Im on a project to build an volley serving machine and now i have difficulties to find the right motor and controller. The setup is as follows: 3 wheels with electric motors with rpm range 500-4500 enough torque, cant really say a number. A rasperry pi to control the motors one by one. What would be the appropriate Motor type and where can i buy that.

 

how do you intend the "serving" sequence to be performed? Something like this:

?

 

I think we need at least to know the mass of the ball being served and the required serving velocity. Also you need to explain how the three wheels interact.

I don't think it is appropriate for AAC members to discuss reverse engineering of a commercial piece of equipment.

 

You dont need to answer specific to the usage case. But some websites to buy a variety of motors would be very helpfull. (200g, 140km/h) the three wheels spaced by 120 degrees to generate top spin or side spin.