For steady state noise, I just ran some data collection without commutating the motor, and colelcted the data shown below. With both signals zeroed at the same point, something odd becomes apparent, which is that both sensors seem to follow a nearly identical nosie path, down to well into the low degrees. Some possible explanations here are coupling (as discussed later), but also temperature could be a factor. Overall measured noise was well below 5% of total signal, and with 18 pole pairs should yield ample accuracy and resolution, with plenty of room for experimentation and improvement.
[<imgsrc="images/encoderNoise.png"width="800">]
[<imgsrc="images/encoderNoise.png"width="800">]
One big question I had was if EMF from the motor would manifest as noise at the sensor, which fortunately seems to not be the case at all. Noise levels did not change with the motor running or not running, and the error down to +/- 0.25 deg appears highly repeatable. To test this, I ran the motor through a full 720 deg sweep, and then took the difference between errors in the first and second revolution, by manually lining up the data. Ignore the +0.25 deg offset, as that's just a result of my lining things up poorly.
One big question I had was if EMF from the motor would manifest as noise at the sensor, which fortunately seems to not be the case at all. Noise levels did not change with the motor running or not running, and the error down to +/- 0.25 deg appears highly repeatable. To test this, I ran the motor through a full 720 deg sweep, and then took the difference between errors in the first and second revolution, by manually lining up the data. Ignore the +0.25 deg offset, as that's just a result of my lining things up poorly.
