errrrCLICK....CLICKerrrrrrCLICK!!!

[Caleb Fulton]

That is the sound our prototype bot makes because the drill motors (on the low speed/high torque setting) will stall and trip the breakers (we are using the 30 amp ones...the 40's haven't come yet) every time we try to move the robot after a while. The battery is fine. The program was only sending 110 to the motor (not that fast).

Is this normal?

Would the 40's really help?

Is this a drivetrain issue (we are using the regular helical gears/gearbox/drill transmission for our prototype)?

BTW...if the robot is lifted off the ground, the motors are much better (they will only do their CLICK thing if you REALLY slam the joystick around).

[Patrick Wang]

I don't know exactly how these year's drill motors will behave, but it seems to me that you may have issues other than simply pulling too much current.

Make sure all your electrical connections are sound. A loose wire will cause you to pull too many amps and trip your breaker.

Also check to see if your drive train is freely running (assuming you took out the backdrive pins) there could be a bent axle or the like that is introducing a lot of friction to your system.

That motor should not pull more than 30 amps driving around freely.

[rbayer]

Try having the program send something faster. 110 probably isn't enough to overcome the friction of your drivetrain. In fact, sending signals less than 20-30 away from 127 probably isn't going to make your 'bot move anyway.

Also, this sounds like your shafts may not be aligned correctly. Have your Mech people double-checked them?

[Caleb Fulton]

"Make sure all your electrical connections are sound. A loose wire will cause you to pull too many amps and trip your breaker."

How?

Also...it had been running for a while (over 10 minutes)...would this change anything?

[rbayer]

Originally posted by Caleb Fulton

Also...it had been running for a while (over 10 minutes)...would this change anything?

It could be starting to over-heat, but a properly supported/aligned drivetrain should be able to go more than 10 minutes if it's not pushing stuff.

[Caleb Fulton]

Those helical gears are awfully inefficient, though

[FotoPlasma]

Originally posted by Caleb Fulton
Also...it had been running for a while (over 10 minutes)...would this change anything?

http://www.eatel.net/~amptech/elecdisc/cirbrakr.htm

The 20 and 30 and 40Amp self-resetting breakers, which we're all familiar with, operate on the principle of a bi-metal strip. Current through conductors generates heat, which causes metals to expand. Using two metals which expand at different rates as a single conductor, you can physically make the combination strip bend because one side expands faster than the other. This physical bending causes the conductive strip to lose contact, and therefore no more electricity flows until it has properly cooled.

Prolonged use can cause large amounts of heat buildup, which makes breakers more prone to pop than a breaker which is at room temperature or below.

#include <disclaimer.h>
I'm not an engineer (of any kind), so if what I've said is obviously flawed, please point it out to me.
Thank you.

[JVN]

What size wheels are you using?
Are you in high or low gear?

It sounds like there is just too much load on the motors. If you reduce inefficiencies in your drivetrain (Note: grease your gears) and use smaller diameter wheels you can greatly reduce the torque load on your motor at any given time.

This will cause it to accelerate better, and draw less current.

[Caleb Fulton]

Would you recommend having a muffin fan mounted on top of the breaker panel?

[ebmonon36]

right now we are using the the 8' plastic wheels from the kit. I think we have tried it in both high and low gear and it clicks in both. Grease does seem like a wonderful idea, and I know that the holes we drilled for the bolts could have been a little bigger to allow for a little more wiggle room
eric b.

[Caleb Fulton]

Eric, you grease monkey

[FotoPlasma]

Actually, what I posted is probably irrelevant given what's actually going on.

I'd think that the problem is mechanical.

I'm reminded of what our prototype (Snowbot, the drill, helical gears, and gearbox) did while in high gear.

Apparently, and this goes along with John's recent post, under not-so-great conditions, it's very easy to pop breakers in high gear.

I'd recheck that the drills were in low gear, and then, as John said, try to reduce any ineffiencies in the system. We slopped a good amount of white grease into the helical gears, covered the openings of the gearboxes with a couple shoptowels, and ran them for a minute or so, to get any excess grease out of the system. It worked very well.

[com]

Is this a drivetrain issue (we are using the regular helical gears/gearbox/drill transmission for our prototype)?

We had the same problem after we built the nice little gearbox setup first game us. After we built our real robot frame and trainy we have run the robot through ever possible thing in sight including people on chairs. (Going at 15fps) Its very hard to get the motors to draw enough current to cause the autoreseting breakers to switch. We found that the shafts on the gearboxes were slighty bent and we believe this was the problem to the mass current draw through the gearbox assembly that first gave away. I must say that chances are you have to order some good quility 5/8 keyed shaft and make sure your spacers and bearings are in good condition. Look for every little thing that could cause the motor to work harder then it should. It doesn't take much resistence to make the motors work many times harder then they should.

[ebmonon36]

I like white lith
yeah it is probably our gearbox. it worked fine on our first prototype, but now it is doing this. Caleb - was it doing this yesterday or when ever it was that we finished v1.2?

[Caleb Fulton]

It's done it before, but not really on the low gear...