RF Resonant Strain Sensor High-Speed Center Frequency Detection
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Solution Overview
Problem
Existing strain sensors require the interrogator device and sensor to be stationary or move slowly relative to each other, making it time-consuming to measure strain at multiple locations, such as along a track or bridge, due to the need for precise detection of the center frequency.
Innovation Solution
A strain sensor system that includes an RF resonant sensor, an RF interrogator device, and a controller, which directs the interrogator to emit coarse and fine interrogation signals while moving relative to the sensor, allowing for rapid identification of the center frequency by analyzing responsive signals across a frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the interrogator device and sensor move quickly relative to each other, then measurement time is reduced and productivity is improved, but the ability to accurately detect the center frequency deteriorates
Solution Approach 1:
The frequency sweep is divided into multiple discrete frequency points rather than a continuous slow sweep. The interrogator device transmits interrogation signals at multiple predetermined frequency points sequentially, allowing accurate center frequency detection even during rapid relative movement between the interrogator and sensor.
Solution Approach 2:
The system performs preliminary actions by pre-defining a set of frequency points to sweep through and using signal strength measurements at these points to identify the center frequency. This preliminary frequency mapping allows the system to quickly determine the center frequency without requiring slow, continuous sweeping, thus enabling rapid movement during measurement.
2Loss of information
If multiple locations are measured sequentially, then comprehensive strain data is obtained, but total measurement time increases
Solution Approach 1:
The measurement process is segmented into discrete frequency point measurements rather than continuous sweeping at each location. This segmentation allows the system to quickly capture essential strain information at multiple locations by measuring only at predetermined frequency points, significantly reducing total measurement time while maintaining data completeness.
Solution Approach 2:
The system uses partial action by measuring at a limited set of predetermined frequency points rather than performing exhaustive continuous frequency sweeps at each location. This partial measurement approach is sufficient to identify the center frequency and obtain strain data, reducing measurement time while maintaining adequate data quality for monitoring purposes.
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
Enables the rapid determination of center frequencies while the interrogator and sensor are moving at high speeds, such as over 112 kilometers per hour, allowing for quick measurement of strain across multiple locations within a short time window, facilitating timely maintenance and inspection.
Implementation Method 1
The resonating cavity causes the antenna to emit an RF signal in response to the received RF signal. The frequency at which the cavity resonates can be referred to as a center frequency of the cavity.
Data Source
AI summary
A strain sensor system emits coarse interrogation signals of different frequencies during a coarse scan while an RF resonant sensor and/or an RF interrogator moves relative to the other. The sensor emits responsive RF signals within a frequency range of a frequency of interest of the sensor. The controller identifies the frequency of interest based on receipt of the responsive signals. The interrogator emits fine interrogation signals of different frequencies during a fine scan subsequent to the coarse scan. The fine signals are emitted at frequencies within a frequency band on both sides of the frequency of interest. The sensor emits responsive RF signals and the controller identifies a center frequency of the RF resonant sensor based on receipt of the responsive signals.