Losing connection when ramping over defenses
 

Has anyone else experienced this? I have checked and made sure that all of the wiring is good on our robot, yet every time we ramp over a defense (i.e. rock wall) and slam down, our robot drops connection. All wires are secured and locked in to their ports (power, ethernet, pwm, etc.)

Could this be a result of shock causing the radio/roboRIO to reboot?

If you have had this problem, please share your solutions.

Re: Losing connection when ramping over defenses
 

Check your main breaker to make sure it isn't bad. There are a couple each year... With the bad ones, you can tell by lightly tapping on the red button while watching the LED's on the robot - with a bad one they'll flicker.

My team's main breaker was bad, but in a different way- the lever inside that lets you turn it on was broken. Brand new, out of the box for may be a day. It was the only one I've seen broken like that. Fortunately, we had a few spares sitting around :)

Re: Losing connection when ramping over defenses
 

Double check that the fuses on the PDP are full inserted. They can look good but are actually far from fully mating. Are you getting just a very short (one or two seconds) drop or are you getting a radio reboot?

Re: Losing connection when ramping over defenses
 

We had this happen to us a few times Saturday during our first test drives over the defenses. We are going to do trouble-shooting this evening. I also saw another thread that described a similar (possibly the same) problem.

Re: Losing connection when ramping over defenses
 

It seems like a radio reboot, I'm just speaking from what the students have told me. It goes down for a good 30 secs.

I'll check the main breaker as well. Thanks guys.

Re: Losing connection when ramping over defenses
 

What do you learn from the driver station logs? http://wpilib.screenstepslive.com/s/...og-file-viewer

Re: Losing connection when ramping over defenses
 

We have been experiencing this exact same issue. When we go over the defences we drop connection. We have isolated the issue to the roborio. We're still trying to figure out how to fix it. We're currently trying to add suspension to our roborio and hoping that fixes it.

Re: Losing connection when ramping over defenses
 

What power plug in to the radio are you using? Wiggle it. If you do not get stable power, that might be your problem.

Re: Losing connection when ramping over defenses
 

I haven't personally seen any of the logs, but I can check when I get to the meeting this afternoon. Usually there aren't any errors from what I've seen, but I could be wrong.

Re: Losing connection when ramping over defenses
 

We had this happen last night too. The power connector for the radio came unplugged while going over the rock wall.

Re: Losing connection when ramping over defenses
 

We had very similar comms issues, which were solved by checking the fuses.

Re: Losing connection when ramping over defenses
 

Those minifuses are very good at pretending to be fully seated when they really aren't. My advice to teams for getting them in all the way:

• Push them in all the way.
• Let go and notice how they look like they're in all the way.
• Push harder. Literally until it hurts.
• Notice that they go in a lot more.

As a rule of thumb (!), if you can pull them out with your fingers they aren't pushed in hard enough.

Re: Losing connection when ramping over defenses
 

If your using a two speed transmission check to make sure your in low.

Re: Losing connection when ramping over defenses
 

Would you be able to post a video of how hard you guys breach?

Re: Losing connection when ramping over defenses
 

This leads to an interesting question: with all of the rough defenses, will bots have increasing comm problems during the tournaments as the systems get shaken up?

Re: Losing connection when ramping over defenses
 

I would not be surprised. This game will *probably* put more stress on robots than Aerial Assault due to the fact that you're pretty much required to go over the defenses.

BTW, we haven't been able to run the robot tonight. Still wiring up sensors and putting some final touches on before we get the code debugged and start practicing.

Re: Losing connection when ramping over defenses
 

We had this problem as well, and we noticed that it was because the ethernet port in the RoboRio was coming loose. We fixed it by using the socket saver from the KOP and ziptieing it to the RoboRio so it had a firm connection even when it was being pulled on.

Re: Losing connection when ramping over defenses
 

Can someone explain why this would be a problem? Currently, we are able to go over the B+D defenses by starting low and shifting to high to gain momentum which gets us over the defenses. If this is actually a problem, we might have some serious problems.

Re: Losing connection when ramping over defenses
 

If you are going over the defenses in a high speed gear, you may not have enough torque to the wheels / belts to actually climb. You can stall the motors, potentially causing the thermal breakers to break, and possibly causing the system voltage to drop below the reset point.

Use the recording capabilities and look at total current draw and voltage drop as you drive over defenses and around the field.

You can also use JVNs drive design tools to look at your drive design and the estimated loads.

My response is all based on a hypothetical situation, not one we actually experienced this season ... ;)

Re: Losing connection when ramping over defenses
 

We had a similar problem with the radio dropping out. I believe all we did to fix it was secure all the connections and tape the power plug to the radio.

Re: Losing connection when ramping over defenses
 

So we were practicing all day on Saturday while repeatedly having connection issues when driving over defenses or if we suddenly accelerated. We thought it was our router and so we taped it up completely. However it was indeed the fuses.

Re: Losing connection when ramping over defenses
 

Sounds like the FTAs (and CSAs to a lesser degree) will be busy this year. At least the bandwidth induced xmas-trees should be a thing of the past. Good trade? :D

Also the fact that no teams have spare radios is kind of an issue. Our team is marking our spare radio the one part we will not lend.

