Navigation system for vehicles including present position calculating means

• US 5,796,613 A
• Filed: 08/01/1995
• Issued: 08/18/1998
• Est. Priority Date: 09/01/1994
• Status: Expired due to Fees

• Current Assignee: Aisin AW Company Limited (Aisin Corp.)
• Original Assignee: Aisin AW Company Limited (Aisin Corp.)
• Inventors: Kato, Shinichi, Nimura, Mitsuhiro, Nanba, Akimasa, Hanasaki, Masaharu
• Primary Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US08/510,088
• Time in Patent Office: 1,113 Days
• Field of Search: 364/449.7, 364/449.8, 364/449.95, 364/561, 342/357, 342/457
• US Class Current: 701/214
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments

Abstract

In order to calculate the traveling distance and heading of a vehicle in highly accurate fashion, a navigation system is provided with a distance sensor for outputting pulses in proportion to rotation of a wheel, a GPS receiving unit for calculating vehicle speed by GPS reception, acquisition unit for acquiring the number of pulses at the same time as GPS reception, distance correction coefficient calculating unit for calculating GPS traveling distance from the GPS-reception vehicle speed and a time difference between any two points, and calculating a distance correction coefficient from the GPS traveling distance and a pulse difference between two points, and present position calculating unit for calculating present position based upon a corrected distance correction coefficient.

Claims

1. A navigation system for a vehicle, comprising:

distance sensor for outputting pulses the number of which is proportional to rotation of a wheel;

a GPS receiving unit for calculating vehicle speed by GPS reception;

acquisition means for acquiring the number of pulses from the distance sensor at the same time as GPS reception;

distance correction coefficient calculating means for calculating GPS traveling distance from vehicle speed, based upon GPS reception, at each of two arbitrary points, and a time difference between these two points, and calculating a distance correction coefficient from the GPS traveling distance and a difference in the number of pulses between the two points; and

present position calculating means for calculating present position based upon a corrected distance correction coefficient.

2. The system according to claim 1, wherein said present position calculating means calculates the traveling distance by multiplying the difference in the number of pulses between the two points by a distance per pulse, which is preset for each vehicle, and by the distance correction coefficient.

3. The system according to claim 2, wherein said distance correction coefficient calculating means calculates, from the GPS traveling distance and the difference in number of pulses, the number of pulses necessary to advance the vehicle a unit distance, and calculates the distance correction coefficient according to the formula

4. The system according to claim 1, wherein traveling distance based upon the GPS is calculated by multiplying the average value of vehicle speed, which is based upon GPS reception, at the two points by the time difference.

5. A navigation system for vehicles according to claim 1, wherein said GPS receiving unit outputs a vehicle speed signal, and a distance correction factor is calculated in case the vehicle speed between two points is higher than a predetermined speed.

6. A navigation system for vehicles according to claim 5, wherein said GPS receiving unit outputs a vehicle speed signal, and a distance correction factor is calculated when a difference of the vehicle speed between two points is within a predetermined speed difference.

7. A navigation system for vehicles according to claim 6, wherein said GPS receiving unit outputs a heading signal, and a distance correction factor is calculated in case an angular change between two points is within a predetermined angle.

8. A navigation system for vehicles according to claim 7, wherein said GPS receiving unit outputs a time signal, and a distance correction factor is calculated when an angular change between two points is within a predetermined angle.

9. A navigation system for vehicles according to claim 8, wherein said GPS receiving unit outputs a status signal received from an artificial satellite, and a distance correction factor is calculated when two points received from said status signal are at positions in the same dimension.

10. A navigation system for vehicles according to claim 1, wherein said GPS receiving unit outputs a vehicle speed signal, and a distance correction factor is calculated in case a difference of the vehicle speed between two points is within a predetermined speed difference.

11. A navigation system for vehicle according to claim 1, wherein said GPS receiving unit outputs a heading signal, and a distance correction factor is calculated when an angular change between two points is within a predetermined angle.

12. A navigation system for vehicles according to claim 1, wherein said GPS receiving unit outputs a time signal, and a distance correction factor is calculated when an angular change between two points is within a predetermined angle.

13. A navigation system for vehicles according to claim 1, wherein said GPS receiving unit outputs a status signal received from an artificial satellite, and a distance correcting factor is calculated when two points received from said status signal are at positions on the same dimension.

14. The system according to claim 1, further comprising:

heading calculating means for calculating heading of the vehicle based upon a signal from said GPS receiving unit;

satellite position sensing means for sensing the position of the satellite based upon the signal from said GPS receiving unit;

travel speed sensing means for sensing the travel speed of the vehicle;

heading error estimating means for estimating error in the heading, obtained by said heading calculating means, based upon the traveling speed obtained by said travel speed sensing means and the position of the satellite obtained by said satellite position sensing means; and

judging means for judging whether the estimated heading error, which has been estimated by said heading error estimating means, is less than a predetermined value;

wherein the heading calculated by said heading calculating means is employed when the estimated heading error is less than the predetermined value.

15. The system according to claim 1, further comprising:

heading calculating means for calculating heading of the vehicle based upon a signal from said GPS receiving unit;

satellite position sensing means for sensing the position of the satellite based upon the signal from said GPS receiving unit;

travel speed sensing means for sensing the travel speed of the vehicle;

heading error estimating means for estimating error in the heading, obtained by said heading calculating means, based upon the traveling speed obtained by said traveling speed sensing means and the position of the satellite obtained by said satellite position sensing means;

judging means for judging whether the estimated heading error, which has been estimated by said heading error estimating means, is less than a predetermined value;

heading estimating means for estimating heading of the vehicle;

correction quantity calculating means for calculating a correction quantity that is for correcting the estimated heading, estimated by said heading estimating means, based upon the heading calculated by said heading calculating means and the estimated heading error estimated by said heading error estimating means; and

heading correcting means for correcting the estimating heading, estimated by said heading estimating means, based upon the correction quantity calculated by said correction quantity calculating means.

16. The system according to claim 1, further comprising:

heading calculating means for calculating heading of the vehicle based upon a signal from said GPS receiving unit;

satellite position sensing means for sensing the position of the satellite based upon the signal from said GPS receiving unit;

traveling speed sensing means for sensing traveling speed of the vehicle;

heading error estimating means for estimating error in the heading, obtained by said heading calculating means, based upon the traveling speed obtained by said traveling speed sensing means and the position of the satellite obtained by said satellite position sensing means;

judging means for judging whether the estimated heading error, which has been estimated by said heading error estimating means, is less than a predetermined value;

heading estimating means for estimating heading of the vehicle;

correction quantity calculating means which, when it is judged by said judging means that the estimated heading error is less than the predetermined value, is for calculating a correction quantity that is for correcting the estimated heading, estimated by the heading estimating means, based upon the heading calculated by said heading calculating means and the estimated heading error estimated by said heading error estimating means; and

heading correcting means for correcting the estimated heading, estimated by said heading estimating means, based upon the correction quantity calculated by said correction quantity calculating means.