Method and system for deriving travel distance of vehicle

• US 5,902,348 A
• Filed: 05/01/1997
• Issued: 05/11/1999
• Est. Priority Date: 05/02/1996
• Status: Expired due to Term

• Current Assignee: Pioneer Electronic Corporation (Pioneer Corporation)
• Original Assignee: Pioneer Electronic Corporation (Pioneer Corporation)
• Inventors: Nishida, Junichi, Sakaguchi, Masahiko, Ishiguro, Motoki, Baba, Toshiharu, Okamoto, Tatsuya, Kaneko, Hitoshi
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US08/847,032
• Time in Patent Office: 740 Days
• Field of Search: 701/70, 701/93, 701/123, 701/200, 701/201, 702/140, 702/148, 702/149, 702/160, 702/142, 702/150, 73/114, 73/146.5, 73/490, 324/166, 324/207.12, 324/175, 324/178, 324/160, 356/5.01, 356/5.1, 356/2.8, 356/5.08
• US Class Current: 701/201
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01C 22/00 Measuring distance traversed on the ground by vehicles, persons, animals or other moving solid bodies, e.g. using odometers, using pedometers

Abstract

A method and system for deriving a travel distance of an object which travels. As one aspect, a travel velocity of the object producing a pulse signal in response to travel of the object on the basis of a number of pulses of the pulse signal per unit time is calculated, and a plurality of unit travel distances corresponding to a plurality of travel states of the object every travel state are calculated. The plurality of travel states are different from each other and the unit travel distance is a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal per unit time. And the plurality of calculated unit travel distances are memorized individually, from the plurality of memorized unit travel distances, the unit travel distance corresponding to the travel state of the object which is under travel is selected, and the travel distance of the object on the basis of the selected unit travel distance and the pulse signal is derived.

Claims

1. A method of deriving a travel distance of an object which travels, comprising the steps of:

calculating a travel velocity of the object which produces a pulse signal in response to a travel of the object on the basis of a number of pulses of the pulse signal per unit time;

calculating a plurality of unit travel distances corresponding to a plurality of travel states of the object at every travel state, said plurality of travel states being different from each other, said unit travel distance being a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal per unit time;

memorizing individually the plurality of calculated unit travel distances;

selecting from the plurality of memorized unit travel distances the unit travel distance corresponding to the travel state of the object which is under travel; and

deriving the travel distance of the object on the basis of the selected unit travel distance and the pulse signal.

2. A method of deriving a travel distance of an object which travels, comprising the steps of:

calculating a travel velocity of the object which produces a pulse signal in response to a travel of the object on the basis of a number of pulses of the pulse signal per unit time;

calculating at every predetermined timing a unit travel distance being a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal;

calculating an error between the current unit travel distance calculated this time and the last unit travel distance calculated last time;

updating the last unit travel distance by replacing the last unit travel distance with the current unit travel distance, if the calculated error is less than a preset specified threshold; and

deriving the travel distance of the object based on the updated last unit travel distance and the number of the pulses of the pulse signal.

3. A method of deriving a travel distance of an object which travels, comprising the steps of:

measuring a forward travel velocity of the object under forward travel;

discriminating whether or not the measured forward travel velocity is greater than a preset specified velocity;

detecting a level of a backward travel signal indicative of a state of the object under backward travel, when the measured forward travel velocity is greater than the specified velocity; and

calculating the travel distance of the object independently of the travel distance of the object in a case that a level of the backward travel signal differs from the detected level.

4. A method of deriving a travel distance of an object which travels, comprising the steps of:

calculating a travel velocity of the object which produces a pulse signal in response to a travel of the object on the basis of a number of pulses of the pulse signal per unit time;

calculating a unit travel distance being a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal;

selecting, from a plurality of filter means having frequency bands different from each other in order to remove noise from the pulse signal, a corresponding one of the plurality of filter means having one of the frequency bands corresponding to the calculated unit travel distance; and

deriving the travel distance of the object based on not only the noise-removed pulse signal by the selected corresponding filter means but also the unit travel distance.

5. A system for deriving a travel distance of an object which travels, comprising:

velocity calculating means for calculating a travel velocity of the object which produces a pulse signal in response to a travel of the object on the basis of a number of pulses of the pulse signal per unit time;

calculating means for calculating a plurality of unit travel distances corresponding to a plurality of travel states of the object at every travel state, said plurality of travel states being different from each other, said unit travel distance being a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal per unit time;

memorizing means for memorizing individually the plurality of calculated unit travel distances;

selecting means for selecting from the plurality of memorized unit travel distances the unit travel distance corresponding to the travel state of the object which is under travel; and

deriving means for deriving the travel distance of the object on the basis of the selected unit travel distance and the pulse signal.

