Method of guiding a robotic lawnmower

A method for guiding a robotic vehicle comprising the steps of:

• providing said vehicle with a plurality of sensors, each sensor comprising an electromagnetic radiation emitter, an electromagnetic radiation detector and a space therebetween, a plurality of intermediate and terminal sensor support members disposed in a substantially linear row, each of said members supporting at least an emitter or a detector of one of said sensors such that a plurality of spaces is defined between adjacent members, each of said spaces having an emitter on one side and a detector on another side, whereby paths of radiation between pair of respective emitters and detectors are substantially parallel to said row, and a central processor adapted to identify a location of a traversing cut-uncut vegetation border relative to said row on the basis of said signals;
• establishing a tracking position along said row of sensors at which said border is to intersect said row;
• positioning said vehicle on said border such that said border intersects said row at an intersecting position;
• advancing said vehicle along said border;
• generating a positive signal when a sensor senses by obstruction, regardless of amount, by vegetation of a path of radiation from a respective emitter to a respective detector;
• generating a negative signal when a sensor does not sense any obstruction by vegetation of said path;
• repeating said generating steps as said vehicle advances;
• sending a plurality of groups of said generated signals to said processor before identifying said intersecting position of said border;
• averaging said signals of said plurality of groups;
• identifying said intersecting position by identifying an adjacent pair of oppositely signalling sensors on the basis of said averaging of said signals and determining whether said tracking position is at or to the right or left of said intersecting position;
• and
• steering said vehicle straight when said tracking position is at said intersecting position, to the left when said tracking position is to the right of said intersecting position, and to the right when said tracking position is to the left of said intersecting position.