This is a simulation program of a robotic lawn mower (2 wheel drive like my Tianchen or 4 wheel drive like my Ambrogio) on a lawn without slope:
The program can also simulate a lawn with slope (going from top to bottom of the lawn). You can see that the mower (like all other mowers) has a tendency to move into the bottom part of the lawn. Due to the slope, even after many hours, the top part of the lawn isn’t mowed properly:
Download (Windows simulation program):