Showing papers in "Chinese Journal of Sensors and Actuators in 2008"

Distance Difference Localization Algorithm Based on RSSI for Wireless Sensor Networks

Abstract: In order to suppress effectively the effects of RSSI error to WSN node localization precision,individual difference coefficient,distance difference coefficient and distance difference localization equation are defined,based on the trilateration localization algorithm.The closest beaconing node to object node as reference node corrects measure distance based on RSSI by difference method.A distance difference correction localization algorithm is put forward through combining difference method and weighted centroid averaging method.This localization algorithm needn't additional hardware spending,easy to be realized,and its location error is less than 2.5m,so it is fit for WSN node whose operation ability and power supply are restricted.

Energy Consumption Balance Improvement of LEACH of WSN

Abstract: LEACH(low-energy adaptive clustering hierarchy)routing protocol is widely used in wireless sensor network.But it has the disadvantage of irrationality of choosing cluster head and of unbalanced energy consumption of nodes.By modeling and analyzing the energy consumption of nodes in LEACH routing protocol,an improved energy consumption balanced protocol LEACH-B is proposed.Finally,the improved protocol is simulated on NS2.The results of simulation show that the improved routing protocol can balance energy consumption of nodes and prolong the lifetime of the whole networks.

Research of Obstacle Recognition Based on Vision for High Voltage Transmission Line Inspection Robot

Abstract: Obstacle recognition and orientation is one of the key techniques in high voltage transmission line autonomous inspection robot.In light of the structure of 220 kV single split transmission line,a method of obstacle recognition based upon vision sensor is put forward.First of all,the shot image is processed by expansion,erosion,Gauss smoothing treatment to relieve the noise.And then,Otsu is used to improve Canny algorithm so as to detect the edge of the image,which can reduce the influence of the light changing.At last,some graph cells are detected and given structure constraint in the edge of image to achieve obstacles recognition.A lot of tests proved that structures such as wire,counterweight,strain clamp and suspension on high voltage transmission line can be effectively recognized using the method.

Combination of Support Vector Machine and Evidence Theory in Information Fusion

Abstract: DS evidence theory is an important method in the field of multi-sensor information fusion, but its advantage is not fully utilized because its BPA is difficult to obtain. SVM is a new learning algorithm based on the statistical learning theory. However, its hard decision output does not adequately facilitate multi-sensor information fusion. In this paper, in order to apply SVM to information fusion, a two-class SVM with BPA output is proposed. By analyzing the essence and deficiency of the Platt’s model, the BPA is obtained through use of the lower bound of the SVM precision to weight the Platt’s probability model, which achieves the combination of SVM and the evidence theory in the information fusion. The simulation results show that multi-sensor information fusion can be realized and the error rate can be greatly lowered through the algorithm proposed in this paper.

A Modified Localization Algorithm of APIT Based on Perpendicular Bisector Feature for Wireless Sensor Network

Abstract: APIT is a canonical range-free localization algorithm for wireless sensor networks.Although it can make a well localization performance,it ignores some features that can be used to further reduce the error of localization.In order to improve the localization accuracy,a novel algorithm is proposed to reach a better performance.To localize an unknown node,the neighbor anchors establish triangles and estimate the topology relationships between the unknown node and these triangles.When a triangle contains the unknown node,it utilizes the perpendicular bisector of each side to divide itself into 4 or 6 sub-areas for further judgment.And,the position of the unknown node is set as the center of mass with overlapped small sub-areas.Simulation experiments prove that PB-APIT algorithm can remarkably improve localization accuracy compared to APIT algorithm,especially in the large scale wireless sensor network.

Design of a Micro Six-Axis Force Sensor Based on Double Layer E-Type Membrane

Abstract: The elastic body structure of Six-axis force sensor based on the double layer E-type membrane was used in the normal situation maturely.The possibility of the same elastic body structure used in the micro-operation is discussed.The working principle of the sensor structure is introduced firstly,and the static and dynamic characteristic of the elastic body is obtained by finite element analysis.The results demonstrate that six-axis force sensor with this kind of structure can be used in micro-operation and the sensor has high sensitivities in each axis and high linearity.The static couple is negligible.

