Piezoelectric SHM Temperature Compensation Using Adaptive Feedback
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Solution Overview
Problem
Current structural health monitoring (SHM) systems face challenges in accurately detecting anomalies due to environmental factors, particularly temperature variations, which cause nonlinearities in piezoelectric sensor responses, leading to false positives or negatives.
Innovation Solution
An adaptive filter system with an optimization algorithm adjusts the amplitude of the excitation signal for piezoelectric actuators based on environmental conditions, using a Wheatstone bridge resistive temperature sensor and feedback loops to compensate for temperature variations, ensuring accurate anomaly detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric sensors are used for structural health monitoring, then anomaly detection capability is provided, but temperature variations cause nonlinearities in sensor response leading to false positives or negatives
Solution Approach 1:
The patent implements a feedback mechanism where the output signal from the piezoelectric sensor is fed back through an adaptive filter that adjusts its parameters based on the detected signal characteristics. This closed-loop system continuously compensates for temperature-induced nonlinearities by comparing the actual sensor response with the expected linear response and applying corrective filtering to eliminate false anomaly detections caused by environmental temperature variations.
Solution Approach 2:
The patent changes the operational parameters of the piezoelectric sensor system by applying an adaptive filter that dynamically adjusts its transfer function parameters based on the detected signal conditions. This parameter adaptation allows the system to maintain linear response characteristics across varying temperature conditions, effectively compensating for the temperature-dependent nonlinearities inherent in piezoelectric materials.
2Measurement precision
If temperature compensation is implemented using adaptive filtering, then sensor performance accuracy is improved, but system complexity increases
Solution Approach 1:
The patent replaces complex mechanical or hardware-based temperature compensation mechanisms with an electronic adaptive filtering system. Instead of using additional temperature sensors, thermal compensation circuits, or mechanical adjustment devices, the system uses signal processing techniques where an adaptive filter digitally or electronically adjusts the sensor output based on detected signal characteristics, thereby substituting physical complexity with computational simplicity.
Solution Approach 2:
The adaptive filter acts as an intermediary between the piezoelectric sensor and the anomaly detection system. This intermediate processing stage receives the raw sensor signal, applies temperature compensation through adaptive parameter adjustment, and outputs a corrected signal that more accurately reflects actual structural anomalies rather than environmental effects, thereby simplifying the overall system architecture while maintaining high 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 system provides real-time temperature compensation, enhancing the accuracy of SHM systems by minimizing environmental interference and improving the reliability of anomaly detection.
Implementation Method 1
one piezoelectric transducer operates as the piezoelectric actuator and the other operates as the piezoelectric receiver. The piezoelectric actuator is activated to generate a vibration signal (e.g., an acoustic wave)
Implementation Method 2
the other operates as the piezoelectric receiver. Any anomaly along the propagation path affects properties of the guided wave, such as, for example, amplitude and phase. Accordingly, comparing amplitude and phase of a received vibration signal
Implementation Method 3
An adaptive filter system with an optimization algorithm adjusts the amplitude of the excitation signal for piezoelectric actuators based on environmental conditions, using a Wheatstone bridge resistive temperature sensor
Data Source
AI summary
A system and method for detecting an anomaly in a structure using an adaptive filter to compensate for variations in piezoelectric transducer performance due to environmental factors such as temperature. A first voltage signal having a first amplitude is sent to a reference piezoelectric actuator. Thereafter, a first reference voltage signal is received from a reference piezoelectric receiver which is acoustically coupled to detect the guided wave generated by the reference piezoelectric actuator. A second amplitude is determined using an optimization algorithm of an adaptive filter to compensate for nonlinear behavior of the reference piezoelectric actuator and receiver based on the first reference voltage signal. Then the adaptive filter sends a second voltage signal having the second amplitude to the reference and test piezoelectric actuators. Reference and test voltage signals are received from the reference and test piezoelectric receivers in response to the second voltage signal. A difference voltage signal representing differences between the reference and test voltage signals received is then recorded.