Adaptive Sliding Door Pattern Cancellation in Metal Detection
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Solution Overview
Problem
Metal detection systems, especially those integrated with EAS systems, face significant interference from moving metal doors, leading to false alarms and reduced accuracy over time due to environmental changes, which can result in substantial costs and vulnerabilities to theft.
Innovation Solution
A method and system that record and cancel the signal patterns caused by metal door movements, allowing for accurate detection of transitory metal objects by subtracting the recorded interference patterns from instantaneous signals, thereby reducing false alarms and maintaining system accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If metal detection systems are installed near metal doors, then the system can be positioned in convenient locations, but the metal door movements cause electromagnetic field disturbances that lead to false alarms and reduced detection accuracy
Solution Approach 1:
The system performs preliminary recording of electromagnetic field patterns during door movements before actual metal detection operations. By capturing and storing these interference patterns in advance, the system can later subtract them from detection signals to eliminate false alarms caused by door movements.
Solution Approach 2:
The system introduces an intermediary reference signal representing the electromagnetic field disturbances caused by door movements. This reference signal acts as a mediator that can be subtracted from the actual detection signals to isolate the true metal detection responses from the door-induced interference.
2Productivity
If the metal detection system operates continuously, then productivity is maintained, but environmental changes cause drift in the electromagnetic field gradient leading to false alarms over time
Solution Approach 1:
The system continuously monitors the electromagnetic field environment and compares current field patterns against stored reference patterns. When drift is detected due to environmental changes, the system can update its reference patterns or adjust its detection thresholds to maintain accurate metal detection and reduce false alarms.
Solution Approach 2:
The system dynamically adapts to environmental changes by allowing the reference electromagnetic field patterns to be updated over time. This dynamic adjustment enables the system to maintain detection accuracy despite drift caused by continuous operation and changing environmental conditions.
3Object-affected harmful factors
If shielding or electrically separating the door from pedestals is implemented, then interference from metal doors is reduced, but the system complexity and installation requirements increase significantly
Solution Approach 1:
The system replaces physical shielding and electrical separation mechanisms with a signal processing approach. Instead of using additional hardware to block or isolate electromagnetic interference, the system uses software-based pattern recognition and subtraction to eliminate the interference from detection signals.
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 effectively nullifies the interference from metal doors, enhancing the accuracy of metal detection systems and reducing the need for frequent recalibrations or system replacements, thus minimizing costs and maintaining effective security.
Implementation Method 1
The system includes one or more transmitters, receivers and antennas, stored in a housing (such as an EAS pedestal) capable of generating an electromagnetic field across the exit
Implementation Method 2
a receiver operable to receive instantaneous signals representing electromagnetic field disturbances during operation of the metal detection system
Implementation Method 3
determining a resulting waveform representing the difference between the instantaneous signals received during operation of the metal detection system and a recorded pattern of signals representing electromagnetic field disturbances
Data Source
AI summary
A metal detection device, system and method are provided. The device includes a receiver that receives a signal pattern representing electromagnetic field disturbances over time caused by movement of metal doors in a detection region. The device further includes a memory in communication with the receiver. The memory stores a recorded signal pattern of a previously received signal pattern and at least one quality criterion. The device further includes a processor in communication with the memory. The processor determines pattern vitals indicating a quality of the received signal pattern. The processor further determines whether the at least one quality criterion is met based at least in part on the pattern vitals. The processor further updates the recorded signal pattern based at least in part on determining whether the at least one quality criterion is met.