different problem. As suggested here: https://www.dfrobot.com/product-1842.html
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MultiMap can transform non-linear A/D values to linear (pressure) values.
Available through the LibraryManager in the IDE.
Leo..
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First of all, thank you very much. I plan to control a servomotor in proportion to the force applied to the sensor. I haven't experimented yet, but I believe that if I don't linearize the sensor's response, the control of the servo might be a bit clumsy or inconsistent. Do you know if there is any way to linearize its response through hardware? Perhaps some configuration with an op-amp or something?
Please explain why you believe that.
Fitting the curve converts the analog reading directly to applied force, which is the only information needed for force-dependent control.
Keep in mind that FSRs are NOT recommended for accurately measuring force. If you need smooth and accurate control of some force-dependent process, choose a different type of sensor.
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I believe it would be necessary to linearize the response because the ADC might not accurately distinguish small resistance variations. This would make it difficult to differentiate, for example, between 9k and 9.1k.
I appreciate your suggestion; however, I am considering the possibility of using this sensor instead of a strain gauge due to its compact size. The FSR is quite convenient in this respect, and resolving its non-linear response issue would be ideal
That has nothing to do with linearization, and would be a result of making the wrong choice of sensor (and ADC).
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