slow death of the robot
 

so we built our drive system a while ago (2.5 weeks) and everything working good. now with with the ship date in like 2 days, we can't turn any more, it's unresponsive and slugish... everything's just not right. Nothing came loose, everything's tight... i don't know what's going on? Can the cim motors wear down or something so they don't work as well? Please help us

Are you using a fresh battery?? That could make the robot sluggish very quickly.

Weight
 

Possibly the weight added in the past two weeks (wiring, arms) have weighed your drivetrain down and creates more rolling/scrubbing friction on your tires.

If you remove weight, does it run better?

Andy B.

This happened to us in 2001, we could drive great- but after we added some weight the motors just didnt have the umph to accelerate us.

Greg

we're using fresh batteries, we only added a few pounds of weight, would it make that much of a difference?

What has run out of grease?
What has been taken apart and put together just a bit diffrent.
What has become loose in 2 weeks of driving.


Wetzel
~~~~~~~~~~~~
Everything has a duty cycle.

You'd be suprised what a little weight added can add in binding and friction. Try to nicley grease up everything, and if that doesn't work, try to take off some of the weight and see if it still works sluggish, or if it goes back to it's own perky self...

C.G.
 

Did you move any of the weight around (i.e. did you change the location of the C.G.?). That can cause problems. If you're using 4-wheel-drive with tank steering OR tank treads (with tank steering, obviously), the closer the C.G. gets to the center of the robot footprint, the more difficult it is to steer. This can be shown with a static analysis.

-Chris

You should check all your sprockets and chain to make sure they are still straight and tensioned correctly. Our drive train slowly destroyed itself last year. If you turned the sprockets the, the chain would hang at one point but turn it a little farther and the chain would be as tight as could be without snapping the chain.

after we finished our drive system, we tightened everythign really really really tight with thread lock, so i don't think they moved..

can the cim motors if heat builds up, and there's alot of internal friction can the parts inside of em get missed up? or no... this is not possible and i'm really confused

The cim motors are designed for near continuous duty cycle... my guess is they are fine unless you've been applying a wicked side-load or something.

Greg

1. Does the robot run OK if you lift it off the floor? If it does then weight/friction/mis-alignment of parts is the probable cause.
2. If it does run but is slow, check the condition of the speed controllers are they showing full forward or full reverse lights when pushed to maximum? If yes then any of the above could be the cause or high resistance connections. Check the crimps and tighten the screws of every electrical connection. If the speed controllers are not going to full throttle then suspect software.
3. If it doesn't run when off the floor and the speed controllers are showing max speed, then measure the voltage being fed to the motor with a voltmeter. It should read the same as the battery when at full throttle. Be sure to place the probes on the motor side of the last connection before the motor. If not, any connection between the motor and the battery could be faulty including those at the battery terminals.
4. Motors can be damaged by a lot of heat. Is this the case? If you are over working the motors and they get hot (remember the cims have no fan or anyway of circulating air) there is a possibility that the windings inside have shorted. The condition results in low power out, high current in and a burned smell when near the motor. Sorry, there is no coming back from this failure, replacement is the only answer.
If you check all the above and still can't determine the cause, take a known good motor and connect it to the speed controller and see if it will run. If that is OK then suspect a bad motor.
Let me know what you find.

ya the robot runs fine i think this is the problem

"If you are over working the motors and they get hot (remember the cims have no fan or anyway of circulating air) there is a possibility that the windings inside have shorted. The condition results in low power out, high current in and a burned smell when near the motor. Sorry, there is no coming back from this failure, replacement is the only answer."

b/c there is a faint smell around them, and the motors are hot to the touch. Can we order replacement motors and bring them with us to the competietion, then switch em out on thursday?

Yes, you can. Bring extra for afterwards, and think about a way you can keep those motors cool.

Of course you can order spares. Did you damage the motors while driving? Please check for as many of the possible causes as you can before ship. You need to know what the problem is so you can plan the fix for your first regional. There is still the possibility that the motor are OK and something else is wrong.