Loss of usb device connection while running an OpMode

[Tom Eng FTC Engineer Find all posts View Profile Close Tom Eng]

Tom, I will post an image when I get a chance. I'm currently unable to physically access our robotics stuff until Tuesday due to timing and other factors. I'll contact MR then, since I need to get the part and serial numbers for the components we're having troubles with. My current hunch is catastrophic overcurrent or manufacturing error, but I would defer to your expertise once I can get the pics posted.

Thanks hexafraction.

[sethmo Junior Member Find all posts View Profile Close sethmo]

This is the issue that our team is facing:
https://www.youtube.com/watch?v=UbDt6JMtpiQ

It seems that any light vibration will kill the opmode and require a robot restart. We never had a single issue with vibrations with the NXT and old motor controllers. Any suggestions? I just sent out an email to Modern Robotics. We have a meet on Nov 7th, and I am afraid that we will not be able to compete unless this issue is resolved soon.

[sethmo Junior Member Find all posts View Profile Close sethmo]

We seem to have fixed our issue. We swapped out parts from our other team, started with motor controllers, then core power, but the issue still existed. We then moved on to cables, we swapped out a USB cable from the core power unit to a motor controller and the issue is now fixed! The "bad" USB cable looks fine, but it must have been giving a poor connection on one of the sides.

We drove around for several minutes and made several attempts at bouncing up the mountain and we did not have a single disconnect. If your team is having disconnect issues, replace the USB cables between the Core Power Distribution Unit and the Motor Controllers!

[Tom Eng FTC Engineer Find all posts View Profile Close Tom Eng]

We seem to have fixed our issue. We swapped out parts from our other team, started with motor controllers, then core power, but the issue still existed. We then moved on to cables, we swapped out a USB cable from the core power unit to a motor controller and the issue is now fixed! The "bad" USB cable looks fine, but it must have been giving a poor connection on one of the sides.

We drove around for several minutes and made several attempts at bouncing up the mountain and we did not have a single disconnect. If your team is having disconnect issues, replace the USB cables between the Core Power Distribution Unit and the Motor Controllers!

sethmo,

I see another thing that you could improve... Your cables are not secured and strain relieved. They might vibrate (even if your robot is driving across the floor) and disconnect, particularly the cable that connects the phone to the POwer Distribution Module. You might want to see if you can secure your cables so that they are not floating in the air. Unlike the RJ-45 style connectors that the NXT used, the USB cables need to be secured (we like to use zip ties and zip tie the cables to the frame near the connection points into the phone or Core Modules).

In general, what we have seen, if the robot stops with that type of comm error message, it's often a loose cable. The cables that you replaced might not necessarily be "bad" but they might have been loose. If you strain relieve them so the connection to the modules are secure, the might be OK to use.

Tom

[sethmo Junior Member Find all posts View Profile Close sethmo]

Thanks Tom. We are definitely going to clean up the wiring and strain relief all the cables. We are going to try some 90 degree mini u.s. cables as well to make things more compact.

[Philbot Senior Member Find all posts View Profile Close Philbot]

Thanks Tom. We are definitely going to clean up the wiring and strain relief all the cables. We are going to try some 90 degree mini u.s. cables as well to make things more compact.

I've had a lot of success with the right-angle connectors from L-COM.com They come in all different directions.
If you plan out your layout, you can get the connector directions that make the most compact layout.

Phil.