A Novel Anti-Collision Protocol in Multiple Readers RFID Sensor Networks

Abstract: The reader collision problem(RCP)is the key problem affecting the reading efficiency in RFID systems.A novel anti-collision protocol——DREAM protocol is proposed to solve the reader collision problem in RFID systems.The new protocol dynamically selects temporal control centers to perform as cluster headers based on interference conditions and arranges the communication sequence of readers reasonably to completely avoid signal collisions among multiple readers.Both analytical and simulation results show that comparing to the current advanced PULSE protocol,DREAM protocol increases the reading efficiency significantly and meanwhile reduces the power consumption.

An Intelligent Localization System Based on RSSI Ranging Technique for WSN

Abstract: An intelligent localization system based on RSSI for WSN is proposed A RSSI( Signal Strength Indicator) model is established based on the study of RSSI theoretical model, and DV-Distance algorithm is improved by adding in weighted factors, which is completed on TinyOS It is proved by practical experiment that the improved DV-Distance has the advantage of precision and stabilization than the standard DV-Distance, so it is appropriate to apply to wireless sensor networks

Optimal Sensor Node Distribution Based on the New Quantum Genetic Algorithm

Abstract: In the wireless sensor networks,the reasonable distribution of sensor nodes plays a vital role in the improvement of sensor ability,information aggregation ability and network survival.For the Sensor network constructed by randomly distribution,better sensor coverage could be achieved by topology adjustment utilizing mobility of sensor node.To solve this problem we defined a coverage control model of the sensors network and a distribution optimization mechanism that based on the new quantum genetic algorithm was proposed.An advantage of the new quantum genetic algorithm over the conventional genetic algorithm was demonstrated in simulation result,thus it can enhance the sensation ability of the whole network effectively.

Fuzzy Approach to Construct Basic Probability Assignment and Its Application in Multi-Sensor Data Fusion Systems

Abstract: In the framework of evidence theory,information fusion relies on the use of combination rule allowing the belief functions for the different propositions to be combined.A crucial role in evidence theory is played by Dempster's combination rule that has several interesting mathematical properties such as commutativity and associativity and can be combined without prior information,which make it widely used in many data fusion systems.However,how to construct basic probability assignment(BPA)is still an open issue.A fuzzy method to obtain basic probability assignment is proposed.A numerical example for target recognition is used to illustrated the efficiency of the proposed method.

Method Based on the Ratio of Signal to Noise for Multi-Sensor Data Fusion

Abstract: Due to data fusion of multi-sensors experiment of many times on some characteristic index, a new fusion method is proposed based on the ratio of signal to noise. The method views the measured data of every sensor as a fuzzy set and measures the approach degree by the maximum and minimum principle. Then the consistent measure of each sensor at any time is given. According to the ratio of signal to noise, the consistent reliability measure of each sensor is defined. Finally the formula of data fusion is obtained based on the consistent reliability measure. The applied example proves that the method is effective. The compared analysis with the average method and the reliable fusion method shows that the method has the strong ability of stableness.

A Capacitive Force Transducer Structure with Improved Linearity

Abstract: In MEMS capacitive force transducers,force is transformed to the variation of capacitance,then the capacitance variation is read out by circuits.Because of the nonlinearity between the displacement of polar plate and the capacitance,the output of the transducer has sever nonlinear relation with the force been measured in large measurement range.A structure with nonlinear force-to-displacement relation,which can counteract the displacement-to-capacitance nonlinearity was introduced.Rayleigh-Ritz method was adopted to analysis the force-to-displacement relation of the hardening spring in the structure.Test result indicated that the nonlinearity of the sensor was reduced by 1/3 in the test range.

