Vehicle tracker, mileage-time monitor and calibrator

• US 6,088,650 A
• Filed: 03/01/1999
• Issued: 07/11/2000
• Est. Priority Date: 10/24/1996
• Status: Expired due to Term

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Janky, James M., Rodal, Eric B., Schipper, John F., Cowl, David J.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Donnelly, Arthur D.
• Application Number:
  US09/260,793
• Time in Patent Office: 498 Days
• Field of Search: 701/207, 701/205, 701/210, 701/213, 701/216, 701/219, 701/29, 701/35, 73/1.37, 340/568, 340/572, 340/825.54, 340/825.49, 342/457
• US Class Current: 701/207
• CPC Class Codes: B60G 2400/824 Travel path sensing; Track monitoring
• CPC Class Codes: B60G 2401/16 GPS track data
• CPC Class Codes: B60G 2600/202 using a remote, e.g. cordless, transmitter or receiver unit
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network
• CPC Class Codes: G01C 22/02 by conversion into electric waveforms and subsequent integration, e.g. using tachometer generator G01C22/002, G01C22/004, G01C22/006 take precedence
• CPC Class Codes: G01S 19/39 the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• CPC Class Codes: G01S 19/52 Determining velocity
• CPC Class Codes: G01S 2205/002 for traffic control, mobile tracking, guidance, surveillance or anti-collision

Abstract

A system for monitoring location and speed of a vehicle, using a location determination system such as GPS, GLONASS or LORAN and an optional odometer or speedometer, for determining and recording the locations and times at which vehicle speed is less than a threshold speed for at least a threshold time (called a "vehicle arrest event"). Vehicle arrest event locations, times and time intervals are stored and/or printed to provide trip and mileage records and for efficiency monitoring. A vehicle odometer and/or speedometer can also be calibrated and/or corrected using this approach.

Claims

1. Apparatus for calibration of at least one of a vehicle odometer and a vehicle speedometer, the apparatus comprising:

a location determination (LD) unit, transported by a vehicle, that receives and processes LD signals to determine location coordinates of present location L and speed v of the LD unit at one or more selected observation times; and

at least one of;

a distance measuring mechanism that receives signals from the vehicle and estimates and records distance traveled by the vehicle from a selected earlier time t₀ to the present time; and

a speed measuring mechanism that receives signals from the vehicle and estimates and records the present speed of the vehicle at a sequence of selected times t_i.

2. The apparatus of claim 1, including said distance measuring mechanism;

and

further comprising a microprocessor that (1) forms an estimate d(t₀ ;

t_f) of the distance traveled by said vehicle from said time t₀ to a selected later time t_f, as determined by said distance measuring mechanism, (2) determines a distance Δ

d1(t₀ ;

t_f) traveled by said vehicle from said time to to the time t_f, as determined by said LD unit, (3) forms an error ratio ε

1=[d(t₀ ;

t_f)-Δ

d1(t₀ ;

t_f)]/Δ

d1(t₀ ;

t_f), and (4) interprets the magnitude and signum of the error ratio ε

1 as representing an amount by which said distance measuring mechanism is out of calibration.

3. The apparatus of claim 2, further comprising a distance measuring adjustment mechanism, connected to said distance measuring mechanism and to said microprocessor, that receives said error ratio ε

1 and said distance estimate d(t₀ ;

t_f) and produces a corrected distance estimate d(t₀ ;

t_f)_corr with an associated error ratio ε

1'"'"' whose magnitude is less than the magnitude of said error ratio ε

1.

4. The apparatus of claim 3, further comprising a display, connected to said distance measuring adjustment mechanism, that displays said corrected distance estimate d(t₀ ;

t_f)_corr in at least one of a visually perceptible form and an audubly perceptible form.

