Parallel Resonant Inductive Sensing Beyond ADC Bit Limits
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Solution Overview
Problem
Existing sensor systems face challenges in achieving high accuracy and cost-effectiveness due to limitations in bit width of analog-to-digital converters and increased circuit complexity from methods like dithering, which are costly and complex, especially in mass-produced products.
Innovation Solution
An apparatus using a parallel resonant circuit with inductance and capacitance, coupled with an electronic control unit that generates a distortion signal to enhance resolution beyond bit width limitations, allowing for efficient and inexpensive measurement of variables like distance or position, utilizing passive components and undersampling for high-frequency measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dithering is used to improve measurement accuracy beyond ADC bit width limitations, then measurement precision is improved, but device complexity increases due to additional circuit requirements
Solution Approach 1:
The measurement inductance itself generates the dither signal through its interaction with the parallel resonant circuit. The resonant circuit naturally oscillates at its resonant frequency, and this oscillation is directly coupled to the ADC input, eliminating the need for external dither signal generation circuits. The system uses its own operational components to provide the dithering function.
Solution Approach 2:
The dither signal generation function is merged with the measurement signal path. The parallel resonant circuit serves dual purposes: it provides the measurement signal through the measurement inductance and simultaneously generates the dither signal through its natural oscillation. This consolidation eliminates separate dither circuitry while achieving both measurement and dithering functions.
2Adaptability or versatility
If multiple measurement inductances are added to scale to multiple inputs, then adaptability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The parallel resonant circuit is designed as a universal measurement interface that can work with multiple different measurement inductances. The same resonant circuit topology and electronic control unit can measure different physical quantities (distance, position, acceleration) by simply changing the measurement inductance, eliminating the need for separate dedicated circuits for each measurement type.
Solution Approach 2:
The system achieves multi-input capability by changing the inductance parameter rather than adding complex multi-channel circuitry. Each measurement inductance has a specific inductance value that corresponds to a particular measurement range or type, allowing the system to adapt to different measurements by selecting appropriate inductance values while maintaining the same basic circuit architecture.
3Measurement precision
If ADC bit width is increased to improve measurement resolution, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The system uses electrical oscillation from the parallel resonant circuit to provide dithering. The resonant circuit oscillates at its natural frequency, creating a time-varying signal that effectively dithers the ADC input. This mechanical-like vibration approach (electrical oscillation) enables resolution enhancement without requiring higher-bit ADCs, maintaining cost-effectiveness while improving 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
The solution enables efficient and cost-effective measurement with improved resolution and scalability, capable of handling high frequencies with minimal additional circuit complexity, overcoming the limitations of traditional sensor systems.
Implementation Method 1
a capacitance that is interconnected with the first inductance to form a parallel resonant circuit. The electronic control unit is configured to excite the parallel resonant circuit into oscillation at an excitation frequency
Implementation Method 2
at least one measurement inductance that is set up to sense the measured variable and that is coupled to the first inductance
Data Source
AI summary
An apparatus for measuring a measured variable, wherein a first inductance and at least one measurement inductance are coupled, and wherein dithering is used to increase accuracy.