Help - possessed robot!!!

Our robot has started acting quite strange. Motors will reverse direction on their own, and sometimes the motors are running full speed even after the operator shows us that his hands are off the controls.

Has this happened to anyone before? Any suggestions? I am going to check for shorts (but it doesn’t only happen with one single motor). Has anyone had any EMI problems with the motors and nearby PWM cables?

Thanks for any suggestions!

recharge your battery(s)

get closer

check crystals

ummm, have you messed up the trim settings?

Try turning your OI off. If the robot is still acting funny, there is some other radio source on that frequency.

it may be your micro controller. I know our went haywire at the NC regionals.
(kept switching from auotnomous to operator control and back during the match.)

I had a loose servo cable on my Vex paintball tank. It went haywire, randomly shooting paintballs in all directions. Goes to show why it’s not a good idea to build dangerous stuff like that…

Without a doubt it has to be interference from another tramsmitter of some type. We have been working on our robot at school when it has taken off and the arm will start moving. We have yet to find the source of this problem. We have shut down computers all cell phones and wireless devices and checked the rooms around us but there is nothing around producing any type of signal.

try to check the trims, and all settings on the controller, or go in the starter guide and find how to reset all of the settings, or try to get another microcontroller and-or controller

Reload the mastercode onto your controller, and then reload your program code. That should take care of random kinks that don’t seem to have an origin.

If you suspect it’s interference from another radio source try using a tether cable between the transmitter and receiver. Remove the crystals from both the transmitter and receiver and plug in a tether cable (a phone handset cable) and test with that setup for several minutes. If the problem goes away it’s an RF problem. It the problem still exists it may be transmitter or microcontroller related.

Hope this helps,

ken is roght, good thinkin’

If you are using any rc code (rcmotorcontrol, tank, rcinput), then using the setmotor function at the same time will cause a robot to go haywire.

We tried many things such as different m/c’s tethers and such but the only thing that helped was a tether.

I’ve heard of several robots randomly switching into autnomous and it seems to be that the M/C has gone bad. A team at my school had that happen to them and it seemed to happen when the M/C was jolted like when they hit something.

Thanks for all the responses!!! Here is what I can gather after some diagnostics. The problem is unrelated to the program and the master code. It may still be due to pwm cables and EMI with each other. This is surprising based on all the bundled pwm’s we use with our FRC bot, but these pwm’s are carrying heavy current to run motors. The FRC pwm’s are really used for sensors only.

The other thing the students have noticed is that it seems to happen only when the batteries get low. Perhaps there is an issue powering the receivers. I hope this may shed some light for those of you claiming similar problems.

We have definitely noticed more strange stuff happening to the robot when the battery’s get low so that could definitely be a problem.