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?
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.
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.
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.