Multi-Axis Magnetometer Door Position Sensing
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Solution Overview
Problem
Existing door position sensors, particularly those using magnetometers, often suffer from false-positive readings, failing to accurately determine the open/closed state of doors due to incomplete extension of the latchbolt.
Innovation Solution
A multi-axis magnetometer system that generates signals related to the magnetic field's net flux point, calculates the incidence angle between the magnetometer and this point, and compares it to a known angle to determine the door's position, ensuring accurate detection of the door's open/closed state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetometer is used to sense the magnetic field and determine door position based on the three-dimensional position of the center of magnetic flux, then the door position can be detected, but false-positive readings occur indicating the door is secured when the latchbolt has not been fully extended
Solution Approach 1:
The patent changes the measurement parameter from three-dimensional position detection to two-dimensional angular incidence detection. By measuring the angle of incidence of magnetic flux lines on the magnetometer sensor plane rather than the absolute 3D position, the system achieves more reliable door position detection that accurately reflects latchbolt extension state without false positives.
Solution Approach 2:
The patent replaces the traditional mechanical switch or contact-based door position sensing with a magnetic field-based optical detection system. The magnetometer detects changes in magnetic flux angle, substituting mechanical detection with a non-contact magnetic sensing mechanism that provides more reliable operation.
2Loss of information
If the three-dimensional position of the center of magnetic flux is used to determine door state, then door position information can be obtained, but the system cannot distinguish between true secured state and mock secured state
Solution Approach 1:
The patent changes the detection parameter from 3D magnetic flux center position to 2D angular incidence measurement on the sensor plane. This angular measurement provides more discriminative information about the relative position between magnetometer and magnet, enabling the system to distinguish between true secured state (latchbolt extended) and mock secured state (door closed but latchbolt not extended).
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 of door position detection by distinguishing between true and mock secured states, reducing false-positive readings and improving the fidelity of door position determination.
Implementation Method 1
a magnetometer that senses the magnetic field of a magnet installed to the strike
Data Source
AI summary
An exemplary method relates to determining an open/closed position of a door. The method generally involves generating, by a multi-axis magnetometer mounted to the door, a plurality of signals relating a magnetic field having a net magnetic flux point, and generating, by a controller and based on the plurality of signals, a current incidence angle defined between the multi-axis magnetometer and the net magnetic flux point. The method further includes comparing the current incidence angle to a known incidence angle, wherein the known incidence angle is defined between the multi-axis magnetometer and the net magnetic flux point when the door is in a known position. The method further includes determining the open/closed position of the door based on the comparison of the current incidence angle to the known incidence angle.