How to return the servo to the origin without external sensors

There is no sensor that can use the encoder's Z-pulse signal. But this can only be returned for one week.
By using a holding register to memorize the current position, when it reaches the vicinity of the original position, the search for the Z pulse signal is executed.

The Festo electric cylinder has a way of returning to its original position, which is to detect the current by colliding with the mechanical limit and then acting in reverse for a certain distance.