US Patent 9798328 Mobile robot area cleaning

A cleaning robot includes a chassis, a drive system connected to the chassis and configured to drive the robot, a signal generator and sensor carried by the chassis, and a controller in communication with the drive system and the sensor. The signal generator directs a signal toward the floor surface. The sensor is responsive to reflected signals from the floor surface. The controller controls the drive system to alter direction of the robot responsive to a reflected signal indicating an edge of the floor surface.