USB drops out when external brake is engaged

7 years 4 months ago #29528118 by hudson
I\'m using three RobotEQ controllers with a six axis PUMA arm that has a dead-man switch for disabling the brake during training. When the E-Stop disconnects the battery from the motors, it also disconnects the brake and the arm holds its position. The training technique is to engage the E-Stop to depower the motors and then to hold the dead-man switch on the base of the arm to disengage the brake while posing the arm.

While I hold in the switch and pose the arm, the controllers are fine and output the updated counts for my FK/IK library. When I release the dead-man switch all three motor controllers stop producing output or responding on their USB ports and my read() call returns with a device error. If I close the device files and reopen them, the controllers seem to still be ok; the counts are not zeroed so I do not believe it has rebooted.

I don\'t believe this is a regeneration issue since the axes do not have any issues with being posed with the motors disconnected from the battery (which would cause voltage to be fed back into the controller). It seems related to the voltage spike caused by the brake re-engaging.

Please Log in or Create an account to join the conversation.

7 years 4 months ago #29528119 by hudson
This might be a similar problem to dev.roboteq.com/dev1/online-forum/troubl...ommunication-hiccups

When I direct connect, instead of a hub, the problem does not appear. I\'ll try a powered hub to see if that helps.

Please Log in or Create an account to join the conversation.

7 years 2 months ago #29528286 by hudson
The powered hub did not solve the problem, but a snubber diode across the brake did. I can now pose the arm without causing the controllers to reset.

Please Log in or Create an account to join the conversation.

Moderators: tonysantoni
Time to create page: 0.106 seconds