I don't think a motion control system is necessary. However, you'll need to provide more information about your system in order to get a helpful answer. Do you already have a data acquisition card, and if so, can you find out what it is? If it's a National Instruments card, and installed in your computer, try opening Measurement and Automation Explorer (MAX) and see what device you have. Do you already have the other components of your system: the proportional valve and the anemometer? If so, what sort of signals do they need and provide? How much accuracy in your control do you need? If you don't already have your valve and meter, have you considered buying a flow controller that already includes both a valve and a meter in one package (I've used Mass Flow Controllers from Brooks Instrument, other companies offer similar valves)? While such valves aren't cheap, you can simply write a voltage to it corresponding to the desired flow, and read back the actual flow rate.
Message Edited by nathand on 02-12-2009 08:49 AM