Stationary Barometer Detection of HVAC State Changes Indoors
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Solution Overview
Problem
Indoor positioning technologies face inaccuracies in altitude data collection due to the stack effect in buildings, leading to unreliable radio maps and position estimates, especially when the air-conditioning system is off, as barometers provide inconsistent pressure readings.
Innovation Solution
Developing methods to detect changes in the air-conditioning system's state, such as analyzing pressure and movement data from mobile devices to distinguish between altitude changes and air-conditioning system changes, allowing for more accurate data collection and radio map generation only when the system is on.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If barometer pressure measurements are used to estimate altitude in indoor environments, then altitude data can be collected ubiquitously in consumer mobile devices, but the measurements become inaccurate due to the stack effect causing abnormal pressure-altitude relationships inside buildings
Solution Approach 1:
The system monitors changes in pressure parameters over time to detect transitions between indoor and outdoor environments. By analyzing the temporal pattern of pressure readings and comparing them against expected atmospheric pressure-altitude relationships, the system can identify when the device is in an environment where barometric altitude measurement is reliable versus when it is affected by the stack effect in buildings.
2Productivity
If crowdsourced altitude data is collected from mobile devices to generate radio maps, then global coverage can be built quickly, but inaccurate data is collected when air-conditioning systems are off, leading to unreliable position estimates
Solution Approach 1:
The system implements feedback mechanisms where pressure measurement quality is continuously evaluated. When poor quality measurements are detected (indicating the device is indoors with air-conditioning off), the system provides feedback to exclude these measurements from radio map generation. This allows rapid crowdsourced data collection to continue while automatically filtering out unreliable data points that would compromise position estimate accuracy.
3Measurement precision
If pressure data is collected from stationary mobile devices to detect air-conditioning system state changes, then more accurate altitude data can be ensured, but additional data collection requirements increase system complexity
Solution Approach 1:
The system designs the mobile device's pressure sensor and processing capabilities to serve multiple functions: routine altitude estimation during movement, detection of air-conditioning system state changes when stationary, and quality assessment of crowdsourced data. By making the pressure measurement subsystem multi-functional, the system achieves improved altitude data accuracy without requiring separate dedicated hardware or systems for each function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves the accuracy of indoor positioning by ensuring reliable altitude data collection and generating more accurate radio maps, enhancing the overall performance of indoor positioning systems.
Implementation Method 1
a barometer is configured to measure atmospheric (air) pressure in the environment. And because air pressure outdoors changes with altitude in a predictable manner (e.g., according to the well-known barometric formula), the barometer's pressure measurement(s) could be used for estimating altitude(s) of a mobile device.
Implementation Method 2
the stack effect (also known as the chimney effect) relates to movement of air into and out of building due to a difference in air density between the inside and outside of the building. This difference in air density could result from temperature (e.g., heat) and/or moisture differences
Data Source
AI summary
Disclosed is an approach for detecting that a state of an air-conditioning system in a building has changed and ultimately determining the air-conditioning system's operating pattern, which could help improve collection and/or use of crowdsourced data for an indoor positioning solution and thus lead to more accurate position estimates. According to the disclosed approach, while a mobile device is in the building, processor(s) may detect that the mobile device is stationary and may responsively (i) cause the mobile device to provide pressure data representing air pressure in the building while the mobile device is stationary and (ii) subsequently receive the pressure data from the mobile device. And based on the pressure data indicating a pressure change and representing air pressure in the building while the mobile device is stationary, processor(s) may detect that a state of the air-conditioning system in the building has changed.