Timothy Hay, Robot Lawn Mower Detects Darting Gophers. Wall Street Journal, Aug. 18, 2010.
http://online.wsj.com/article/SB10001424052748703649004575437462518391800.html?mod=WSJ_hpp_sections_smallbusiness
http://blogs.wsj.com/venturecapital/2010/08/18/a-robot-lawn-mower-that-can-detect-darting-gophers/
(The blog contains a video tape that is not in newspaper)
My comment: Precise Path Robotics Inc.
http://www.precisepath.com/
Click "ABOUT" and then "Technology": Onboard the RG3 is a Local Positioning System (LPS) that provides positioning data within a golf course green at 1/10the the cost of comparable GPS devices. The LPS utilizes a combination of Ultrasonic and infrared communications to precisely locate the position and orientation of the mower on the putting green. This gives the mower the capability to travel in straight lines and along the perimeter of a green without the need of a human operator to guide it. In addition to the precise location information provided by th ePrecise Path LPS, the RG3 has a built-in laser that can detect and avoid running over any object in its path that might result in damage or a reduced quality of cut to the green.