Francisco Antonio Belo

Embedded System Integrated Into a Wireless Sensor Network for Online Dynamic Torque and Efficiency Monitoring in Induction Motors

The system proposed in this paper aims at monitoring the torque and efficiency in induction motors in real time by employing wireless sensor networks (WSNs). An embedded system is employed for acquiring electrical signals from the motor in a noninvasive manner, and then performing local processing for torque and efficiency estimation. The values calculated by the embedded system are transmitted to a monitoring unit through an IEEE 802.15.4-based WSN. At the base unit, various motors can be monitored in real time. An experimental study was conducted for observing the relationship between the WSN performance and the spectral occupancy at the operating environment. This study demonstrated that the use of intelligent nodes, with local processing capability, is essential for this type of application. The embedded system was deployed on a workbench, and studies were conducted to analyze torque and system efficiency.

Correlation between Spectral Occupancy and Packet Error Rate in IEEE 802.15.4-based Industrial Wireless Sensor Networks

This paper aims at evaluating the communication performance of the IEEE 802.15.4 standard in an industrial environment. We investigated the correlation between Packet Error Rate (PER) and Spectral Occupancy (SO) in the network environment. For this goal, we studied the impact on SO and PER resulting from the insertion of interference from other sources within the same range of the channels defined by the standard. The results show that an IEEE 802.15.4-based sensor network can suffer large drop in performance with the addition of new sources of interference. The information provided by the experiments can be used to guide the development of new spectrum-aware techniques and protocols to mitigate the interference in IEEE 802.15.4-based industrial wireless sensor networks.

Telemetric system for monitoring and automation of railroad networks

This paper describes a new method of real-time train monitoring based on the ZigBee/IEEE 802.15.4 protocol. The system consists of a mobile device embedded in the moving train which transmits parameter signals that are being measured by a base unit with the help of routers. When applied, the technique monitors and controls vehicles operating on permanent routes, making a real-time evaluation of their performance and location, and allowing an effective planning of trains. It consists of a low cost, low power consumption and safe modular technology capable of monitoring many different variables simultaneously.

Experimental and theoretical study of a telemetric dynamic torque meter

This paper presents the development of a dynamic torque meter to be applied to rotating shafts using electronic transduction, strain gage, telemetry and LabView Graphic programming. A mathematical model was developed. The electronic transduction signal is transmitted by digital modulation from a remote transduction unit fixed to a shaft to a base station, sending the signal to a PC, by means of a VI (Virtual Instrument) developed in LabView. It can also be delivered to other units besides the PC. The use of digital modulation to transmit the radiofrequency signal, replacing conventional couplings, allows communication with a high signal/noise ratio. A clamp acts as sealant, protecting it from the environment and making it easier to install. The prototype can be used at situation that it is impossible to use flanges or sockets (the most of the industrial applications) and it is installed directly on the surface of the shaft. The use of superbatteries allows the remote unit to remain independent of a feed for several days, with long periods between maintenance. After thousands of experimental essays, the theoretical model seems to confirm the proposed idea. The system presented has a potential for high precision, low cost, long work life and easy maintenance.

On the Impact of Local Processing for Motor Monitoring Systems in Industrial Environments Using Wireless Sensor Networks

This paper presents a theoretical study for verifying the impact of using smart nodes in motor monitoring systems in industrial environments employing Wireless Sensor Networks (WSNs). Structured cabling and sensor deployment are usually more expensive than the cost of the sensors themselves. Besides the high cost, the wired approach offers little flexibility, making the network deployment and maintenance a complex process. In this context, wireless networks present a number of advantages compared to wired networks as, for example, the ease and speed of deployment and maintenance and the associated low cost. However, WSNs have several limitations, such as the low bandwidth and unreliability, especially in harsh environments (e.g., industrial plants). This paper presents a theoretical study on the performance of WSNs for motor monitoring applications in industrial environments, taking into account WSNs’ characteristics (i.e., unreliability and communication and processing latency). The results obtained through mathematical models were analyzed together with experimental results, and it was demonstrated that employing intelligent nodes with local processing capabilities is essential for the applications under consideration, because it reduces the amount of data transmitted over the network allowing monitoring even in scenarios with high interference rate, paying off the extra latency resulting from local processing.

