The servos have a pulse (step and direction) interface, allowing drop-in replacement for stepping systems. Systems start at $895 for a 15A drive, 100W motor and 10' cable.
Companies in this article
MotionOnline.com: Economical AC servos
High-performance Sanyo Denki AC servo drives from MotionOnline.com (Duluth, GA) are said to be economical servo systems that can be an alternative to open-loop stepper drives.
May 31, 1999
