Inductive Position Sensor Coil Segmentation for Noise Rejection
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Solution Overview
Problem
Inductive sensors, particularly rotational sensors, face limitations in measuring distance due to noise and manufacturing variations, which affect the accuracy of positional signals in applications like electronic throttle controls, where linear sensors could provide more sensitive measurements over a longer range.
Innovation Solution
An apparatus comprising an exciter coil, a receiver coil, and an optional reference coil, where the receiver coil is divided into sections to induce opposed voltages, and an electronic circuit processes signals to correct for common mode factors using a reference signal independent of the coupler element's position, allowing for improved positional measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rotational sensors are used, then the device structure is simple, but the measurement range is limited and accuracy is reduced due to noise and manufacturing variations
Solution Approach 1:
The receiver coil is divided into multiple sections (e.g., four sections arranged in a circular pattern), with each section contributing to the measurement of different components of the coupler element's position. This segmentation allows for differential measurement techniques that cancel out common-mode noise and manufacturing variations, thereby improving measurement precision while maintaining a relatively simple device structure.
Solution Approach 2:
A reference coil is introduced as an intermediary element that provides a reference signal independent of the coupler element's position. This reference signal serves as a mediator to compensate for noise and manufacturing variations by providing a baseline for comparison, enabling the system to distinguish between actual position changes and spurious signals caused by environmental factors or manufacturing tolerances.
2Measurement precision
If linear sensors are used, then measurement sensitivity and range are improved, but device complexity increases
Solution Approach 1:
The coil assembly serves multiple functions: the exciter coil generates the magnetic field, the receiver coil sections measure position in multiple directions, and the reference coil provides noise compensation. This multi-functionality allows the system to achieve linear sensor-level measurement sensitivity and range while maintaining a structure that is more compact and integrated than traditional linear sensors, thereby reducing overall device complexity.
Solution Approach 2:
The patent combines the exciter coil, multiple receiver coil sections, and reference coil into a single integrated coil assembly that can be formed on a common substrate. This merging of multiple sensor functions into one unified structure reduces the number of separate components and interconnections required, thereby achieving high measurement sensitivity without proportionally increasing device complexity.
3Reliability
If receiver coil sections are used to induce opposed voltages, then common mode factors are corrected, but signal processing complexity increases
Solution Approach 1:
The reference coil provides a feedback signal that is used to compensate for common-mode factors in the receiver coil signals. By continuously monitoring the reference signal and using it to adjust or correct the position measurement, the system achieves high signal accuracy without requiring complex digital signal processing, as the correction is performed through analog feedback mechanisms.
Solution Approach 2:
The patent utilizes the phase and amplitude parameters of the induced voltages in different receiver coil sections to encode position information. By measuring changes in these parameters and using differential measurement techniques, the system extracts precise position data while naturally rejecting common-mode disturbances, thereby achieving high reliability with relatively simple signal processing that leverages the inherent properties of the induced voltages.
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 enhances the accuracy and linearity of positional signals by correcting for noise and manufacturing variations, enabling more reliable measurements over longer distances in applications such as electronic throttle controls.
Implementation Method 1
The exciter coil generates magnetic flux when the exciter coil is energized by a source of electrical energy, such as an alternating current source
Implementation Method 2
The receiver coil generates a receiver signal when the exciter coil is energized, due to an inductive coupling between the receiver coil and the exciter coil
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3A~4
AI summary
An apparatus for providing a signal related to a position of a part comprises an exciter coil, and a receiver coil disposed proximate to the exciter coil. The exciter coil generates magnetic flux when the exciter coil is energized by a source of electrical energy, such as an alternating current source. The receiver coil generates a receiver signal when the exciter coil is energized, due to an inductive coupling between the receiver coil and the exciter coil. The receiver coil has a plurality of sections, the inductive coupling tending to induce opposed voltages in at least two of the sections. Embodiments of the present invention include linear sensors, rotational sensors, and novel configurations for improved ratiometric sensing.