Wireless Vibration Sensor Research Articles

A High-Efficiency, Miniaturized Sensor Node With 3-D Machined-Substrate Antennas for Embedded Wireless Monitoring

This paper presents a compact, energy-efficient, passive, and wireless vibration sensor node for embedded monitoring. The narrowband radio frequency (RF) communication system employs a frequency doubler on the sensor node to return the second harmonic of the interrogation signal. The compactness and high efficiency of the node are achieved by employing 3-D, machined-substrate small antennas on the transceiver. The node operates by receiving a signal at 2.4 GHz and reradiating a modulated signal at 4.8 GHz, and is optimized for an RF input power between -30 and -20 dBm. The node fits within a 21-mm diameter sphere (λ/6 at 2.4 GHz) and its measured efficiency is 10% at -20-dBm input power. A commercial piezoelectric vibration sensor and mechanical switches are used to modulate the return signal. Experimental tests show that vibrations of <;0.1-Hz frequency and 0.01-g amplitude can be detected. The communication range is greater than 60 m using a 43-dBm effective isotropic radiated power transmitter.

Wireless monitoring of typhoon-induced variation of dynamic characteristics of a cable-stayed bridge

In this paper, wireless monitoring of typhoon-induced variation of dynamic characteristics of a cable-stayed bridge is presented. Firstly, cable-stayed bridge with the wireless monitoring system is described. Wireless vibration sensor nodes are utilized to measure accelerations from bridge deck and stay cables. Also, modal analysis methods are selected to extract dynamic characteristics. Secondly, dynamic responses of the cable-stayed bridge under the attack of two typhoons are analyzed by estimating relationships between wind velocity and dynamic characteristics. Wind-induced variations of deck and cable vibration responses are examined based on the field measurements under the two consecutive typhoons, Bolaven and Tembin. Finally, time-varying analyses are performed to investigate non-stationary random properties of the dynamic responses under the typhoons.

An Intrinsically Safe Study on Accuracy Wireless Vibration Sensor

In order to solve the problem of shearer automation for the automated mining, analysis and processing by a plurality of sensors or observation information sources is the most promising solution to automatically control the shearer’s posture, while there is no vibration sensors with intrinsically safety that can be directly equipped on the shearers under coal mines. In the paper, study on a new intrinsic safe mode vibration sensor to solve the problem, it includes the hardware system designing and data collection programming. At the end, an experiment proves that the intrinsic safe wireless vibration sensor is able to collection the three-dimensional vibration data reliably and in time compared with the other vibration sensors.

Seismic assessment of guyed towers: A case study combining field measurements and pushover analysis

Telecommunication structures are essential components of communication and post-disaster networks that must remain operational after a designlevel of earthquake. This study provides dynamic field measurements of 138m guyed tower located at Qussia city, Upper Egypt. In situ measurements of ambient tower vibrations are used to determine the dominant natural frequencies of the tower. The measurements were made using a LMS SCADAS system and four wireless vibration sensors for recording the ambient vibrations of the mast. The tension in the guy wires was measured by mechanical equipment. The dynamic properties of the guyed mast (natural frequencies and mode shapes) were extracted from these measurements. Results of the eigenvalue analysis of numerical models of the tower were compared with the natural frequencies and mode shapes extracted from the in situ measurements. The field measurements were used to update the finite element model. The nonlinear static analysis based on the updated finite element model was carried out. Seismic assessment and comparison between the original and updated models taking into account the deterioration in elements are presented.

Software Test of Wireless Vibration Nodes of Nuclear Power Plants

To do Validation and Verification" of wireless vibration sensor nodes in NPPs (nuclear power plants), embedded system software test should be done. The test index is analyzed firstly; then the method of 'Temb' was introduced to analysis ADXL202 vibration nodes; the characteristic of system was used to establish LITO(life cycle, Infrastructure, Techniques, Organization) matrix, they are of emphasizing safety, application in harsh environment, using algorithms of technology and science and so on. The acceleration circulation method using fixed time cycle pretest by instrument and other weak was proved to be infeasible though FMEA (failure modes and effects analysis). Then FTA (fault tree analysis) is used to analyze system, so the software filter and real-time cycle test method were used to improve test precise and reliability of node vibration measurement. Experiments have proved its effective.

