Weirdest issue with our robot!

[Al Skierkiewicz]

Andy,
It could be a variety of problems including a low battery. Were the jaguars slowly flashing red? This is an indication of a fault, usually over current. It lasts 3-4 seconds before the jaguars return to function. Were they flashing yellow like they do when the robot is disabled, then the battery voltage was so low that the Crio went into voltage protect mode. Certain robot designs draw very high currents in turns. It is also possible that there is something wrong mechanically on one side or the other of the robot drive system.

[rsegrest]

What code/language are you using? If it is LabView are you using scalars in your programming?

[J_Beth]

If the problem started when you were turning hard to the left and it got worse as you kept turning to the left, could it be that your joysticks have gone bad, or is that even possible.

[reversed_rocker]

the joysticks can become uncalibrated. they center themselves when you plug them into the driver station, if you accidentally bump them while you're starting up you can have a joystick thats not centered properly. i dont think thats the issue but its a problem thats good to be aware of

[J_Beth]

Originally Posted by reversed_rocker

the joysticks can become uncalibrated. they center themselves when you plug them into the driver station, if you accidentally bump them while you're starting up you can have a joystick thats not centered properly. i dont think thats the issue but its a problem thats good to be aware of

well, i am not quite sure of how joysticks operate, if they use pots or something else to measure their location, but could a sensor have gone bad so that it no longer reads that the stick is going left?

[Al Skierkiewicz]

Andy,
The Crio goes into protect when the battery voltage falls below 5.5 volts for some length of time. You can get a little insight to this if you watch the voltage reading on the drivers station. Voltage samples are not continuous but if you notice voltage running up and down in turns and getting as low as say 7 or 8 volts, the dips are likely much lower. Reboot of the Crio can take place if the battery voltage should dip to around 4.5 volts at which time the 24 volt regulator in the PD starts to cut out. You know how long the Crio takes to boot so this is a risky issue for competition. Tank turns with high friction drives and wheels, cause CIM motors to draw near stall current. That is 129 amps per motor.

[voteforandy1]

For some reason our classmate shows our battery voltage is at 0.01 at all times when enabled, but that can't be true. How do I fix that?

[Zac Pilarski]

how are you getting your voltage value

[weinertj]

I'm on the same team as Andy. Yes, we are using Labview, and we have scalars.

[voteforandy1]

We think the problem is with the cRio voltage protection mode. How can we be sure? What is the indicator of voltage protection mode other then low voltage? Is it a light flashing on the cRio? And if this is the problem, then how do we lower the voltage we're using when we turn? Thanks to anybody who responds!

[PAR_WIG1350]

I once had a bike that did something very similar. Every time I turned left, I fell off the bike. I turned out the brake cable was in an unusual position so when I turned left, the front brakes were applied.

Sorry for being off topic

try zip-ties, they fix everything.

ON-TOPIC EDIT: I think the cRIO actually power cycles in voltage protection mode so I would look for signs of the cRIO rebooting. (Flashing lights, erratic starting-stopping of the motors, etc.) Also, If any thing, I think you would be drawing too much current which should trip the breakers in the PD board; the PD board limits the voltage already. Are the transmissions lubricated sufficiently? Are the wheels too soft? Remember, the CIMs can only output so much power, to get more torque you could try a different gear ratio or you could run the jaguars (assuming you are using them) in torque (current) control mode.

[J_Beth]

Originally Posted by voteforandy1

For some reason our classmate shows our battery voltage is at 0.01 at all times when enabled, but that can't be true. How do I fix that?

Look at <R66> it tells you to install a jumper on the breakout board that is installed in slot 1 of the CRio. We had this same issue last year, and i believe this was how we solved it.

[Al Skierkiewicz]

Justin,
The jumper is needed for the Crio to monitor battery voltage. When the voltage falls to about 5.5 volts, the Crio disables PWM outputs. This is done in anticipation of the voltage falling to 4.5 volts at which point the 24 volt power supply becomes unstable. It is possible to draw the battery down when you have multiple CIM motors in stall.

[voteforandy1]

Originally Posted by Al Skierkiewicz

Andy,
It could be a variety of problems including a low battery. Were the jaguars slowly flashing red? This is an indication of a fault, usually over current. It lasts 3-4 seconds before the jaguars return to function. Were they flashing yellow like they do when the robot is disabled, then the battery voltage was so low that the Crio went into voltage protect mode. Certain robot designs draw very high currents in turns. It is also possible that there is something wrong mechanically on one side or the other of the robot drive system.

SMART!!! I didn't think about the voltage turning off the crio or putting it in protection mode. I think that is the most likely problem considering what I've seen. It makes perfect sense for what's happening. And it would make sense that it would only happen turning to the right because we sanded our wheels down and I bet one side is still much rougher than the other which makes it tough to turn which take a lot of energy. I will definetly look into that tomorrow! Thank you a billion times, chief Delphi rocks!