View Full Version : [Question(s)] Replacing DYNAMIXEL on PincherX 150 Robot Arm

Taeke de Haan
10-02-2020, 05:21 AM
Due to an error on my side I need to replace the px150 shoulder motors (XL430-W250). It seems that in the px150 old versions of the DYNAMIXELs are used. The new XL430-W250 motors I received come with a slightly different shaft, which do not seem compatible with the robot [1].

As a solution I took the shaft and front plate of the old (broken) DYNAMIXELs, and put these on the new motors. Everything seems to work correctly, however since the encoder magnets are now swapped the motors need to be re-calibrated. This can be done by changing the Homing Offset.

When in Position Control Mode this offset can only be modified by a maximum of -90 to +90 degrees as stated [2] . However, on motor ID:002 I need an offset of approximately +140 degrees. Such offset can only be applied when in Extended Position Control Mode. This seems like a dangerous solutions since the Min and Max Position Limits will be ignored in that Control Mode.

I assume this Homing Offset limit exists since there is a mechanical fix when the offset is larger than 90 degrees. The only fix I can think of is rotating the encoder magnet by 180 degrees. Since messing with the encoder seems a bit sketchy. I would like to ask you whether this approach is correct. Or am I overlooking something?

[1] https://imgur.com/P2HT6Ep
[2] https://emanual.robotis.com/docs/en/dxl/x/xl430-w250/#homing-offset20