Sensor Resonant Frequency Determination via Three-Point Linear Refinement
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Solution Overview
Problem
Existing mobile devices with mechanical buttons face issues such as aging, wear, and tear, which reduce their lifespan and make them difficult to manufacture as waterproof devices, while virtual buttons require sensors that accurately detect user interaction with acceptable sensitivity, power consumption, and size, but struggle with varying resonant frequencies due to manufacturing tolerances and environmental changes.
Innovation Solution
A method and system for determining sensor parameters of an actively-driven sensor system by obtaining as few as three samples of a measured physical quantity versus frequency, performing refinement operations based on a linear model of asymmetry between slopes, and iteratively repeating the process until the difference between successive refined versions is below a defined threshold, to output updated sensor parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If virtual buttons are used to replace mechanical buttons, then device waterproofing and manufacturing ease are improved, but sensor sensitivity and detection accuracy deteriorate due to varying resonant frequencies
Solution Approach 1:
The system dynamically adjusts the driving frequency of the sensor based on detected resonant frequency shifts. Instead of using a fixed frequency, the system continuously monitors the sensor's resonant characteristics and adapts the drive signal frequency accordingly, ensuring optimal detection accuracy despite environmental variations and manufacturing tolerances.
Solution Approach 2:
The system changes the operating parameters (driving frequency and amplitude) based on the detected resonant frequency and quality factor. By adjusting these parameters in real-time, the system maintains high detection precision for virtual button interactions even when the sensor's resonant characteristics drift due to temperature, humidity, or manufacturing variations.
2Measurement precision
If resonant frequency detection is performed with high precision, then sensor sensitivity is improved, but measurement time and processing complexity increase
Solution Approach 1:
The system performs preliminary measurements at three strategically selected frequency points (below, at, and above the expected resonant frequency) to quickly establish the resonant characteristics. This preliminary action provides sufficient information to determine both resonant frequency and quality factor without requiring extensive sweeping measurements, thus reducing measurement time while maintaining accuracy.
Solution Approach 2:
Instead of performing a complete frequency sweep to map the entire resonant curve, the system uses a partial measurement approach with just three key frequency points. This partial action is sufficient to extract the necessary parameters (resonant frequency and quality factor) and achieves the required precision without the time cost of comprehensive measurements.
3Measurement precision
If sensor parameters are adjusted frequently to maintain accuracy, then detection precision is improved, but power consumption increases
Solution Approach 1:
The sensor system performs self-calibration by autonomously detecting its own resonant frequency and quality factor using the three-point measurement method. This self-service capability allows the system to maintain accurate detection without requiring frequent external recalibration or continuous high-power operation, thereby reducing overall power consumption while preserving detection 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 approach reduces the disadvantages of virtual buttons in mobile devices by improving sensor sensitivity, power efficiency, and size, while ensuring accurate detection of user interaction and adaptation to changing resonant frequencies, enhancing the user experience and device reliability.
Implementation Method 1
a linear resonant actuator may vibrate in response to user interaction with the human-machine interface
Data Source
AI summary
A method for determining sensor parameters of an actively-driven sensor system may include obtaining as few as three samples of a measured physical quantity versus frequency for the actively-driven sensor system, performing a refinement operation to provide a refined version of the sensor parameters based on the as few as three samples and based on a linear model of an asymmetry between slopes of the measured physical quantity versus frequency between pairs of the as few as three samples, iteratively repeating the refinement operation until the difference between successive refined versions of the sensor parameters is below a defined threshold, and outputting the refined sensor parameters as updated sensor parameters for the actively-driven sensor system.