Inductive Angular-Position Sensor Coil Structures for Off-Axis Accuracy
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Solution Overview
Problem
Conventional inductive angular-position sensors face accuracy issues when the target is off-axis, leading to compromised angular-position sensing due to phase-shifting between sine and cosine profiles, which affects sensor reliability and redundancy.
Innovation Solution
The design incorporates redundant inductive angular-position sensors with distinct coil structures and sense coils arranged in a way that maintains little to no phase-shift even when the target is off-axis, utilizing separate excitation and sense coils with specific lobe configurations to ensure accurate position sensing across a 60° measurement range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inductive angular-position sensors are used, then the sensor structure is simple, but the measurement precision deteriorates when the target is off-axis due to phase-shifting between sine and cosine profiles
Solution Approach 1:
The sensor is divided into multiple independent coil structures, each with specific sine and cosine lobes arranged in distinct patterns. This segmentation allows each coil to contribute to both sine and cosine signal generation independently, enabling accurate off-axis position detection without phase-shifting errors while maintaining manageable structural complexity through modular design
Solution Approach 2:
The coil structures employ asymmetric lobe configurations where sine lobes and cosine lobes are positioned at different angular locations and orientations. This asymmetry is deliberately designed to compensate for off-axis target positions, ensuring that the phase relationship between sine and cosine signals remains consistent even when the target is not centered, thereby improving measurement precision without requiring symmetric simplification
2Reliability
If redundant sensors are implemented to enhance reliability, then the reliability improves, but the device complexity increases
Solution Approach 1:
Multiple sensor functions are merged into a single integrated coil structure that simultaneously generates sine and cosine signals with proper phase relationships. This merging approach provides redundant sensing capabilities within one unified structure, enhancing reliability and fault tolerance while avoiding the complexity of multiple separate sensor assemblies
Solution Approach 2:
The coil structure is designed to perform multiple functions: generating sine signals, generating cosine signals, providing redundancy for fault tolerance, and accommodating off-axis target positions. This multi-functionality is achieved through a single versatile coil structure rather than requiring separate dedicated components for each function, thereby improving reliability without proportionally increasing device 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 configuration provides high sensor accuracy and reliability by minimizing phase-shifts when the target is off-axis, enhancing the redundancy and fault tolerance of the sensing system.
Implementation Method 1
If a coil of wire is placed in a changing magnetic field, a voltage will be induced at ends of coil of wire
Implementation Method 2
it is possible to disturb a predictably changing magnetic field and measure a resulting change in the voltage induced in the coil of wire
Data Source
AI summary
An apparatus comprises a target to rotate about an axis; an excitation coil to carry an excitation signal; and a first sense coil to carry a sense signal induced by the excitation signal. The first sense coil comprises two or more lobes in one or more planes that are perpendicular to the axis. The two or more lobes comprise a first lobe at a first position relative to the axis and a second lobe at a second position relative to the axis. The second position is substantially the same radial distance from the axis as the first position is from the axis. The second position is at an angular distance of Θ from the first position, where Θ=180°±α/2, and α is a measurement range for angular-position sensing (e.g., α=60°) within a range of 50% to 150% of α.