servo controller schematics
They are a bit expensive, but I recommend you look at the SmartMotors from Animatics Corp.
They offer a combination brushless motor/encoder that has a RS232/RD485 addressable controller that will drive the motor to a specific position, at a constant speed, at a rate, as if it were a stepper, etc. Basically anything you might want to do with the moter can be commanded over the serial port. All the closed loop stuff is handled for you (after you tune it).
They offer a range of motor sizes & the controller by itself.
We replaced a number of applications with the smartmotor solution because of teh flexibility & easy of customization.