On our 4WD drive robot (two drill motors and two Atwoods)we had 8 good matches with no problems, then on our last match the clips fell out of one of our drill motor transmissions, so we replaced both the drill motor and transmission. Then we noticed the voltage readout on our OI would drop to around 7v and reset our RC, when taking our robot from full reverse to full forward or full left to full right. Then we tried changing the 40 amp breakers around and the problem went away for the next match. Then it came back later in another match. Does anyone have suggestions to narrow down our problem?
We had our controller reset a lot too in LA in our last two qualifying rounds. We would have a fully charged battery before the match and it would be so dead that the controller would reset by the end of the match. We found that we had a lot of new friction in our drivetrain. Two of our chains were actually scraping on an aluminum plate. So, we fixed that. That helped our current draw a lot. Another thing we did was to buy a couple 6 Amp manual automotive battery chargers. These really pumped the juice in and we had no more problems. I would just check for excessive friction or things not lining up and charge your batteries really well and replace them after every match.
Guys,
You should invoke Nottke’s First Law of Maintenance, “Go where the last person was.” (Rich Nottke was a very knowledgeable guy I worked with a long time ago.) What this means is look to the last thing someone touched or changed as the source of the problem. Sanddrag, you said you changed the motor and transmission so I am suggesting that the assembly is misaligned or mounted in such a way as to increase friction and as such draw way more current.(enough to seriously load down the battery.) Check that all is correct and the hardware is tight but not too tight. I bet you find it.
You should know that a sudden shift from full forward to full reverse under load on many transmissions causes a HUGE and sudden current draw. (In Excess of 100 amps for each motor for a brief period of time) This sudden draw is enough to cause the terminal voltage of your battery to drop low enough to reset your controller.
Best advice is to not drive that aggressively. This has been our solution to that problem, we encountered it last year in the tug-of-wars.
*Originally posted by Al Skierkiewicz *
**Sanddrag, you said you changed the motor and transmission so I am suggesting that the assembly is misaligned or mounted in such a way as to increase friction and as such draw way more current.(enough to seriously load down the battery.) Check that all is correct and the hardware is tight but not too tight. I bet you find it. **
We have never replaced a drill motor and/or transmission. Like I said above, we corrected the problem by fixing the chains which were scraping on the plate. The hardware was tightened so much that our nylon spacers under the pillow blocks compressed and lowered the shaft to where the chain now scraped on the plate directly below it. So, we added in a washer to raise it back up and we have been okay since.
We don’t have any chain drive, just a simple gear box for the chips and the gearbox and drill motors that was supplied in the kit. We checked and there is no extra friction because of binding, everthing looks OK. We notice the RC reset during full forward to full reverse when it is up on the bench. Maybe the solution is not to drive it that aggressively.
I would suggest dropping a filter into the program to prevent going directly from full-forward to full-reverse no matter what the driver does. You shouldn’t have to depend on the driver’s skill. Mistakes can easily be made in the heat of competition and by less-experienced drivers.
See the “Programming” forum and white papers for details on filters.
Our team had the same problem, only when we would go forward the controller instantly reset, and when we went backwards, it didnt. It ended up just being a few loose wire connections, so check those out.
At the Manchester, NH regionals many teams (including ours) were having controler reset problems from seemingly unknown sources. The resets happened towards the ends of matches.
I don’t remember who suggested it, but the idea was put forth that static buildup from the rubber tires on the carpeting might have been a problem.
Many of the teams attached grounding straps from the chassis of their robots to drag on the floor and the problem more or less dissapeared.