Satellite navigation system using multiple antennas

• US 7,693,659 B2
• Filed: 07/27/2005
• Issued: 04/06/2010
• Est. Priority Date: 04/07/2003
• Status: Active Grant

• Current Assignee: Novariant Incorporated (Kubota Corporation)
• Original Assignee: Novariant Incorporated (Kubota Corporation)
• Inventors: Montgomery, Paul, Lawrence, Dave, O'Connor, Michael L., Zimmerman, Kurt R.
• Primary Examiner(s): Tran; Khoi
• Assistant Examiner(s): Peche; Jorge O
• Application Number:
  US11/190,640
• Publication Number:
  US 20050278119A1
• Time in Patent Office: 1,714 Days
• Field of Search: 701/207, 701/213, 701/214, 701/215, 342/357.01, 342/357.02, 342/357.04, 342/357.06, 342/357.11, 342/357.12, 342/357.15, 342/357.17, 342/358, 340/988
• US Class Current: 701/215
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks
• CPC Class Codes: G01S 19/54 using carrier phase measurements; using long or short baseline interferometry

Abstract

A satellite navigation system using multiple antennas for providing the position of multiple fiduciary points on an object even when fewer than four satellites are visible to some or all the antennas. Satellite signals from the multiple antennas are fed into at least one receiver. The receiver or receivers utilize constraint information, which is independent of the satellite signals. These external constraints are used to augment the signals received from the satellites, to obtain the position solution for each antenna. In a preferred embodiment, a common reference clock is used to provide an external constraint. Examples of other external constraints that can be used in the current invention are distance between the antennas, inertial measurement of attitude, rotational or linear position sensors, etc.

Claims

1. A method of obtaining an initial position solution in a satellite navigation system for an object using a plurality of antennas, the antennas connected to at least one receiver, the antennas having a common reference clock, the method comprising:

a. providing the common reference clock for each antenna;

b. receiving satellite signals at each antenna;

c. the receiver determining the initial position solution for the antennas using an external constraint in addition to the common reference clock and the satellite signals received at the antennas, wherein the external constraint is independent of received satellite signals and incorporated into an observation matrix, the initial position solution being solved from the observation matrix, and the external constraint corresponding to a spatial relationship between the antennas, the antennas being connected by a mechanical linkage; and

d. the initial position solution being obtained using signals from fewer than four satellites at some or all antennas;

wherein determining the initial position further comprises;

calculating an integer cycle ambiguity resolution for input signals to compute position at two or more antennas;

predicting signal information from all potentially visible satellites using the calculated antenna positions; and

initializing the processor of the receiver for all the potentially visible satellites using the predicted signal information;

the position solution being obtained using signals from fewer than four satellites at some or all antennas.

2. The method of claim 1 further comprising:

checking for a consistency of phase between the plurality of antennas; and

correcting any inconsistency using the external constraint.

3. The method of claim 1 further comprising initializing the plurality of antennas using an already initialized antenna.

4. The method of claim 1 further comprising obtaining correction factors for each of the received satellite signals from a reference station.

5. The method of claim 1 wherein the external constraint is a previously surveyed position of at least two antennas relative to each other.

6. The method of claim 1 wherein the external constraint is an inertial measurement of attitude of the object.

7. The method of claim 1 wherein the external constraint is a measurement of relative motion of one antenna with respect to another.

8. A method of obtaining a position solution in a satellite navigation system for an object using a plurality of antennas, the antennas connected to at least one receiver, the antennas having a common reference clock, the method comprising:

a. providing the common reference clock for each antenna;

b. receiving satellite signals at each antenna;

c. the receiver determining the position solution for the antennas using an external constraint in addition to the common reference clock and the satellite signals received at the antennas, wherein the external constraint is independent of received satellite signals and wherein the antennas are connected with different components of a mechanical linkage, one of the components connected with one of the antennas linked with and operable to move relative to another one of the components, connected with another one of the antennas, of the mechanical linkage, wherein the external constraint is obtained by measuring a linkage position or angle of one component of the mechanical linkage relative to the other component of the mechanical linkage such that a vector between the antennas is determined, the external constraint being a function of the vector;

d. the position solution being obtained using signals from fewer than four satellites at some or all antennas.