A Novel Closed-Loop Drive Circuit for the Micromachined Gyroscope

Abstract: The closed-loop drive circuit is widely used in high performance micromachined gyroscopesMost of the closed-loop drive circuit consists of an AGC module to control the amplitude of the output signalBut the AGC module may restrict the linear operational range of the whole circuit and limit the amplitude of the output signal,so that deteriorates sensitivity and stability of the gyroscope systemThe equivalent model of the closed-loop drive system is investigated,based on this,a novel closed-loop drive circuit is presentedIn this circuit,a comparator is used to instead of the AGC circuit,which overcomes the disadvantages of limited linear operational range and limited output signal amplitude

A Data Aggregation Algorithm Based on Gird and Mobile Agent in WSN

Abstract: Energy efficiency is an important concern in the routing algorithm design for Wireless Sensor Networks(WSN).Data aggregation can efficiently decrease energy consumption by aggregating the redundant information.This paper presents a data aggregation algorithm that integrates grid generation and mobile agent(MA) in WSN,which is based on MA retransmitting interest agent packets sent by sink node and data agent packets sent by target nodes.In this algorithm,MA routing can be treated as an optimization problem.WSN is evenly divided into many two-dimensional grids,forming the initial population of adaptive genetic algorithm(AGA).AGA is applied to find out the optimal nodes' sequence of MA routing.Simulation results show that compared with Local Closest First algorithm(LCF),with the increasing of the network scale,the proposed algorithm can produce less energy consumption and network delay.

Simulation of the Lift-off Effect of Eddy Current Testing Based on ANSYS

Abstract: The lift-off effect of eddy current is an important factor in eddy current testing.This paper takes the numerical simulation to the lift-off effect on the basis of ANSYS,and builds two dimension model of lift-off effect,acquires the changes of impedance of the probe coil,and normalizes the impedance data of the probe coil,and the result that we get is identical to the actual characteristic of the transducer,which provides a meaningful method of analyzing and reference for the application of eddy current testing.

Study of Online Oil Monitoring Technology Based on Dielectric Constant Measurement

Abstract: Engine's malfunction information is contained in the wearing off process of lubricating oil.Meanwhile,the oil's dielectric constant has some change during the wearing out process.The method of online oil monitoring based on dielectric constant measurement is proposed,and the principle for oil monitoring is introduced.Oil monitoring system is also developed,which includes capacitance sensor,tiny capacitance detecting circuit and software of monitoring and analysis.Experiments are carried out on lubricating oil with different contamination.The results show that change of lubricating oil's dielectric constant can be detected effectively and properly,which has some reference meaning in lubricating oil replacing and fault diagnosis.

Three-Dimensional Node Localization Algorithm of High-Precision in Wireless Sensor Network

Abstract: A centralized three dimensional localization algorithm is proposed with the name of NMDS-MEEF,which is based on the location requirements of wireless sensor network used for monitoring large electrical equipment fault.The localization algorithm adopts a changed nonmetric multidimensional scaling in which the iterations process only makes use of the correlated data of one-hop neighbor nodes.The algorithm is more straightforward and practical.The simulation results demonstrate that the algorithm is of great advantages in improving localization accuracy,decreasing the dependence on the density of anchor nodes and reducing the influence by the accuracy of position estimation.

Theoretical Analysis and Numerical Simulation of Closed-Loop Self-Oscillation System for MEMS Vibratory Gyroscopes

Abstract: We analyze self-oscillation system with AGC(automatic gain control)for MEMS vibratory gyroscopes using averaging and phase-plane techniques,and present analytical equations for system design.Numerical simulations are implemented,and the simulation results show a good agreement with the analytical results.In our self-Oscillation drive system,the stable error of the oscillation amplitude is eliminated by the PI controller.The analytical equations can be used to direct the design of the closed-loop drive system in hardware.

On Heat Insulation of Micro Thermal Sensor Using FEA

Abstract: Heat insulation is crucial to develop micromachined thermal sensors with high performance.By using FEA,typical heat insulation structures were studied,including the structure with different heat barrier layer beneath sensitive element,with or without cavity on silicon substrate,and using polymer as whole flexible substrate.Influence of heat insulation structures on sensor's sensitivity and response time was investigated,and the inherent mechanism was analysed.The research results are useful for design or optimization of micro thermal sensors.

