Handheld observation device comprising a digital magnetic compass

• US 9,918,044 B2
• Filed: 04/09/2015
• Issued: 03/13/2018
• Est. Priority Date: 04/09/2014
• Status: Active Grant

• Current Assignee: Safran Vectronix AG (Safran SA)
• Original Assignee: Safran Vectronix AG (Safran SA)
• Inventors: Kirschner, Holger, Gnepf, Silvio
• Primary Examiner(s): Fulton, Christopher
• Application Number:
  US14/682,693
• Publication Number:
  US 20150296185A1
• Time in Patent Office: 1,069 Days
• Field of Search: 33272, 33356, 702 93
• CPC Class Codes: G01C 17/02 Magnetic compasses
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

The invention relates to a handheld observation device including a digital magnetic compass for measuring a magnetic field direction of a magnetic field present, a gravitation sensor for measuring a gravitational field direction of a gravitational field present, and a control and evaluation unit configured for determining an externally referenced orientation of the observation device depending on a measured magnetic field direction and a measured gravitational field direction and with application of an algorithmic disturbance suppression, for which compensation parameters are stored. The observation device can also include a video tracking system (4) for recording an image sequence and for deriving orientation changes of the observation device.

Claims

1. A handheld observation device comprising

a digital magnetic compass for measuring a magnetic field direction of a magnetic field present,

a gravitation sensor for measuring a gravitational field direction of the gravitational field present, and

a control and evaluation unit configured for determining an externally referenced orientation of the observation device depending on a measured magnetic field direction and a measured gravitational field direction and with application of an algorithmic disturbance suppression, for which compensation parameters—

relating to a compensation of local magnetic field disturbance influences—

are stored,

further comprising;

a video tracking system for recording an image sequence and for deriving—

carried out on the basis of the image sequence—

orientation changes of the observation device,

and in that

the control and evaluation unit is configured in such a way that the determination of the externally referenced orientation is furthermore influenced by orientation changes derived by the video tracking system, in particular by virtue of the fact that the stored compensation parameters are based, inter alia, on orientation changes derived by the video tracking system.

2. The handheld observation device according to claim 1,

wherein,

the evaluation and control unit provides a calibration functionality designed to carry out a calibration of the disturbance suppression in a user-assisted manner in the field, wherein for the calibration a sequence of a plurality of calibration measurements is defined, in particular at least five, for which the observation device is to be brought into a plurality of different rotational positions, and wherein calibration measurement variables are automatically detected in the context of the calibration functionality, including—

at least for each of the calibration measurements—

a magnetic field direction measured by the magnetic compass, in particular also a gravitational field direction measured by the gravitation sensor, and on the basis of said calibration measurement variables the stored compensation parameters are checked and in particular, if appropriate, updated, in particular overwritten.

3. The handheld observation device according to claim 2,

wherein,

the control and evaluation unit is configured in such a way that in the context of the calibration functionality, as the calibration measurement variables used for checking and, if appropriate, updating the compensation parameters, furthermore differences between the rotational positions of the observation device adopted in the respective calibration measurements are automatically detected among one another, which are calculated on the basis of orientation changes derived by the video tracking system.

4. The handheld observation device according to claim 3,

wherein,

the control and evaluation unit is configured in such a way that the differences—

detected as part of the calibration measurement variables—

in the adopted rotational positions among one another, which are calculated on the basis of orientation changes derived by the video tracking system, are detected in at least one rotational degree of freedom, namely with respect to an azimuthal component, in particular in three rotational degrees of freedom, i.e. with respect to an azimuthal, an elevational and a rolling-angle component.

5. The handheld observation device according to claim 2,

wherein,

the control and evaluation unit is configured in such a way that in the context of the calibration functionality for bringing the observation device into the plurality of different rotational positions on the part of the user automatically

orientation changes are derived by the video tracking system,

depending on the orientation changes respectively derived a respective item of user guidance information is derived regarding a rotational position change to be carried out, in order thereby to attain a respective rotational position from the plurality of different rotational positions, and

the user guidance information is output via output means provided on the observation device.

6. The handheld observation device according to claim 1,

wherein,

the orientation changes of the observation device are derived by the video tracking system in at least one rotational degree of freedom, namely with respect to an azimuthal component, in particular in three rotational degrees of freedom, i.e. with respect to an azimuthal, an elevational and a rolling-angle component.

7. The handheld observation device according to claim 1,

wherein,

the video tracking system is furthermore configured for deriving—

carried out on the basis of the image sequence—

translational position changes of the observation device, and in that the determination of the externally referenced orientation is furthermore also influenced by translational position changes derived by the video tracking system, in particular by virtue of the fact that the stored compensation parameters are based, inter alia, on translational position changes derived by the video tracking system, especially wherein the derived translational position changes are used for the compensation of translational location changes of the observation device that are caused in the context of bringing the observation device into the plurality of different rotational positions.

