Positioning apparatus, positioning method, and storage medium for measuring position using both autonomous navigation and GPS

• US 8,692,709 B2
• Filed: 09/14/2011
• Issued: 04/08/2014
• Est. Priority Date: 09/15/2010
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Sambongi, Masao
• Primary Examiner(s): Issing, Gregory C
• Application Number:
  US13/232,591
• Publication Number:
  US 20120062414A1
• Time in Patent Office: 937 Days
• Field of Search: 342/357.32, 342/357.3, 342/357.74, 342/357.31
• US Class Current: 342/357.32
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01C 21/1656 with passive imaging devices, e.g. cameras
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled

Abstract

A positioning apparatus including: a first positioning unit which intermittently receives signals from satellites and carries out a first position measurement; a second positioning unit which carries out a second position measurement by adding information of a moving direction and a moving amount to positional information of a reference position; a positioning control unit which obtains positional information corresponding to positions along a movement path by the first position measurement and the second position measurement; a reference position updating unit which updates the positional information of the reference position based on a result of the first position measurement; a distance calculating unit which calculates a distance between two positions, i.e., between the reference position and a position obtained by the second position measurement; and a positioning timing control unit which controls timing to carry out the first position measurement based on the distance.

Claims

1. A positioning apparatus comprising:

a first positioning unit which intermittently receives signals from a plurality of positioning satellites to obtain positional information of a reference position;

a second positioning unit which obtains a present position by continuously calculating a moving direction and a moving amount of the positioning apparatus, and by adding information of the moving direction and the moving amount to the positional information of the reference position;

a reference position updating unit which updates the positional information of the reference position by causing the first positioning unit to newly obtain positional information of the reference position;

a count unit which counts an elapsed period of time each time after the reference position updating unit updates the positional information of the reference position;

a distance calculating unit which calculates a distance between a last-obtained reference position and a present position obtained by the second positioning unit, each time the second positioning unit obtains a predetermined number of present positions;

a distance judging unit which judges whether a currently-calculated distance calculated by the distance calculating unit is longer than a predetermined distance and shorter than a last-calculated distance calculated by the distance calculating unit; and

a positioning timing control unit which controls a timing when the reference position updating unit updates the positional information of the reference position so as to cause the reference position updating unit to update the positional information of the reference position when it is determined that the elapsed period of time counted by the count unit exceeds a predetermined amount of time, or when the distance judging unit judges that the currently-calculated distance is longer than the predetermined distance and shorter than the last-calculated distance.

2. The positioning apparatus according to claim 1, wherein the second positioning unit obtains a series of present positions, the distance calculating unit calculates a series of distances between the last-obtained reference position and the respective positions of the series of present positions obtained by the second positioning unit, and the distance judging unit judges whether the currently-calculated distance is longer than the predetermined distance and shorter than the last-calculated distance based on the series of distances calculated by the distance calculating unit.

3. The positioning apparatus according to claim 2, further comprising a prohibiting unit which prohibits the first positioning unit from newly obtaining positional information when the elapsed period of time counted by the counting unit has not exceeded the predetermined amount of time and the distance judging unit judges that the distance calculated by the distance calculating unit is shorter than the predetermined distance.

4. The positioning apparatus according to claim 2, further comprising a correcting unit which corrects a series of positional information sets corresponding to the series of present positions obtained by the second positioning unit, based on the newly-obtained positional information of the reference position, when the positional information of the reference position is updated.

5. The positioning apparatus according to claim 2, further comprising a precision level obtaining unit which obtains a precision level representing a position measurement precision of the first positioning unit at a time when the first positioning unit obtains positional information, wherein the positional information obtained by the first positioning unit is not used when the position measurement precision is lower than a predetermined precision threshold value.

6. The positioning apparatus according to claim 1, further comprising a prohibiting unit which prohibits the first positioning unit from newly obtaining positional information when the elapsed period of time counted by the counting unit has not exceeded the predetermined amount of time and the distance judging unit judges that the distance calculated by the distance calculating unit is shorter than the predetermined distance.

