Redundant Position Sensor Stacked Boards
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Solution Overview
Problem
Inductive position sensing systems face inaccuracies due to non-uniform electromagnetic fields, wire trace connections, air-gap variations, and mismatches between receiver coils, leading to inaccurate position measurement.
Innovation Solution
A redundant position sensor design utilizing stacked sensor boards with sensor coils, where one board has an active transmit coil and the others are shorted, providing redundant measurements to enhance accuracy by controlling signal damping and amplification through a stack control circuit and processing circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single transmit coil is used in the position sensor, then the device complexity is reduced, but the reliability deteriorates because the system fails when the transmit coil is shorted
Solution Approach 1:
The patent applies local quality by making the transmit coils redundant with different functional roles. The first transmit coil is configured for normal operation while the second transmit coil is specifically designed as a backup that activates when the first coil is shorted. This localized differentiation in coil functionality ensures system reliability without requiring complete redundancy of all components.
Solution Approach 2:
The patent implements beforehand cushioning by pre-configuring the second transmit coil as a backup component that remains inactive during normal operation but is ready to take over immediately when the first transmit coil fails. This prior preparation of backup capability protects against future failures without adding complex active redundancy management systems.
2Measurement precision
If multiple receiver coils are used to improve measurement accuracy, then the measurement precision improves, but the device complexity increases due to additional coils and signal processing
Solution Approach 1:
The patent applies segmentation by dividing the receiver coil system into multiple independent coils (first and second receiver coils) that can be selectively activated. This segmentation allows the system to use only the necessary number of receiver coils for accurate measurement, reducing complexity compared to always using all available coils, while still providing the option to engage additional coils when higher precision is required.
3Measurement precision
If the air-gap between the metallic target and coils is reduced to improve signal strength, then the measurement precision improves, but the ease of operation deteriorates due to stricter alignment requirements
Solution Approach 1:
The patent applies merging by combining the output signals from multiple receiver coils through signal processing circuits. This signal combination effectively increases the overall signal strength and improves the signal-to-noise ratio, allowing the system to achieve good measurement precision without requiring the air-gap to be minimized, thus maintaining easier operation with larger alignment tolerances.
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 solution achieves more accurate position measurement by compensating for signal damping and frequency changes, ensuring system functionality even when one transmitter is shorted, thereby improving the reliability and precision of position sensing.
Implementation Method 1
a transmit coil is used to induce eddy currents in a metallic target that is sliding or rotating above a set of receiver coils. Receiver coils receive the magnetic field generated from eddy currents and the transmit coils
Implementation Method 2
the electromagnetic field generated by the transmitter, and the resulting fields generated in the metallic target
Data Source
AI summary
A position sensor according to some embodiments includes a first position sensor board having first sensor coils and a first transmit coil; a second position sensor board having second sensor coils stacked with, and separated from by a distance Z, the first position sensor; and at least one target positioned relative to the stacked first position sensor and second position sensor. A redundant position sensor according to some embodiments includes a plurality of stacked sensor boards, each of the plurality of sensor boards including sensor coils, wherein one of the plurality of stacked sensor boards includes an active transmit coil; and a target positioned over the plurality of stacked sensor boards.