8. The handheld observation device according to claim 1,

wherein,

the control and evaluation unit is configured for determining a series of externally referenced orientations for a series of adopted rotational positions of the observation device and in this case the respective externally referenced orientations are determined depending on

a respectively measured magnetic field direction,

a respectively measured gravitational field direction, and

differences between the rotational positions of the observation device respectively adopted in the context of the series among one another, which are calculated on the basis of orientation changes derived by the video tracking system, and

with application of the algorithmic disturbance suppression.

9. The handheld observation device according to claim 1,

wherein,

the control and evaluation unit is configured in such a way that in the context of a determination of a series of externally referenced orientations for a series of adopted rotational positions of the observation device the stored compensation parameters are automatically checked by virtue of the fact that

differences between the respectively determined externally referenced orientations

are compared with

differences between the rotational positions of the observation device respectively adopted in the context of the series among one another, which are calculated on the basis of orientation changes derived by the video tracking system,

in particular wherein for the case where a deviation of the differences between the respectively determined externally referenced orientations from the differences calculated—

on the basis of orientation changes derived by the video tracking system—

exceeds a defined permitted deviation maximum, an item of user information recommending or initiating a further calibration is output automatically via output means provided on the observation device.

10. The handheld observation device according to claim 1,

wherein,

the evaluation and control unit provides a referencing functionality designed to produce a magnetic-compass-independent external referencing relative to an orientation of the observation device in a user-assisted manner in the field, for which purpose a sequence of at least one targeting of a known target is defined, about which target information enabling the external referencing is stored or is present by way of user input, for which targeting the observation device is to be brought into a referencing rotational position targeting the at least one target, and in this case in said referencing rotational position and in continuation an image sequence is automatically continuously recorded by the video tracking system and orientation changes of the observation device are derived on the basis thereof, such that in continuation automatically externally referenced orientations are determinable also exclusively depending on

differences between the referencing rotational position and respective rotational positions of the observation device adopted in continuation among one another, wherein said differences are calculated on the basis of orientation changes derived by the video tracking system, and

with inclusion of the available information about the known target enabling the external referencing.

11. The handheld observation device according to claim 10,

wherein,

the control and evaluation unit is configured in such a way that in the context of a determination of an externally referenced orientation for adopted rotational positions of the observation device a check in particular with regard to influencing by regional magnetic field disturbances can be carried out automatically on the basis of a comparison of the determined externally referenced orientation with an externally referenced orientation determined separately in the context of the referencing functionality, in particular wherein a compensation of regional magnetic field disturbance influences is carried out automatically on the basis thereof.

12. The handheld observation device according to claim 1,

wherein,

the digital magnetic compass is equipped with inclination sensors, wherein measurements of the inclination sensors can be assisted by orientation change measurements by the video tracking system, and/or the evaluation and control unit is configured in such a way that measurement values of an inertial measurement unit and/or navigation data, in particular GPS data, can be included in the determination of the externally referenced orientation of the observation device.

13. The handheld observation device according to claim 1,

wherein,

the observation device has at least one continuous observation beam path having an input objective and an output eyepiece for an observer, and/or

the video tracking system has an objective, by which at least part of surroundings captured by the objective can be imaged onto a camera sensor, in particular wherein the objective is embodied as a compound objective having a front objective part and a rear objective part, in particular wherein the front objective part is additionally usable as an objective for a telescope for visual observation.

14. A method for determining an externally referenced orientation of a handheld observation device comprising

measuring a magnetic field direction of a magnetic field present by means of a digital magnetic compass provided in the observation device,

measuring a gravitational field direction of a gravitational field present by means of a gravitation sensor provided in the observation device, and

determining the externally referenced orientation of the observation device depending on the measured magnetic field direction and the measured gravitational field direction and with application of an algorithmic disturbance suppression, for which compensation parameters—

relating to a compensation of local magnetic field disturbance influences—

are present,

wherein,

determining the externally referenced orientation is furthermore influenced by orientation changes derived by a video tracking system provided in the observation device, wherein the orientation changes are derived on the basis of an the image sequence recorded by the video tracking system,

in particular wherein an influencing is afforded by virtue of the fact that the stored compensation parameters are based, inter alia, on orientation changes derived by the video tracking system,

especially wherein a procedure for which the control and evaluation unit and/or the video tracking system are/is configured according to claim 1 is carried out in the context of the method,

in particular wherein the method is carried out by means of an observation device.

15. A computer program product comprising program code, which is stored on a machine-readable carrier, for controlling or carrying out the method according to claim 14, in particular for controlling or carrying out a procedure for which the control and evaluation unit is configured if the program is executed on an electronic data processing unit, especially wherein the electronic data processing unit serves as the control and evaluation unit of an observation device.