Design of Data Video Base Station of WSNs Oriented Water Environment Monitoring

Abstract: Water environment monitoring system based on wireless sensor networks (WSNs) consists of three parts: data monitoring nodes, date video base station and remote monitoring center. For the sake of realizing to monitor large range waters such as reservoir, wetland, lake, river and ocean ,etc, the monitoring system has the function of perception, acquisition, processing and transmission to video-information in key areas and various water environment parameters, such as water temperature, PH, turbidity, electric conductivity, dissolved oxygen and so on. As the gateway between those data monitoring nodes and CDMA network, the data video base station is the communication center in the monitoring network. Based on ARM-DSP double processors architecture, this paper researches the date video base station for the water environment monitoring system and offers the design of software and hardware of system. Moreover, by means of ZigBee and CDMA wireless transmission technology, the base station realizes data bidirectional communication between the base station and the sensor networks or the remote monitoring center. It well meets the need of remote real time water environment monitoring system and also has wide application prospect in industrial control, smart home, medical telemetry and intelligent traffic, etc.

Study Routing Metrics Based on EWMA for Wireless Sensor Networks

Abstract: Selecting an effective routing metric is very important for improving the routing performance of wireless sensor networks. This paper firstly finds the several key characteristics of wireless sensor networks communication link, such as high loss rate, obvious asymmetry, according to the experimental study; then analyzing relations between LQI, RSSI and receives package ratio. From these, the LETX route metric algorithm based on EWMA is provided. Finally, the route metric is adapted to AODV routing protocol. Simulation results show that the LETX routing metric is an excellent routing metric that provide valuable reference to design efficient routing protocols in wireless sensor networks.

Electrical Method to Measure the Dynamic Behaviour of a MEMS Gyroscope Sensor

Abstract: It is very important to find a rapid and efficient method to evaluate the parameter of the MEMS gyro.To testing the MEMS device's dynamic characterater,differente measures were used with regarding to precision,rapidity and convenience,etc.A reliable electric measure system to test the vibration performance of the MEMS device was proposed.Several testing schemes were compared via analysis and experiment,and the ways of testing and data processing were discussed respectively.

Authentication and Key Negotiation Protocol Between Two Nodes of Wireless Sensor Networks

Abstract: Due to their own characteristics,wireless sensor networks are facing more security challenges than traditional networks.Their security mechanism should take into account both the security and the system performance.Authentication and key negotiation is an elementary protocol in constructing a secure network system,and it is the implementation foundation of the key management protocol and the secure routing protocol.By all appearances,most of the existing wireless networks authentication and key negotiation protocols are inapplicable to wireless sensor networks,including those in traditional Ad hoc networks.Motivated by these concerns,on the enough consideration on the attack methods for wireless networks and the characteristics of wireless sensor networks,a node-to-node authentication and key negotiation protocol is proposed,in which the ID-based public-key cryptography and the ellipse curve bilinear pair are adopted.Analyses show that this protocol can be used to guarantee the security of wireless sensor networks,and at the same time,it can meet the special application requirements of wireless sensor networks.

Design and Analysis of Woven Structure-Based Flexible Strain Sensor

Abstract: The electrical equivalent circuit model of woven fabrics has been fabricated and the relation between strain and resistance of the woven fabrics has been deduced based on strain-resistance effect on conductive elastic fiber material.The plain structure of woven fabrics and the signal converting circuit for woven fabrics have been designed.The input-output properties and sensitivity of flexible strain sensor have also been deduced.The analysis of structure parameters of woven fabrics indicates that fabrics woven with conductive elastic yarn in parallel connection is expected to be made of conductive elastic fiber with a moderate or low resistivity and be applied to large strain measurement for any scale objects in theory,while fabrics woven with conductive elastic yarn in serial connection is expected to be made of conductive elastic fiber with a low resistivity and be applied to large strain measurement for small scale objects only.

Research of Passive Infrared Wireless Sensor Network Target Tracing

Abstract: Target tracking in wireless sensor networks is a hot research issue.Passive infrared sensors are highly sensitive in detecting moving people.However,passive infrared detecting is mostly used in binary detecting but not in target tracing.This paper proposes a passive infrared target tracing model(PITM)for wireless sensor networks,which can detect the position and moving speed of the target with the cooperation of multiple infrared sensors.We validate the model by simulating,and the simulation results show that with the density of 24 sensors in 1 000 m2,the average position error of PITM is about 0.5 m.With the density of node increasing,the average target position error is decreasing.

