Re: Losing connection when ramping over defenses
 

So here is my fix for battery terminals (you can find this in several other posts).
Buy #10 external tooth lock washers. These are sometimes called "star" washers depending on what part of the country you live in. Add the lockwasher between the battery terminal and the cable terminal when you assemble the battery wiring. Use locking hardware for the screw and nut you use as well. The lock washer will prevent the terminals from twisting and they will never loosen. The projections on the washer will also bite through the surface crud and give you a good electrical connection. We just retired a battery from 2010 this week that had never given us "loose terminal syndrome". Remember to insulate both connections, I recommend heat shrink.

Re: Losing connection when ramping over defenses
 

Our robot also exhibited loss-of-power after roughly jumping over one of the defenses at high speed.
We believe it's due to our battery cable flopping around on the landing, causing the battery cables to twist within the battery-side or breaker-side Anderson housings, and causing a voltage drop sufficient to reset the roboRio and/or the access point.

We were able to duplicate the observations by twisting the mated Anderson connector pair (with our hands) relative the the control board and thus the cables, and observing similar intermittent power behavior on our 'RIO and the PDP.

Looking at the unmated connector end-on and twisting the Anderson connector relative to the cables, we can see the SBB-style terminals twist against their spring retention and deflect far enough to plausibly explain the loss-of-power behavior.

We haven't solved this problem yet on the competition bot, but we're contemplating mounting the battery connection and the wires to something rigid to prevent the cables from twisting.
We've also improve cable routing to take some of the tension off of the battery cables relative to the battery's Anderson connection.

Early duct-tape-supported experiments holding the Anderson connector pair rigidly to the control board appeared to mitigate the issue.

Re: Losing connection when ramping over defenses
 

dakott,
That is almost impossible for correctly assembled SB50 connectors. If the terminals were bent during insertion or if the springs were bent to make mating easier, the terminals can rotate. Under normal conditions that would not occur. Can you include a picture of your installation with the battery connected?

Re: Losing connection when ramping over defenses
 

If the SB50 connectors are not defective and are assembled properly, that should not be able to happen. Do you have a way to post a good-quality video showing what you're describing?

[edit]Yeah, what Al said.[/edit]

Re: Losing connection when ramping over defenses
 

We had the same issue a few weeks back when we first started going over the rock wall.

Fixed this issue by putting a cushion (~2" of foam padding) underneath the RoboRIO. The cushion in question is some leftover padded packing material or foam. We used the ziptie holsters on the four corners and still affix the RoboRIO to the electronics board, but now it does not cut out when going over.

Cheap. Simple. Solved. :-)

Re: Losing connection when ramping over defenses
 

Sounds like a nightmare year for the FTAs and CSAs... :D :ahh:

Re: Losing connection when ramping over defenses
 

At every event, before quarterfinals, I personally go to our alliance partners' pit areas, and try to twist the 6ga cables on their batteries, PDP, and main breaker. Every year, I found about 50% need to be tightened. If yours are not tight, I will be watching you do it, or I will be doing it for you.

Teams, torque your terminals!

Re: Losing connection when ramping over defenses
 

That's a good idea. Once in 2014 someone didn't fully plug in their battery on our alliance and so as soon as someone touched the robot (like 3 sec into the match), the robot just turned off and that was it for the match. They were just dead in the middle of the field like a construction cone. :mad:

Re: Losing connection when ramping over defenses
 

Im not sure if this is just our new radio but every time we start up the robot it will start and then restart. If this isn't just our radio then field setup is going to take a long time.

Re: Losing connection when ramping over defenses
 

How do you tell?
Does the startup light sequence on the radio repeat twice?

Re: Losing connection when ramping over defenses
 

Yes, I am pretty sure that means it is restarting

Re: Losing connection when ramping over defenses
 

All the radio LEDs (including the power LED) do go out during the regular boot sequence, but the overall pattern should be:

• Flashes all the LEDs (including red for the last WiFi LED)
• Then they go out
• Next the power LED comes back solid followed by the next two in sequence (but not the last WiFi LED)
• Then they all go out
• Then the power starts rapid blinking, then slows down
• The next two LEDs come up together, closely followed by the last WiFi LED

But yes, when we get our robots onto the field we want to turn the robot on as soon as humanely possible.

Re: Losing connection when ramping over defenses
 

The question box is going to get killed with people claiming brown outs and physical shock induced communication problems are field faults.

I have an extreme degree of sympathy for our FTAs and head referees this year with your comment and brown out both in mind.

I'm inclined to suspect a router issue. In 2014 we had a router with an internal issue that would cause a reset with large shock loading. It took us out in 3 or so matches before we caught it and replaced it.

Re: Losing connection when ramping over defenses
 

A couple things that will help determine whether it's a robot or field problem:

. new radio seems to reduce chance of Christmas tree
. telemetry improvements over last couple years (DS log, FMS log, logging of roboRIO reboots)
. smooth operation last year makes it more difficult to argue

We'll see more of:

. battery on the field
. upside down robot
. Anderson connector came apart
. intermittent issues

I think I'm going to sell baggies of these at the competitions.

Re: Losing connection when ramping over defenses
 

I agree! This year's game presents some of the roughest field elements in recent memory. You almost have to go back to the ramps and collisions of Stack Attack in 2003 or the stairs in 2004 to see something similar.

In recent years it's been more robot-to-robot contact that has been the big factor. For the majority of teams competing this is all new territory.

I definitely anticipate loose batteries, flipped over robots and machines going dormant while they reboot during the match.

As has been mentioned earlier good breaker connections and wire connections plus a judicious application of zip ties and hot glue will help as far as connectivity.

Either way this year should most definitely be a fun game for spectators