This is another personal mod of mine. It's not been fully tested, but so far it seems to work fine.

This mod edits the Brahmin that your provisioners use and turn them into robots. The robots have the proper voices and sounds and so on, and behave just like the Brahmin does AI/Gameplay wise. They follow around and behave properly.

The robots are completely unarmed, and they use the pack armour from Automatron so they look like proper transporation droids. As such, the DLC is required. To make this mod work in an existing save, you have to move your provisioner to another settlement, instantly move them back (you can do this before they even leave so it takes like a second), and then assign their supply route again. Resulting the brahmin to be deleted, and spawn a new working robot.

Only known issue for now is that their names didn't change. I don't know why and I think it has to do with the script. So they're still called Pack Brahmins if you examine them. Even so, that's a small cosmetic issue and they still look and behave like robots.

Also, before any boring nerds decide to make a pedantic comment about lore, then explain how the Rust Devils can build literally thousands of robots from scratch, but the settlers can't make one per settlement?

Also worth noting that the robots have a smaller collision geometry than the brahmin. Which means that if you get the bug where they spawn inside your house or whatever, they should be able to exit on their own. Making life a lot easier.

Update: 

Vagabond has posted a compatibility patch for those who also wish to use Yagisan's Better Caravans, take a look here: 
https://www.nexusmods.com/fallout4/mods/71901