Weird Problem With Grey Jags

[Talguy]

This weekend we were wiring up our chassis just to test it and get the feel of it. We wired up four jags with PWM input signals. Our left side worked just fine but our right side would not work. Everything worked fine when we put victors in for out right side controllers. So the Problem, when we pushed our right sticks forward to 100% our motors would only move at 1/2 power. Measured the voltage at forward movement and it was 10.5V. At 100% reverse on the stick the drive train moved at 100% 12V. when the stick was zeroed and not touched the jags were putting out 10V to the motors and they were not moving. We checked the transmission and it was always in the correct gear. We do plan to use can when our cables we ordered come in. Does anyone have any ideas what could be going on.

[Jon Stratis]

Try replacing your battery for starters. A few weeks ago I got called in because last years robot wasn't working - two motors turned just fine, but the other two didn't. Very odd problem that I spent an hour or so scratching my head over. We swapped Jags in an out, redid wiring, replaced the digital side car... it was a mess. Finally I decided to start completely over with the obvious things I assumed they had checked before calling me over... to find the battery extremely low (somewhere around 9 V, IIRC). Replaced it, and everything worked fine.

If the battery isn't your problem, you may need to calibrate your PWM inputs. You can find instructions for that on page 2 of the "Getting Started (MDL-BDC)" link here: http://www.luminarymicro.com/jaguar

[Alan Anderson]

You're having problems with some of your PWM signals when commanding high forward power, but reverse works fine? That's a specific symptom with a common cause.

It suggests that your Digital Sidecar isn't getting 12 volt power. Check your wiring and verify that you have a 20A breaker in the Power Distribution board for the terminals you're connected to. Make sure the BAT, 5V, and 6V LEDs on the Digital Sidecar are brightly lit.

[drakesword]

Had a simular issue this weekend but with CAN

One jag would quit responding. Figured it was just a programming glitch (yes I am a programmer I blamed myself)

reset the robot and it worked again.

problem came up occasionally again within the next 20 minutes.

Finally two jags went down at the same time. I was called back in and heard the PDB squalling (which happens when the battery starts getting low)

Replaced the battery and didn't have any more issues.

Just FYI the robot was run for a good 45 minuets total which I found amazing for it still working ... mostly.

[Talguy]

Originally Posted by Alan Anderson

You're having problems with some of your PWM signals when commanding high forward power, but reverse works fine? That's a specific symptom with a common cause.

It suggests that your Digital Sidecar isn't getting 12 volt power. Check your wiring and verify that you have a 20A breaker in the Power Distribution board for the terminals you're connected to. Make sure the BAT, 5V, and 6V LEDs on the Digital Sidecar are brightly lit.

How would it be the digital side card when we replaced the jags with victors and it worked like it was suppose to.

[Jon Stratis]

Talguy - the Victors, Gray Jaguars, and Black Jaguars all have different operating characteristics. What affects one may not affect the others as much. Regardless, it's important in situations like these to double check everything that could possible affect it - battery, power wires, cRio, Digital Side Car, Jags themselves, code... there could be a problem anywhere in the chain.

So, check everything out, consider all the advise you've gotten thus far (starting with the easiest - replacing the battery and checking the wiring on the DSC - and working your way towards the most complicated), and report back. That way, we can help you work through the steps of resolving the issue until we find the problem and fix it.