Deadbolt Engagement Detection Using Motor Current Signatures
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Solution Overview
Problem
Existing door lock detection systems fail to reliably determine whether a door lock bolt is actually engaged with the door jamb, as they rely on unreliable methods such as reed switches that can be easily defeated by magnets, and do not accurately detect the bolt's engagement with the jamb recess.
Innovation Solution
A door lock detection system using a motor-driven bolt with a force or vibration applicator to apply resistance, coupled with a current or vibration sensor to detect motor current or bolt vibration signatures, comparing these signatures to expected profiles to confirm engagement with the door jamb.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing deadbolt systems are used to detect whether a bolt is extended or retracted, then the bolt position can be detected, but the system is unable to detect whether the bolt is actually engaged with the door jamb
Solution Approach 1:
The patent replaces traditional mechanical detection methods (reed switches, Hall effect sensors) with motor current signature analysis. By monitoring the electrical current characteristics of the motor during bolt movement, the system can detect engagement forces without additional mechanical sensors, thereby improving reliability while maintaining detection capability
Solution Approach 2:
The system changes the detection parameter from simple position detection to motor current signature analysis. By analyzing variations in motor current during the locking cycle, the system can infer engagement status based on the force required to move the bolt, providing more reliable detection of actual engagement with the door jamb
2Ease of operation
If reed switches are used to detect door lock state, then the system can monitor lock status, but the detection can be easily defeated by magnets
Solution Approach 1:
The patent eliminates magnetic field-based detection (reed switches) and replaces it with electrical current analysis of the motor driving the bolt. This substitution removes the vulnerability to magnetic interference while preserving the ability to remotely monitor lock status through wireless communication of the analyzed engagement data
3Measurement precision
If a force applicator is used to apply force to the bolt during movement, then engagement detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The system uses the motor's own current signature as the detection mechanism. The motor that drives the bolt also provides the sensing function through its electrical characteristics, eliminating the need for separate force applicators or additional sensors. This self-service approach improves engagement detection accuracy without significantly increasing device complexity
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
Provides a reliable method to determine if the door lock bolt is engaged with the door jamb, reducing false positives and ensuring accurate detection of the lock's state, suitable for integration into home automation systems.
Implementation Method 1
a current sensor configured to sense current of the motor as the bolt is driven by the motor from the retracted position to the extended position
Implementation Method 2
a vibration sensor configured to sense vibration of the bolt relative to bolt position as the bolt is moved from the retracted position to the extended position
Data Source
AI summary
Systems and methods for detecting whether a door lock bolt is engaged with a door jamb recess in a locked position are provided. Certain of the systems and methods described herein detect engagement between a door lock bolt and door jamb recess using a motor current signature. Certain of the systems and methods described herein detect engagement between a door lock bolt and door jamb recess using a bolt vibration signature.