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J4 cannot rotate reversely

Hi everyone,

I’ve recently assembled my AR4 robot, and while most things are functioning well, I’m encountering an issue with the J4 joint.

The problem is that J4 can only rotate in the positive direction. When I try to rotate it in the reverse direction, I get an error message saying, "J4 Collision or Motor Error."

I’ve already checked the encoders and switches, and they all work fine. All the other motors are also functioning properly.

Could anyone help me diagnose what might be causing this issue? I’ve attached photos and a video for reference.

Thank you so much in advance!

Error log:

6 comments

Comments (6)

Chris Annin

Aug 16

There could be a potential wiring issue. Can you check with a multimeter that the dir input to the driver for J4 has a solid connection from the teensy and that the signal is + in one direction and - in the other?

Ming

Aug 22

Replying to

Hi Chris,

I replaced the driver for J4, and it's now working well -- I can jog J4 to rotate in both directions.

But I met another new issue: after finishing the encoder and switch tests, the control software freezes everytime I click the auto-calibration button. This happens even when I chose to calibrate just one joint. Do you have any ideas what might be cuaing this problem?

Many thanks for your help!

Ming

ANNIN ROBOTICS

J4 cannot rotate reversely