Self-Powered Telemetric Torque Meter

This paper presents a self-powered telemetric torque meter. The idealized instrument uses strain gauge, telemetry, and LABVIEW graphic programming. The electronic transduction signal is transmitted by digital modulation from a remote transduction unit fixed to a rotation shaft to a base station sending signals to a personal computer (PC) by means of a virtual instrument developed in LABVIEW . The signal can also be delivered to other units besides the PC. The ZigBee/IEEE 802.15.4 protocol is the standard protocol for wireless communications and is highly used in industrial monitoring and control applications. A low-noise method for supplying the remote transduction unit components in the rotation shaft—using its rotating movement to generate the demanded energy—has also been developed. After extensive experimentation, the theoretical model seems to confirm the idea proposed. The system presented in this study is robust, precise, cost-effective, and has high-noise immunity even in abrasive and strong vibration environments.

Transporte de Materia con Reducción de Volumen en el Interior de Sólidos Paralelepípedos

Se describe un modelo matematico tridimensional transitorio aplicado al fenomeno de difusion de agua en el interior de solidos paralelepipedos. Se utilizo el metodo de los volumenes finitos considerando propiedades termica y mecanicas constantes, equilibrio en la superficie y reduccion de volumen del material. El modelo fue utilizado para estudiar el proceso de secado de un ladrillo de ceramica. Se muestran los resultados de la cinetica de secado y la distribucion del contenido de humedad en varios planos, para un determinado tiempo y para dos coeficientes de encogimiento. Los resultados muestran que el fenomeno de reduccion de volumen afecta considerablemente la tasa de secado del solido, asi como la distribucion del contenido de humedad en el interior del mismo. Se encuentra tambien que los gradientes mas altos del contenido de humedad se situan en las proximidades del vertice del solido, en cualquier instante de tiempo. El conocimiento de las diferencias de humedad y la cinetica de secado permiten optimizar este proceso y aumentar la calidad del producto final.

A high frequency electronic transducer for multiphase flow measurements

This paper describes an electronic transducer for multiphase flow measurement. Its high sensitivity, good signal to noise ratio and accuracy are achieved through an electrical impedance sensor with a special guard technique. The transducer consists of a wide bandwidth and high slew rate differentiator where the lead inductance and stray capacitance effects are compensated. The sensor edge effect is eliminated by using a guard electrode based on the virtual ground potential of the operational amplifier. A theoretical modeling and a calibration method are also presented. The results obtained seem to confirm the validity of the proposed technique.

Experimental Drying of Ceramics Bricks Including Shrinkage

This work presents an experimental study on the behavior of clays during the drying process. Experimental tests were carried out with clay material for the production of red ceramics and white ceramic (ball clay). Different dimensions and the material initial moisture content plus temperature and relative air-drying humidity were taken into account. Drying kinetics and volume changes of parallelepiped-shaped samples were shown and analyzed. It has been verified that air-drying temperatures and body shape have an enormous influence on the drying rate process. The drying process occurs during the falling drying period and the volume changes display two linear periods.

Transmisión de Calor y Materia con Reducción de Volumen Durante el Secado de Ladrillos de Cerámica

Se presenta un modelo matematico tridimensional transitorio aplicado al fenomeno de difusion de calor y materia con reduccion de volumen en el interior de solidos paralelepipedos. El modelo se ha aplicado al proceso de secado de ladrillos ceramicos. Se uso el metodo de los volumenes finitos considerando propiedades termicas y mecanicas constantes y una condicion de contorno convectiva en la superficie del material. El modelo fue utilizado para estudiar el proceso de secado de un ladrillo de ceramica a temperaturas de 60 y 80oC y en con humedades relativas del aire de 10,07 y 4,66%. Los resultados numericos de contenido de humedad, temperatura y reduccion de volumen, fueron comparados con datos experimentales para determinar los coeficientes de transporte. Se pudo concluir que: el fenomeno de reduccion de volumen tiene dos periodos y afecta considerablemente la velocidad de secado del solido, asi como la distribucion del contenido de humedad en el interior del mismo.