Abstract: A method and apparatus is provided for controlling the parallel blade slope angle of a blade in order to maintain a desired cross slope during normal operation of a motorgrader regardless of whether the motorgrader is turning, the front wheels are side-tilted or the blade supporting A-frame is side-shifted. The present invention controls the cross slope angle cut by the blade of a motorgrader by substantially continuously sensing the perpendicular slope angle of the blade by means of a slope sensor and the angle of rotation of the blade relative to the direction of the travel by means of a noncontact sensor. The sensed angles are used to calculate the parallel slope angle of the blade relative to horizontal which is required to maintain a desired cross slope angle. The parallel slope angle is sensed by means of the slope sensor and controlled such that it is maintained substantially equal to the calculated parallel slope angle to thereby define the desired cross slope angle set by an operator.

Abstract: A position sensing system calculates the X-Y coordinates of a point using triangulation and determines the direction in which the point is moving. The triangulation calculation is based on the coordinates of at least three retroreflective elements spaced apart from each other around the periphery of a two-dimensional coordinate frame, and the measured angles between the lines projected radially outward from the point to each of the retroreflective elements. The accuracy of the measured angles is achieved by using a rotating member supported by dedicated hardware and controlled by software. The member rotates with a beam of light generated by a light transmitting and detecting device positionable at the point. The light transmitting and detecting device receives the beam of light reflected back from the retroreflective elements and generates an output signal in response thereto.