Robot looses comms when hit/jolted

Our robot, for the last 2 or 3 years, seems to loose connection whenever its hit pretty hard by another robot. It was never that big of a deal, but today we got our bot driving and attempted the bump. It did make it over, but we lost communication when it got to the other side.

The only thing I can think of is something inside the cRIO could be damaged, seeing as this happens year after year. Or possibly the D-link, but I somewhat doubt that.

Anyone have this happen, or any ideas?

D-link power plug or Ethernet connection, maybe?

If you have the wrong size of power plug, or the connection is finicky, that could be the issue.

What you said is possible, however it’s also possible that something is becoming disconnected when you bump things. I’d look into it further at your next meeting and get is figured out quick. If your robot looses communications every time it gets bumped, an accidental robot-to-robot collision will leave you helpless on the field. From me to you, fixing this problem should be a number 1 priority for your team now.

it was usually a harder hit, not every robot-robot hit. but going over the bump seems to trigger it. I’ll check the dlink wires tomorrow, but it is the right type. Its the one that came with the dlink.

Well let’s hope for your sake you never have to play defense. :stuck_out_tongue:

Loose wire or possibly a cracked solder joint inside the AP.

Tripple check every electrical power connection. A loose connection could easily cause what you’re describing, and if in the right place (like your battery terminals) could occur year after year. If you can wiggle the wires at all, tighten them down.

And check for little metal shavings in places they shouldn’t be (like in between digital sidecar pins). When knocked around, they have a tendency to short things out and cause problems.

We had a similar issue back in 2010 whenever we would kick the ball (caused the entire bot to shake). Apparently the power connector to the cRio was lose. Check that out.

  • Sunny G.

The wires going into the cRIO or the black connector? thanks!

Um, I believe it was the wires but I’ve slept since then.

  • Sunny G.

You need to find out what exactly is making you lose connection.
If you regain connection after a few seconds, the problem probably lies in the cRIO. Make sure you have a solid connection to the PD board
If it takes some time, its the DAP. If its the DAP, make sure you have a solid connection to one of the dedicated power lines on the PD board.

There are a few things that could lead to your problem.

  1. The power connector on the DAP has a spring clip for one side of the power input. If you tried to insert a large diameter plug at some point or if the connector was bumped in the past, this spring could be deformed enough to cause intermittent connection. The plug should be snug when inserted. Sometimes a small probe can be used to bend the spring back into position.
  2. The power cable to the radio is not supported near the radio. My recommendation to all teams is to use a wire tie near the radio to secure the wire. During violent robot action, the wire and connector will not move.
  3. Loose wires or stray strands of wire can easily move to an adjacent contact during violent robot action. Make sure the screws holding the wire are tight, tug test the wire and make sure there are no strands visible.
  4. Some PD boards were manufactured with a small, surface mount capacitor near the edge of the board where the radio and crio power supplies are located. It is possible that this cap has come loose and is floating around in the vicinity of the radio power supply.
    I am of course, expecting that you are using the 5 volt regulator, connected to the +12 volt radio connector on the PD and that all regulator connections are tight/soldered and insulated.

Thanks, Yes it is through the 5v supply through the 12v converter.

What exactly do you mean by the DAP? that black connector in the cRIO and distribution board?

The radio is a DAP 1522, sorry for the confusion.

A couple seasons ago, this was very common. The easiest diagnostic was to time how long it took to regain power on the field, or to walk to the robot and observe the LEDs to see which devices are still powered and which are not. Finally, try if you have it narrowed down, wiggle and yank on various wires to simulate the shock of the hit. Keep in mind that it could also be a short, so look for bare wires that could be hitting anything, frayed wires, and messy wiring connections entering the cRIO or other devices.

Greg McKaskle

We had the same problem and finally traced it to a loose ground. We fixed the ground and that solved it.

Jim Wick

The c-Rio input wires on our practice bot have come loose, our main breaker wires have come loose, pwm’s have come loose. We’re in the process of hot gluing everything at the moment. Strange things happen when you pretend that your robot is the General Lee. :smiley: :smiley:

This was happening to us early on, I narrowed it to two things…
1.) I had quickly wired the DAP-1522 to the 5v converter and that into a normal 12v output on the PD board. Well those were dipping voltage as my motors stalled working their way across the bump. So I wired that up to the 12v WAGO dedicated on the front of the PD board.

…that worked for awhile and it started happening again… SOOO

2.) I figured out that as the cRio bumped it’d lose comms… a simple tightening up of its mounting screws, and now the bot can bump, rock and roll all it wants, I stay connected.

Don’t use hot glue. Figure out why they are coming loose. To hot glue something that is incorrectly assembled means you can’t fix it when you need to. Most often when wires come loose on the Crio, it is because they were improperly striped. If the wires to not fully insert into the connector they will be pushed out when you tighten the screw on the side. If the main breaker comes loose, I have to ask if you are using the locking hardware that came with the breaker? For those items that move with the robot, find a place near the connection and use a wire tie to secure them to the robot. We loop the wire going to anything and then take it straight down to the deck. Since we use perf stock to mount everything, we simply pass a tie through the perf stock and around all the wires. The loop allows some movement, and the tie restricts the movement so that it can’t be pulled off.