Let's Make Robots!

Motor with encoder

Hello everyone. My college has some project organised, to introduce mobile robotics to highschools in my country, and they asked me to design a robot which would be used for that. And it needs geared motors with encoders, and since the only thing I ever used was servos, I need help choosing them.

Robots would be around 1-2kg, and it would be good to be able to carry atleast 1 more kg. Batteries would be 4 AA, either rechargable (4.8V) or normal (6V), so the motors should work for both. They should be as cheap as possible, because if we can lower the cost of one robot we can get more robots! And the shop would have to have around 100 of them.

So I need your recomendations for motors and place to buy them! Thank you very much in advance everyone :) 

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
You might consider Rover 5 chassis's. The two motor version is cheaper but still has enough torque to handle 2-3Kg. This would give you the built in quadrature encoders and a complete chassis to build upon. It might be possible for me to offer you a special deal as it is for a school.

Well, I have to say that motors with built in encoders don't come cheap for the weight you're planning. To move 3kg on a level surface, the motor needs to put out half that weight (you will have 2 motors) at the surface of the wheel that touches the ground (the wheel's radius). Say that the wheels have 10cm diameter, at 5cm radius the motor needs to put out 1.5kg, that means at 1cm, it needs to put out 7.5kg force. This is the minimum, always is a good idea to have stronger motors. So, motors that have 8-10kg-cm torque with built in encoders you can find at Pololu: http://www.pololu.com/catalog/category/116 but will cost you $40 a piece.

If you can lower the weight limit, here is a motor that has built in encoders and about 1.2kg-cm torque. http://www.goldmine-elec-products.com/prodinfo.asp?number=G16279 Watch out for it, from time to time they have it on sale for $7.95. Here is a good read about it: http://www.robotroom.com/FaulhaberGearmotor.html