Broad ocean bathymetric fix

Details Broad ocean bathymetric fix Broad ocean bathymetric fix

1998-09-04

2001-02-06

Cuchlinski, Jr., William A. (Department: 3661)

Data processing: vehicles, navigation, and relative location

Navigation

Employing position determining equipment

C701S221000, C367S012000, C367S087000, C367S088000, C367S118000, C367S124000, C367S131000, C367S900000

Reexamination Certificate

active

06185505

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention pertains to the field of ship inertial navigation, and more particularly to the application of external measurements to correct errors in the predicted position provided by an inertial navigation system.
2. Description of the Prior Art
Periodic external position information is required to correct errors in the predicted position given by a ship's inertial navigation system. These errors are caused by inaccuracies that are inherent in the inertial navigation systems comprising the overall navigation system. One source of position information is the Classical Bathymetric Fix (Classical Fix) which requires the ship to transit a pre-surveyed area, known as a Precise Bathymetric Navigation Zone (PBNZ), maintain constant speed and heading while traversing the area, and produce pulsed acoustic signals at a rapid repetition rate. Each PBNZ must meet bottom slope and along and cross track variation requirements. Because of these requirements, PBNZs are only available sparsely throughout the oceans of the world. To implement the Classical Fix the nearest PBNZ to the ship must first be identified and the ship navigated to it. When the ship arrives at the PBNZ the rapid repetition rate acoustic radiation (sonar transmissions) commences. The sonar must first obtain and retain bottom lock-on and second collect sufficient depth data for position fix computation. Sonar transmissions continue for both bottom tracking and depth data collection as the ship traverses the length of the PBNZ. As the ship traverses the PBNZ it is required to maintain constant speed and heading. After the ship has traversed the entire PBNZ, the sonar depth data collected is used with previously collected and processed “truth” map data, representative of the depths in the PBNZ, in a map-matching algorithm. The differences between the two sets of data are resolved into latitude and longitude corrections which are applied to the navigation system.
SUMMARY OF THE INVENTION
The present invention utilizes bathymetric data collected during the Ocean Survey Program (OSP) in place of PBNZ data. During this program wide tracks (swaths) of bathymetric data were collected throughout the worlds oceans. Since OSP swaths are a great deal more prevalent than PBNZs, a ship need not transit to a PBNZ to begin the inertial navigation system fix process. This process begins by collecting data when a ship crosses or transits along an OSP swath while the ship maintains its course. As the ship is in transit within or crosses over an OSP swath, sonar transmissions begin and continue only until a bottom depth has been acquired. These depth data points are contained within areas of predefined dimensions. The data areas are used subsequently for the navigation fix and must satisfy at least three requirements. First, they must be a predetermined distance apart in order to guarantee independence. Second, they must be sufficiently within the OSP swath to provide buffers, on either side of the collected depth data, that are at least equal to the largest possible error of the inertial navigation system. Third, the buffer areas must exhibit contour variations in either or both along-track and cross-track directions.
After sonar data has been collected in a predetermined number of data areas a virtual linear map is formed using the OSP data corresponding to the inertial navigation system's indicated locations of the collection areas. The linearization of the OSP data areas creates a map similar to that used by the Classical Bathymetric Fix. Thus, the map matching algorithms of the classical fix may be utilized for the comparison of the collected sonar data to the OSP map data. The results of these comparisons may be employed to provide latitude and longitude corrections to the inertial navigation system.
The invention will now be described in greater detail with reference to the accompanying drawings.


REFERENCES:
patent: 5122990 (1992-06-01), Deines et al.
patent: 5422860 (1995-06-01), Bradley et al.
patent: 5640369 (1997-06-01), Capell, Sr.

Affiliated with

Also associated with

Rating

Broad ocean bathymetric fix does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Broad ocean bathymetric fix, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Broad ocean bathymetric fix will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2583067