Rubber sheeting of a map

• US 5,815,118 A
• Filed: 11/29/1996
• Issued: 09/29/1998
• Est. Priority Date: 11/03/1994
• Status: Expired due to Fees

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Schipper, John F.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/757,614
• Time in Patent Office: 669 Days
• Field of Search: 342/450, 342/457, 342/451, 342/357, 364/449.2
• US Class Current: 342/451
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G09B 29/106 using electronic means

Abstract

Methods for determining the present location coordinates of a user moving in a two-dimensional or three-dimensional space, with reference to an old map that may be inaccurate. Location coordinates of two or three non-collinear landmarks in two dimensions, or coordinates of three or four non-coplanar landmarks in three-dimensions, are indicated on the old map. Corresponding location coordinates are also estimated using a location determination (LD) system, such as GPS, GLONASS, Loran, Tacan, Decca, Omega, VOR, DME, JTIDS, PLRS or an FM subcarrier system. Location coordinates for two or more physical landmarks can be used to determine coordinates for a landmark representative. The user'"'"'s location coordinates are also determined or provided using the LD system. A distance or separation vector from the user location to landmark number i (i=1, . . . , N; N=2,3) is computed in the LD system. Two or more locations are computed on the old map for which the estimated distance (or estimated vector) from landmark number i to the computed location on the old map is also equal to the computed distance (or computed vector), and one of these computed locations is designated as a user location on the old map. Several metrics are developed to measure the relative acceptability of an old map user location, as determined above.

Claims

1. A method for determining the coordinates of a location in a region, with reference to a map that may be inaccurate and that indicates the locations of at least first and second landmarks, the method comprising the steps of:

receiving location determination (LD) signals at an LD unit, from each of a plurality of LD signal sources, where the LD unit can estimate the LD unit location and can estimate a vector from the LD unit location to a selected location that is visible to and spaced apart from the LD unit, and using the LD unit to estimate the LD unit location and to estimate first and second separation vectors from the LD unit to selected first and second visible landmarks, respectively, whose locations are shown on a map;

computing coordinates on the map of a location with vectors from the computed location to the first landmark and second landmark on the map that are approximately equal to the first separation vector and to the second separation vector, respectively; and

interpreting the computed location coordinates as candidate coordinates for the LD unit on the map.

2. The method of claim 1, further comprising the steps of:

using said LD unit to estimate a third separation vector from said LD unit to a selected third visible landmark whose location is shown on the map; and

computing coordinates on said map of a new location with vectors from the computed new location to said first landmark to said second landmark and to the third landmark on the map that are approximately equal to said first separation vector, to said second separation vector and to the third separation vector, respectively; and

interpreting the computed new location coordinates as candidate coordinates of the LD unit on the map.

3. The method of claim 2, wherein said region is chosen to be a three-dimensional region.

4. The method of claim 1, wherein said region is three-dimensional, the method further comprising the steps of:

using said LD unit to estimate a third separation vector and a fourth separation vector from said LD unit to selected third and fourth visible landmarks, respectively, whose locations are shown on said map; and

computing coordinates on said map of a new location with vectors from the computed location to said first landmark, to said second landmark, to the third landmark and to the fourth landmark on the map that are approximately equal to said first separation vector, to said second separation vector, to the third separation vector and to the fourth separation vector, respectively,

interpreting the computed new location coordinates as candidate coordinates of the LD unit on the map.

5. A method for determining the coordinates of a location in a region, with reference to a map that may be inaccurate and that indicates the locations of at least first and second landmarks, the method comprising the steps of:

providing a map of a region that includes locations of at least first and second visible landmarks in a selected map coordinates system;

receiving location determination (LD) signals at an LD unit, from each of a plurality of LD signal sources, where the LD unit can estimate the LD unit location and can estimate a vector from the LD unit location to a selected location that is visible to and spaced apart from the LD unit, and using the LD unit to estimate the LD unit location and to estimate first and second separation vectors from the LD unit to selected first and second visible landmarks, respectively;

using a computer to compute coordinates on the map of a location with vectors from the computed location to the first and second landmarks that are approximately equal to the first separation vector and to the second separation vector, respectively; and

interpreting the computed location coordinates as candidate coordinates for the LD unit on the map.

