DIY robotmower garage port?

Devices
1

I want to build a garage for my robotmower and I want a port that opens when the robot leave the charging station, close again during the time the robot mows and then opens again when it´s time for the robot to return to the charger.

I have a Mammotion Luba 2 Mini, that doesn’t have any app in Homey. It does have a intergration in Home Assistant but I have never used HA and have zero knowleage when it comes to how to use HA.

Opening the port could be done easy with a switch that sends a signal when the robot leaves the charger. But I don’t know what to use to be able to open it again when the robot returns.
Another issue would be that the port needs to be able to open very fast, both when the robot leaves and returns, a linear actuator would probably be too slow. Maybe a electro magnet would work? But then I don’t know how to close the port again.

There must be someone that have made something similar?

2

Use a servo motor used in rv hobby. Will open very fast. Why not leave the port open when the lawn mower is active?

3

A servermotor might be the solution. The reason why I don’t want it open is simple, that’s the easy way of doing it and how most people do it. I don’t like the look of an open port but if I can’t figure out a solution that’s might be what I end up with.

4

Maybe a proximity sensor. I do not have any experience with this