Inductive Coil Position Sensing via Delay-Based Digital Evaluation
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Solution Overview
Problem
Conventional inductive positioning systems for motor vehicles require complex and costly coil manufacturing, high accuracy, and multistage electronic amplification, which can lead to increased production costs and sensitivity to component tolerances.
Innovation Solution
A device comprising a coil, a signal generator, a delay element, a comparator, an integrator, and an evaluator, where the delay element is based on the coil and provides a digital differential impulse whose length depends on the inductance, allowing for easier setup and reduced component tolerance, with the ability to be implemented using customary logic gates and a programmable microcomputer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inductive positioning systems use large inductances and multistage electronic amplification, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces complex multistage electronic amplification systems with a digital signal processing approach using a delay element, comparator, and integrator. The analog measurement system is transformed into a digital evaluation system that processes signals through logical operations rather than multiple amplification stages, reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent changes the evaluation parameter from direct inductance measurement to time-based differential impulse measurement. By measuring the time difference between input and output signals of the delay element, the system determines position based on time parameters rather than analog voltage levels, simplifying the overall system architecture.
2Manufacturing precision
If conventional inductive positioning systems use printed circuit coils with several layers, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent replaces expensive, complex multi-layer printed circuit coils with simpler, cheaper coil constructions that can be manufactured more easily. The invention tolerates lower manufacturing precision in the coil itself because the overall measurement precision is achieved through the digital evaluation method rather than relying on perfectly manufactured high-precision coils.
3Measurement precision
If conventional inductive positioning systems require high accuracy coil manufacturing and testing, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The patent implements a self-testing capability where the evaluation device automatically compensates for component tolerances and coil variations through its digital processing method. The system performs built-in calibration and adjustment, eliminating the need for separate manual testing steps and improving production productivity while maintaining measurement precision.
4Measurement precision
If conventional inductive positioning systems use multistage electronic amplification, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent replaces complex analog amplification circuits with a digital signal processing system that uses a delay element, comparator, and integrator. This substitution transforms a system requiring careful analog adjustment and calibration into one that operates more simply through digital logic, improving ease of operation while maintaining or enhancing measurement precision.
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 solution simplifies the setup of inductive positioning, reduces component tolerance issues, and enhances the signal-to-noise ratio, enabling more accurate and cost-effective position determination with improved resolution and handling of nonlinearity.
Implementation Method 1
a coil (105), an element (155) for influencing a magnetic field in the area of the coil (105)
Implementation Method 2
The position of the selector lever can be scanned by a series of coils mounted to a console and an electrically conductive damping element mounted to the selector lever, which is movable with respect to the console. The closer the damping element is to one of the coils, the more the inductivity of this coil is reduced by means of the damping element.
Data Source
AI summary
A device for inductive positioning comprises a coil, an element for influencing a magnetic field in the area of the coil, a signal generator for providing a digital signal and a delay element with an input and an output, wherein the delay element is designed on the basis of the coil and a delay period between a signal edge at the input and a corresponding signal edge at the output is dependent on the inductance of the coil. The device further comprises a comparator to provide a digital differential impulse, whose length is dependent on a time difference of corresponding signal edges at the input and the output of the delay element, an integrator to provide a voltage depending on the length of the differential impulse and an evaluator to determine the position of the coil in reference to the coil based the voltage.