Here is a modular autonomous robot that not only mows the lawn but also shovels snow and removes leaves. Just set boundaries for it, and the rest is easy. It comes with 3 modules that you can change easily. The robot takes a proactive approach to finishing its tasks. For instance, it removes the snow as more is falling down. It also cuts your grass a fraction of an inch each time, so work never piles up.
Kobi has a max coverage of 7 acres (for the lawn module) and 0.37 acre for the snow module. It goes as fast as 2mph.