Jaguars/CIMS halting during operation

[EthanMiller]

While driving the robot, our drive CIMS randomly cut out. We're using the ToughBoxes to gear together two CIMS on each side, and they're definitely going in the same direction.

Each CIM has it's own Jaguar, which has been connected correctly as near as I can tell.

This happens mostly when a quick change of direction takes place. Afterwords, the motors cease working until we disable the robot from the Classmate, then reenable it. Using the default Java code, the only thing that stops working are the CIMS/Jaguars, which have flashing yellow lights. If joystick buttons are pressed, the solenoid LEDs light correctly and the NetBeans output shows the correct output, as when switching from Tank to Arcade Drive.

Although I don't remember it, our robot last year had the same problem by a few accounts, and stopped as soon as we got to competition. I've tried everything I can think of short of programming in an acceleration curve. Also, searching on CD turned up nothing of use.

Any ideas?

[mdecello]

We had the same problem last year. Although my knowledge base is much more mechanical than electrical, I recall that it had something to due with a voltage drop. To solve the problem, the power wiring to all motor and Jaguars was increased to 10 gauge wire and all connections were changed from crimped to solder. I hope this helps.

[JesseK]

Perhaps this post will help:
http://www.chiefdelphi.com/forums/sh...65&postcount=6

It might also help to figure out if your code potentially sends a 0 instead of 255 based upon joystick input to motor control algorithms. Excel or Matlab would be great to detect this since you could map out expected motor outputs based upon the joystick input map.

The 'filtering' Russ refers to is as simple as 'smoothing' the outputs to the motors by not allowing two chronological outputs to have a difference greater than N, where N is determined experimentally. Typically we found that if we gave it 300-500ms in between full forward/reverse this problem never came up, yet that was also on a slick field.

[EthanMiller]

Ok, that makes sense. I'll try these. Thanks for your time.

[apalrd]

We had a similar problem on a shooter motor last year, after about 1/2 hours of continuous practice or demo. The control algorithm set the CIM, geared around 1:4 reduction to a 6" diameterx18"long drum, into full reverse for a short time while the feed belts backed the balls down to prevent balls that were already touching it from firing before it was spun up, then switched into full forward and spinning up while the feed belts slowed, reversed, and fed the balls into the shooter wheel. This sudden change in direction could cause the battery voltage to drop enough to reset the Jaguar controlling it, but after waiting a few seconds it would return to normal operation. A battery change would always fix the problem. We used 12 gauge wire for all 40 and 30 amp motors (CIM, F-P, 545) with crimped connectors last year without problems.

[Joe Ross]

What does the Jaguar's LED do when this occurs?

[Al Skierkiewicz]

Ethan,
What you describe is a classic symptom of powering the wireless adapter from a breaker on the PD instead of the dedicated 12 volt supply connector designed for this application. That 12 volt output is a regulated power supply, not the battery. If you had this last year but it stopped, a knowledgeable inspector likely saw it and had you change it. During start and direction changes and especially during hard turns with tank drive, the battery voltage will pull down to as little as 4 volts for short periods of time. This is enough to cause the wireless to reboot.

[EthanMiller]

Thanks, everyone. Seems that powering the digital sidecar fixed it.

@Al - Not with the bot now, but I'm pretty sure that's not the case, due to following the PD diagram pretty closely while wiring, to catch things like that.

@Joe - The lights flashed the "no signal" yellow blink.

[Al Skierkiewicz]

OK,
Let us know what you find.