DETECTING INSTRUMENT OF POSTURE OF EXCAVATOR

PURPOSE:To enable the measurement of a direction angle without using a condenser lens and to measure the slipping off quantity of a position by providing the 1st and 2nd photodetectors of photodetecting position detecting type in uniaxial direction having a photodetecting surface parallel to a datum axial line with its photodetecting surface parallel to the datum line and yet by providing the 3rd photodetector at right angls to the standard line. CONSTITUTION:The displacement quantity DELTAX0 of to the direction of an axis X (horizontal direction) of a datum axial line P' parallel along the central axial line of an excavator against a light axis P of a laser beam L projected to the direction of an excavating target, is directly measured from the detected result of photodetecting position DELTAX0 of either of the 1st, and 2nd photodetectors 5, 6, and with adding the correction of measured distance difference (a)-(c) to a detected result of photodetecting position DELTAYa or the 3rd photodetector 7, the displacement quantity DELTAY0 of to the direction of axis Y (vertical direction) of the datum axial line P is measured and also a direction angle thetaX against the beam light axis P of the datum line of excavator P' is measured from the difference DELTAXb-DELTAX0 of the detected result caused by the measured distance difference (b) of the 1st, 2nd photodetectors 5, 6.