Servo Vs. Induction?

[KNRO]

We have a decommissioned 5m radio dish that we plan to use for amateur radio astronomy purposes. There is a lot of mechanical & electrical work to be done before the system can be ready for automation. Currently, you can move the dish using a jackscrew in either direction (left-right 0-360, up-down 0-90). For motion control, some folks proposed that we use a 1-2 HP 3 phase AC induction driver for both axis. Since I'm responsible for writing the control software that will eventually utilize these motors, I'm interested in closed-loop control. So they proposed we utilize a computer controlled VFD (Variable Frequency Driver) and add encoders to the gears of the axis and that's our feedback.

 

But since we really need precision control (on the order of arcminutes, 1/60 of a degree), wouldn't make more sense to use servo motors? From googling a bit, it also seems there is a lot of servo motion controllers out there that can everything but the kitchen sink. So which option is more sensible? Do I need to consider more options?

 

Any help is highly appreciated!