Estimation of barometric pressure measurement bias with adjustment based on a value expected for a wireless terminal

Patent metadata

Field	Value
Publication number	US-11467291-B2
Application number	US-202117236592-A
Country	US
Kind code	B2
Filing date	Apr 21, 2021
Priority date	May 20, 2020
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

A method for estimating the pressure measurement bias of a barometric sensor in a wireless terminal. A location engine using the method generates an enhanced estimate of the measurement bias. The location engine generates the enhanced estimate based in part on relatively coarse estimates of the elevation of the wireless terminal. The coarse estimates are used to generate instantaneous estimates of measurement bias and bias uncertainty. As needed, the location engine adjusts the instantaneous estimate of bias uncertainty, in order to reflect an instantaneous estimate of measurement bias that is recognized as being in error. The adjustment is based on what is expected as a probable measurement bias value for the particular wireless terminal. Once the location engine generates the enhanced estimate of measurement bias, it can generate improved estimates of elevation of the wireless terminal.

First claim

What is claimed is:

1. A method of estimating measurement bias of barometric pressure measured by a wireless terminal, the method comprising:
receiving, by a data processing system, a first estimate of a first elevation made by the wireless terminal based on signals transmitted by Global Navigation Satellite System (GNSS) satellites that are received by the wireless terminal;
receiving, by the data processing system, a first measurement of barometric pressure made by the wireless terminal;
generating, by the data-processing system, a first estimate of bias uncertainty based on comparing a first estimate of bias of barometric pressure to a predetermined set of bias values, wherein the first estimate of bias of barometric pressure is based on (i) the first measurement of barometric pressure made by the wireless terminal and (ii) the first estimate of the first elevation made by the wireless terminal; and
generating, by the data processing system, an enhanced estimate of bias of barometric pressure, by applying a filter having a current state, wherein the current state is based on (i) the first estimate of bias of barometric pressure, and (ii) a gain, wherein the gain is based on (i) the first estimate of bias uncertainty and (ii) a previous estimate of bias uncertainty existing prior to the first estimate of bias uncertainty.

2. The method of claim 1 , further comprising:
receiving, by the data processing system, a second measurement of barometric pressure made by the wireless terminal at a second elevation; and
generating, by the data processing system, an estimate of the second elevation of the wireless terminal based on:
(i) the second measurement of barometric pressure made by the wireless terminal, and
(ii) the enhanced estimate of bias of barometric pressure.

3. The method of claim 2 , further comprising transmitting the estimate of the second elevation of the wireless terminal to a location-based application server.

4. The method of claim 1 , further comprising setting the value of the first estimate of bias uncertainty to a first value, only if the first estimate of bias of barometric pressure is outside of the predetermined set of bias values.

5. The method of claim 4 , wherein the first value is equal to the value of the first estimate of bias of barometric pressure.

6. The method of claim 1 , further comprising:
receiving a first uncertainty of the first estimate of the first elevation; and
receiving a second uncertainty of the first measurement of barometric pressure; and
wherein the value of the first estimate of bias uncertainty is based on (i) the first uncertainty and (ii) the second uncertainty, only if the first estimate of bias of barometric pressure is within the predetermined set of bias values.

7. The method of claim 1 , wherein the predetermined set of bias values is based on at least one of (i) the make of the wireless terminal and (ii) the model of the wireless terminal.

8. The method of claim 1 , wherein the wireless terminal makes the first estimate of the first elevation based on ephemeris data for one or more of the GNSS satellites.

9. The method of claim 1 , further comprising:
receiving, by the data processing system, a second estimate of a second elevation made by the wireless terminal;
receiving, by the data processing system, a second measurement of barometric pressure made by the wireless terminal;
generating, by the data processing system, a second estimate of bias of barometric pressure measured by the wireless terminal based on a difference between (i) the second measurement of barometric pressure made by the wireless terminal and (ii) a second reference pressure value corresponding to the second estimate of the second elevation made by the wireless terminal;
generating, by the data-processing system, a second estimate of bias uncertainty based on comparing the second estimate of bias of barometric pressure to the predetermined set of bias values; and
wherein the previous estimate of bias uncertainty is based on the second estimate of bias uncertainty.

10. The method of claim 9 , further comprising setting the value of the first estimate of bias uncertainty to the value of the first estimate of bias of barometric pressure, and wherein the second estimate of bias of barometric pressure is within the predetermined set of bias values.

11. A method of estimating measurement bias of barometric pressure measured by a wireless terminal, the method comprising:
receiving, by a data processing system, a first estimate of a first elevation made by the wireless terminal based on signals transmitted by Global Navigation Satellite System (GNSS) satellites that are received by the wireless terminal;
receiving, by the data processing system, a first measurement of barometric pressure made by the wireless terminal;
generating, by the data processing system, a first estimate of bias of barometric pressure measured by the wireless terminal based on a difference between (i) the first measurement of barometric pressure made by the wireless terminal and (ii) a first reference pressure value corresponding to the first estimate of first elevation made by the wireless terminal, wherein the first estimate of bias of barometric pressure has a corresponding first estimate of bias uncertainty;
generating, by the data-processing system, a first estimate of bias uncertainty based on determining whether the first estimate of bias of barometric pressure is within or outside of a predetermined set of bias values; and
generating, by the data processing system, an enhanced estimate of bias of barometric pressure, by applying a filter having a current state, wherein the current state is based on (i) the first estimate of bias of barometric pressure, and (ii) a gain, wherein the gain is based on (i) the first estimate of bias uncertainty and (ii) a previous estimate of bias uncertainty existing prior to the first estimate of bias uncertainty.

12. The method of claim 11 , further comprising:
receiving, by the data processing system, a second measurement of barometric pressure made by the wireless terminal at a second elevation; and
generating, by the data processing system, an estimate of the second elevation of the wireless terminal based on:
(i) the second measurement of barometric pressure made by the wireless terminal, and
(ii) the enhanced estimate of bias of barometric pressure.

13. The method of claim 12 , further comprising transmitting the estimate of the second elevation of the wireless terminal to a location-based application server.

14. The method of claim 11 , further comprising setting the value of the first estimate of bias uncertainty to a first value, only if the first estimate of bias of barometric pressure is outside of the predetermined set of bias values.

15. The method of claim 14 , wherein the first value is equal to the value of the first estimate of bias of barometric pressure.

16. The method of claim 11 , further comprising:
receiving a first uncertainty of the first estimate of the first elevation; and
receiving a second uncertainty of the first measurement of barometric pressure; and
wherein the value of the first estimate of bias uncertainty is based on (i) the first uncertainty and (ii) the second uncertainty, only if the first estimate of bias of barometric pressure is within the predetermined set of bias values.

17. The method of claim 11 , wherein the predetermined set of bias values is based on at least one of (i) the make of the wireless terminal and (ii) the model of the wireless terminal.

Assignees

• Polaris Wireless Inc

Inventors

• Blaha Jr Jerome Arthur
• Gordon Scot Douglas
• Wu Jeffrey Noel
• Zhu Jian

Classifications

• G01L27/002

  Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination · CPC title

• G01L19/02

  Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means (for aneroid barometers G01L7/14) · CPC title

• G01S19/48

  by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system · CPC title

• H04W4/029 Primary

  Location-based management or tracking services · CPC title

• Y02A90/10

  Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation · CPC title