US-12618672-B2 - Method and device for orienting

US12618672B2US 12618672 B2US12618672 B2US 12618672B2US-12618672-B2

Abstract

A method for orienting includes: setting a digital optical imaging device including a photosensitive device, a lens, and a global navigation satellite system (GNSS) receiver; allowing an optical axis of the lens to pass through a geometric center of the photosensitive device, so that a celestial body is imaged on the photosensitive device; and positioning a current position by using the GNSS receiver, and recording an accurate time; calculating an accurate azimuth angle of the celestial body at this moment, wherein, at this time, an imaging position of the celestial body on the photosensitive device is located on an extension line of a ligature of the azimuth of the celestial body and a geometric center of the photosensitive device, thereby through accurately extracting the imaging position of the celestial body, a placement orientation of the digital optical imaging device is determined, and a north direction is obtained.

Inventors

Tao Zhang
Jingui ZOU

Assignees

WUHAN UNIVERSITY

Dates

Publication Date: 20260505
Application Date: 20230331
Priority Date: 20220331

Claims (2)

1 . A method for orienting, comprising: 1) Setting a digital optical imaging device comprising a photosensitive device, a lens, and a global navigation satellite system (GNSS) receiver; 2) allowing an optical axis of the lens to pass through a geometric center of the photosensitive device, so that a celestial body is imaged on the photosensitive device; and 3) positioning a current position by using the GNSS receiver, and recording an accurate time; calculating an accurate azimuth angle of the celestial body at this moment; and through accurately extracting the imaging position of the celestial body, and based on a relationship between the accurate azimuth angle of the celestial body and the imaging position of the celestial body on the photosensitive device, a placement orientation of the digital optical imaging device is determined, and a north direction is obtained; wherein in 3), an imaging result of the photosensitive device is read and binarized, and a binarization threshold is adjusted until a white value is reduced to a region; the region is an image of the celestial body; a center of mass of the region is obtained; coordinates (Xi, Yi) of the center of mass are the coordinates of a center of the image of the celestial body; an angle of the celestial body in an XOY coordinate system is b=arctan(Yi/Xi)+(Y<0)*180; an output result of the GNSS receiver is read, and current time and position information is extracted from the output result; a pre-stored algorithm for calculating the azimuth angle and altitude angle of the celestial body according to the current position and time is called according to the time and position information to obtain the current azimuth angle a of the celestial body; according to a latitude of the current position, determining the current position is in the northern hemisphere or the southern hemisphere, and the azimuth of a target is obtained by using the following formulae: in the northern hemisphere, c=a−b+ 180− e; in the southern hemisphere, c=a−b− 180− e; the result is normalized to 0 to 360 degrees; c =( c+ 360)mod 360, where c is an azimuth angle of the target; and e is a system error.
2 . The method of claim 1 , wherein the method further comprises calibrating the system error as follows: setting e=0, and mounting a calibration part on a horizontal operation platform by using a gyroscope north-finder; orienting the calibration part towards due north; attaching a horizontal long edge of a shell of the digital optical imaging device to the calibration part, and calculating the c value; at this time, the correct c should be 0; if the c value measured at this time has a system error, storing c as system error e, thus completing the calibration.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS Pursuant to 35 U.S.C. § 119 and the Paris Convention Treaty, this application claims foreign priority to Chinese Patent Application No. 202210336535.0 filed Mar. 31, 2022, the contents of which, including any intervening amendments thereto, are incorporated herein by reference. Inquiries from the public to applicants or assignees concerning this document or the related applications should be directed to: Matthias Scholl PC., Attn.: Dr. Matthias Scholl Esq., 245 First Street, 18th Floor, Cambridge, MA 02142. BACKGROUND The disclosure relates to the field of mapping and exploration, and in particular to a method and device for orienting. Orienting (or north-finding) is a basic requirement in mapping, surveying and other fields. Rough method and device for orienting can be realized by using a magnetic compass, which is low in accuracy and easily interfered by an external magnetic field. Accurate north-finding is usually realized by using an astronomical method, a gyroscopic method and a dual-GNSS receiver baseline direction method. These methods have relatively high accuracy, but require complex device and long observation time. SUMMARY To solve the deficiencies in the prior art, the disclosure provides a method and device for orienting with low cost and high accuracy. To achieve the above objective, the disclosure provides a method for orienting, comprising: 1) setting a digital optical imaging device comprising a photosensitive device, a lens, and a global navigation satellite system (GNSS) receiver;2) allowing an optical axis of the lens to pass through a geometric center of the photosensitive device, so that a celestial body is imaged on the photosensitive device; and3) positioning a current position by using the GNSS receiver, and recording an accurate time; calculating an accurate azimuth angle of the celestial body at this moment, wherein, at this time, an imaging position of the celestial body on the photosensitive device is located on an extension line of a ligature of the azimuth of the celestial body and a geometric center of the photosensitive device, thereby through accurately extracting the imaging position of the celestial body, a placement orientation of the digital optical imaging device is determined, and a north direction is obtained. In a class of this embodiment, in 3), an imaging result of the photosensitive device is read and binarized, and a binarization threshold is adjusted until a white value is reduced to a region; the region is an image of the celestial body; a center of mass of the region is obtained; coordinates (Xi,Yi) of the center of mass are the coordinates of a center of the image of the celestial body. The angle of the celestial body in the XOY coordinate system is b=arctan(Yi/Xi)+(Y<0)*180. Meanwhile, the output result of the GNSS receiver is read, and the current time and position information is extracted from the output result. A pre-stored algorithm for calculating the azimuth angle and altitude angle of the celestial body according to the current position and time is called according to the time and position information to obtain the current azimuth angle a of the celestial body. It is determined according to the latitude of the current position whether it is in the northern hemisphere or the southern hemisphere, and the azimuth of the target is obtained by using the following formulae, respectively: in the northern hemisphere, c=a−b+180−e; in the southern hemisphere, c=a−b−180−e; finally, the result is normalized to 0 to 360 degrees. c=(c+360)mod 360, where c is an azimuth angle of the target. The e value is a system error. The method further comprises calibrating the system error as follows: setting e=0, and mounting a calibration part on a horizontal operation platform by using a gyroscope north-finder; orienting the calibration part towards due north; attaching a horizontal long edge of a shell of the digital optical imaging device to the calibration part, and calculating the c value; at this time, the correct c should be 0; if the c value measured at this time has a system error, and storing c as system error e, thus completing the calibration. In another aspect, the disclosure further provides a device for orienting, comprising a photosensitive device, a panoramic lens, a three-axis tilt sensor, a GNSS receiver, a calculation unit, a storage unit, a display unit, a power supply unit and a shell, an optical axis of the panoramic lens is perpendicular to a photosensitive surface of the photosensitive device, and a focal length is adjusted to be close to infinity, so that an astronomical target is imaged clearly; an intersection point of the optical axis of the panoramic lens and the photosensitive device is used as an origin O, two edges of the photosensitive device are used as coordinate axes, and a rectangular plane coordinate system XOY is established on the photosensitive device; the three-axis tilt sensor is rigidly