Portable altimeter and altitude computing method

• US 6,678,629 B2
• Filed: 01/19/2001
• Issued: 01/13/2004
• Est. Priority Date: 01/31/2000
• Status: Expired due to Term

• Current Assignee: Seiko Instruments Incorporated (Seiko Group)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Tsuji, Tomoharu
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): VO, HIEN XUAN
• Application Number:
  US09/765,552
• Publication Number:
  US 20020032539A1
• Time in Patent Office: 1,089 Days
• Field of Search: 702/139, 702/98, 702/104, 702/138, 702/150, 702/177, 701/4, 701/123, 701/214, 737/18.R, 737/23, 733/84, 738/61
• US Class Current: 702/139
• CPC Class Codes: G01C 5/06 by using barometric means

Abstract

A portable altimeter of the present invention is provided with a movement determining unit for determining whether or not the altimeter is at a standstill or moving by comparing an amount of change in altitude with a prescribed standstill threshold value and movement threshold value. When the standstill mode is set, the moving mode is then set only when the amount of change equals or exceeds the movement threshold value, and when the moving mode is set, the standstill mode is then set only when the amount of change falls below the standstill threshold value.

Claims

1. A portable altimeter comprising:

a pressure sensor for measuring external atmospheric pressure;

a pressure/altitude calculating unit for calculating an altitude of the portable altimeter based upon a pressure measured by the pressure sensor;

an altitude variation calculating unit for calculating a difference in altitude between a current altitude calculated by the pressure/altitude calculating unit and a previously calculated altitude; and

a movement determining unit comprising a first determining unit for determining whether or not the portable altimeter is in a standstill state in which it is not changing in altitude based upon an altitude difference calculated by the altitude variation calculating unit, and a second determining unit for determining whether or not the portable altimeter is in a moving state in which it is changing in altitude based upon the altitude difference calculated by the altitude variation calculating unit.

2. A portable altimeter according to claim 1;

wherein the movement determining unit has a movement duration timer for measuring a duration or a number of fixed durations occurring while the portable altimeter is in the moving state.

3. A portable altimeter according to claim 1;

further comprising a pressure gradient calculator for calculating changes in pressure occurring while the portable altimeter is in the standstill state.

4. A portable altimeter according to claim 2;

further comprising a pressure gradient calculator for calculating changes in pressure occurring while the portable altimeter is in the standstill state.

7. A portable altimeter according to claim 1;

further comprising a controller for calculating an altitude of the portable altimeter based on pressure changes accompanying actual changes in altitude of the portable altimeter and excluding changes in pressure accompanying fluctuations in atmospheric pressure unaccompanied with changes in altitude of the portable altimeter, and producing a time/altitude graph based on a relationship of the calculated altitude and time.

10. A portable altimeter according to claim 1;

further comprising a controller for calculating an altitude of the portable altimeter based on pressure changes accompanying actual changes in altitude of the portable altimeter and excluding changes in pressure accompanying fluctuations in atmospheric pressure unaccompanied with changes in altitude of the portable altimeter, and producing a time/estimated-altitude graph based on a relationship of the calculated altitude and time.

13. A portable altimeter according to claim 1;

further comprising a controller for calculating an altitude of the portable altimeter based on pressure changes accompanying actual changes in altitude of the portable altimeter and excluding changes in pressure accompanying fluctuations in atmospheric pressure unaccompanied with changes in altitude of the portable altimeter, and producing a rate of ascent/descent graph based on a relationship between a rate of ascent/descent calculated based upon a value for the obtained results, and time.

5. A portable altimeter comprising:

a pressure sensor for measuring external atmospheric pressure;

a pressure/altitude calculating unit for calculating an altitude of the portable altimeter based upon a pressure measured by the pressure sensor;

an altitude variation calculating unit for calculating a difference in altitude between a current altitude calculated by the pressure/altitude calculating unit and a previously calculated altitude; and

a movement determining unit comprising a determining unit for determining whether or not the portable altimeter is in a moving state in which it is changing in altitude based upon the altitude difference calculated by the altitude variation calculating unit, and a movement duration timer for measuring a duration or a number of fixed durations occurring while the portable altimeter is in the moving state.

