US 4,717,251 AGranted

Elevation measurement in high order surveying

AssigneeCubic Corporation

InventorsLeon W. Wells, William E. Mimmack, Werner Hauschild

Life of this patent

Estimating the term…

Loading patent…

Abstract

A surveying instrument and procedure are provided for the precise determination of elevation differences in the course of a surveying traverse. The instrument comprises an optical wedge 13 situated on the horizontal longitudinal line of sight axis 27 of the primary optical system between the objective lens 11 and a target under observation. The wedge is arranged for rotation about this axis and with such rotation angularly displaces the diverted line of sight 28 from the horizontal to the plane of the target. The degree of rotation required of the wedge to acquire the target 33 is measured by electro-optical angle encoder means 10, and the distance to the target by EDM means 24, 26. The difference in elevation is calculated trigonometrically by computer means utilizing as data the wedge diversion angle, the sine function of its rotation, the computed angular displacement of the line of sight, and the distance to the target. The procedure further includes the cooperative employment of two such instruments 20, 30 each as the target for the other, to thereby increase the accuracy of measurement through the averaging of the combined results. Also included in the instrument is a mislevel compensation system 60 which provides both optical and electronic correction in the event of mechanical deviations in the orientation of the instrument.

Claims7

Dependent claims

Measuring apparatus comprising:

(a) an instrument including optical target viewing means comprising an objective lens;
(b) an optical wedge element situated on a first segment of the line of sight of said viewing means at a point between said objective lens and a target under observation, thereby to divert said line of sight a fixed degree from said first segment;
(c) means mounting said wedge for controlled incremental rotation about said line of sight segment, thereby to cause said diverted line of sight to be displaced a controlled distance along a circle segment at the perpendicular plane of said target;
(d) controllable drive means for rotating said wedge mounting means and effecting said incremental wedge rotation;
(e) angle-measuring means associated with said wedge mounting means for indicating the extent of said incremental rotation thereof;
(f) azimuth base means mounting said instrument in a substantially horizontal plane;
(g) controllable azimuth base drive means for incrementally rotating said instrument about an axis substantially perpendicular to said first line of sight segment;
(h) photoelectric image sensing means situated on the line of sight of said viewing means at a focal plane thereof for providing electrical data indicative of the relative position of a sensible photic target image with respect to a predetermined point on the photosensitive surface of said image sensing means;
(i) means responsive to said electrical data for controlling the respective wedge- and instrument-rotating drive means, thereby to cause movement of said target image toward said predetermined point;
and
(j) distance measuring means for determining the distance between said instrument and said target.

8 more elements

A procedure for determining the difference in elevation between two horizontal datum planes, said procedure comprising:

(a) positioning a target in the first of said datum planes;
(b) providing optical target viewing means comprising an objective lens and having an internal longitudinal line of sight;
(c) orienting said viewing means so as to position said longitudinal line of sight coincident with the second of said datum planes and its field of view encompassing said target;
(d) situating an optical wedge having a fixed diversion angle upon the viewing means line of sight at a point adjacent said objective lens and intermediate said lens and the line-of-sight-perpendicular vertical plane of said target;
(e) orienting said wedge to divert the viewing means line of sight by said fixed angle on said second datum plane;
(f) rotating said wedge about the segment of said line of sight extending between said lens and said wedge to thereby displace the diverted line of sight along a circular arc at said vertical target plane to intersection with said first datum plane;
(g) simultaneously with said wedge rotation, rotating said viewing means upon its vertical axis to thereby displace said diverted line of sight to intersection with said target;
(h) determining the degree of said wedge rotation required to effect said line of sight target intersection;
(i) calculating trigonometrically from said degree of wedge rotation and said wedge diversion angle the vertical angular displacement of said line of sight from said wedge to said target;
(j) determining the distance between said wedge and said target;
and
(k) calculating trigonometrically from said distance and said vertical displacement angle the difference in elevation between said datum planes.

9 more elements

Dependencies are inferred from the claim text.