The ones I have seen use the same "invisible fence" transponders that dog collars use. It might work like a roomba though, you would just need to program the boundary once, and it would still be able to navigate around things inside that area.
The ones I have seen use the same "invisible fence" transponders that dog collars use. It might work like a roomba though, you would just need to program the boundary once, and it would still be able to navigate around things inside that area.