8. A portable altimeter according to claim 5;

further comprising a controller for calculating an altitude of the portable altimeter based on pressure changes accompanying actual changes in altitude of the portable altimeter and excluding changes in pressure accompanying fluctuations in atmospheric pressure unaccompanied with changes in altitude of the portable altimeter, and producing a time/altitude graph based on a relationship of the calculated altitude and time.

11. A portable altimeter according to claim 5;

further comprising a controller for calculating an altitude of the portable altimeter based on pressure changes accompanying actual changes in altitude of the portable altimeter and excluding changes in pressure accompanying fluctuations in atmospheric pressure unaccompanied with changes in altitude of the portable altimeter, and producing a time/estimated-altitude graph based on a relationship of the calculated altitude and time.

14. A portable altimeter according to claim 5;

further comprising a controller for calculating an altitude of the portable altimeter based on pressure changes accompanying actual changes in altitude of the portable altimeter and excluding changes in pressure accompanying fluctuations in atmospheric pressure unaccompanied with changes in altitude of the portable altimeter, and producing a rate of ascent/descent graph based on a relationship between a rate of ascent/descent calculated based upon a value for the obtained results, and time.

6. A portable altimeter comprising:

a pressure sensor for measuring external atmospheric pressure;

a pressure/altitude calculating unit for calculating an altitude of the portable altimeter based upon pressure measured by the pressure sensor;

an altitude variation calculating unit for calculating a difference in altitude between a current altitude calculated by the pressure/altitude calculating unit and a previously calculated altitude; and

a movement determining unit comprising a determining unit for determining whether or not the portable altimeter is in a moving state in which it is changing in altitude based upon the altitude difference calculated by the altitude variation calculating unit, and a movement duration timer for measuring a duration or a number of fixed durations occurring while the portable altimeter is in the moving state; and

a pressure gradient calculator for calculating changes in pressure occurring while the portable altimeter is in a standstill state in which it is not changing in altitude.

9. A portable altimeter according to claim 6;

further comprising a controller for calculating an altitude of the portable altimeter based on pressure changes accompanying actual changes in altitude of the portable altimeter and excluding changes in pressure accompanying fluctuations in atmospheric pressure unaccompanied with changes in altitude of the portable altimeter, and producing a time/altitude graph based on a relationship of the calculated altitude and time.

12. A portable altimeter according to claim 6;

further comprising a controller for calculating an altitude of the portable altimeter based on pressure changes accompanying actual changes in altitude of the portable altimeter and excluding changes in pressure accompanying fluctuations in atmospheric pressure unaccompanied with changes in altitude of the portable altimeter, and producing a time/estimated-altitude graph based on a relationship of the calculated altitude and time.

15. A portable altimeter according to claim 6;

further comprising a controller for calculating an altitude of the portable altimeter based on pressure changes accompanying actual changes in altitude of the portable altimeter and excluding changes in pressure accompanying fluctuations in atmospheric pressure unaccompanied with changes in altitude of the portable altimeter, and producing a rate of ascent/descent graph based on a relationship between a rate of ascent/descent calculated based upon a value for the obtained results, and time.

16. An altitude measuring method for a portable altimeter which measures altitude based on atmospheric pressure sampled at prescribed intervals, comprising:

a threshold setting step for setting a standstill threshold value indicating a change in pressure corresponding to a standstill state in which the portable altimeter is not changing in altitude and setting a movement threshold value indicating a change in pressure corresponding to a moving state in which the portable altimeter is changing in altitude; and

a movement determination step for determining that the portable altimeter is at a standstill state when an absolute value of a current change in pressure corresponds to an intermediate range between the standstill threshold value and the movement threshold value or falls below the standstill threshold value, determining that the portable altimeter has moved from a standstill state to a moving state when the absolute value of the current change in pressure exceeds the movement threshold value, and, determining that the portable altimeter remains in a moving state when the current change in pressure corresponds to an intermediate range between the standstill threshold value and the movement threshold value or exceeds the movement threshold value and the portable value was determined to be in a moving state in an immediately preceding measurement, and determines that the altimeter has moved from the moving state to the standstill state when the absolute value of the change in pressure falls below the standstill threshold value.

17. An altitude measuring method according to claim 16;

wherein the movement determination step further comprises the step of determining that the altimeter has moved from the moving state to the standstill state when the absolute value of the a change in pressure continues to be in the intermediate range for a predetermined number of measurements.

