Checking out radio during competition

Technical Control System
1

OK you Motorolla types - I’m looking for input to help my propose a rules change that I think is necessary (especially after our competition experience yesterday). Here’s the problem - there is no way to tell if your telemetry system is working until you are on the field, since you have to be on tether.

During our next to last qualifying match our robot went dead. The word I got from our field team was that the pressure switch PWM pulled loose and shorted something out. Didn’t sound likely, but could be. So we get to the pits, hook everything up (tethered) and it runs OK. We go out for the last qualifying match and have no radio signal, so we sit immobile for the match.

Post match, Tytus notices that the radio modem box cover is loose; apparently the student who put it together after the firmware change didn’t get the screws in well. So, it appears that something inside the modem must have broken. Before alliance selection I verify that we can get a replacement modem and we accept the selection.

First quarterfinal match we get on the field, power up, no radio. we beat on every connection, then notice that the modem to RC cable is frayed. We change this out (as fast as possible), still no radio. IFI says we may haved fried something in the RC due to the frayed wire. By this time, it is well past 2 minutes after field reset so we can’t call a timeout and can’t call in a replacement team. Our alliance plays 2 on 3 while we change out the RC, losing the match.

As it turns out, there were other radio problems with the field that match, so a decision is made to replay the match. We now go out 3 on 3 and win. We won the second match as well, so I guess theoretically we would have won 2 out of 3, but who knows. Our opposing alliance was (I’m sure) disappointed but very gracious about it.

So… can someone recommend a reasonable way to test the radio coms at the competition? Can we put the 2 modems in a tempest enclosure? Have people wearing aluminum foil suits stand around the robot? Dedicate one of the channels to non-field use and let teams test them in one area so only one at a time is running? What’s a good answer?

2

If I recall correctly at NJ, the IFI guys had a station in a room to update the firmware. They were testing the radios out live after they were updated. I don’t know if they packed the place up, but if they did not I am sure there would be a way to test the radios out in there.

3

Hm…our radio dropped a couple times for no apparent reason and when we checked right after the matches, everything was still connected. At one point, when we were ranked 1st, our allies’ radios dropped dead almost at the start of the match and we lost ours about halfway through. The refs said their transmitters indicated we were all still getting signal and didn’t give us a rematch, which was pretty disappointing because we lost 0-32.

4

I was a field re-set person at the GLR and also an inspector. I had a very up close and personal view of the radios and issues associated. Here are my observations.

Most (90%) of the on field radio problems were robot related and not really radio IFI problems. Loose wires, the cable not secured in by the thumb screws, on/off breakers not fully on and the major issue was loose wires in the NEW Distruibition block.

The remaining issues seemed to be associated with placement of the radio (suggested it be vertical and as high as possible) and massive shielding ( ramps with alum perf and alum boiler plate as thick as 1/8 inch acting as a shield) that is a common robot configuration with this game.

The IFI guy ( John V ) was very detailed at keeping records of robots with issues and talking with teams. Every match was monitored for signal quality. Thanks John! Appropriate steps and preventative measures were taken to maintain a quality signal.

To answer your question… always consult with the inspectors and the IFI person for monitoring your robot. DO-NOT run your robot on radio in the pit… IFI monitors all signals and knows which team is running on radio and not tether. This is dangerous to all persons working on robots. There are loaner radios and RC /OI units available if the situation warrants a transplant.

5

Mike - I think you missed the point of my post altogether.

It was not an IFI radio problem / signal problem; we had a hardware problem - we apparently fried the radio connection in the RC when something else shorted out. The issue is that there is no way to verify where the problem is or if you have fixed the problem until you are on the field. You can check out every other system on your robot (hardware or software) except telemetry.

Here’s what we knew - our RC was not communicating with the RC modem. That means it was either the modem, the cable, or the RC, or any combination of those. We suspected the modem since the case was open, so we changed it out. It turns out that was not problem, so we’re stuck on the field with a bad RC.

When I borrowed the loaner modem, I specifically asked the IFI rep if I could try it out off tether to make sure that fixed the problem since it was during the time between alliance selection and elimination matches when no robots were on the field. I was told no.

Could we have done it anyway? Sure. But I asked the question and was told no, so as far as I’m concerned that was the rule and doing otherwise would be cheating. So we were stuck with the consequences.

6

I REALLY think there should have been an area to test the radios. We would have gone much farther into the finals (if not won) if we had been able to test it.

First match of ours in the Finals, the radio failed, we tried switching out the radio, putting it higher up on the robot, switching out the controller “brain”, and we checked every wiring system. The radio system just didn’t work. We ended up having to call in a replacement team for ourselves and they didn’t have enough height to get up the ramp at the end of the match. We sat back and did nothing as our alliance lost.

And still we dont know what’s wrong with it. Next time we’ll get to test it we’ll be starting practice rounds. And if we can’t get the radio working by the end of the first practice round, all we’ll be able to do is wait for the next practice round to try again. If we had a way to test if it was working, we could have possibly avoided losing so soon…

7

Gary,
The IFI station behind the field has a monitor device that can look at your link, determine your team number and see the level of your backup battery and main battery. But it doesn’t work if the radio is not working. I would think that your particular problem should have caused the IFI rep and the perhaps the FTA to offer to do a radio check between matches to check operation. In the interest of maximizing the experience for all teams, it seems that a test would have been the best course of action. Sorry you had such a problem.