Analysis on Shock Resistance of Micromachined Angular Rate Sensor Based on Convection Heat Transfer

Abstract: Micromachined thermal gas angular rate sensor is kind of novel inertial device,which takes an advantage of high shock resistance due to use gas instead of conventionally used proof-mass as the key sensing elementThe calculation of the static and transient strain and stress in supporting layer of heating wire and detection wires is performed,and the position with the largest stress is figured out by means of finite element software ANSYSThe results show that the largest stress point of support layer of heating wire is close to the clamped edgesThe largest stress point of support layer of detection wire is close to the clamped edges and cornersWhen an acceleration loading is applied along z direction,the largest stress of support layer of heating wire is larger than that of support layer of detection wireExperimental results show that our device can withstand the shock of 21 200 gn,and the theoretic prediction of the shock resistance of the device can reach 200 000 gn,all of which indicates the sensor has a good shock resistance

Research on Calibration Techniques for MEMSMicro Inertial Measurement Unit

Abstract: Based on the introduction of the composing structure of MEMS-MIMU(micro inertial measurement units),according to the output model of MEMS gyro and MEMS accelerometer,a new calibrating method for MEMS-MIMU is proposed and deduced.The basic thought of calibrating MEMS gyro in this method is to set the swivel table running in the speeding mode,and to choose the appropriate interval the angle speed,and to make the individual MEMS gyro sense the different angle speed,and then to compute the zero-bias voltage,the scale factors,the across couple coefficients,and the corresponding fixing angle error by a series of computation.The method of calibrating MEMS accelerometer is similar to the method for MEMS gyro,the different is to set the rotating table running in the position mode.The theory analysis and experiment results show the new method can well and truly transform the outputting voltages of MEMS-MIMU into the corrsponding angle rates and the ratio information,so that to establish the base for the following attitude resolve and the navigation computation.

Design and Research of a Photoelectrical Apparatus for Lateral-Flow Based on CCD

Abstract: A photoelectrical apparatus with CCD detector was designed for on-site detection,to quantify the measurement results of pesticide residues by lateral-flow.The apparatus is composed of the light path module and circuitry module.In the circuitry module,the FIFO chip was used for cache memory,which greatly reduced the cost of designing;auto locating devices were introduced to increase the target positioning accuracy.The working curve and parameters of the system were derived from the experiments.Results showed that the measurement accuracy reached 1 ng/mL,and the linear range was 1-20 ng/mL.The apparatus can meet the demand of detection criteria for pesticide residues.

Gait Silhouette Extraction Algorithm Using Gauss Model

Abstract: Gait silhouette is mostly used as recognition feature in human gait recognition,so the prerequisite of correct recognition is to extract complete and closed moving human silhouette to express gait feature exactly.A gait silhouette extraction algorithm using Gauss model is proposed.Under the condition that the motion direction of object is parallel to the imaging plane of the camera and the camera is static,it is supposed that in the serial images, the distribution of the pixel's gray level at the time of background on time axis is Gaussian distribution,while the distribution at the time of object does not satisfy this distribution,then moving object silhouette is extracted using statistical inference approach.The experimental results demonstrate that the proposed algorithm can not only extract human silhouette completely and accurately,but also can remove noise and shadow and increase recognition rate.The algorithm can be directly used on RGB space or grey space,without changing color space or building the background model,it is less computative and has high real-time processing performance.

Fragile Transportation Detecting Based on Microsystems Design with Multi-Microaccelerometer

Abstract: The paper puts forward a kind of transportation detecting system based on Microsystems with MEMS accelerometer and SoC processor for ensuring the safety of the goods and detecting the status of the vehicles.The system can detect transportation and load process separately,and it has two different range MEMS sensors and a piece of real time clock recording chip that shows the time of the acceleration.This can provide the customer and the driver with the data to analysis the accident.Through the simulation on vibration platform experiment,it proved that the system can detect the vibration condition with high reliability.