19. An altitude measuring method according to claim 16;

further comprising a tendency calculating step for obtaining a tendency value indicating a tendency in the amount of change of pressure by subjecting the amount of change in pressure obtained when the altimeter is determined to be at a standstill state to prescribed statistical processing; and

wherein a current altitude of the portable altimeter is decided based on determination results of the movement determination step and the tendency value obtained in the tendency calculating step.

20. An altitude measuring method according to claim 17;

further comprising a tendency calculating step for obtaining a tendency value indicating a tendency in the amount of change of pressure by subjecting the amount of change in pressure obtained when the altimeter is determined to be at a standstill state to prescribed statistical processing; and

wherein a current altitude of the portable altimeter is decided based on determination results of the movement determination step and the tendency value obtained in the tendency calculating step.

22. An altitude measuring method according to claim 16;

further comprising an altitude recording step for acquiring altitude values of the portable altimeter at prescribed times based on pressure changes accompanying actual altitude changes and excluding changes in pressure accompanying fluctuations in atmospheric pressure but unaccompanied by changes in altitude of the portable altimeter; and

a graph making step of making a time/altitude graph based on a relationship of the recorded altitude and time.

23. An altitude measuring method according to claim 17;

further comprising an altitude recording step for acquiring altitude values of the portable altimeter at prescribed times based on pressure changes accompanying actual altitude changes and excluding changes in pressure accompanying fluctuations in atmospheric pressure but unaccompanied by changes in altitude of the portable altimeter; and

a graph making step of making a time/altitude graph based on a relationship of the recorded altitude and time.

25. An altitude measuring method according to claim 16;

further comprising an altitude recording step of acquiring altitude values of the portable altimeter at prescribed times based on pressure changes accompanying actual altitude changes and excluding changes in pressure accompanying fluctuations in atmospheric pressure but unaccompanied by changes in altitude of the portable altimeter;

an estimation step of estimating and recording a recorded altitude; and

a graph making step of making a time/estimated value graph based on a relationship of estimated values and time.

26. An altitude measuring method according to claim 17;

further comprising an altitude recording step of acquiring altitude values of the portable altimeter at prescribed times based on pressure changes accompanying actual altitude changes and excluding changes in pressure accompanying fluctuations in atmospheric pressure but unaccompanied by changes in altitude of the portable altimeter;

an estimation step of estimating and recording a recorded altitude; and

a graph making step of making a time/estimated value graph based on a relationship of estimated values and time.

28. An altitude measuring method according to claim 16;

further comprising an altitude recording step of acquiring altitudes of the portable altimeter at prescribed times based on pressure changes accompanying actual altitude changes and excluding changes in pressure accompanying fluctuations in atmospheric pressure but unaccompanied by changes in altitude of the portable altimeter;

an ascent/descent rate calculating step of calculating and recording a rate of ascent/descent of the portable altimeter from the recorded altitude; and

a graph making step of making an ascent/descent rate graph based on a relationship of ascent/descent rate values obtained through calculation, and time.

29. An altitude measuring method according to claim 17;

further comprising an altitude recording step of acquiring altitudes of the portable altimeter at prescribed times based on pressure changes accompanying actual altitude changes and excluding changes in pressure accompanying fluctuations in atmospheric pressure but unaccompanied by changes in altitude of the portable altimeter;

an ascent/descent rate calculating step of calculating and recording a rate of ascent/descent of the portable altimeter from the recorded altitude; and

a graph making step of making an ascent/descent rate graph based on a relationship of ascent/descent rate values obtained through calculation, and time.

18. An altitude measuring method for a portable altimeter which measures altitude based on pressure sampled at prescribed intervals, comprising:

a movement threshold value setting step for setting a movement threshold value for an amount of change in pressure or altitude per prescribed period of time indicating a moving state of the portable altimeter in which the portable altimeter is changing in altitude; and

a movement determination step for determining that the altimeter remains at a standstill state in which it is not changing in altitude when the portable altimeter was previously in the standstill state and an absolute value for a current amount of change in pressure or altitude falls below the movement threshold value, determining that the altimeter has moved from the standstill state to the moving state when the amount of change exceeds the movement threshold value, determining that the altimeter remains in a moving state when the portable altimeter was previously in the moving state and the current amount of change exceeds the movement threshold value, and determining that the altimeter has moved from the moving state to the standstill state when the absolute value of the amount of change falls below the movement threshold value but continues to be above a predetermined value.

