That's not hard. The hard bit is adding capabilities for when people leave obstacles in the hallway, or little kids are running around and playing with it, or s

That's not hard. The hard bit is adding capabilities for when people leave obstacles in the hallway, or little kids are running around and playing with it, or some arsehole decides to tip it over, or the bin is damaged, or is over filled, or isn't positioned correctly, or the dumping spot is full, or the stairs just got new carpet. The problems with consumer robotics rarely are to do with the actual mechanics. Most electrical undergrad degrees have a module where you program a robot to follow a line or course, and it's quite simple to do. The problems occur when you take it out of it's test environment and 'leave it to the elements' as it were.