A robot includes a robot body having forward and rearward portions, a sonar system, a drive system, and a control system. The sonar system is disposed on the robot body and has an array of emitters and an array of receivers arranged along a forward surface of the forward portion of the robot body. The emitters emit a sound wave and the receivers receive reflections of the sound wave. The array of emitters includes an odd number of emitters and the array of receivers includes an even number of receivers. The drive system supports the robot body and is configured to maneuver the robot across a floor surface along a path. The control system is supports by the robot body and is in communication with the drive system and the sonar system. The control system processes sensor signals received from the array of receivers.