Re: Losing connection when ramping over defenses
 

We had the same issue a couple years ago, had to mash the lever or a little bit of vibration would cut power to the bot. OP, if it isn't your breaker, check to see if the power cable for your router is firmly attached. We found that those hard impacts can cause it to get loose unless securely mounted. If it's available to you, I strongly suggest a 3D printed holder for the plug to keep it well secured.

Re: Losing connection when ramping over defenses
 

We have been having this issue, and I think ours came from the voltage supply blacking out. We plan to modify our drive train so that hopefully it won't recur.

Re: Losing connection when ramping over defenses
 

We had the exact same problem, it was a faulty connection between the on/off switch and the PDP. It was loose on the PDP end causing voltage to drop for a moment and the robot to reset.

Re: Losing connection when ramping over defenses
 

We are having the same problem, one of our mentors pointed out that our battery connection termintals was loose, maybe check that?

Re: Losing connection when ramping over defenses
 

One issue that could be occurring, is a problem with dropped packets.
Last year we picked up on this issue when testing driving over the step quickly. I guess the extra stress was making us notice.

One thing that can cause alot of dropped packets is programs on the computer trying to connect to the internet.
I think in our case it was the NI or Autodesk auto updater.
I believe the problem is those eat up bandwidth trying to look for updates, and with them not being connected to internet they obviously won't be able to update and just eat bandwidth.

I'm not sure if we were throttling our bandwidth to competition levels or not when this happened.

Re: Losing connection when ramping over defenses
 

We had this issue. Tightening the bolts that held the battery/breaker leads to the PDP solved the problem for us.

Our radio kept rebooting when going over the rock wall. Turned out to be a loose wire from the PDP to the VRM.

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

Re: Losing connection when ramping over defenses
 

We are seeing the same behavior, with both the competition and practice robots. Both robots worked well for the first couple of minutes and now any forceful contact with the defenses causes a loss of comms. We have double checked the fuses, ethernet cables, all connections, main breaker, battery terminals, etc. and cannot find anything questionable. We have wiggled and jiggled all wires and even done drop tests of the robot on all sides and cannot replicate the problem - only when physically driving. I took a high speed video (240fps) of the control board during impact and what I see is this:

Robot impacts the defense, about 10 frames later (about .05s) the RoboRio power light turns orange for a few frames, then back to green for a few frames, then goes dark for about 10-12 frames, then goes back to green.

So it seems to be a power issue to the RoboRio, at least in our case. Lights on all the Talons behaved as normal during this and lights on the router behaved as normal during this.

We will continue to investigate...

Re: Losing connection when ramping over defenses
 

If you're sure the fuses are good and the roboRIO power wiring in both ends is good and you're battery, main breaker, and PDP terminals are secure I would open up your roboRIO and vacuum out any debris.

Re: Losing connection when ramping over defenses
 

Kevin,
Did you perform a tug test on the Robo Rio power cables? I have seen this when power wiring is just a little too short in the push type connectors. Others have reported damaged power connectors that appear to be OK but in fact are partially depressed allowing a pretty good connection but not a perfect connection. The only sure sign is to look down into the terminal with a bright light and watch for the contact to return to fully closed after pushing on the actuator.

Re: Losing connection when ramping over defenses
 

We tried pulling on every wire, but we'll try some more tomorrow morning :)

We'll also look at the power connectors, and check to see if there is any debris in the RoboRios (this happens on both our practice and competition bots, which is concerning).

The only consistent thing we could see in our DS logs that was bad (as far as I know, which is not a lot :o ) is that a bunch of "5V brownouts" happen. We aren't really seeing the battery voltage on the DS go that low at all, and they also seem to pop up when driving normally, so I am unsure if that is a normal thing to see happen every so often while driving. It might also be worth noting that we don't actually have any 5V stuff wired up to the roborio at the time.

Re: Losing connection when ramping over defenses
 

Josh,
Kevin can give me call tomorrow morning. We are trying to get our robot together (big surprise I know) but I should be available. I am pretty sure he has my cell phone #.

Re: Losing connection when ramping over defenses
 

Seeing "a bunch of 5V brownouts" suggests that you have debris shorting the 5 volt rail on the RoboRIO. It might not even be on the inside of the housing. Look very closely with a bright light at the recessed areas around the PWM, DIO, and Analog pins. You might find a nearly invisible strand of wire, or a crumb of metal, or a thin film of aluminum dust, that sporadically connects the 5V and GND pins together.

Re: Losing connection when ramping over defenses
 

For what it's worth we discovered a few weeks back that hitting some of the defenses, for example the rock wall, can cause a hard stall depending on angle of approach, tires, etc.

We had made a mistake in putting 8" numismatics on the stock KOP chassis with only slightly adjusted gear ratios. According to the JVN calculator Excel we would be at over 90 amps per motor.

The power draw was so high in this situation that we observed arcing across the primary breaker polls. This lead to many brown outs most typically the radio dropping.

What a lot of you are describing sounds very much like what we experienced. Make sure you've run the numbers on your drive train.

Re: Losing connection when ramping over defenses
 

We tried everything suggested, cleaned out the roboRios, etc. We were about to call Al when another mentor tried yanking the connection to the main breaker pretty hard.

After uninsulating it turns out our connection was loose there on both robots, but not loose enough to disconnect with our normal tug test. the shock of running into defenses must have provided strong enough force to jostle it and momentarily disconnect.

After tightening and reinsulating we went over rockwall/ramparts roughly 10 times without problem where before we would disconnect on the first or second try.

Thanks for the help everyone!