Inductive Position Sensor Using Phase Shifted Coils
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Solution Overview
Problem
Conventional inductive position sensors require complex signal processing circuits, including demodulators, gain stages, analog-to-digital converters, and digital arctangent calculations, which increase complexity and cost.
Innovation Solution
An inductive position sensor design utilizing two phase-shifted transmitter coils and a single receiver coil, where the phase-shift between transmitter and receiver signals is used to determine the position of a conductive target, simplifying the processing to a simple phase measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inductive position sensors use complex signal processing circuits including demodulators, gain stages, analog-to-digital converters, and digital arctangent calculations, then position detection accuracy is maintained, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the complex signal processing circuits (demodulators, gain stages, ADCs, and arctangent calculation units) from the sensor system. Instead of using these complex components, the invention uses a simplified phase comparison approach where the phase difference between transmitter and receiver signals directly indicates target position, removing unnecessary circuitry while maintaining measurement capability
Solution Approach 2:
The patent changes the measurement parameter from amplitude-based detection (requiring complex demodulation and arctangent calculations) to phase-based detection. By measuring the phase difference between the transmitter signal and receiver signal, the system achieves position detection with simpler circuitry, as phase comparison can be performed with basic phase detectors or even microcontroller timers
2Measurement precision
If conventional inductive position sensors implement complex processing circuits, then position detection capability is ensured, but manufacturing cost increases
Solution Approach 1:
The patent removes expensive components such as demodulators, precision gain stages, and high-resolution ADCs from the bill of materials. The simplified phase comparison method requires only basic signal routing and phase measurement capability, which can be implemented with inexpensive microcontrollers or dedicated phase detector ICs, significantly reducing manufacturing cost
Solution Approach 2:
The patent replaces expensive, precision-analog signal processing components with cheaper digital or mixed-signal alternatives. Phase comparison can be performed using standard microcontroller timer/counter functions or simple phase-frequency detectors, which are much less expensive than precision analog demodulators and ADCs, making the sensor more cost-effective for mass production
3Measurement precision
If conventional inductive position sensors use multiple receiver coils (sine and cosine coils), then position detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the functionality of separate sine and cosine receiver coils into a single receiver coil. By using phase modulation and phase comparison techniques, the system extracts position information from the phase difference between transmitter and receiver signals, eliminating the need for multiple spatially arranged coils while maintaining the ability to determine target position accurately
Solution Approach 2:
The patent replaces the mechanical/geometric arrangement of multiple coils (sine coil and cosine coil positioned at specific orientations) with an electromagnetic phase modulation approach. Instead of relying on physical coil geometry to generate sine and cosine signals, the system uses phase-modulated excitation and phase detection to achieve the same mathematical relationship, simplifying the physical structure
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
Simplifies signal processing by eliminating the need for demodulators, gain controls, and digital arctangent calculations, reducing complexity and cost while maintaining accurate position detection.
Implementation Method 1
an oscillator that generates a radio-frequency signal, which is applied to the transmitter coil to create a static high frequency magnetic field. This static high frequency magnetic field is picked up by the receiver coils
Implementation Method 2
utilizing the physical principles of eddy currents or inductive coupling to detect the position of a target
Data Source
AI summary
An inductive position sensor and method for detecting a movement of a conductive target, having: at least a first and a second transmitter coil having the same shape and which are phase-shifted to each other, at least one oscillator for generating a first and a second transmitter signal having the same shape and which are phase shifted to each other and are applied to the first transmitter coil and second transmitter coil respectively, at least one receiver coil, and a processing unit for determining a phase-shift between the first or second transmitter signal and a receiver signal received at the receiver coil; the determined phase-shift corresponding to the position of the conductive target above the first and second transmitter coils.