Barometric altimeter for indoor use

• US 9,574,877 B2
• Filed: 11/21/2013
• Issued: 02/21/2017
• Est. Priority Date: 12/04/2012
• Status: Active Grant

• Current Assignee: Asahi Kasei Kabushiki Kaisha (Asahi Kasei Corporation)
• Original Assignee: Asahi Kasei Kabushiki Kaisha (Asahi Kasei Corporation)
• Inventors: Sasaki, Hiroyuki
• Primary Examiner(s): Patel, Harshad R
• Assistant Examiner(s): Shah, Samir M
• Application Number:
  US14/440,628
• Publication Number:
  US 20150292885A1
• Time in Patent Office: 1,188 Days
• US Class Current: 1/1
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: G01C 5/06 by using barometric means

Abstract

There is provided a barometric altimeter to detect a floor number at the current position in especially a high-rise building, and to calculate a height or a floor number more precisely. To this end, a barometric altimeter (100) stores, at a barometric pressure/height conversion coefficient storage unit (2), a plurality of barometric pressure/height conversion coefficients that is calculated beforehand based on temperature of air indoors in accordance with a month and a date, and an arithmetic expression, for which the plurality of barometric pressure/height conversion coefficients are used. For the actual operation, while a reference barometric pressure measurement/storage unit (1) measures and stores a barometric pressure at a position as reference barometric pressure, a current barometric pressure measurement unit (3) measures the barometric pressure at the position to be measured. Then a height calculation unit (5) calculates the height through predetermined calculation using the result of processing at these blocks.

Claims

1. A barometric altimeter, comprising:

a pressure sensor;

a reference barometric pressure measurement storage unit configured to store a respective barometric pressure measurement, by the pressure sensor, at a respective height, as a reference barometric pressure;

a barometric pressure/height conversion coefficient storage unit configured to store;

a plurality of barometric pressure/height conversion coefficients to convert respective barometric pressure measurements, by the pressure sensor, to corresponding respective heights, and

an arithmetic expression using one of the plurality of barometric pressure/height conversion coefficients as appropriate,

wherein each of the plurality of barometric pressure/height conversion coefficients are calculated beforehand based on a respective temperature of air, indoors, in accordance with a particular respective date in a particular respective month so that the plurality of barometric pressure/height conversion coefficients correspond to a plurality of months and dates; and

a height calculation unit configured to receive a desired height-measurement month and date information as an input, and to calculate a corresponding height or a corresponding variation in height at a respective indoor measurement position on a basis of the reference barometric pressure and the arithmetic expression using a respective barometric pressure/height conversion coefficient corresponding to the inputted height-measurement month and date information, and on a basis of a barometric pressure measurement by the pressure sensor at the respective indoor measurement position.

2. The barometric altimeter according to claim 1, further comprising an indoor determination unit configured to detect whether the pressure sensor is present indoors or not.

3. The barometric altimeter according to claim 2, wherein the indoor determination unit detects whether the pressure sensor is present indoors or not based on a radio signal having respectively different indoor and outdoor signal strengths.

4. The barometric altimeter according to claim 3, wherein the radio signal is a WiFi signal or a GPS signal.

5. The barometric altimeter according claim 1, further comprising a barometric pressure/height conversion coefficient calculation unit configured to calculate the plurality of barometric pressure/height conversion coefficients, wherein

the barometric pressure/height conversion coefficient calculation unit calculates the barometric pressure/height conversion coefficients based on temperature of air indoors and molecular weight or humidity of air indoors.

6. The barometric altimeter according to claim 5, further comprising a temperature sensor configured to measure the temperature of the air indoors, wherein

the barometric pressure/height conversion coefficient calculation unit calculates the plurality of barometric pressure/height conversion coefficients based on measurements made by the temperature sensor.

7. The barometric altimeter according claim 1, further comprising:

a barometric pressure/height conversion coefficient calculation unit configured to calculate the plurality of barometric pressure/height conversion coefficients; and

a humidity sensor configured to measure humidity of air indoors, wherein

the barometric pressure/height conversion coefficient calculation unit calculates the barometric pressure/height conversion coefficients based on temperature of the air indoors and the measured humidity.

8. The barometric altimeter according to claim 1, wherein

the plurality of barometric pressure/height conversion coefficients are set in accordance with four seasons, and

a season when a height is measured is input as the height-measurement month and date information.

9. The barometric altimeter according to claim 1, wherein the arithmetic expression is defined as the following expression (1):

H=−

Psens×

P0×

loge(P/Pref) 

 

(1),

wherein “

loge”

represents a natural logarithm having a base (e=2.71828) of the natural logarithm,

H=Height,

Psens=Barometric pressure/height conversion coefficient,

P0=Reference barometric pressure value at a sea level of 0 m of the international standard atmosphere,

P=Barometric pressure at the measurement position, and

Pref=Reference barometric pressure.

10. The barometric altimeter according to claim 9, wherein the barometric pressure/height conversion coefficient is defined as the following expression (2):

Psens=(R×

T)/(M0×

G×

P0) 

 

(2),

wherein;

R=gas constant,

T=absolute temperature at the indoor measurement position,

M0=molecular weight of air at the indoor measurement position, and

G=gravity acceleration at the indoor measurement position.