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US-12625241-B2 - Method and system for aligning surveying instruments

US12625241B2US 12625241 B2US12625241 B2US 12625241B2US-12625241-B2

Abstract

A method for aligning two surveying instruments in a common space in a process that uses an autocollimation of a collimated light beam transmitted by a first surveying instrument and reflected by a second surveying instrument. In the alignment process, the first surveying instrument may emit a collimated light beam towards the second the surveying instrument and receive a reflection of the collimated light beam from the second surveying instrument in an autocollimator. The reflection may be generated for example by a mirror at the second surveying instrument. When the light beam is reflected such that autocollimation of the collimated light beam is achieved at the first surveying instrument, the first and second surveying instruments are in a predetermined positional relation with respect to one another. With a known predetermined positional relation between the reflecting mirror and the line of sight of the second surveying instrument, measurements by both surveying instruments can be made in a common coordinate system.

Inventors

  • Michael Vogel

Assignees

  • TRIMBLE INC.

Dates

Publication Date
20260512
Application Date
20221025
Priority Date
20211130

Claims (14)

  1. 1 . A method for aligning a first surveying instrument and a second surveying instrument, comprising: emitting a collimated light beam from the first surveying instrument towards the second surveying instrument, the collimated light beam being aligned with a line of sight of the first surveying instrument; receiving at the first surveying instrument a reflection of the collimated light beam from an autocollimation mirror at the second surveying instrument, a normal of the autocollimation mirror (i) being arranged with a predetermined relationship with respect to the line of sight of the second surveying instrument, and (ii) intersecting an intersection of rotational axes of the second surveying instrument; moving at least one of the first and second surveying instruments to auto collimate the reflection of the collimated light beam at an autocollimator of the first surveying instrument; and registering the first and the second surveying instruments in a common space based on an orientation of the line of sight of the first surveying instrument and the predetermined relationship between the normal of the autocollimation mirror and the line of sight of the second surveying instrument when the collimated light beam is autocollimated at the first surveying instrument.
  2. 2 . The method according to claim 1 , further including emitting an adjustment instruction from a control unit for moving at least one of the first and second surveying instruments.
  3. 3 . The method according to claim 1 , wherein the moving includes rotating the at least one of the first and second surveying instruments around at least one of its vertical and horizontal axes.
  4. 4 . The method according to claim 3 , wherein the rotating of the first surveying instrument around at least one of its vertical and horizontal axes is performed in a searching and tracking mode of the first surveying instrument for searching and tracking the second surveying instrument.
  5. 5 . The method according to claim 1 , further including rotating the first surveying instrument to direct the collimated light beam towards the autocollimation mirror of the second surveying instrument.
  6. 6 . The method according to claim 1 , further including performing a coarse alignment of at least one of the first and second surveying instrument by emitting a search beam for coarse search from one of the first and second surveying instruments; detecting whether a reflection of the search beam from one of a plurality of reflecting elements arranged with a predetermined relationship with respect to the line of sight of the other of the first and second surveying instruments is received; and if the reflection of the search beam is not received, rotating at least one of the first and second surveying instruments and repeating the search beam emission and detection operations.
  7. 7 . The method according to claim 6 , further including emitting an EDM laser beam from the one of the first and second surveying instruments; wherein, if a reflection of the EDM laser beam is received from one of the plurality of reflecting elements arranged in the predetermined relationship with respect to the line of sight of the other of the first and second surveying instruments, measuring a distance to the reflecting element; and rotating the other of the first and second surveying instruments in at least one of a vertical and horizontal direction until a distance measured by the EDM laser beam is minimum.
  8. 8 . The method according to claim 6 , wherein the plurality of reflecting elements are arranged in circumferential direction of the other of the first and second surveying instruments such that for each orientation of the other of the first and second surveying instruments, one of the plurality of reflecting elements reflects the search beam.
  9. 9 . The method according to claim 6 , wherein two reflecting elements are arranged along a horizontal axis on either side of a base of the other of the first and second surveying instruments and wherein another two of the plurality of reflecting elements are arranged on either end of a telescope of the other of the first and second surveying instruments with a first and second angular offset from the line of sight of the other of the first and second surveying instruments.
  10. 10 . The method according to claim 9 , wherein when a reflection of the search beam is received, setting the one of the first and second surveying instruments into a tracking mode of the reflecting element to obtain a tracked position of the other of the first and second surveying instruments; and rotating the other of the first and second surveying instruments around a trunnion axis and determining whether a change of the tracked position corresponds to the first or second angular offset to identify the reflecting element and the corresponding predetermined relationship.
  11. 11 . The method according to claim 10 , wherein if the change does not correspond to either of the first or second angular offset, rotating the other of the first and second surveying instruments by 90 degrees and repeating the rotating around the trunnion axis to determining whether a change of the tracked position corresponds to the first or second angular offset to identify the reflecting element and the corresponding predetermined relationship.
  12. 12 . The method according to claim 10 , further including rotating the other of the first and second surveying instruments based on the predetermined relationship between the reflecting element and the line of sight of the other of the first and second surveying instruments such that the autocollimation mirror is oriented substantially perpendicular to a line interconnecting the first and second surveying instruments prior to performing the autocollimation.
  13. 13 . The method according to claim 1 , wherein the collimated light beam includes infrared light.
  14. 14 . A surveying system comprising a first surveying instrument and a second surveying instrument, the surveying system configured to carry out the method of claim 1 .