6. The method of claim 5, further comprising the steps of:

using said LD unit to estimate a third separation vector from said LD unit to a selected third visible landmark whose location is shown on the map; and

using said computer to compute coordinates on said map of a new location with vectors from the computed location to said first landmark, to said second landmark and to the third landmark that are approximately equal to said first separation vector, to said second separation vector and to the third separation vector, respectively.

interpreting the computed new location coordinates as candidate coordinates of the LD unit on the map.

7. The method of claim 5, wherein said region is three-dimensional, the method further comprising the steps of:

using said LD unit to determine a third separation vector and a fourth separation vector from said LD unit to selected visible third and fourth landmarks, respectively, whose locations are shown on said map;

using said computer to compute coordinates on said map of a new location with vectors from the computed location to said first landmark, to said second landmark, to the third landmark and to the fourth landmark that are approximately equal to said first separation vector, to said second separation vector, to the third separation vector and to the fourth separation vector, respectively; and

interpreting the computed new location coordinates as candidate coordinates of the LD unit on the map.

8. Apparatus for determining the coordinates of a location in a region, with reference to a map that may be inaccurate and that indicates the locations of at least first and second landmarks, the apparatus comprising:

a location determination (LD) unit that receives LD signals from a plurality of LD signal sources, that estimates the distance to a selected location that is visible to and spaced apart from the LD unit, that estimates location coordinates of the LD unit, and that can estimate the distance of the LD unit from each of selected first and second visible landmarks that have locations shown on a map; and

a computer that receives the location coordinates of the LD unit location, that receives the estimated distances of the LD unit from the first and second landmarks, that receives the locations of the first and second landmarks, and that is programmed to determine the coordinates of a location on the map that is separated from the first and second landmarks on the map by approximately the respective first and second distances.

9. The apparatus of claim 8, wherein:

said LD unit can estimate a third distance from said LD unit to a selected third visible landmark whose location is shown on said map; and

said computer receives the third distance and location of the third landmark and is programmed to determine the coordinates of a new location on the map that is separated from said first landmark, from said second landmark and from the third landmark on said map by approximately the respective first, second and third distances.

10. Apparatus for determining the coordinates of a location in a region, with reference to a map that may be inaccurate and that indicates the locations of at least first and second landmarks, the apparatus comprising:

a location determination (LD) unit that receives LD signals from a plurality of LD signal sources, that determines location coordinates of the LD unit from the LD signals received and that can estimate first and second separation vectors from the LD unit to selected first and second visible landmarks that have locations shown on a map; and

a computer, that receives the location coordinates of the LD unit, that receives the first and second separation vectors, that receives the locations on the map of the first and second landmarks, and that is programmed to determine the coordinates of a location on the map that is separated from the first and second landmarks by approximately the respective first and second separation vectors.

11. The apparatus of claim 10, wherein:

said LD unit can estimate a third separation vector from said LD unit to a selected third visible landmark whose location is shown on said map; and

said computer receives the third separation vector and map location of the third landmark and is programmed to determine a new location on the map that is separated from said first location, from said second location and from the third location by the respective first, second and third separation vectors.

12. The apparatus of claim 10, wherein:

said LD unit can estimate a third separation vector and a fourth separation vector from said LD unit to a selected third visible landmark and to a selected fourth visible landmark, respectively, whose locations are shown on said map; and

said computer receives said third separation vector and said fourth separation vector and map location of the third landmark and the fourth landmark and is programmed to determine a new location on the map that is separated from said first location, from said second location, from the third location and from the fourth location by the respective first, second, third and fourth separation vectors.