Magnetic Field Sensor Network Self-Calibration
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Solution Overview
Problem
Magnetic field sensors, especially multi-axis sensors, face challenges in producing linear output due to varying temperature and orientation relative to Earth's magnetic North, requiring complex and expensive calibration methods, and often fail in environments with excessive magnetic fields.
Innovation Solution
A sensor assessment network (SAN) with multiple magnetic field sensors, each having x, y, and z axes, using sensor transducers with digitally controlled potentiometers and controllers to generate stepped voltage, sample output frequencies, and convert non-linear responses to magnetic field values, determining magnetic field vectors and trajectories through a SAN controller, which can also integrate with cameras for target localization and identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If advanced electronic components and circuits are used to force calibration of magnetic field sensors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system performs self-calibration by automatically generating a baseline signal from average values of electronic signals at previous time periods, eliminating the need for manual calibration procedures and complex external calibration equipment. The controller automatically compares current signals against the baseline and generates calibrated output signals when differences exceed thresholds.
Solution Approach 2:
The system changes the operating parameters of the sensor transducer using a digitally controlled potentiometer to obtain quantitative linear output when calibration is not possible due to excessive magnetic fields. This allows the sensor to operate in calibration mode or uncalibrated mode depending on environmental conditions.
2Adaptability or versatility
If magnetic field sensors operate in environments with excessive magnetic fields, then adaptability is improved, but measurement precision deteriorates due to output bias
Solution Approach 1:
The system dynamically adjusts its operation mode based on environmental conditions. When excessive magnetic fields are detected that would prevent calibration, the controller switches to operating the sensor transducer in an uncalibrated mode, allowing continuous operation across varying environmental conditions while maintaining measurement capability.
Solution Approach 2:
The digitally controlled potentiometer changes the operating parameters of the sensor transducer to obtain quantitative linear output when standard calibration is not possible, enabling the system to adapt to environments with excessive magnetic fields by adjusting electrical parameters rather than relying solely on physical calibration.
3Measurement precision
If multi-axis magnetic field sensors are used to detect targets, then measurement precision is improved, but device complexity increases due to multiple axes orientation requirements
Solution Approach 1:
The system performs self-calibration for all three axes (x, y, and z) automatically by generating baseline signals from average values of electronic signals at previous time periods for each axis. This eliminates the need for manual orientation and calibration procedures for each axis, reducing complexity while maintaining the precision benefits of multi-axis sensing.
Solution Approach 2:
The system combines the calibration and measurement functions into a unified automated process where the controller manages both x, y, and z axis calibration and operation simultaneously, reducing the operational complexity that would otherwise require separate procedures for each axis.
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 SAN provides reliable, quantitative, and linear output over a wide bandwidth, enabling effective target detection, localization, and identification, even in complex magnetic environments, with improved accuracy and reduced need for expensive calibration methods.
Implementation Method 1
Each magnetic field sensor has x, y and z axes and produces x, y and z channels at respective axes, and each may include a sensor transducer having a sensor coil
Implementation Method 2
a digitally controlled potentiometer connected to the sensor coil. A sensor controller may be connected to the sensor coil and digitally controlled potentiometer and configured to apply a stepped voltage from negative to positive over the sensor coil, sample an output frequency at each stepped voltage value
Data Source
AI summary
A security portal includes magnetic field sensors in a sensor assessment network (SAN) for tracking a magnetic dipole target. Each sensor includes a sensor transducer, a sensor coil, and a digitally controlled potentiometer. A sensor controller applies a stepped voltage, samples an output frequency at each stepped voltage value, generates a magnetic sensor response curve, and converts a non-linear response of the sensor transducer to a magnetic field value for each x, y and z channel as a function of frequency for a specific potentiometer setting based upon the sensed magnetic dipole that is tracked in the security portal. A SAN controller receives the magnetic field values from each channel and determines the magnetic field vectors of the target over each sample.