INITIAL POSITION DETERMINATION METHOD, POSITIONING METHOD, AND POSITIONING APPARATUS

• US 20100176988A1
• Filed: 08/11/2009
• Published: 07/15/2010
• Est. Priority Date: 08/20/2008
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: MAEZAWA, Hidekazu, MURAKI, Kiyotaka
• Granted Patent: US 8,373,592 B2
• Time in Patent Office: Days
• US Class Current: 342/357.250
• CPC Class Codes: G01S 19/45 by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement

Abstract

A method of determining an initial position in executing a positioning calculation based on satellite signals from positioning satellites, includes: (a) executing position converging calculation based on the satellite signals using each of a plurality of first candidate positions as a provisional initial position; (b) selecting at least one second candidate position from the first candidate positions based on a calculation result of the position converging calculation; and (c) selecting the initial position from one of the second candidate positions using the satellite signals.

Claims

1. A method of determining an initial position in executing a positioning calculation based on satellite signals from positioning satellites, comprising:

executing position converging calculation based on the satellite signals using each of a plurality of first candidate positions as a provisional initial position;

selecting at least one second candidate position from the first candidate positions based on a calculation result of the position converging calculation; and

selecting the initial position from the second candidate positions using the satellite signals.

2. The method of determining an initial position according to claim 1, further comprising

selecting a predetermined number of first candidate positions based on a difference obtained with respect to each of third candidate positions set in a predetermined range of at least 300 km square, the difference being between a first distance calculated using the third candidate position and positions of the positioning satellites and a second distance calculated based on the satellite signals from the third candidate positions.

3. The method of determining an initial position according to claim 2, wherein

the third candidate positions are disposed in the predetermined range in a reticular pattern.

4. The method of determining an initial position according to claim 1, wherein

selecting the initial position from the second candidate positions is based on a difference between a third distance calculated using the second candidate positions and the positions of the positioning satellites and a fourth distance calculated based on the satellite signals.

5. The method of determining an initial position according to claim 1, further comprising

determining appropriateness of the initial position based on a difference between a first Doppler frequency and a second Doppler frequency, the first Doppler frequency being calculated using the initial position and position and orbit of the positioning satellite, and the second Doppler frequency being calculated based on the satellite signals.

6. The method of determining an initial position according to claim 5, wherein

determining the appropriateness of the initial position includes calculating a first Doppler frequency using the initial and a velocity vector of the positioning apparatus well as the position and velocity vector of the positioning satellite, the position and the velocity vector of the positioning satellite being obtainable from orbital information of the positioning satellite.

7. A positioning method comprising:

executing positioning calculation based on the satellite signals using the initial position determined by the method according to claim 1.

8. A positioning apparatus being configured to execute positioning calculation based on satellite signals from positioning satellites, comprising:

a position converging calculation section being configured to execute position converging calculation based on the satellite signals using each of a plurality of first candidate positions as a provisional initial position;

a second candidate position selection section being configured to select at least one second candidate position from the first candidate positions based on a calculation result of the position converging calculation;

an initial position selection section being configured to select an initial position in executing the positioning calculation using the satellite signals out of the second candidate positions; and

a positioning section being configured to execute positioning calculation based on the satellite signals using the initial position selected.

9. A positioning method, comprising:

capturing a predetermined number of satellites;

extracting satellite combinations for the captured satellites;

determining for each of the captured satellite combinations whether an initial position confidence is within a certain range;

expanding a grid search process in which a first APR value is calculated if the initial position confidence is outside the certain range for each of the captured satellite combinations;

calculating a geometric distance between each candidate initial position and each captured satellite if the grid search process is expanded for each of the captured satellite combinations;

executing a first positioning calculation process for each candidate initial position if the geometric distance between each candidate initial position and each captured satellite is calculated for each of the captured satellite combinations;

determining whether the solution has converged for each candidate initial position for each of the captured satellite combinations if the first positioning calculation process is executed;

calculating a second APR value if the solution has converged for each candidate initial position for each of the captured satellite combinations;

storing the second APR value for the candidate initial position for each of the captured satellite combinations;

selecting and storing the candidate initial position with the minimum second APR value as a provisional initial position for each of the captured satellite combinations;

executing a Doppler check process for each of the captured satellite combinations if the candidate initial position with the minimum second APR value is selected and stored;

storing the provisional initial position as an update of the initial position if the Doppler check process is successful;

determining the initial position confidence and storing it as an update if the provisional initial position is stored as an update;

executing for each of the captured satellite combinations a second positioning calculating process if the initial position confidence is stored as an update or if the initial position confidence is within the certain range;

storing a positioning location obtained by the second positioning calculation process as a candidate output position for each of the captured satellite combinations;

determining, storing, and displaying an output position from the candidate output positions.