HVAC-Affected Pressure Sensor Calibration for Accurate Altitude
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Solution Overview
Problem
Conventional systems for determining the altitude of a computing device in environments affected by HVAC effects are inadequate when data is sporadic, leading to imprecise altitude estimates that can have life-threatening consequences in emergencies and affect the functionality of various applications.
Innovation Solution
A system and method to determine the location context of a computing device, identify HVAC effects, and calibrate the pressure sensor using sporadic and regular data by comparing altitude or pressure differences across different environments, thereby improving altitude estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If barometric-based altitude determination is used in HVAC environments, then altitude estimation can be obtained, but measurement precision deteriorates due to HVAC effects on pressure sensor readings
Solution Approach 1:
The patent identifies HVAC-affected environments through location context (building/vehicle detection) and transforms the harmful pressure variations into useful calibration data. By comparing pressure readings at known altitudes within HVAC environments, the system calculates calibration values that compensate for HVAC effects, converting the previously harmful pressure variations into beneficial calibration information that improves subsequent altitude measurements.
Solution Approach 2:
The system dynamically adjusts the barometric altitude calculation by applying HVAC-specific calibration values derived from environmental parameters. When the device is detected to be in a HVAC environment (building or vehicle), the system modifies the pressure-to-altitude conversion using calibrated offsets specific to that environment, thereby compensating for the HVAC-induced pressure variations and restoring measurement precision.
2Reliability
If pressure sensor calibration is performed without considering location context, then calibration process is simplified, but reliability deteriorates due to undetected HVAC effects
Solution Approach 1:
The system performs preliminary location context determination (detecting whether the device is in a building or vehicle) before executing the calibration process. This preliminary action enables the system to select appropriate calibration strategies - using HVAC-specific calibration procedures when in controlled environments versus standard barometric calibration when outdoors - thereby ensuring measurement reliability without unnecessarily complicating the process in simple scenarios.
Solution Approach 2:
The calibration process is segmented into environment-specific procedures: outdoor calibration, building HVAC calibration, and vehicle HVAC calibration. Each segment uses tailored methods appropriate to that environment, with building calibration using floor-level references and vehicle calibration using motion-state detection. This segmentation improves reliability by applying the right calibration method to the right context while keeping each individual calibration routine relatively simple.
3Measurement precision
If altitude determination is performed using sporadic data points, then data collection requirements are reduced, but measurement precision deteriorates
Solution Approach 1:
The patent transforms sporadic, low-quantity pressure readings into accurate altitude estimates by applying environment-specific calibration values. Instead of requiring dense data streams, the system uses calibrated offset values derived from location context (building floor levels, vehicle motion states) to correct individual pressure measurements, thereby achieving high precision with minimal data quantity.
Solution Approach 2:
The system introduces location context information (building databases, vehicle motion data, GPS coordinates) as an intermediary that bridges the gap between sparse pressure readings and accurate altitude determination. This intermediary provides environmental reference data that compensates for the lack of frequent measurements, enabling precise altitude estimation even with sporadic data points by contextualizing each measurement within its environmental framework.
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
Enhances the accuracy of altitude determination in HVAC environments, particularly in emergencies, by providing precise floor information and improving the functionality of location-dependent applications.
Implementation Method 1
determining a measured altitude of the computing device based on a reference pressure and a measured pressure from a pressure sensor of the computing device
Data Source
AI summary
A location context indicates whether a computing device is in an HVAC environment or a non-HVAC environment. When the computing device is in the HVAC environment, an expected altitude of the computing device is obtained, and a measured altitude of the computing device is determined. An altitude difference is determined between the expected altitude and the measured altitude. The HVAC effect is determined based on the altitude difference. A pressure sensor of the computing device is calibrated based on the HVAC effect, or a corrected measured altitude of the computing device is estimated based on the HVAC effect. In some cases, instead of the altitude difference, the HVAC effect is determined based on a pressure difference.