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims priority to European Patent Application No. 21 211 319.5, filed Nov. 30, 2021, the entire contents of which are incorporated herein by reference for all purposes. FIELD The present invention relates to surveying instruments, e.g. to survey geologically. More precisely, the present invention relates to a method and system for aligning surveying instruments. TECHNOLOGICAL BACKGROUND Surveying instruments like total stations or tachymeter generally such as for geological survey can measure angles and distances, such as to or between targets and may be used to determine positions of targets as for example in the field or on a construction site. A target may be a reflector at a stationary or moving object or any other element. The positions of the targets may be determined in three dimensions in a coordinate system spanned by the surveying instrument or any other coordinate system. Generally, surveying instruments are equipped with a telescope that may be aimed at a target. After aiming at the target horizontal and vertical angles of the telescope may be read out. Combined with a distance measurement a position of the target in the coordinate system can be found. The measurement of angles may be performed in the two face orientations of the telescope, as known in the art, allowing to eliminate errors. Surveying instruments may also be used to search a target and/or to track a movement of the target. For this purpose, the target may be equipped with a reflecting element and the search process may be performed by emitting a search beam from the surveying instrument used for the search and/or tracking. The surveying instrument may be moved until a reflection from the target or a reflecting element at the target is received. After locking onto the target or reflecting element, the motion of the target may be tracked, such as a moving vehicle on a construction site. The searching, tracking and positioning of targets in three-dimensional space can be performed by a single surveying instrument. However, on a larger site multiple surveying instruments may be needed for extended coverage. If multiple surveying instruments are used together for measurements, the positioning operations may advantageously be performed in the same coordinate system. For this purpose the multiple surveying instruments need to be registered in the same coordinate system. This, however, may be a time-consuming and error prone process during which operators of the first and second surveying instrument need to determine a position and orientation of the surveying instruments in a common three-dimensional space. For example, if multiple surveying instruments are used, a position of the surveying instruments and an orientation of the lines of the sight of the respective telescopes may be determined. Subsequently, when measurements are performed with the surveying instruments, angles and positions obtained by the measurements may be transformed into a common space or coordinate system by a conversion calculation. The conversion calculation allows to align or register the surveying instruments in a common coordinate system, subsequent to which the surveying instruments may be used to determine orientations, distances and positions in the common coordinate system. The process of aligning the two surveying instruments in the same coordinate system, however, is time-consuming and requires careful measurements at the involved surveying instruments. The process of alignment furthermore inherently lacks precision in the determination of the position and orientation of the surveying instruments relative to one another and in turn, the common coordinate system cannot be defined with high precision. Consequently, the precision generally available for measurements made by a single surveying instrument is no longer available for measurements performed in a common coordinate system. SUMMARY It is therefore an object of the invention to provide an improved method and system for precisely aligning surveying instruments in a common space. This object of the invention is solved by the subject matter of the independent claims. Advantageous embodiments are disclosed in the dependent claims. The invention allows to align multiple surveying instruments in a common space at high precision. An autocollimation process can be employed at a first surveying instrument based on a collimated light beam reflected by a second surveying instrument. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates operations of a method for aligning surveying instruments according to an embodiment of the invention based on an autocollimation process. FIG. 2 illustrates a system for aligning surveying instruments based on an autocollimation process according to an embodiment of the invention. FIG. 3 illustrates operations for aligning surveying instruments according to another embodiment of the invention, particularly illustr