8

Here’s my non-answer answer from IFI

I’m going to try again

9

OK, I got a straight answer.

Does anyone understand what he means by “The IFI Rep can also test you on radio in the Pits.”? If that’s the case that should solve the problem.

10

Your problem sounds very similar to ours.
We had been having alot of static build up on our robot. We multiple measures to fix it and it seemed to work. Then the same thing happened to us. We put the robot on the field and nothing. We replaced the modems, cables, everything. Tethering the robot worked fine. Eventually, we replaced the RC (missing 3 matches, oh well) and everything worked fine from then on.
The conclusion was that our static build up had fried the radio connection.

Throughout the whole troubleshooting process the IFI rep, RIcky, was very helpful.

11

Just couple things to keep in mind if you run into problems. We had a communication failure QF2-3. We ended up having IFI attach a second antenna and cable for the match. It did look a little strange seeing two antennas side-by-side. We found out after the match that the cable had gone bad, until that point we were not aware of any problems. We will now keep a spare cable and antenna on the cart along with a couple zip ties for a quick replacement just in case IFI does not come through. It would have been easier and quicker if we could have tried the replacement cable immediately instead of waiting for IFI with the referees watching the clock and almost asking us to leave the field. The IFI guy really pulled through and we were able to complete.

12

Gary,
The IFI monitor can pick up radio traffic for a fairly large range. When I was inspecting at Boilermaker their first year, I was informed by the IFI guy that there were other robots operating on radio that were not on the field. After checking around we found that a robot demonstration had been set up outside and those radios were being picked up by the field system.
In addition to the data I mentioned earlier, the IFI monitor also looks at packet loss and can determine the condition of your link on the field. With the IFI rep and FTA working together, they should be agreeable to let you link up in the pits to check radios. Please remember that this might be difficult if there are active matches on the field.
At Championships, the pits are far enough from the playing fields that the monitor might not pick up your robot in the pits. There is some good communications at the event though and someone should be able to coordinate things for you.
As a side note, there have been many modem cable failures over the years. Since the radio power passes through the cable it may just go high resistance and prevent perfect communication. Just one spare may not be enough. Keep a couple and toss the defective one when they appear.

13

It sounds like we just need some consistency in rulings here; as I noted in my second post above, I asked the IFI rep if we could try it out during lunch before the eliminations started and was told no. Sounds like the answer can be “yes” sometimes. I’m going to propose some things to IFI/GDC for next year.

As to IFI’s response about having time to change out components while on the field, I agree a modem or cable can be changed (if you have a spare modem), but if it’s your RC then good luck - and you won’t know until you’re on the field and you’ve changed everything else out. Thankfully we had labeled all of our PWM cables or it would have been a nightmare.

14

Just to add another experience in here …

The comment about IFI being able to check the radio in the pits, is shaky at best. The odds of you being able to get the IFI rep off the field and into the pits to assist you in radio testing, is slim to none.

We had our RC radio reprogrammed at our first regional, and still had problems with it (transmit radio wasn’t working, but the receive portion was, IIRC). As a result, we had to run both our regionals on loaner radios. At our first regional, the IFI rep told us that we would probably have to pull the radio off after every match, so another team could use it. While it didn’t have to come to that, it was still very upsetting to have that option presented. Going to a regional with 55 teams, and in a season with a plethora of radio problems, you would think they would bring more than 6 spare radios.

We seemed to run ok at our first regional, but we did have several problems at our second one that while IFI told us they were problems with our robot, we weren’t buying it. The robot ran flawlessly tethered. On a match Saturday morning (#2), we lost control, although according to IFI we had radio comm. the whole time. The match before (#1), a robot out the radio tower, literally knocking it over to the ground. The match was paused, the tower was picked back up, and the match was resumed. I don’t recall if any teams had radio problems after they restarted that match, but the match right after it (which we were in) 3 of the 6 robots had control issues (2 of the teams knew it was radio/comm, I don’t know if the 3rd was radio related)

I’m not here to put down IFI, they have done an amazing job over the years providing the control system - it just seems like very poor judgment on their part to go flying into a new season with unproven radios, and then denying problems until the end of the build season (we were having radio issues during build season, but because everyone else was having problems, we didn’t bother to call IFI; mainly because we would hear the same thing everyone else was hearing - “Follow the guidelines on our support forums for mounting the radio, your radio is fine, but it’s getting interference from your robot”)

Either way, you should of been allowed to check your radio during downtime. I agree that there needs to be some kind of controlled setup for checking radios, especially after this year. They are 40 channel radios, and even at the championships, only 24 channels are being used at once.

IMO, practice fields should be allowed to run radio (assuming the channels are controlled by arena controllers) - once again, even at the championships, that’s only 24+12 channels. Radios would probably end up being safer anyways, I’ve seen too many people trip over the tether cable on the practice fields.