How to select DC motor?

[Eklmn]

I am building a chassis for small robot car. Its max weight including load will be about 20 pounds; power supply upto 12V.
What is general way to define appropriate DC motor/servo for the car approximately? What motor characteristic is most important here?

Thanks,
Ek

 

[ScottyUK]

Power output will determine ultimate speed.

Torque characteristics will determine acceleration to that ultimate speed.

Other things to consider are:

Do you need speed control?
Do you need to be able to precisely control movement?
Do you need to reverse?
Do you want to regenerate power on decelleration or travelling downhill?



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If we learn from our mistakes,
I'm getting a great education!

 

[Eklmn]

Thanks Scotty.
Yes, I have purchased OOBOT40

http://www.oricomtech.com/oobot41.htm

that does speed, reverse control and more. I will buy more powerful H-bridges if requires. Initially I selected Futaba S148 servos, but they do not look powerful to carry 5-10kg (20lb).
The issue is how to estimate what motors needed.