Low-cost Piezoelectric Sensors Research Articles

A low cost system for acoustic monitoring of partial discharge in power transformer by Piezoelectric Sensor

Partial discharge damages in power transformers require high cost monitoring procedures based on corrective maintenance or even interruptions of the power system. The development of online non-invasive monitoring systems to detect partial discharges in power transformers has great relevance since it can reduce significant maintenance costs. Some critical factors in the operation of transformers such as overload, nonlinear loads, transient voltage surges by atmospheric origin and switching, can make the insulation system of transformers to lose their physical and chemical properties. Therefore, these operating conditions can cause early deterioration of the insulation, causing internal partial discharges that may develop into major defects and thus shorten the useful life of electrical equipment. This research aimed to apply a low cost piezoelectric sensors (PZTs) for partial discharge identification in power transformers and a study was conducted on the obtained a good results for identification with PZTs.

Investigation into use of piezoelectric sensors in a wheeled robot tire for surface characterization

A differential steered, 13.6kg robot was developed as an intelligent tire testing system and was used to investigate the potential of using piezoelectric film sensors in small tube-type pneumatic tires to characterize tire–ground interaction.The robot was instrumented with low-cost piezoelectric film sensors between the inner tube and the tire. An unlaminated and a laminated sensor were placed circumferentially along the tread and an unlaminated sensor was placed along the sidewall. The analog signal passed to the robot via a slip ring. The robot was tested with a controlled power sequence carried out on polished cement, ice, and sand at three power levels, two payload levels, and with two tire sizes.The results suggest that the sensors were capable of detecting normal pressure, deflection, and/or longitudinal strain. Added payload increased signal amplitude for all sensors. On the smaller tires, sensors generally recorded a smaller, wider signal on sand compared to cement, indicating potential to detect contact patch pressure and length. The signals recorded by the unlaminated sensor along the tread of the smaller tire were smaller on ice than cement, indicating possible sensitivity to tractive force. Results were less consistent for the larger tires, possibly due to the large tread pattern.

Small-area low-power heart condition monitoring system using dual-mode SAR-ADC for low-cost wearable healthcare systems.

Heart rate monitoring is useful to detect many cardiovascular diseases. It can be implemented in a small device with low power consumption, and it can exploit low-cost piezoelectric pressure sensors to measure heart rate. However, it is also desirable to transmit heartbeat waveform for emergency treatment, which significantly increases transmission power. In this paper, a low-cost wireless heart condition monitoring SoC is proposed. It can monitor and transmit both heart rate and heartbeat waveform, but the hardware is extremely simplified to achieve in a small package. By slight modification of successive-approximation analog-digital converter, it can count heart rate and read out heartbeat waveform with the same hardware. In the normal mode, only an 8-bit heart rate is transmitted for power reduction. If the heart rate is out of a given range, it goes to the emergency mode and a 10-bit heartbeat waveform is transmitted for fast treatment. The fabricated chip size is 1.1 mm2 in 0.11 μ m CMOS technology, including the radio-frequency transmitter. The measured power consumption is 161.8 μ W in normal mode and 507.3 μ W in emergency mode, respectively. The proposed SoC achieves low-cost, small area, and low-power. It is useful as part of a disposable healthcare system.

Automated acoustic identification of beetle larvae in imported goods using time domain analysis

The detection of insect pests in imported goods is of considerable economic importance and the automation of this process is becoming more viable both technologically and financially. As a result, the Department for Environment, Food and Rural Affairs in the UK has funded a research project to develop instrumentation facilitating real-time acoustic detection of the feeding activity of insect larvae inside imported goods, such as timber. The instrumentation will also be capable of species-level identification. Previous work at York has shown that detection of beetle larvae in wood is possible using low cost piezoelectric sensors. The project described here extends this work by investigating a number of signal analysis methods for robust detection of biting events, including fractal dimension analysis. Identification is currently being carried out using time domain signal coding and artificial neural networks. This paper will concentrate on the results of various algorithms for the estimation of fractal dimension and their relative suitability for bite detection. The effects of varying sampling rates, threshold levels and signal-to-noise ratio on the detection rate will be demonstrated.

An On-Line Monitoring System to Recognize Stitch Defects Through Thread Motion and High Speed Image Analyses

A sensor system that inspects a garment as it is being sewn has the potential to eliminate much of the cost associated with inspection and to improve product quality. An economically feasible on-line stitch quality monitoring system is under development that utilizes commercially-available, low-cost piezoelectric sensors and a PC-based Linux data acquisition system. The sensors respond to the vibration caused by the thread motion and output a corresponding waveform used to study and model the formation of single stitches. As a result, the presence of periodic occurrences can be identified and attributed to proper stitch formation. Conversely, the absence of such events can be utilized to signal the presence of single stitch defects and diagnose their causes. Finally, high speed image analysis of the sewing threads has verified conclusions drawn from the output signals of the piezoelectric sensors and contributed to a better understanding of the dynamics involved in high speed sewing.

Using low-cost piezoelectric ultrasonic sensors for 3D measurement in robots : G. Lindstedt, G. Olsson, pp 35–40

Using low-cost piezoelectric ultrasonic sensors for 3D measurement in robots : G. Lindstedt, G. Olsson, pp 35–40