Jaguar Lights

Hi all,

On one of our chassis which uses four or five Jaguars, we will have a very hard time driving. The drivetrain motors will appear to slow down or stop responding at all. It is not like I am switching directions of the motor very fast and this results, it just happens kind of randomly. When I was looking at the robot while someone else was driving, I noticed that the lights on the Jaguars were flashing green.

We put the robot on blocks to see if it was a motor problem or a electrical. Whenever I would bring the motors up to around 50% power, they would start flashing red or yellow. I could do it like that one one time and get flashing red and another way and get flashing green.

I looked on the Jaguar website and apparently flashing red is just like general bad things (over heated or over current), but I do not see how that would be happening at 50% power. Flashing green appears to be a corrupt PWM signal to the Jaguars.

Dad thought it could be that I programmed the drivetrain to use Victors, but it is not such - the drivetrain is programmed for Jaguars.

I’m not really sure what is wrong, this is the first time we’ve used the Jaguars in a major part of the robot.

Cheers
-Tanner

Check for metal shavings. If found, vaccum them out!

The same thing happened to us in Atlanta last year, the Jag. was still functional after the shavings were removed.

The next thing to check would probably be PWM’s. they are very finicky

On all four of them though? I’m not saying it couldn’t happen, but I don’t recall us doing any major cutting metal around the robot. All our saws and things are downstairs, far away from robots. Worth checking though.

Thanks
-Tanner

My bad, I misread your statement.

All four having shavings in them is kinda unlikely.

Check the PWM’s, I recommend hot-gluing them into the jags once you get everything fixed up. Also check the little black jumpers on the Sidecar, they could have been jarred loose at some point.

good luck!

I’m not certain, but my memory of our production robot when we tested the drivetrain yesterday is that the Jaguar lights were not steady red or green (as I would expect from a Victor) but fast blinking red and green. Everything was functioning as expected.

Just what you are seeing.

I won’t be able to re-check that for several days, but perhaps someone else can chime in and explain it.

I think we checked the PWM cables and they all seem fine.

If that is so, which kinda seems odd to me, what else would cause this erratic inability to drive well?

Looking at the Jaguar manual “Getting Started”, it appears you are correct that the Jaguars will flash fast red/green when the motor is not going full speed and only solid when going full power.

So that explains that part, but it doesn’t explain why our robot would cease working when we’re driving it. Naturally not knowing anything about the Jaguars, flashing lights seemed bad.

Hm…

Thanks
-Tanner

Does your digital sidecar have power? If you remove the 37 pin cable, do the 3 power LEDs remain lit? Is the 37 pin cable firmly mounted?

I would take a closer look at your color codes for the LEDs. On a Jaguar quick flashing green means that it is receiving a forward signal that is less than 100%. Quick flashing red means that the Jaguar is receiving a backwards signal that is less than 100%. Check on the speed of the flashes.

I’m not sure, but I would have to assume so since the motors were moving. I’d have to check tomorrow.

-Tanner

Goodness, many things.

For one, does everything seem to work OK when the wheels are in the air? Run the drivetrain like that for a while, to break in the gearboxes (and, to a lesser degree, motors). 30 to 60 minutes of unloaded movement will help.

Next, what’s the robot configuration? If you have 4 wheels, one in each corner of the robot, and are trying to turn with high-traction wheels - you may be popping breakers. That’s about the worst-case for turning. Does it drive well when you go in only straight lines (no turns)?

The gear ratio also affects this - very high ratios (slow speeds) allow better turning. Low ratios don’t leave enough torque to turn well, even with 6 or 8 wheel drive.

Lastly, check the system voltage while the problem is present. Voltages dropping to less than 10.5 volts or so may indicate a wiring or battery charge issue. Run all the motors (off the ground) and, using a voltmeter. find where the voltage drops are. From the - battery terminal (the metal of the battery itself, NOT what you have connected to the terminal!) to the PDB it should be very small; similarly, from the + terminal to the PDB should be almost the same (we expect a larger voltage because of the main circuit breaker). Then from the PDB input bolts to the input screws of the Jaguars (one at a time).

If you find a high voltage (as compared to the rest of them, assuming at least one is “good”) you need to correct it. Voltages around 0.1 to 0.5 are in the range I’d expect.

So, tell us more…

Tanner,
The condition you describe is a classic over current condition particularly in turns. However, the LED colors you report are not consistent with that condition. I would expect a steady ON RED indicator if the Jaguar was in a fault condition.

According to the Jaguar manual, a flashing yellow indicates a loss of CAN or servo control. That points back to the sidecar, it’s power connector and wiring, or the cable between the sidecar and Crio. Since you did not indicate you are using CAN, I am guessing the other flashing yellow code do not apply. If you are using CAN, the flashing yellow can indicate CAN ID problems.