Method for estimating the accuracy of azimuthal orientations and portable sighting device

• US 20050229411A1
• Filed: 04/15/2005
• Published: 10/20/2005
• Est. Priority Date: 04/17/2004
• Status: Active Grant

• Current Assignee: ‎Vectronix AG
• Original Assignee: ‎Vectronix AG
• Inventors: Gees, Jurg, Gnepf, Silvio
• Granted Patent: US 7,325,320 B2
• Time in Patent Office: Days
• US Class Current: 33/356
• CPC Class Codes: F41G 3/02 using an independent line of sight
• CPC Class Codes: F41G 3/06 with rangefinder rangefinders per se G01C
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

In a method according to the invention for estimating the accuracy of azimuthal orientations (a) of a measuring device (1) having an electronic magnetic compass (2), a plurality of determinations of an azimuthal orientation (a, a′, a″, a′″, a″″) are carried out, in which the measuring device is aligned with one and the same measuring points at different measuring locations (P, P′, P″, P′″, P″″) adjacent to one another. On the basis of these determined azimuthal orientations (a, a′, a″, a′″, a″″), the value of the accuracy is automatically estimated by the measuring device (1) by means of a computational method. The adjacent measuring locations (P, P′, P″, P′″) are advantageously located one above the other or along a straight line to the measuring point. By means of this method, stationary stray fields of local scale can be detected and the effects thereof on the accuracy can be estimated. Further methods according to the invention are designed in each case specifically for further types of stray fields.

Claims

1. Method for estimating the accuracy of azimuthal orientations (a) of a measuring device (1), in which

the azimuthal orientations (a) are determined by measuring components of a magnetic field (M) and possibly of a gravitational vector (G) by means of an electronic magnetic compass (2) and

a value of the accuracy is automatically estimated by means of a computational method which is based on a plurality of determinations of an azimuthal orientation (a), in which the measuring device (1) is aligned with one and the same measuring point (5, 6) at different measuring locations (P, P′

, P″

, P′

″

, P″

″

) adjacent to one another.

2. Method for estimating the accuracy according to claim 1, wherein

the magnetic compass (2) has sensors for measuring the horizontal field strength of the magnetic field (M) and

the computational method is additionally based in each case on the product of the measured horizontal field strength and of the sine of the determined azimuthal orientation (a) and/or the product of the measured horizontal field strength and the cosine of the determined azimuthal orientation (a).

3. Method for estimating the accuracy according to claim 2, wherein

the magnetic compass (2) has sensors for the, especially three-dimensional, measurement of the components of the magnetic field (M) and of the gravitational vector (G) and

the computational method is additionally based in each case on the measured vertical field strength of the magnetic field (M).

4. Method for estimating the accuracy according to any of claims 1 to 3, wherein first adjacent measuring locations (P, P′

, P″

) are arranged substantially on a perpendicular.

5. Method for estimating the accuracy according to any of claims 1 to 4, wherein second adjacent measuring locations (P, P′

″

) are arranged substantially on a straight line (z) through the measuring point (5).

6. Method for estimating the accuracy according to any of claims 1 to 5, wherein third adjacent measuring locations (P, P″

″

) are present substantially on a normal to the straight line (z) and the measuring point (5, 6) is preferably far away.

15. Method for providing an azimuthal orientation (a) of a portable sighting device (1) and an estimated value of the accuracy thereof, in particular for a firing control post or a GIS, in which

the value is estimated by means of a method according to any of claims 1 to 14 and

a signal with information about an azimuthal orientation (a) and the estimated value is provided at an interface (3) of the measuring device (1).

7. Method for estimating the accuracy of azimuthal orientations (a) of a measuring device (1), the measuring location (P) of which is known on a regional scale, in which

the azimuthal orientations (a) are determined by means of an electronic magnetic compass (2) which has sensors for a, especially three-dimensional, measurement of components of a magnetic field (M) and, preferably also of components of a gravitational vector (G), and

a value of the accuracy is automatically estimated by means of a computational method, in which, as a function of the measuring location (P), at least one field parameter of a model of the Earth'"'"'s magnetic field, for example of the IGRF model, is related to at least one determine value of the magnetic field (M) which can be coordinated with the field parameter.

8. Method for estimating the accuracy according to claim 7, wherein the at least one field parameter is the magnetic field strength and/or the magnetic inclination.

9. Method for estimating the accuracy of azimuthal orientations (a) of a measuring device (1), in which

the azimuthal orientations (a) are determined by means of an electronic magnetic compass (2) which has sensors arranged in a fixed manner in relation to the device, for the, especially three-dimensional, measurement of components of a magnetic field (M) and, preferably also of components of a gravitational vector (G),

in a determination of azimuthal orientations (a) stray magnetic fields relating to the device itself are arithmetically compensated by means of a vector equation whose parameters were determined by means of an optimization method which is based on values of a specified sequence of measurements of components of the magnetic field (M) and possibly of the gravitational vector, in which sequence the measuring device (1) is in each case oriented differently in space, and

a value of the accuracy of azimuthal orientations (a) is automatically estimated by means of a method for statistical compensation calculation, which method is based on the values of the sequence of measurements, taking into account the parameters of the vector equation.

10. Method for estimating the accuracy according to claim 9, in which

a plurality of control measurements of the components of the magnetic field (M) and possibly of the gravitational vector (G) are carried out at one and the same measuring location (P), in which control measurements the measuring device (1) is oriented in each case differently in space,

the differences between determined values of the magnetic field (M) which can be coordinated with at least one field parameter, for example the respective horizontal and vertical field strength, are related to a specified threshold value and

when the threshold value is exceeded, the value of the accuracy is correspondingly adapted or the parameters of the vector equation for the arithmetic compensation of the stray magnetic fields relating to the device itself are determined again by means of the specified sequence of measurements.

11. Method for estimating the accuracy according to claim 10, in which the differences between the respective product of the horizontal field strength and of the sine of the azimuthal orientation (a) and/or the product of the horizontal field strength and of the cosine of the azimuthal orientation (a) are additionally related to a further threshold value.

12. Method for estimating the accuracy according to claim 10, wherein the measuring device (1) is in each case differently azimuthally oriented in the control measurements.

13. Method for estimating the accuracy according to claim 10 or 11, wherein the measuring device (1) is in each case oriented identically with respect to azimuth and differently with respect to the zenith in the control measurements.

14. Method for estimating the accuracy according to claim 10 or 11, wherein the measuring device (1) is in each case tilted identically with respect to azimuth and differently about the sighting axis (z) of the measuring device (1) in the control measurements.

16. Portable sighting device (1) comprising

an electronic magnetic compass (2) for determining azimuthal orientations (a) of the sighting device (1) and

an interface (3) for providing a signal, in particular for a firing control post or a GIS, which signal comprises information about the azimuthal orientation (a) and a value of the accuracy thereof,

characterized in that

a means for estimating the value of the accuracy of the azimuthal orientation (a) determined by the magnetic compass (2) is provided, with which means further sensors for measuring the magnetic field (M) are coordinated a distance away from the magnetic compass (2).