Nonlinear Sequential Bayesian Analysis-Based Decision Making for End-Point Detection of Chemical Mechanical Planarization (CMP) Processes

Chemical mechanical planarization (CMP) process has been widely used in the semiconductor manufacturing industry for realizing highly polished (surface roughness Ra ~1 nm ) and planar [WIWNU ~ 1%, thickness variation standard deviation ~3 nm] surfaces of an in-process wafer. In CMP, accurate and timely decisions for end-point detection (EPD) are extremely important to enable the process to effectively respond to demand variations and disruptions. In this paper, we apply nonlinear sequential Bayesian analysis and decision theory to establish a quantitative relationship that connects the features (inputs) extracted from on-line wireless vibration sensor signals with the process performance measures, such as material removal (outputs) for EPD in copper CMP process. A case study with actual CMP data is provided to demonstrate the effectiveness of the present approach. Note to practitioners. The semiconductor industry widely uses CMP process for realizing highly polished planar surfaces on inter-level dielectrics and metallic interconnects in the fabrication of integrated circuits. Accurate and timely detection of the end-point (EPD) of the CMP process is critical to prevent over-polishing or under-polishing of wafer surfaces, and thus meet the wafer yield requirements under growing demands on wafer density and performance. An EPD system uses information from in-process sensors and/or inspection instruments to facilitate decisions on when to stop the polishing process, and adjust process settings for optimal performance. However, the issue of developing cost-effective sensors, and addressing the uncertainty in the sensor information remains a challenge. We have developed an EPD system based on deriving and sequentially updating a cost-function using the uncertain information from wireless MEMS vibration sensors mounted on a CMP apparatus. Decisions on EPD are made based on optimizing the updated cost function at every time-step. Our experimental investigations suggest that the sensor information can be effectively used for implementing EPD, and it can minimize the costs of over-polishing and under-polishing of wafers during CMP process. As part of future work, we are investigating the robustness of the EPD system to different forms of uncertainty in the sensor information, and much wider configurations of sensors and CMP setups.

Wireless vibration sensors track condition of highway bridges

Wireless vibration sensors track condition of highway bridges

Process Performance Prediction for Chemical Mechanical Planarization (CMP) by Integration of Nonlinear Bayesian Analysis and Statistical Modeling

Chemical mechanical planarization (CMP) process has been widely used in the semiconductor manufacturing industry for realizing highly finished (Ra ~ 1 nm) and planar surfaces (WIWNU ~ 1%, thickness standard deviation (SD) ~ 3 nm) of in-process wafer polishing. The CMP process is rather complex with nonlinear and non-Gaussian process dynamics, which brings significant challenges for process monitoring and control. As an attempt to address this issue, a method is presented in this paper that integrates nonlinear Bayesian analysis and statistical modeling to estimate and predict process state variables, and therewith to predict the performance measures, such as material removal rate (MRR), surface finish, surface defects, etc. As an example of performance measure, MRR is chosen to demonstrate the performance prediction. A sequential Monte Carlo (SMC) method, namely, particle filtering (PF) method is utilized for nonlinear Bayesian analysis to predict the CMP process-state and for tackling the process nonlinearity. Vibration signals from both wired and wireless vibration sensors are adopted in the experimental study conducted using the CMP apparatus. The process states captured by the sensor signals are related to MRR using design of experiments and statistical regression analysis. A case study was conducted using actual CMP processing data by comparing the PF method with other widely used prediction approaches. This comparison demonstrates the effectiveness of the proposed approach, especially for nonlinear dynamic processes.

