An Accessible Electronic Circuit Design for Structural Health Monitoring

Vollständiger Abstract

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The development of an accessible electronic circuit for analyzing Structural Health Monitoring (SHM) algorithms using piezoelectric elements is a relevant research topic in current structural health monitoring projects [1]. This is because the development of SHM requires harmony between its mathematical methods and low-cost technological design [1]. Moreover, removing the analog-to-digital converter (ADC) in SHM systems can address key technical hurdles, particularly in reducing overall power consumption for practical applications, among other important issues [1]. In this presentation, we introduce a novel electronic circuit for SHM that employs analog reference signals, building upon the suggestion in [1]. We also integrated an electrically manipulable boost DC-DC converter into our electronic system to manage the main 12V voltage source. This voltage management was possible because our DC-DC converter is a controllable power source that utilizes a hysteresis loop circuit via a microcontroller device of 8-bits from Microchip manufacturer [2]. See Figure 1. A photograph of the experimental setup is also provided. Our experimental setup comprises three aluminum bars representing different structural states: Case A (healthy), Case B (moderate damage via a single perforation), and Case C (severe damage via two perforations). Three piezoelectric transducers (PZTs) mounted on each bar base serve as actuators; these are connected in parallel and driven by a single power exciter. Three additional PZTs are positioned at each bar top to serve as receiving elements. Figure 1 also displays the experimental residual signal, which was acquired via a powerful digital oscilloscope (Picoscope technology) and displayed on a computer. This device was configured to ensure the residual signal was clearly visible. For each measurement scenario, the boost converter was deactivated to allow for the establishment of a new sensor connection point (the sensor selector switch on Figure 1) before being restarted. The resulting residual signal clearly shows that a stable average voltage can effectively distinguish among each testing case (A, B or C case). From a SHM data processing perspective, our closed-loop design relies on analog circuitry, with the exception of a PIC microcontroller. This microcontroller functions as the primary interface among analog control signals and the gate drive of the boost DC-DC converter. The converter requires a PWM (Pulse Width Modulation) signal to regulate its operation. The PIC microcontroller is configured to generate a PWM signal with a nominal frequency of about 15 kHz. Consequently, our system processes signals in the analog domain, eliminating the sampling rate requirements typically imposed by digital-to-analog conversion. Additionally, each piezoelectric actuators is driven by an analog signal ranging from 10V to 60V (these levels adjustable via the P1 and P2 trimmers) with a 30 Hz harmonic content, a direct result of the NE555N timer’s operational frequency. Therefore, our SHM approach, which employs analog signals for damage detection, aligns with established procedures in residual signal analysis [3]. References [1] Owen, R., et al. (2011). (No. NASA/CR-2011-217153). [2] Acho, L. (2025). Cybernetics and Physics, 14(4), 315-319. [3] Vidal, Y., et al. (2012). Mechanical Systems and Signal Processing, 29, 447-456.