Patent ID: 6729796
Filing Date: 2004-05-04
Classification: E01C

Abstract:
A method for automatically controlling the height of a tool hydraulically carried by a machine, comprising:providing a first sensor that outputs a first-side output signal indicative of the height of a first side of the tool; providing a second sensor that outputs a second-side output signal indicative of the height of a second side of the tool; providing a controller that is responsive to the first-side output signal for controlling the height of the first side of the tool, and is responsive to the second-side output signal for controlling the height of the second side of the tool; operating the controller to control the height of the tool hydraulically carried by the machine by responding to the first-side and second-side output signals when both are available; and if the first-side or second-side output signal is unavailable, then automatically using an alternative sensor to control the height of the tool on the side of the unavailable output signal, said alternative sensor being insensitive to movement of the tool in the horizontal direction,wherein the alternative sensor is a transducer arrangement comprising a detection device provided at one end of the tool and a source provided at the other end of the tool providing a reference beam, the output signal indicating the relative height between the ends of the tool from the detection device detecting the reference beam.