Let's Make Robots!

3kg sumo with servos?


This is our first post. We need some advice.

We want to make a 3kg sumo robot with Arduino UNO. We have been doing our first programing experiments with temporal full-rotation servos, and now we wan't to choose some good ones and buy them.

We know most sumo bots use gear motors, but we would have to learn how to program them, and we have seen some sumos with servos, the problem is the torque ( we don't know if something like 15kg/cm is too much, too litle or what) and the rpm, since servos usually are slow.

We would appreciate any hint you could give us about the magnitudes of torque and rpm usually used









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First off, past the issue of speed, I don't think putting 7lbs on top of servos is going to fly...

In terms of drill motors --I have used them and I have 2 DeWalt drill motors on my robot Walter. I would not recomend them. They are pretty amazing in terms of power and handy in that you have a motor, gearbox and a threaded output shaft all in one case --they are also amazing in terms of how much power they can actually draw. If they are fully stalled, 50, 60 or even 70 amps can be drawn. When running normally, they still draw around 10 amps each. One more issue is the fact that they are designed to run much better forward than reverse and because one motor will be on the "other" side of the robot, one motor will always be running "backward". This can be a royal pain in the butt to get and keep your motors balanced (going the same speed). Bottom line: if you go with drill motors, be prepared for A) a huge controller and B) constant tweaking to keep them happy.

You may want to look at the motors used for electric windows in cars. They are worm-drive, pull around 3amps a peice, and come in right and left models.

Thanks a lot Chris, this is becoming more complicated than what I expectet hahahah.

I'm checking the window motors, the problem is that they come with very litle info (no torque, no rpm) and a high price. I'll keep checking. 

If you are going into a competition then I do not think continuous rotation servos are the best. They will be too slow, your robot will be a 3Kg tortise.

You really should consider a couple of cordless drill motors and a decent "H" bridge to drive them.

Drill motors seem complicated, do they work like a dc motor?

what about dc motors? what kind do they usually use in competitions??


Thank you very very much, we are really lost in this motor stuff.


bear in mind that although your sumo will be 3kg, so will the other one, so when trying to push the other one from the ring your pushing 6kg. you then have to factor that they will be trying to push you aswell.

I dont have first hand experience but i dont think (correct me if im wrong) that there is such thing as too much torque for sumo 

Thanks a lot mlandergan, I allready saw that article yersterday.

The problem is that in sumo I really don't know what's the usual acceleration of the robots.

And what about in the case when your robot is pushing againts another robot?