Choosing a PLC and an optical encoder for a high-precision rotary table

[Yegor 0]

We consider making a rotary table capable of two operation modes: 1) rotating at speeds up to 3 rpm, and 2) positioning with precision of 60 arcseconds. This gives us 21600 positions per turn and 1080 positions per second at max speed. Current position must be recorded upon signal from an ultrasonic scanner (which is a blackbox atm) with aforementioned precision level to be fetched by a PC later. This kind of control is new to our company. I think it could be implemented using a PLC with high-speed inputs and an incremental optical encoder attached to a VFD motor shaft. Am I right? Particular products? Any suggestions at all? Thank you!

[RussB 22]

With a very good VFD and motor it might work, but this is better done with a Servo motor. IMHO, a good rule of thumb is VFD do a very good job of speed control but for position control a Servo is best. Another thing you need to verify is that your ultrasonic sensor can react within 1 millisecond.