Dual Magnetic Sensor Assembly for Absolute Position Tracking
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Solution Overview
Problem
Existing position measurement systems for relative movement of two elements within a device, especially in optical devices, face challenges in achieving precision below 10 μm, compatibility with vibrations and shocks, and the need for recalibration after disturbances, while maintaining compactness and cost-effectiveness.
Innovation Solution
Incorporating a second magnetic sensor to detect the end of a magnetic track, providing a reference point for continuous counting of magnetic pole orientation alternations, ensuring absolute position measurement even during vibrations or shocks, and allowing for high-frequency measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnetic sensor is used to detect magnetic pole orientation alternations, then the measurement system is simple and cost-effective, but the system cannot differentiate positions that differ by integer numbers of periods and requires recalibration after shocks or vibrations
Solution Approach 1:
The measurement system is segmented into two functional parts: a first magnetic sensor for continuous position measurement and a second magnetic sensor for reference point detection. This segmentation allows each sensor to specialize in specific tasks, resolving the ambiguity of periodic position detection while maintaining system simplicity.
Solution Approach 2:
The second magnetic sensor acts as an intermediary that detects the end of the magnetic track and provides reference points. This intermediary element enables the system to resolve position ambiguities without requiring complex processing of the first sensor's data alone.
2Productivity
If magnetic pole orientation alternations are counted continuously, then high measurement frequency is achieved, but shocks or vibrations cause loss of continuous counting and position uncertainty
Solution Approach 1:
The second magnetic sensor provides feedback by detecting the end of the magnetic track and establishing reference points. This feedback mechanism allows the system to recover and realign after shocks or vibrations, maintaining reliable continuous measurement despite disturbances.
Solution Approach 2:
The second magnetic sensor performs preliminary detection of the magnetic track end before position ambiguities arise. By establishing reference points in advance, the system prepares for potential shocks or vibrations and can quickly realign without losing measurement continuity.
3Device complexity
If the measurement system is made compact and inexpensive, then device integration is easier, but achieving measurement precision below 10 μm becomes more difficult
Solution Approach 1:
Two magnetic sensors are merged into a single compact assembly that works together to provide both continuous measurement and reference detection. This merging achieves high precision below 10 μm while maintaining system compactness and cost-effectiveness through shared components and integrated design.
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
Enables continuous, accurate, and absolute measurement of relative position with reduced uncertainty, eliminating the need for external recalibration and supporting high-frequency monitoring of rapid movements within the device.
Implementation Method 1
a first magnetic sensor, which is capable of detecting a passage of magnetic poles whose respective orientations are different between two successive poles
Implementation Method 2
a second magnetic sensor, which is capable of detecting a passage of at least one magnetic pole of the end of the magnetic track of the ribbon
Data Source
Figure 1
AI summary
An assembly for measuring a relative position of two movable elements (11, 12) with respect to one another comprises a ribbon (1) having a magnetic strip, and two magnetic sensors (2, 3). The ribbon is intended to be fastened to one of the two elements, and the magnetic sensors both to be fastened to the other element. One of the two sensors serves to precisely measure a relative position of the two elements within a period of orientation alternation of magnetic poles, and the other sensor serves to define an origin of the measurements in order to obtain an absolute-measurement result for the relative position of the two elements with respect to one another.