Hi Vincenzo,
You’ll need a transport protocol between the robot and UE4. HTTP is a very reliable transport.
If you search youtube and the Epic Unreal Marketplace, you should be able to find a UE4 http:// client. There are Node.js robot libraries if you’re looking for a server interface. https://nodebots.io/
If you don’t want to do client/server request/response, check out Socket.io. This creates a two-way web socket.
I wouldn’t use raw UDP as it’s unreliable (TCP recovers from packet loss, UDP doesn’t), and unreliable makes for uncomfortable live events 
I’m a freelance web dev who got really excited about WebVR and wanted better tools (UE4). I could build this, PM me if you’re interested in hiring some help.
Cheers!
Michael