Guiding principles in controlling small automated vehicles

This paper describes the principles of a control program that was used to drive a self-propelled, 25 HP lawnmower. The course to follow was predetermined and an integral part of the software program. It consisted of straight lines, 90 and 180 degree turns. The two critical pieces of information were the offset error and the angle the mower was, relative to the desired course. Determination of the angle was difficult and was achieved with limited success. The lawnmower was able to follow the course with an error of less than 8 cm (first standard deviation). The author discusses the Accutrak Positioning System, the control computers, and steering control.