21. An altitude measuring method according to claim 18;

further comprising a tendency calculating step for obtaining a tendency value indicating a tendency in the amount of change of pressure by subjecting the amount of change in pressure obtained when the altimeter is determined to be at a standstill state to prescribed statistical processing; and

wherein a current altitude of the portable altimeter is decided based on determination results of the movement determination step and the tendency value obtained in the tendency calculating step.

24. An altitude measuring method according to claim 18;

further comprising an altitude recording step for acquiring altitude values of the portable altimeter at prescribed times based on pressure changes accompanying actual altitude changes and excluding changes in pressure accompanying fluctuations in atmospheric pressure but unaccompanied by changes in altitude of the portable altimeter; and

a graph making step of making a time/altitude graph based on a relationship of the recorded altitude and time.

27. An altitude measuring method according to claim 18;

further comprising an altitude recording step of acquiring altitude values of the portable altimeter at prescribed times based on pressure changes accompanying actual altitude changes and excluding changes in pressure accompanying fluctuations in atmospheric pressure but unaccompanied by changes in altitude of the portable altimeter;

an estimation step of estimating and recording a recorded altitude; and

a graph making step of making a time/estimated value graph based on a relationship of estimated values and time.

30. An altitude measuring method according to claim 18;

further comprising an altitude recording step of acquiring altitudes of the portable altimeter at prescribed times based on pressure changes accompanying actual altitude changes and excluding changes in pressure accompanying fluctuations in atmospheric pressure but unaccompanied by changes in altitude of the portable altimeter;

an ascent/descent rate calculating step of calculating and recording a rate of ascent/descent of the portable altimeter from the recorded altitude; and

a graph making step of making an ascent/descent rate graph based on a relationship of ascent/descent rate values obtained through calculation and time.

31. A portable altimeter comprising:

a pressure sensor for measuring external atmospheric pressure;

an altitude calculating unit for calculating an altitude of the portable altimeter based upon a pressure measured by the pressure sensor;

an altitude variation calculating unit for calculating a difference in altitude between a current altitude calculated by the altitude calculating unit and a previously calculated altitude;

a movement determining unit for determining whether or not the portable altimeter is in a moving state in which it is changing in altitude based upon the altitude difference calculated by the altitude variation calculating unit; and

a controller for controlling the altitude calculating unit to calculate an altitude of the portable altimeter only when the movement determining unit determines that the portable altimeter is in a moving state.

32. A portable altimeter according to claim 31;

wherein the controller controls the altitude calculating unit to calculate an altitude of the portable altimeter based on pressure changes accompanying actual changes in altitude of the portable altimeter and excluding changes in pressure accompanying fluctuations in atmospheric pressure but unaccompanied with changes in altitude of the portable altimeter.

33. A portable altimeter according to claim 31;

wherein the movement determining unit determines that the portable altimeter is in a moving state when the altitude difference exceeds a prestored movement threshold value and determines that the portable altimeter is in a standstill state in which an altitude thereof is not changing when the altitude difference is below a prestored standstill threshold value.

34. A portable altimeter according to claim 33;

wherein the movement threshold value is larger than the standstill threshold value so that an intermediate range lies therebetween.

35. A portable altimeter according to claim 34;

wherein the movement determining unit determines that the portable altimeter is in a moving state when a predetermined number of successively measured altitude difference values are in the intermediate range.

36. A portable altimeter according to claim 31;

wherein the movement determining unit comprises a first determining unit for determining whether or not the portable altimeter is in a standstill state in which it is not changing in altitude based upon an altitude difference calculated by the altitude variation calculating unit, and a second determining unit for determining whether or not the portable altimeter is in a moving state in which it is changing in altitude based upon the altitude difference calculated by the altitude variation calculating unit.

37. A portable altimeter according to claim 31;

further comprising a movement duration timer for measuring a duration or a number of fixed durations occurring while the portable altimeter is in the moving state.

38. A portable altimeter according to claim 31;

further comprising a pressure gradient calculator for calculating changes in pressure occurring while the portable altimeter is in the standstill state.