Development of wireless vibration sensor using MEMS for tunnel construction and maintenance

Many tunnels have been constructed in Korea, where 70% of the nation is composed of mountain area, for the development of infrastructures such as the highways, subways, railways, electricity lines, and many other utilities due to the increase of traffic congestion. However, during and after tunnel construction, many problems including civil petitions and construction delay result from tunnel deformation, ground settlement, ground vibration, and tunnel lining crack. In relation to tunnel construction and maintenance, this study explains a development background of small wireless vibration sensors and their applications based on RF(Radio Frequency)-MEMS (Micro Electro Mechanical System) technology. The advantages and usefulness of the wireless automatic monitoring system is addressed compared with the conventional wired or survey measurement systems. Thus, the study provides a framework of the process for monitoring, manipulating, and transferring data from MEMS sensor and explains the application of the new developed automatic monitoring system for tunnel construction and maintenance. (A) This paper was presented at Safety in the underground space - Proceedings of the ITA-AITES 2006 World Tunnel Congress and the 32nd ITA General Assembly, Seoul, Korea, 22-27 April 2006. For the covering abstract see ITRD E129148. Reprinted with permission from Elsevier.

Daily Monitoring Reduces Cost of Production in Marginal Wells

The economics of a marginal well is highly sensitive to the price of oil and cost of production. Without improvements to production efficiency, marginal wells often must be shut down or risk operating at a loss. Because rod-pumped wells correspond to this pattern, with many of the wells producing less than 10 BOPD, a 4-year system-development effort was undertaken by Petrolects, a California-based engineering consulting firm, and Bakersfield-based independent producer Vaquero Energy to improve production efficiency. The Marginal Expense Oil Well Wireless Surveillance (MEOWWS) oil-production monitoring system is the result of this development effort, primarily funded by the U.S. Dept. of Energy. The system allows marginal wells to be economically monitored daily, allowing operation with near-optimal efficiency. Detection Methods During the first 2 years of the study, small, self-contained, wireless vibration sensors were attached to different sections of rod pump units. Signals induced by vibration of the pumping unit during fluid pounding were transmitted to a base-station computer in the field office. The operator could then identify problem wells by reviewing transmitted data. Statistical analysis of the vibration data was performed, demonstrating that acceleration sensors were able to detect fluid pound when the well was pumped off. Problems encountered during testing of the vibration-detection system included high power usage, which led to short battery life, and the high cost of the sensors. In the third and fourth years of the MEOWWS project, the method used to detect the pump-off condition was re-evaluated in an attempt to overcome the most serious problems encountered during the first phase. Three methods to determine the operating condition of the pumping unit in real time were tested and compared—vibration measurement, acoustic emissions from surface equipment, and flow measurements of produced fluids. Flow measurement was determined to hold the greatest promise for a reliable, economical, easily installed well-operation sensor and was chosen for further investigation. System Development A proprietary method of detecting outflow from a beam pump was conceived by the investigators. The method involves a simple and direct detection of flow through surface piping. A surveillance system was designed to suit the advantages of the flow-detection method: simplicity, reliability, direct monitoring of production, ease of installation, and low cost. The flow sensors are integrated into a well pump surveillance unit (WPSU). Each WPSU contains an inexpensive low-power microcontroller and a 900-MHz spread-spectrum radio modem. The microcontroller interprets readings from the flow sensor, using proprietary software to measure the well’s state of health and the volumetric pumping efficiency. Readings are saved over a period of hours or days. The power requirements of the WPSU are low enough to permit practical battery-powered operation over a period of years without an external electrical supply, eliminating the need for installation of expensive alternating-current power lines or costly and vulnerable solar-power arrays. The WPSU transmits data to a base station located in the field operations office as frequently as is required by the customer’s needs. The system is designed to transmit information on a daily basis, minimizing its contribution to the problem of radio frequency congestion that is increasingly troubling users of supervisory-control and data-acquisition systems. At the base station, readings are compiled by software to a tabular or graphical format that is easily interpreted by operations personnel. Base-station data are made available through a local area network, or across the Internet, by an integrated Web server. Data are also archived for future reference.