Expanding a bit on the project, I have a shaft connected to a blade and a spring that continually hits the objects that pass through. If the objects don't have the correct shape, the shaft will rotate more or less, and that is the angle variation that I have to identify.
wvmarle:
How about a rotary encoder? You may need a quadrature type to sense direction together with angular movement but they can be really precise. 1800 pulses per rotation should be possible.
I am thinking I need an absolute angle sensor since I need to detect exactly the angle variation.
mikb55:
If you use an analogue sensor, pick an Arduino that has an ADC with better than 10 bit resolution otherwise you'll be limited to 0.35 degree resolution. Use the ADC internal voltage reference for better accuracy.
What if I used an arduino Zero or Due, would that be a good solution?