What does the AS5600 contactless encoder do, and how does it differ from potentiometer feedback?
The AS5600 is a contactless magnetic angle sensor that measures the angle of a diametric magnet placed on the axis using the Hall effect; at 12-bit resolution, that is 4096 steps over 360 degrees. On the GS740-3P the position feedback of the servo actuator is taken from this sensor. Its difference from potentiometer feedback is that there is no part that rubs or wears.
In the classic solution the position feedback is taken from a potentiometer or a microswitch. These parts work by mechanical contact: under dust, mud, oil and vibration the resistive track wears, the measurement becomes noisy over time and a dead zone eventually forms.
On the AS5600 a diametric magnet sits on the actuator shaft and the sensor reads the angle of this magnetic field without contact. The results:
- No contact that wears by rubbing
- More stable measurement than contact solutions under dust, oil and moisture
- 12-bit resolution, 4096 steps, that is, fine position discrimination
- According to manufacturer data, works in the -40 °C ... +125 °C range
The GS740-3P uses this position information together with a P controller and a soft ramp: the 0-3.3V proportional command from the potentiometer sets the target angle, the encoder reports the actual angle, and the controller closes the difference. Note: this feedback is for actuator position; it does not measure engine speed.
Full topic: Electronic speed and throttle control on diesel engines