Mobile Device Pressure Sensor Calibration for Indoor Altitude Accuracy
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Solution Overview
Problem
Mobile devices face challenges in accurately determining altitude, especially in urban or indoor environments due to imprecise pressure sensor readings and adverse pressure variations from HVAC effects, leading to unreliable location estimates.
Innovation Solution
A method to determine when an estimated altitude can be used for calibration or location determination, including identifying areas where a mobile device resides and assessing pressure profiles to detect adverse pressure variations, allowing for calibrated pressure sensor usage and accurate altitude computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensor calibration is performed using ambient pressure measurements in indoor environments, then altitude computation can be achieved, but measurement precision deteriorates due to adverse pressure variations from HVAC effects
Solution Approach 1:
The system performs preliminary detection of HVAC effects by monitoring pressure variations over time before attempting altitude computation. By identifying adverse pressure variation patterns in advance, the system can determine when calibration should be avoided or when alternative methods should be used, preventing inaccurate altitude measurements from being computed in the first place
Solution Approach 2:
The system introduces an intermediary assessment layer that evaluates the suitability of current environmental conditions for pressure-based altitude measurement. This intermediary mechanism analyzes pressure profile characteristics and determines whether the environment is appropriate for calibration, acting as a mediator between the pressure sensor and the altitude computation process
2Measurement precision
If pressure sensor calibration is performed frequently to maintain accuracy, then measurement precision improves, but loss of time increases due to calibration interruptions
Solution Approach 1:
The system implements feedback by continuously monitoring pressure variations and comparing them against known HVAC effect patterns. This feedback mechanism allows the system to dynamically adjust calibration timing, performing calibration only when environmental conditions are favorable, thereby maintaining sensor accuracy while minimizing calibration frequency and associated time losses
Solution Approach 2:
The system changes the parameter of calibration timing from a fixed schedule to a condition-based approach. By monitoring environmental parameters (pressure variations, temperature changes) and adjusting calibration timing based on these parameter changes, the system optimizes the balance between maintaining accuracy and minimizing calibration interruptions
3Productivity
If altitude estimation is computed using pressure measurements in environments with HVAC effects, then location determination can proceed, but measurement precision deteriorates due to pressure pushing or pulling
Solution Approach 1:
The system converts the harmful effect of HVAC-induced pressure variations into a beneficial detection opportunity. By specifically looking for pressure variation patterns characteristic of HVAC effects, the system can identify when such effects are present and take appropriate corrective actions, such as avoiding calibration or alerting the user to reduced accuracy, thereby turning a source of error into a detectable condition
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
This approach enhances the accuracy and reliability of altitude determination and pressure sensor calibration, improving location precision and reducing errors caused by indoor pressure variations, thus supporting timely emergency responses and accurate positioning.
Implementation Method 1
altitude can be computed using a measurement of pressure from a calibrated pressure sensor of a mobile device along with ambient pressure measurement(s) from a network of calibrated reference pressure sensors
Implementation Method 2
a measurement of ambient temperature from the network or other source
Data Source
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AI summary
Sensor calibration and location determination. Aspects of this disclosure relate to determining when an estimated altitude of a mobile device can be used for calibration or location determination, determining when to calibrate a pressure sensor of a mobile device, and determining whether a mobile device is inside an environment experiencing adverse pressure variation conditions.