Barometric altimeter for indoor use

Patent metadata

Field	Value
Publication number	US-9574877-B2
Application number	US-201314440628-A
Country	US
Kind code	B2
Filing date	Nov 21, 2013
Priority date	Dec 4, 2012
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

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.

First claim

The invention claimed is:

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=−P sens× P 0×loge( P/P ref)  (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):
P sens=( R×T )/( M 0× G×P 0)  (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.

Assignees

• Asahi Chemical Ind

Inventors

• Sasaki Hiroyuki

Classifications

• G01C25/00

  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 title

• G01C5/06 Primary

  by using barometric means · CPC title