Method and apparatus for locating an object using reduced number of GPS satellite signals or with improved accuracy
US5977909A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 13, 1998 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Mar 13, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S19/09
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The number of simultaneous equations needed to find the location solution of an asset being tracked, such as a railcar, or, in the alternative, to improve the localization accuracy of any of several positioning methods used to track assets, is reduced by using a railway track database. Known railway track locations are used to constrain the railcar (i.e., asset) location solutions. This constraint makes the Cartesian coordinate location x, y and z values interdependent and reduces the number of simultaneous equations needed to find the location solution. Since all relevant railcars must be supported on railway tracks, and railway track locations and elevations throughout North America are available in a database, the number of satellite signals required is reduced. The railway track database represents a complex set of railway tracks. Instead of forming the complete set of function factors that make up the railway track data base every time a railcar location solution is needed, a start is made from a previous solution and only those railway tracks and/or branches that are feasible (i.e., nearby) are tried. Thus, the complexity of forming all railway track function terms is reduced…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.