Stalling Issue

Does anyone have any idea how to fix stalling issues on the drive train? My robot was working perfectly fine for about 2 months now, and all of a sudden it just started stalling out. I have no idea why, but i tried changing everything, motors, wires, cortex, and power expander. The only thing that may be the issue is the drivers not driving properly, or bumping into the field (that hasn’t been a problem since we always bump into the field, but that might be a reason). So can anyone give me any solutions on how to prevent this from happening?

Have you guys added a lot of weight since the time that it was working before? That could be the reason. It could also be your drivers. If the drivers are rapidly changing between forwards and backwards, that might be severely heating up the motors. You may be able to program something to slow down the switch if you find that that is the issue. Good luck!

Can the wheels spin freely for 5-10 seconds if they are not physically connected to the motors? Sometimes a chassis can get bent after somebody drops it or steps on it, for example, and that can cause misalignments in the system. Are you sure all the bearings and shafts are still lined up properly?

We haven’t added any weight since, all we have been doing is programming and driving

yeah the wheels can spin properly 5-10 seconds without contact to the floor, and everything is aligned

How many different main batteries have you tried on this robot? Is there a chance you have a couple of failing batteries that can’t hold a charge for very long?

As Electrobotz already pointed out, if you think it’s a driver problem, you can write your controller code to prevent a driver from jerking the power back and forth so much. The code can ramp the motor speed up and down so quickly that a human might not even notice it but it could make a difference to the motors.

Pushing into the wall could be it. It’s a pretty heavy load to apply to your drive if it’s geared high to speed. How many motors are on your drive? Is it chained? There could be too few motors for your applied load, or the chain tension could be too much. Just small things to check.

The robot may not be the problem in your case. Has your driving style changed at all from 2 months ago. If you were testing the bot 2 months ago your motors may have not burnt out since testing stages dont usually stress the motors. But if you guys are starting to practice for comp. your driving style usually changes because you begin to drive more competitively and usually this is when problems happen. if you have motors left you could just add it to the base to fix the problem.

@Duke4221c and @g_sawchuk i’ll definetley try those suggestions and see if it helps prevent the stalling.

Do you have a way to weigh your robot? If so, what weight, wheel diameter, and gear ratio are you using? I have compiled physics equations for this exact reason.

@legomstr1 Sorry for the late response it took me a while to get the weight of the robot, so the robot is 15 lbs we r using 4 inch ominwheels and we have a 1:1 ratio with 3 turbo motors on each side

IMO, you are way over-geared, especially for a field that is only 12x6. Change out those turbo gears for high-speed, or, even better, gear it for 100 RPM and win some pushing matches under the wall. This will have the bonus benefit that your drive motors will never shut off because of overheating.

That’s the same gear ratio I used last year and, it didn’t stall that much for me last year and that robot was 18lbs. That said, I agree with @Rick TYler in that, that kind of speed isn’t necessary with so little space this year.

I agree with this. I found this out the hard way at my most recent competition. I downgraded to high speed gears afterwards.

This is usually perfect
4 inch- high strength
3.25 inch- high speed
2.75 or 3.25- turbo

will a 3:1 around 4-5 kg robot and 3.25 inch wheels stall?

You’ll be pushing it… I can neither confirm nor deny but I can say you should try.

just to play it safe i should just use turbro internal gearing