Inductive Sensor Target Angular Opening for Linearity
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Solution Overview
Problem
Angular inductive sensors suffer from insufficient linearity in measuring the angular position of rotating parts, leading to measurement errors, despite previous solutions like reference loops and compensation loops, which do not provide reliable results across the entire measurement range.
Innovation Solution
The solution involves analyzing the angular position measurements using Fourier transform to reduce the angular opening of the target by a specific proportion, adjusting the target's angular sectors to eliminate harmonic deviations, particularly the 4th order harmonic, thereby improving linearity by adjusting the target's angular opening based on the sensor's course and the number of loops and sectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the target angular opening is increased to cover the loop sectors, then the measurement range is improved, but the linearity of the sensor deteriorates due to harmonic deviations
Solution Approach 1:
The patent applies parameter changes by modifying the target angular opening from its conventional value to a reduced value calculated using a specific formula. This formula incorporates the sensor course, number of loops per secondary winding, and number of target sectors to determine the optimal reduced angular opening that eliminates 4th order harmonic deviations, thereby improving linearity while maintaining adequate measurement range.
2Measurement precision
If the target angular opening is reduced to improve linearity, then measurement precision is improved, but the measurement range is reduced
Solution Approach 1:
The patent resolves this contradiction by precisely calculating the optimal reduced angular opening using a formula that balances linearity improvement with measurement range requirements. The formula considers the sensor course, number of loops, and number of sectors to determine the exact reduction needed to eliminate 4th order harmonics while preserving sufficient measurement capability.
3Measurement precision
If reference loops and compensation loops are added to reduce measurement errors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the linearity improvement function from complex additional loops and reference circuits, and instead implements it through a simplified modification of the target angular opening parameter. This approach achieves the same measurement accuracy improvement without adding reference loops or compensation loops, thereby reducing 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 approach enhances the linearity of angular inductive sensors by reducing measurement errors, ensuring more accurate positional measurements across the entire range by adjusting the target's angular sectors to align with the sinusoidal variation of induced voltages, thereby improving sensitivity and reliability.
Implementation Method 1
The primary winding, centered about an axis that is coincident with the central rotation axis of the target, carries a high-frequency alternating current which can induce a voltage in each secondary winding
Implementation Method 2
This current produces a magnetic field at the same frequency as the current flowing in the primary circuit
Data Source
AI summary
An inductive sensor includes a primary winding, two secondary windings and a moveable target, the primary winding being centered about a central axis and carrying a high-frequency alternating current which can induce a voltage in secondary windings, the secondary windings also being centered about the central axis and made up of a number k of substantially identical loops, which are successively crossed and arranged opposite the primary winding. In this case, the target is made up of a part having p=1 angular sector with an angular opening. The opening of the angular sector of the target is less than that of a loop of secondary winding with a deviation calculated such as to eliminate the fourth harmonic of the linearity deviation Fourier decomposition, between the measured angular value and real angular value for the position of the target over the measurement course.