Inductive Sensor Linearization for Position Precision
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Solution Overview
Problem
Inductive position sensors experience imprecision at the ends of the target's travel due to linearization of the arctangent function, reducing the useful travel range to about 60% of the sensor's length, leading to significant edge effects and reduced precision.
Innovation Solution
A method that calculates an arctangent function from sine and cosine voltage signals, determines error points, and applies corrections using a sinusoidal distribution of linearization points to enhance precision, thereby extending the useful travel range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear regression is applied to the arctangent function to linearize the position measurement, then the measurement precision is improved in the central region, but the useful travel range is reduced to about 60% of the sensor length due to significant edge effects at the ends of travel
Solution Approach 1:
The sensor travel range is divided into multiple segments: a central region where linear regression provides accurate linearization, and end regions where alternative processing methods are applied. This segmentation allows each region to be optimized independently, extending the useful travel range while maintaining precision where it matters most.
Solution Approach 2:
Different signal processing qualities are applied to different regions of the travel range. The central region receives full linear regression processing for maximum precision, while end regions receive adapted processing that accounts for edge effects. This local differentiation maintains measurement quality across the entire extended range.
2Device complexity
If the linearization method is applied across the entire travel range, then the position determination is simplified, but significant errors occur at the ends of the target's travel
Solution Approach 1:
The system performs preliminary identification of the target's position region (central vs. end regions) before applying the appropriate processing method. This preliminary action allows the system to switch between different processing strategies based on the detected region, preventing edge effects from degrading measurement precision while maintaining overall system simplicity.
Solution Approach 2:
The signal processing approach is made dynamic rather than static. The system adaptively changes the processing method based on the target's current position within the travel range, transitioning between linear regression processing for central regions and edge-aware processing for end regions. This dynamic adaptation maintains precision throughout the entire range without significantly increasing 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
The method significantly reduces errors at the ends of the target's travel, extending the useful travel range by about 20% compared to prior art, improving precision and usability.
Implementation Method 1
The operating principle of an inductive sensor is based on the variation of coupling between a primary winding and secondary windings of a transformer operating at high frequency, without the use of a magnetic circuit. The coupling between these windings varies as a function of the position of a moving (electrically) conductive part, usually called a 'target'. Currents induced in the target have the effect of modifying the currents induced in the secondary windings.
Implementation Method 2
Currents induced in the target have the effect of modifying the currents induced in the secondary windings. By adapting the configuration of the windings, and given a knowledge of the current injected into the primary winding, the measurement of the current induced in the secondary windings can be used to determine the position of the target.
Data Source
AI summary
A method for determining the position θ of a moving part (T) along an axis (X), using an inductive sensor (10) including: a primary winding (B1) generating an electromagnetic field; a first secondary winding (R1), generating a first voltage signal (V1), of the sine function type; a second secondary winding (R2), generating a second voltage signal (V2) of the cosine function type; and a calculation unit (20′), wherein the method includes the steps of calculating and distributing linearization points i on the arctangent function tan(θ) resulting from the ratio of the first voltage signal to the second voltage signal, the linearization points i being distributed according to a sinusoidal function in order to reduce the error on the position (θ) of the target (T) at the ends (E1, E2) of the primary and secondary windings (R1, R2).