Abstract: A transducer arrangement and method that generates control signals indicating relative positions of the ends of a hydraulically movable tool of a machine. The generated control signals of the present invention are used by a conventional control circuit of the machine to control the ends of the hydraulically movable tool having elevation receivers as an desired mode of operation or when reception by one of the elevational receivers of a elevational reference, which provides an absolute position of the ends of the tool, is interrupted. The conventional control circuit of the machine uses the generated signal of the transducer arrangement of the present invention to maintain a relative elevation position of one side of the tool to the absolute position of the other side of the tool as desired or until both receiver can reacquire the elevational reference.

Abstract: A blade control system is configured to control the spatial orientation of an earthmoving blade mounted on a frame of an earthmoving machine for working a surface of earth to a desired shape. The blade slope angle required to maintain a selected cross-slope angle is calculated and the blade slope is then controlled so that the sensed blade slope angle is substantially equal to the calculated blade slope angle. The method and apparatus of the present invention is capable of maintaining the desired cross-slope even when the motorgrader is steered through a turn. The control system includes an input circuit, a sensor system and a processor. The input circuit is arranged to generate an output signal representative of the desired shape of the surface of earth to be worked. The sensor system includes a first sensor coupled to the frame of the earthmoving machine to generate a first signal indicative of a longitudinal slope angle of the frame with respect to horizontal.