7. The positioning apparatus according to claim 1, further comprising a precision level obtaining unit which obtains a precision level representing a position measurement precision of the first positioning unit at a time when the first positioning unit obtains positional information, wherein the positional information obtained by the first positioning unit is not used when the position measurement precision is lower than a predetermined precision threshold value.

8. A positioning method for a positioning apparatus comprising a first positioning unit and a second positioning unit, the first positioning unit intermittently receiving signals from a plurality of positioning satellites to obtain positional information of a reference position, and the second positioning unit obtaining a present position by continuously measuring a moving direction and a moving amount of the positioning apparatus, and by adding information of the moving direction and the moving amount to the positional information of the reference position, the method comprising:

obtaining positional information of the reference position with the first positioning unit, and obtaining a present position with the second positioning unit;

updating the positional information of the reference position by causing the first positioning unit to newly obtain positional information of the reference position;

counting an elapsed period of time each time after the positional information of the reference position is updated;

calculating a distance between a last-obtained reference position and a present position obtained by the second positioning unit, each time a predetermined number of present positions is obtained with the second positioning unit;

judging whether a currently-calculated distance is longer than a predetermined distance and shorter than a last-calculated distance; and

controlling a timing of updating the positional information of the reference position such that the positional information of the reference position is updated when it is determined that the counted elapsed period of time exceeds a predetermined amount of time, or when it is judged that the currently-calculated distance is longer than the predetermined distance and shorter than the last-calculated distance.

9. The positioning method according to claim 8, wherein:

a series of present positions are obtained by the second positioning unit,

a series of distances are calculated between the last-obtained reference position and the respective positions of the series of present positions obtained by the second positioning unit, and

it is judged whether the currently-calculated distance is longer than the predetermined distance and shorter than the last-calculated distance based on the series of calculated distances.

10. A non-transitory computer readable storage medium having recorded thereon a computer program for controlling a computer which communicates with a positioning apparatus comprising a first positioning unit and a second positioning unit, the first positioning unit intermittently receiving signals from a plurality of positioning satellites to obtain positional information of a reference position, and the second positioning unit obtaining a present position by continuously measuring a moving direction and a moving amount of the positioning apparatus and by adding information of the moving direction and the moving amount to the positional information of the reference position;

wherein the program controls the computer to cause the first positioning unit to obtain positional information of the reference position, and to cause the second positioning unit to obtain a present position; and

wherein the program controls the computer to function as;

a reference position updating unit which updates the positional information of the reference position by causing the first positioning unit to newly obtain positional information of the reference position;

a count unit which counts an elapsed period of time each time after the reference position updating unit updates the positional information of the reference position;

a distance calculating unit which calculates a distance between a last-obtained reference position and a present position obtained by the second positioning unit, each time the second positioning unit obtains a predetermined number of present positions;

a distance judging unit which judges whether a currently-calculated distance calculated by the distance calculating unit is longer than a predetermined distance and shorter than a last-calculated distance calculated by the distance calculating unit; and

a positioning timing control unit which controls a timing when the reference position updating unit updates the positional information of the reference position so as to cause the reference position updating unit to update the positional information of the reference position when it is determined that the elapsed period of time counted by the count unit exceeds a predetermined amount of time, or when the distance judging unit judges that the currently-calculated distance is longer than the predetermined distance and shorter than the last-calculated distance.

11. The storage medium storing the program according to claim 10, wherein the program further controls the computer so that:

the second positioning unit obtains a series of present positions,

the distance calculating unit calculates a series of distances between the last-obtained reference position and the respective positions of the series of present positions obtained by the second positioning unit, and

the distance judging unit judges whether the currently-calculated distance is longer than the predetermined distance and shorter than the last-calculated distance based on the series of distances calculated by the distance calculating unit.