I would settle for one where I could mix up a tote or three of chemical, set a docking station on top the like oil MegaFunnel with a drop tube and a 240V plugin from a farm building, pivot panel, or generator, and hop on my iphone app to tell it to spray X, Y, Z fields on this approximate schedule overnight, text me when done or with issues, I'll be along later to move and refill. 

If you can make it fly the field with various sensors and get actionable remote data without groundtruthing, great, but we've been chasing that for at least 30 years.

Now you can spoon feed the crop like the irrigation guys.