glitching motors

I am having a problem with our motors. In autonomous, when we put the robot on blocks the motors don’t glitch but when we put the robot on the ground the robot goes for about 10 cm, stops, goes for about 10 cm, and then stops. It does this over and over again and I can’t figure out why. Our motors are on pwm03, pwm04 , pwm05, and pwm06 so I don’t think it is an interrupt problem. Help is appreciated.

Is it possible that you are tripping circuit breakers? You would hear a click if that were the case.

Sorry but I am pretty sure that no clicks were herd from the breakers. To be sure I’ll check that first thing tomorrow. Would anything else cause the motors to glitch.

It could also be dropping voltage on the 12v battery causing the Robot Controller to keep resetting.

I agree. I have seen this exact behavior in our '04 robot when the main battery is low. (It is actually rather hazardous) What happens is that under a heavy load the voltage they main battery supplies drops, and since the robot controller needs ~7V to function it turns off. Since the Victors are no longer receiving a signal, the default to neutral. This stops the motors drain on the main battery, allowing the voltage to come back up, which then allows the controller to reboot. The pause is caused by the time it takes to reinitialize the robot controller. The robot then reinitializes and the motors start moving it, closely followed by them pulling the voltage down and reseting the robot controller again. The reason this wouldn’t be present during testing on blocks is that the motors aren’t under significant load. Try installing the backup battery, or charging it if it is installed and see if that clears up the issue.

Watch the lights on the Victors to see what they do:
Green = Full Forward
Orange = Neutral / Brake
Red = Full Reverse
Flashing Orange = no PWM

If they flash when the motors stop, then they are not getting a PWM signal. Also, do you have a charged back up battery connected to the robot controller? It will provide power to the controller if the main battery dips for a short time.

Brian

Thanks for all of the replies. I’ll test it with a full backup battery and a full 12 volt battery first thing tomorrow. Thanks

Hey don’t forget… if youre running your PWM cables right under or around or very near the CIMs you could be having electrical noise issues…

it is just a floating 5v signal after all…

-q