METHOD FOR INERTIAL NAVIGATION UNDER WATER

• US 20120022820A1
• Filed: 04/17/2009
• Published: 01/26/2012
• Est. Priority Date: 04/17/2008
• Status: Abandoned Application

• Current Assignee: Fachhochschule Aachen
• Original Assignee: Fachhochschule Aachen
• Inventors: Schmitz, Guenter, Schmitz, Tim
• Application Number:
  US12/934,721
• Publication Number:
  US 20120022820A1
• Time in Patent Office: Days
• US Class Current: 702/95
• CPC Class Codes: G01C 21/1654 with electromagnetic compass

Abstract

The invention relates to a method for underwater navigation, particularly for scuba divers, and for autonomous, manned, or remote-controlled underwater vessels, wherein the signals of at least one sensor, comprising at least one acceleration sensor for determining the actual position, are integratively analyzed, accuracy is improved by means of the use of reference measurements, and a correction is carried out by way of a correction vector obtained from the transformation of the vector of the accelerations measured by the acceleration sensor in the diving computer coordinate system into the global coordinate system, the comparison to at least one of the reference measurement values, the determination of the deviation and the reverse transformation of the deviation to the diving computer coordinate system.

Claims

1. A method of underwater navigation of scuba divers or autonomous, manned or remotely controlled underwater vehicles wherein

the signals of at least one sensor, comprising at least one acceleration sensor for determining the actual position are integratively analyzed,

the precision is improved by utilizing reference measurements, and

a correction takes place by a correction vector that is obtained from the transformation of the vector of accelerations measured by the acceleration sensor in the diving computer coordinate system in the global coordinate system, comparison with at least one of the reference measurement values, determination of the deviation and the reverse transformation of the deviation into the diving computer coordinate system.

2. The method according to claim 1, wherein the signals of a combination resulting from the at least one, in particular straight-line acceleration sensor and at least one angle of rotation or line-of-site rate sensor or angular acceleration sensor are integrated.

3. The method according to claim 1 wherein the reference measurement takes place in the form of a pressure measurement of the ambient water pressure.

4. The method according to claim 1 wherein the reference measurement is performed in the form of utilizing signals of a satellite navigation system.

5. The method according to claim 4, wherein the signals of the satellite navigation system are utilized as reference when at or in the proximity of the water surface, in particular directly prior or after starting the dive.

6. The method according to claim 1 wherein the reference measurement is performed by utilizing signals from the measurement of the earth'"'"'s magnetic field.

7. The method according to claim 1 wherein a navigation aid is displayed for the diver on a display.

8. The method according to claim 7, wherein the display provides information about the direction or distance to a reference point.

9. The method according to claim 8, wherein the reference point is the starting point of the dive.

10. The method according to claim 8, wherein the display has an illustration that is similar to a map.

11. The method according to claim 7, wherein the display additionally shows a map that was previously loaded into the device or previously recorded or loaded or recorded reference points.

12. The method of recording the path traveled under water according to claim 1 wherein position information is recorded from acceleration sensors or angular sensors or line-of-sight rate sensors or magnetic field sensors or pressure sensors for storing position information depending on the time or a meter reading.

13. The method according to claim 1, wherein reference positions are stored in the memory of the diving computer prior to or during the dive.

14. The method according to claim 1, wherein the position of a diver is forwarded to another diver, in particular by radio communication or other types of communication.

15. The method according to claim 1, wherein pressure depth is corrected by information about the salt content of the water.

16. The method according to claim 15, wherein pressure depth and depth from other calculations are compared and that the salt content is determined from such.

17. The method according to claim 1, wherein a calibration of the map direction takes place in a map in the diving computer, in particular a stored map by a a determination of the direction north by a magnetic compass, analysis of the movements of the diver when a GPS signal is available, or diving to at least one reference point and confirmation by the diver to the diving computer that this at least one point was reached.

18. The method according to claim 1, wherein the calibration of the absolute position is derived from an at least one momentarily received GPS signal.

19. The method according to claim 1, wherein a correction of the delay time of the GPS data with respect to the propagation properties of the GPS signals takes place under water.

20. The method according to claim 1, wherein a measured temperature is used for error correction.

21. The method according to claim 1, wherein an average value formation of the depth occurs in order to reduce the influence of the waves on the depth determination.

22. The method according to claim 1, wherein a correction of the measured values obtained by the angular sensors is performed by the direction of the gravitational force.

23. The method according to claim 1, wherein a recalibration of the system takes place in calm phases.

24. The method according to claim 1, wherein the system is divided into measuring unit and display unit and that the measuring unit is attached to a part of the diver or his equipment, in particular a part that is not moved very much.

25. The method according to claim 1, wherein gravity is corrected by the information captured about the degree of latitude.

26. The method according to claim 1, wherein the temperature or salt content of the water or the date or the elevation are included in the determination of the degree of latitude or the gravitational constant prior to the dive.

27. The method according to claim 1, wherein a determination of the degree of latitude takes place in addition to or exclusively by the analysis of the earth'"'"'s magnetic field.

28. The method according to claim 1, wherein from the amplitude of the pressure fluctuations a degree of waviness is derived.

29. The method according to claim 28, wherein the degree of waviness that was determined is stored.

30. The method according to claim 1, wherein the position of the diver is transmitted to a remote receiver.

31. The method according to claim 1, wherein the receiver is another diver or is on a boat or is on land.

32. The method according to claim 1, wherein the controls of an underwater propulsion device are controlled based on position data.