Position Sensor (Position Feedback)
This is the feedback element that tells the control board where the actuator actually is. The board can then compare the command with the actual position, stop at the end points, and know whether the movement has been completed. The AXI LFT54 has a position sensor for protection purposes; the LFT20 has no sensor at all.
Without feedback a system runs "open loop": it gives a command and does not see the result. The position sensor closes the loop and provides two practical gains. The first is end point protection; when the mechanism reaches its limit the motor does not strain unnecessarily. The second is repeatability; the same command gives the same position every time.
- Common types: potentiometer (absolute, simple), Hall/magnetic sensor (contactless, no wear), encoder (high resolution, relative counting).
- Fault symptom: in a system with a failed sensor the movement either never starts or does not stop at the end point and keeps straining.
- Link to calibration: position data only becomes meaningful after the lower and upper references have been taught.
Because the LFT20 contains no board, processor or sensor, this protection layer does not exist; the switch drives the motor directly. This explains why the correct fuse choice and a bench test before installation are especially emphasised on the LFT20. On the LFT54 the position and current sensors work together to intervene in a jam.
The context in which this term is used: Converting a tractor hydraulic lever to electronic control