Smartphone Sensor Fusion for Reliable Door Event Detection
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Solution Overview
Problem
Current surveillance systems, particularly those using barometer sensors in smartphones for door event detection, are unreliable in buildings without HVAC systems, limiting their applicability for home and vehicle security monitoring.
Innovation Solution
A door event detection system utilizing a combination of air pressure sensors and microphones in mobile devices to recognize pressure and sound patterns, enabling reliable detection of door opening and closing events without the need for infrastructure integration, with low power consumption and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barometer sensors in smartphones are used for door event detection, then the system can detect opening/closing events in buildings with HVAC systems, but the system becomes unreliable in buildings without HVAC systems
Solution Approach 1:
The patent combines barometer sensor data with accelerometer data to detect door events. The barometer detects pressure changes while the accelerometer detects vibration patterns characteristic of door opening/closing actions. This multi-sensor fusion approach maintains reliability across both HVAC-equipped and non-HVAC buildings by providing multiple detection mechanisms that work independently or together.
Solution Approach 2:
The system is designed to function universally across different building types by implementing multiple detection modes. It can operate using pressure changes alone (for HVAC buildings), vibration patterns alone (for non-HVAC buildings), or a combination of both. This multi-functional capability ensures the system adapts to various environmental conditions and building configurations.
2Reliability
If electrical circuitry is installed at door periphery for event detection, then reliable detection is achieved, but the system becomes expensive and requires infrastructure integration
Solution Approach 1:
The system uses sensors already present in smartphones (barometer and accelerometer) to perform door event detection without requiring any additional infrastructure installation. The smartphone itself serves as the detection device, eliminating the need for specialized electrical circuitry at door peripheries. Users simply need to carry or place their smartphone near the door to enable detection.
Solution Approach 2:
Instead of installing specialized detection circuitry at each door, the system uses the smartphone's existing sensors to replicate detection functionality. The smartphone acts as a portable copy of a door monitoring system, providing the same detection capability without requiring physical installation of dedicated infrastructure at each location.
3Ease of manufacture
If simple monitoring applications are implemented for homes and vehicles, then cost is reduced, but detection reliability deteriorates compared to security systems
Solution Approach 1:
The patent merges data from multiple low-cost sensors (barometer and accelerometer) to achieve reliable detection. By combining pressure change detection with vibration pattern recognition, the system maintains high reliability while using only consumer-grade components already present in smartphones, making it suitable for both simple home monitoring and security applications.
Solution Approach 2:
The system dynamically adjusts detection parameters based on environmental conditions. It can switch between pressure-based detection (when HVAC pressure differences exist), vibration-based detection (when doors are opened/closed), or hybrid modes. This adaptive parameter adjustment maintains detection reliability across different scenarios while using inexpensive consumer electronics.
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
The system effectively detects door events in various environments, including those without HVAC systems, providing robust and reliable intrusion monitoring by combining air pressure and acoustic data for accurate pressure peak recognition and sound pattern analysis.
Implementation Method 1
barometer sensors as provided in smart phones can be used for detecting opening/closing events of doors in buildings... a sharp change of indoor pressure occurs when a building door is opened. This change can be detected e.g. using a smart phone pressure sensor.
Implementation Method 2
in buildings equipped with HVAC (heating, ventilating and air conditioning) systems—which maintain a convenient pressure difference between indoor and outdoor environments—a sharp change of indoor pressure occurs when a building door is opened
Implementation Method 3
collecting (100, 200), at a building opening (such as e.g. a door, a window, a shutter and the like, D), air pressure signals (as produced e.g. by movement of a door or window leaf, PW) from a pressure sensor (e.g. AP) and sound signals (as produced e.g. by a handle, lock, leaf hitting the opening frame, SW) from a sound sensor (e.g. M)
Data Source
AI summary
A method includes collecting, at a building opening, air pressure signals from a pressure sensor and sound signals from a sound sensor. The method also includes sensing pressure peaks occurring in the air pressure signals and sensing sound pulses occurring in the sound signals. A joint occurrence of a pressure peak in the air pressure signals and a sound pulse in the sound signals is indicative of an opening/closing event of the building opening.