Magnetic Rotary Position Sensors

The ams.com website is down currently so I couldn't see the datasheet, but that's really impressive if they can achieve this accuracy, and if the resolution is high. Glad you're investigating!!! I wonder if that means people don't need to spend a fortune on optical encoders for some high-accuracy applications. For a tool application, it would be interesting to know if motors/cables nearby or any other magnetic fields affect it. Have you noticed any fluctuations in your measurements?

EDIT: just saw the Farnell link. That's very low cost! But, I was unsure, the datasheet on the Farnell site said +-0.5 degree accuracy, is this different to the manufacturer site? I guess with gearing and keeping a count of revolutions, that is still pretty good. But then there is the issue of eliminating backlash I guess :-(

I remember reading some micrometers don't use optical encoders either, but use some accurately spaced parallel PCB tracks, and capacitance. Just as a slight digression,  it doesn't help your use-case directly, but the FRDM-KL25Z boards have a lot of capacitive sensor inputs. I wonder if they can be re-tasked to some measurement purpose. That would be pretty amazing.

The encoders still have their purpose; firstly they go to even higher resolution (2000 pulses per revolution no exception in robotics). Secondly, resolution is not the only concern:

• Accuracy is not 14-bit, as you have 2.7 bit rms noise. Of course you can average, but that will cost speed
• Sampling rate is 11kHz, so in very fast rotating axes the bandwith of measurement is impaired; not so with encoders

Nevertheless, magnetic rotational encoders have a very wide range of applications, and it's cool to measure just by adding a magnet!

A company that has made a very high accuracy motor driver for us told me that they're primarily using IC's from IC-Haus: http://www.ichaus.de/keyword/Magnetic%20Encoder%20iCs.

This company is also interesting: http://www.rls.si/en/am512b-9-bit-rotary-magnetic-sensor-chip--15882#ElementMediaList40407

The encoders still have their purpose; firstly they go to even higher resolution (2000 pulses per revolution no exception in robotics). Secondly, resolution is not the only concern:

• Accuracy is not 14-bit, as you have 2.7 bit rms noise. Of course you can average, but that will cost speed
• Sampling rate is 11kHz, so in very fast rotating axes the bandwith of measurement is impaired; not so with encoders

Nevertheless, magnetic rotational encoders have a very wide range of applications, and it's cool to measure just by adding a magnet!

A company that has made a very high accuracy motor driver for us told me that they're primarily using IC's from IC-Haus: http://www.ichaus.de/keyword/Magnetic%20Encoder%20iCs.

This company is also interesting: http://www.rls.si/en/am512b-9-bit-rotary-magnetic-sensor-chip--15882#ElementMediaList40407