Patent ID: 6300737
Filing Date: 2001-10-09
Classification: A01D,G05D

Abstract:
An electronic bordering system (1) for a working tool (2), in which system a border cable (3) is placed above, under or on ground or floor, so that it separates an inner area (4) within the border cable (3) from an outer area (5), which working tool is preferably intended for attendance of ground or floor and a signal generator (6) feeds the border cable with current, whose magnetic field (7) affects at least one sensing unit (8,8') located on the working tool (2), so that the sensing unit (8,8') emits signals (9) to a control unit (10), which in cooperation with an engine control (11), or a signal system for a driver, and at least one driving source (12, 13) directs the tool's movement in order to prevent it from remoting from the inner area (4), characterized in that the signal generator feeds the border cable with current containing at least two components (14, 15) of alternating-current with different frequency, and the components (14, 15) are lying in a known time relation to each other and hereby the control unit can evaluate the difference in the signals (9) caused by the magnetic field's different directions in the inner area (4) and the outer area (5), and the control unit can therefore emit an area signal (16), which mainly takes up one of two states depending on the position of the sensing unit (8) in relation to the border cable.