Cascaded Permanent Magnets for Position Sensor Range Extension
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Solution Overview
Problem
Existing displacement sensors are limited in their ability to operate effectively underwater and in hazardous environments with high vibrations, and they struggle to determine various types of displacement, such as linear, angular, and helical displacement, especially when sensors and magnets fail.
Innovation Solution
The use of an extended range position sensor system that employs cascaded sets of permanent magnets and Anisotropic Magneto-Resistive (AMR) sensors, which encode positional information through unique magnetic field outputs, allowing for the determination of displacement even if sensors and magnets fail, and can be used in harsh environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional displacement sensors are used, then the sensor structure is simple, but the sensor cannot operate effectively underwater and in hazardous environments with high vibrations
Solution Approach 1:
The patent replaces traditional mechanical displacement sensors with a magnetic field-based sensing system. Magnets are attached to the moving object, and magnetic field sensors (such as Hall effect sensors or magnetoresistive sensors) detect the magnetic field changes to determine displacement. This substitution eliminates the need for complex mechanical linkages and protective housings required for mechanical sensors in harsh environments, thereby improving reliability without significantly increasing system complexity.
Solution Approach 2:
The patent introduces magnetic fields as an intermediary between the moving object and the sensor system. Instead of directly measuring mechanical displacement, the system uses magnets to generate magnetic fields that serve as a medium for transmitting position information to the sensors. This intermediary approach allows the system to operate effectively in environments where direct mechanical contact would fail, such as underwater or in high-vibration conditions.
2Measurement precision
If single-pulse wheel encoding is used, then the device complexity is low, but the measurement precision and range are limited
Solution Approach 1:
The patent transitions from one-dimensional single-pulse encoding to multi-dimensional magnetic field sensing. Instead of using a single pulse per rotation, the system employs multiple magnetic field sensors arranged in specific geometries to detect magnetic field vectors in multiple dimensions. This allows for more precise position determination and extended measurement range while maintaining manageable system complexity through standardized sensor arrays.
Solution Approach 2:
The patent divides the position measurement function across multiple magnetic field sensors rather than relying on a single sensor or single-pulse encoding. Each sensor contributes to the overall position determination, and the system segments the measurement task into multiple independent sensing points. This segmentation improves measurement precision and provides redundancy, while the modular nature of adding sensors keeps the complexity increase manageable.
3Adaptability or versatility
If conventional sensors are used, then the device cost is low, but the dynamic range of position sensing is limited
Solution Approach 1:
The patent creates a universal magnetic field-based sensing system that can measure multiple types of displacement (linear, angular, helical, and arbitrary paths) using the same fundamental technology. By attaching magnets to different configurations on the moving object and using appropriate sensor arrangements, the system can adapt to various measurement requirements without requiring different sensor types, thereby extending dynamic range while controlling overall system 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
This solution provides a cost-effective means to increase the dynamic range of position sensing, enabling the measurement of various displacement types, including linear, angular, and helical displacements, even in challenging environments, by decoding coarse position codes from sensor outputs and averaging position estimates based on magnet orientation and spacing.
Implementation Method 1
cascaded sets of permanent magnets and Anisotropic Magneto-Resistive (AMR) sensors, which encode positional information through unique magnetic field outputs
Data Source
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AI summary
Apparatus and associated methods relate to cascaded sets of two or more individual permanent magnets distributed in a predetermined spatial relationship on a source carrier configured to translate proximate two or more magnetic field sensors distributed in a predetermined spatial relationship on a reference carrier. In an illustrative example, the permanent magnets may be arranged in at least two predetermined orientations. For example, each of the permanent magnets may direct its field in a predetermined orientation to produce a unique output code from a set of the magnetic field sensors. The output code may, for example, uniquely identify a relative position between the source carrier and the reference carrier. The magnetic field sensors may be, for example, anisotropic magneto-resistive elements. Cascaded sets of permanent magnets may cost-effectively increase the dynamic range of the relative position between the source carrier and the reference carrier by adding additional magnetic targets.