You might look at the Neato robotic vacuums. Unlike Roomba's random wandering, the Neato bots have 360-degree LIDAR on top and a wall-finder on the side to do SLAM. They also have a USB port on the side that supposedly provides raw data from the sensors as well as direct motor control. They get a good 1-1.5 hours of run-time per charge with the vacuum turned on, probably longer with it turned off. All that robot for under $200 if you watch for sales.