6. A system for deriving a travel distance of an object which travels, comprising:

velocity calculating means for calculating a travel velocity of the object which produces a pulse signal in response to travel of the object on the basis of a number of pulses of the pulse signal per unit time;

distance calculating means for calculating at every predetermined timing a unit travel distance being a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal;

error calculating means for calculating an error between the current unit travel distance calculated this time and the last unit travel distance calculated last time;

updating means for updating the last unit travel distance by replacing the last unit travel distance with the current unit travel distance, if the calculated error is less than a preset specified threshold; and

deriving means for deriving the travel distance of the object based on the updated last unit travel distance and the number of the pulses of the pulse signal.

7. A system for deriving a travel distance of an object which travels, comprising:

measuring means for measuring a forward travel velocity of the object under forward travel;

discriminating means for discriminating whether or not the measured forward travel velocity is greater than a preset specified velocity;

detecting means for detecting a level of a backward travel signal indicative of a state of the object under backward travel, when the measured forward travel velocity is greater than the specified velocity; and

calculating means for calculating the travel distance of the object independently of the travel distance of the object in a case that a level of the backward travel signal differs from the detected level.

8. A system for deriving a travel distance of an object which travels, comprising:

velocity calculating means for calculating a travel velocity of the object which produces a pulse signal in response to a travel of the object on the basis of a number of pulses of the pulse signal per unit time;

distance calculating means for calculating a unit travel distance being a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal;

a plurality of filter means having frequency bands different from each other in order to remove noise from the pulse signal;

selecting means for selecting, from the plurality of filter means, a corresponding one of the plurality of filter means having one of the frequency bands corresponding to the calculated unit travel distance; and

deriving means for deriving the travel distance of the object based on not only the noise-removed pulse signal by the selected corresponding filter means but also the unit travel distance.

9. A program storage device readable by a travel distance deriving apparatus for use in a navigation system for navigating a mobile object, embodying a program of deriving a travel distance of the object which travels, said method comprising the steps of:

calculating a travel velocity of the object which produces a pulse signal in response to a travel of the object on the basis of a number of pulses of the pulse signal per unit time;

calculating a plurality of unit travel distances corresponding to a plurality of travel states of the object at every travel state, said plurality of travel states being different from each other, said unit travel distance being a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal per unit time;

memorizing individually the plurality of calculated unit travel distances;

selecting from the plurality of memorized unit travel distances the unit travel distance corresponding to the travel state of the object which is under travel; and

deriving the travel distance of the object on the basis of the selected unit travel distance and the pulse signal.

10. A program storage device readable by a travel distance deriving apparatus for use in a navigation system for navigating a mobile object, embodying a program of deriving a travel distance of the object which travels, said method comprising the steps of:

calculating a travel velocity of the object which produces a pulse signal in response to a travel of the object on the basis of a number of pulses of the pulse signal per unit time;

calculating at every predetermined timing a unit travel distance being a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal;

calculating an error between the current unit travel distance calculated this time and the last unit travel distance calculated last time;

updating the last unit travel distance by replacing the last unit travel distance with the current unit travel distance, if the calculated error is less than a preset specified threshold; and

deriving the travel distance of the object based on the updated last unit travel distance and the number of the pulses of the pulse signal.

11. A program storage device readable by a travel distance deriving apparatus for use in a navigation system for navigating a mobile object, embodying a program of deriving a travel distance of the object which travels, said method comprising the steps of:

measuring a forward travel velocity of the object under forward travel;

discriminating whether or not the measured forward travel velocity is greater than a preset specified velocity;

detecting a level of a backward travel signal indicative of a state of the object under backward travel, when the measured forward travel velocity is greater than the specified velocity; and

calculating the travel distance of the object independently of the travel distance of the object in a case that a level of the backward travel signal differs from the detected level.

12. A program storage device readable by a travel distance deriving apparatus for use in a navigation system for navigating a mobile object, embodying a program of deriving a travel distance of the object which travels, said method comprising the steps of:

calculating a travel velocity of the object which produces a pulse signal in response to a travel of the object on the basis of a number of pulses of the pulse signal per unit time;

calculating a unit travel distance being a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal;

selecting, from a plurality of filter means having frequency bands different from each other in order to remove noise from the pulse signal, a corresponding one of the plurality of filter means having one of the frequency bands corresponding to the calculated unit travel distance; and

deriving the travel distance of the object based on not only the noise-removed pulse signal by the selected corresponding filter means but also the unit travel distance.