5. The apparatus of claim 1, including said distance measuring mechanism;

and

further comprising a microprocessor that (1) forms an estimate d(t₀ ;

t_f) of the distance traveled by said vehicle from said time to t₀ a selected later time t_f, as determined by said distance measuring mechanism, (2) determines a distance Δ

d2(t₀ ;

t_f) traveled by said vehicle from said time t₀ to the time t_f, using said estimates of said vehicle speed by said LD unit, (3) forms an error ratio ε

1=[d(t₀ ;

t_f)-Δ

2(t₀ ;

t_f)]/Δ

d2(t₀ ;

t_f), and (4) interprets the magnitude and signum of the error ratio , ε

1'"'"' as representing an amount by which said distance measuring mechanism is out of calibration.

6. The apparatus of claim 5, further comprising a distance measuring adjustment mechanism, connected to said distance measuring mechanism and to said microprocessor, that receives said error ratio ε

1'"'"' and adjusts said distance measuring mechanism to reduce the magnitude of the error ratio ε

1'"'"' toward zero.

7. The apparatus of claim 1, including said speed measuring mechanism;

and

further comprising a microprocessor that (1) forms a first estimate v of an average speed of said vehicle from said time t₀ to a selected later time t_f, at an approximately constant vehicle speed, as determined by said speed measuring mechanism, (2) determines a distance Δ

d(t₀ ;

t_f) traveled by said vehicle from said time t₀ to the time t_f, as determined by said LD unit, (3) determines a second estimate of average speed of said vehicle v(avg)=Δ

d(t₀ ;

t_f)/(t₀ -t_f) from said time t₀ to the time t_f ;

(4) forms an error ratio ε

2=[v -v(avg)]/v(avg), and (5) interprets the magnitude and signum of the error ratio ε

2 as representing an amount by which said speed measuring mechanism is out of calibration.

8. The apparatus of claim 7, further comprising a speed measuring adjustment mechanism, connected to said speed measuring mechanism and to said microprocessor, that receives said error ratio ε

2 and said distance estimate d(t₀ ;

t_f) and produces a corrected distance estimate v _corr with an associated error ratio ε

2'"'"' whose magnitude is less than the magnitude of said error ratio ε

2.

9. The apparatus of claim 8, further comprising a display, connected to said speed measuring adjustment mechanism, that displays said corrected distance estimate v _corr in at least one of a visually perceptible form and an audubly perceptible form.

10. The apparatus of claim 1, including said speed measuring mechanism;

and

further comprising a microprocessor that (1) forms a first estimate v of an average speed of said vehicle from said time t₀ to a selected later time t_f, at an approximately constant vehicle speed, as determined by said speed measuring mechanism, (2) determines a second estimate of average speed of said vehicle v(avg) from said time t₀ to the time t_f, using said estimates of said vehicle speed by said LD unit, (3) forms an error ratio ε

2"=[v -v(avg)]/v(avg), and (4) interprets the magnitude and signum of the error ratio ε

2" as representing an amount by which said speed measuring mechanism is out of calibration.

11. The apparatus of claim 10, further comprising a speed measuring adjustment mechanism, connected to said speed measuring mechanism and to said microprocessor, that receives said error ratio ε

2" and adjusts said distance measuring mechanism to reduce the magnitude of the error ratio ε

2" toward zero.

13. The method of claim 11, wherein said distance measuring signals are received, and further comprising the step of:

programming a microprocessor to (1) form an estimate d(t₀ ;

t_f) of the distance traveled by said vehicle from said time t₀ to a selected later time t_f, as determined by said distance measuring mechanism, (2) determine a distance Δ

d1(t₀ ;

t_f) traveled by said vehicle from said time t₀ to the time t_f, as determined by said LD unit, (3) form an error ratio ε

1=[d(t₀ ;

t_f)-Δ

d1(t₀ ;

t_f)]/Δ

d1(t₀ ;

t_f), and (4) interpret the magnitude and signum of the error ratio ε

1 as representing an amount by which said distance measuring mechanism is out of calibration.

14. The method of claim 13, further comprising the step of adjusting said distance measuring mechanism to produce a corrected distance estimate d(t₀ ;

t_f)_corr with an associated error ratio ε

1'"'"' whose magnitude is less than the magnitude of said error ratio ε

1.

