Troubleshooting problems with intermittent robot operation

[Ted-Werd]

This is our first year, so we are shall we say inexperienced. We are having a problem with our robot. It dirves really good for about 6-12 seconds. Then it losses power for 3-5 seconds before it runs again. any ideas on what the problem could be? We have looked at our power connections and they seem good but i could be wrong. Another thing is that it is completly unpredictable some times it runs fine for a while but others it is spasmadic. If there is any help out there i would appreciate it.

[Dave Flowerday]

Are you tripping any breakers? You can usually hear the "click" when they trip if you listen closely.

What do the LEDs on the OI and RC look like when this happens?

What is the battery voltage when this happens (use the select button on the OI so that the numerical readout is showing you the voltage)?

[Greg Needel]

This defiantly sounds like tipping breakers. Could you give us some information as to your drive setup (number &type of motors, wheels, gear ratios, etc) You might also want to look for mechanical problems in your system like chain alignment, and any resistance to free movement in your drive system.

[Ted-Werd]

we are not triping a breaker as far as the voltage, we will check that, thanks. I could be wrong i will check it out.

[Dad1279]

Try to operate it with a tether cable, and see if it does the same thing.

You can read the battery voltage from the OI. See if it drops.

Is the backup battery connected & charged?

[Alan Anderson]

Originally Posted by Ted-Werd

we are not triping a breaker...

Are you certain? The breakers are self-resetting, and your description of power loss for a few seconds sounds like what would happen if you do have too much current being pulled.

What motors are you using to drive? What are they electrically connected to? What breakers power them? A clear description of the drivetrain's electrical system will help diagnose your problem, or at least to rule out possible causes.

[Al Skierkiewicz]

Guys,
I am betting that you are running without a backup battery or one that is not charged. The condition you describe is classic RC rebooting which takes about 3-4 seconds. When the input voltage falls below 8 volts for a short period of time the RC shuts down. In the absence of a backup battery, this is a full power off kind of reset. Everything shuts down.
Now as to the cause...
Generally this is due to high currents developed in your drive system. As they pull current, the battery terminal voltage is also dragged down. If your electrical system also includes motors that are fed from the black fuse blocks, (the small one the RC is plugged into) and you have a lot of cable, a bad crimp or a loose connection then the RC will see much less than 12 volts while driving. Your electrical system should have one #6 wire from the terminal block to the 40 amp Maxi block. It should have a second #6 wire from the terminal block to the small black fuse block. I bet in the haste of wiring, you ran the second #6 wire from the Maxi block to the black block. When you do this, all the current for the drive system drops the voltage across the #6 wire. If you did this, and your drive system is using 4 of the Chalupa motorsin a tank setup and your drive system is inefficient, then you can easily drop 4 volts across the #6 wire especially when turning.
Ted, if you would like additional help, please PM me and I will do what I can. A picture would be nice for us to reference.

[Ted-Werd]

I will get as much information as i can and if possible a picture as well. Thanks for the help

[Ted-Werd]

I have checked, and the voltage does not fall below 11 with a freshly charged battery. So i don't believe that the battery is the problem, as far as the breakers,I have gotten close when it is running to listen, and I haven't heard anything sound like it has flipped. Our Electrician is saying that the operator interface does is not recieve a signal from the RC on the robot when it cuts out. If you would like to see some pictures of our wiring e-mail me tro620@sanjuanschools.org

[Joe Ross]

[quote=Ted-Werd;579007]Our Electrician is saying that the operator interface does is not recieve a signal from the RC on the robot when it cuts out.

Please follow Dad1279's suggestion of tethering it and read the thread that T. Hoffman posted as well as this thread at the IFI forums: http://www.ifirobotics.com/forum/viewtopic.php?t=51

[Travis Hoffman]

Originally Posted by Ted-Werd

This is our first year, so we are shall we say inexperienced. We are having a problem with our robot. It dirves really good for about 6-12 seconds. Then it losses power for 3-5 seconds before it runs again. any ideas on what the problem could be? We have looked at our power connections and they seem good but i could be wrong. Another thing is that it is completly unpredictable some times it runs fine for a while but others it is spasmadic. If there is any help out there i would appreciate it.

If your electrical system checks out (test this first!), could your radio connection be a problem? It seems to be a common issue among many teams this year. Check out this thread to see if any of your symptoms match what others are experiencing.