Last week our team did a demonstration outdoors on a rather warm (~75 degrees) and sunny day. Our robot powered up just fine and started off working like normal, but after about a minute the robot would stop working. It would basically randomly start and stop working throughout the day. Upon closer inspection, the “No Data/Signal” light was blinking red on and off. After about an hour or two of checking every wire on the robot (we even had the same trouble when using tether!) and kicking the robot violently, we were convinced our robot controller or operator interface was screwed up in some way. Then we postulated that the robot was working whenever the sun went behind the clouds (or clouds in front of the sun, depending on your views and personal beliefs of how the solar system works), and stopped when it was sunny. This was hard to rigorously check, but it did seem to have a greater chance of working after being in the shade for a bit.
Then, we did another demo that night – indoors – and everything worked fine.
Has anyone seen this before??? It had me mighty confused.
Last year (ie 2001), we had problems with our robot controller and the cold. The controller would refuse to boot when it was too cold. The InnovationFIRST people diagnosed it as a bad solder joint and told us to replaces. As you’re having the exact opposite problem, I doubt that’s the problem but figured this might help in some way.
Could there have been a devise that jammed your radio signal? If it works now, off the field, than it probably works was some other devise that was using channel 40, on a 900mhz radio. Than you will have to make a yellow dongle. It is in the white pages of CD. I had a similar problem like this @ a demo about 2 months ago.
I really doubt the weather really affects the brain’s performance. I mean we work at a warehouse that is partly heated, but it is still preaty cold in the winter and hot in the summer time. I remember that I demoed our robot at a fair that the temperature was at least 90 degrees and it stilled performed great.
Last summer, we drove our practice robot in the - very hot, I must say - Brazilian sun, to the point we couldn’t touch the battery (a black one :)) without burning fingers. So, I really don’t think your problem is temperature. Since you have the problem with either radio or tether, my optimistic guess would be the cable, if you used the same one, or in the worst case, something more serious with the Robot Controller or Operator Interface.
Could be all of the above or none. I would vote for RFI (radio frequency interference) first. Just look around and you will probably see a cell tower in the distance. (or right next door) Cold solder joints have a way of becoming downright cantakerous as the temp changes, in either direction. It is a matter of expansion and contraction with temp, remember. The fact that the device was telling you no data, you could suspect anything with the radio link including an intermittant cable between the interface and the modem at either end. Look for a severly bent cable close to the connector on any cable. This is a good candidate for wire fatigue, i.e. intermittant connections. Let us know what you find.
Al
Just look around and you will probably see a cell tower in the distance. (or right next door)
Buzz (175) was doing a demonstration and they seemed to have this sort of problem, but in their case the readout on the operator interface would just blink… i’m fairly sure there was a cell tower somerwhere nearby causing interferance.
Don’t discount the heat theory.
I work in electronics and I have seen a few problems that were heat and cold related. Sometimes we use heat guns on components to make them fail. Other times we may use freeze spray.
It could be a part in the Innovation FIRST interface has a borderline part that when heated fails.
We had an odd problem at National’s where it looked like the controller wouldn’t power up properly (it was stuck in some odd state where all the led’s would blink). According to a guy from Innovation FIRST (sorry, I don’t remember the name), they were having problems where a crystal was out of spec and causing problems at cold tempertures. After a few prodding questions I became less convinced with this answer, but the problem did go away as the day got warmer. Perhaps if they had a bad enough design to have their timing diagram waveforms be effected by cold, it could have been by heat as well.
But… my money is on interference, or a bad cable. A week or so ago we were getting a random “no data” light, though sometimes the light (and thus the controller state) would oscillate for several seconds. My guess here was a bad cable - this problem has since gone away with a different cable.
Speaking if interference. At our first regional (Western MIchigan) for the first three matches our robot would not perform. It would stop and go, lurch forward or backwards and do all kind of things we weren’t telling it to. We discovered that some teams were operating there robot WITHOUT the tether. Once an announcement was made, concerning this fact, our problems went away.
So please do not operate your robot, in the pits, without the tether.
This has been a public announcement brought to you by our sponsors. Your mileage may very
At the Philly regional, I saw very few people using the tether in the pits. But, by the nature of the different frequencies used, no two robots should ever interfere with one another, especially a competition-tethered bot and a non-tethered pit bot. You ever hear an announcement about no RF communication? You ever notice how the jugdes commyunicate? None of the problems anyone mentioned about RF interference would logically ever happen, unless you were within 5 miles of a major military base. Your problems are all most likely reception and heat related.
Guys,
No one should ever run untethered in the pits. The possibility for you to interfere with the the main event is as real as them interferring with you. Imagine a robot in the pits running without control, this is a safety issue as well as a competition issue.
There are not an infinite number of frequencies in use by the radio modems. This is a common misconception. Please see the docs on the Innovation First products and how they are configured during competitions. More than two modems on the same frequency could conceivably handshake to the wrong controllers.
In all cases of strange behavior, check the LED’s on the controller, they tell a lot about what is happening. The Innovation First engineers have really built a lot of nice things into that box. ABove all, remember that the controller will reset below 8 volts at the supply terminal, this will take out the controller for a few seconds to reboot, modems to handshake and begin running your software. Stalled motors combined with low charge on the battery will make this happen.
Al