15. The method of claim 14, further comprising the step of displaying said corrected distance estimate d(t₀ ;

t_f)_corr in at least one of a visually perceptible form and an audubly perceptible form.

12. A method for calibrating at least one of a vehicle odometer and a vehicle speedometer, the method comprising the steps of:

receiving and processing location determination (LD) signals at an LD unit, transported by a vehicle, to determine location coordinates of present location L and speed v of the LD unit at one or more selected observation times; and

receiving and recording at least one of;

distance measuring signals from the vehicle that provide an estimate of distance traveled by the vehicle from a selected earlier time t₀ to the present time; and

speed measuring signals from the vehicle that provide an estimate of the present speed of the vehicle at a sequence of selected times t_i.

16. The method of claim 12, wherein said distance measuring signals are received, and further comprising the step of:

programming a microprocessor to (1) form an estimate d(t₀ ;

t_f) of the distance traveled by said vehicle from said time t₀ to a selected later time t_f, using said estimates of said vehicle speed by said speed measuring mechanism, (2) determine a distance Δ

d2(t₀ ;

t_f) traveled by said vehicle from said time t₀ to the time t_f, using said estimates of said vehicle speed by said LD unit, (3) form an error ratio ε

1'"'"'=[d(t₀ ;

t_f)-Δ

d2(t₀ ;

t_f)]/Δ

d2(t₀ ;

t_f), and (4) interpret the magnitude and signum of the error ratio ε

1'"'"' as representing an amount by which said distance measuring mechanism is out of calibration.

17. The method of claim 16, further comprising the step of adjusting said distance measuring mechanism to produce a corrected distance estimate d(t₀ ;

t_f)_corr with an associated error ratio ε

1'"'"' whose magnitude is less than the magnitude of said error ratio ε

1.

18. The method of claim 17, further comprising the step of displaying said corrected distance estimate d(t₀ ;

t_f)_corr in at least one of a visually perceptible form and an audubly perceptible form.

19. The method of claim 12, wherein said speed measuring signals are received, and further comprising the step of:

programming a microprocessor to (1) form a first estimate v of an average speed of said vehicle from said time to to a selected later time t_f, at an approximately constant vehicle speed, as determined by said speed measuring mechanism, (2) determine a distance Δ

d(t₀ ;

t_f) traveled by said vehicle from said time t₀ to the time t_f, as determined by said LD unit, (3) determine a second estimate of average speed of said vehicle v(avg)=Δ

d(t₀ ;

t_f)/(t₀ -t_f) from said time t₀ to the time t_f ;

(4) form an error ratio ε

2=[v -v(avg)]/v(avg), and (5) interpret the magnitude and signum of the error ratio ε

2 as representing an amount by which said speed measuring mechanism is out of calibration.

20. The method of claim 19, further comprising the step of adjusting said speed measuring mechanism to produce a corrected speed estimate v _corr with an associated error ratio ε

2'"'"' whose magnitude is less than the magnitude of said error ratio ε

2.

21. The method of claim 20, further comprising the step of displaying said corrected speed estimate v _corr in at least one of a visually perceptible form and an audubly perceptible form.

22. The method of claim 12, wherein said speed measuring signals are received, and further comprising the step of:

programming a microprocessor to (1) form a first estimate v an average speed of said vehicle from said time t₀ to a selected later time t_f, at an approximately constant vehicle speed, as determined by said speed measuring mechanism, (2) determine a second estimate of average speed of said vehicle v(avg) from said time t₀ to the time t_f, using said estimates of said vehicle speed by said LD unit, (3) form an error ratio ε

2"=[v -v(avg)]/v(avg), and (4) interpret the magnitude and signum of the error ratio ε

2" as representing an amount by which said speed measuring mechanism is out of calibration.

23. The method of claim 22, further comprising the step of adjusting said speed measuring mechanism to produce a corrected speed estimate v _corr with an associated error ratio ε

2'"'"'" whose magnitude is less than the magnitude of said error ratio ε

2".

24. The method of claim 23, further comprising the step of displaying said corrected speed estimate v _corr in at least one of a visually perceptible form and an audubly perceptible form.