English English | 中文 中文

Most Cited Nanotechnology and Precision Engineering Articles

The most cited articles published since 2014, extracted from Scopus.

Influence of material characteristics on machining performance of hydrophilic fixed abrasive pad

Volume 11, Issue 1, January 2013, Pages 51-56
Yongwei Zhu | Yongwei Zhu | Jie Fu | Zhilan Ju | Xiaoxiao Tang | Jun Li

To study the impact of material characteristics on the machining performance of hydrophilic fixed abrasive pad (FAP), K9 optical glass and silicon wafers were chosen as the work-pieces to explore the effect of machining sequence on the acoustic emission signal and friction coefficient during lapping. Scanning electron microscope (SEM) was employed to analyze the size and morphology of debris. Results show that material removal rate (MRR) varies greatly with the change of the machining sequence. Compared with the direct lapping of silicon wafer, if the silicon wafer is lapped after the lapping of a K9 glass work-piece, its MRR will greatly decrease. In contrast, the MRR of K9 glass is almost the same no matter whether it is lapped directly or after the lapping of a silicon wafer. The average surface roughness of both directly lapped silicon wafer and K9 glass is lower than that of work-pieces which are lapped after the lapping of the other. The size of most silicon debris is about 600 nm-1.5 μm, with clear edge; while that of K9 glass is around 300 nm-500 nm, edgeless. The greater size and clear edge of debris created during the lapping of silicon wafer are helpful for the self-conditioning process of hydrophilic FAP. Therefore, brittle materials such as silicon are helpful for the self-conditioning behavior of FAP.

Adaptive identification and inverse control of piezoelectric actuators based on PI hysteresis model

Volume 11, Issue 1, January 2013, Pages 85-89
Guilin Zhang | Chengjin Zhang | Kang Li

Piezoelectric ceramic actuators generally exhibit strong hysteresis nonlinearity effects in their output responses, which may cause inaccuracies and oscillations in the closed-loop system responses. In this paper, the classical Prandtl-Ishlinskii (PI) model is used to capture the hysteresis nonlinearity in the piezoelectric actuators. The adaptive projection algorithm is utilized to identify the weighting values and the identification result is compared with the least-square optimization method. The adaptive inverse controller is used to track the piezoelectric actuator considering that PI model has its analytical inverse. We first identify the weighting values of the PI model in situ using the adaptive projection algorithm based on the error between reference displacement and actual displacement of the actuator, and then calculate the weighting values and threshold values of the PI inverse model. At last, we obtain the feedforward input voltage. Experimental results demonstrate that the tracking ability of adaptive inverse controller is 49.8% higher than that of the conventional inverse controller.

Realization of self-conditioning process of hydrophilic fixed abrasive pad

Volume 12, Issue 1, January 2014, Pages 68-73
Xiaoxiao Tang | Yongwei Zhu | Cheng Wang | Yongbing Gu | Zhilan Ju | Jun Li

Self-conditioning process of hydrophilic fixed abrasive pad (FAP) affects its maching performance stability. In this paper, FAP was prepared with hydrophilic polymer and copper powder, and different amount of triethanolamine (TEA) was added to the lapping aqueous solution, to explore the influence of TEA on the slurry abrasion ratio of polymer and material removal rate (MRR) of FAP, which can reflect the self-conditioning performance and realization mechanism of hydrophilic FAP. The results show that within the investigation scope of this experiment, with the volumetric ratio of TEA added to the lapping aqueous solution increased from 0 to 5.0%, the slurry abrasion ratio of polymer increased from 0.003 3 g to 0.009 1 g, and the stability of MRR was improved from 11% to 42.9%. It is indicated that adding TEA to the lapping aqueous solution can improve the self-conditioning performance of hydrophilic FAP embedded with copper powder.

Rotary ultrasonic machining of hard and brittle materials

Volume 12, Issue 3, January 2014, Pages 227-234
Fengzhou Fang | Hao Ni | Hao Ni | Hu Gong

Hard and brittle materials, such as optical glass, functional crystal and ceramics, enjoy such advantages as high strength, resistance to elevated temperatures, withstanding wearing and tearing, etc. They have been, therefore, widely applied to the fields of aviation, automobile and military industries, etc. Because of their good performance in hardness and brittleness, it is quite difficult and inefficient to machine them using traditional methods. As a result, their application is limited. As one of the non-conventional machining methods, rotary ultrasonic machining (RUM) is an effective way for machining hard and brittle materials. With the advantages of less cutting force and less cutting heat, RUM can be applied to almost all hard and brittle materials. Therefore, RUM has been used widely and it develops quickly. After decades of development, it has taken an important part in manufacturing hard and brittle materials. In this paper, the RUM history and its characteristics were introduced firstly, and then the development of RUM equipment and research on machining mechanism and process were presented. Finally, the development tendency was summarized.

Magnetic field intensity model for giant magnetostrictive rod and coil optimization analysis

Volume 12, Issue 2, January 2014, Pages 85-90
Guangming Xue | Zhongbo He | Dongwei Li | Yulong Li | Zhaoshu Yang

The magnetic field intensity of the giant magnetostrictive rod is critical to the giant magnetostrictive actuator (GMA), as its amplitude and rise-time and fall-time affect output force and response time of the actuator directly. The magnetic field intensity is modeled from voltage, and rational optimization program of the coil is proposed. The coil's charging and discharging process is simplified as transient process of a first-order RL linear circuit and the coil current is achieved, and the magnetic field intensity of the rod is modeled from the current. The model shows that the optimization of the rod's magnetic field intensity relies mainly on the coil's circle number when the size of the actuator is restricted. The preferable range of the coil's circle number is determined by analysis of the circle number's influence on steady intensity, rise-time and fall-time of the magnetic field intensity. Square wave voltage signals with changed frequencies and amplitudes are put in the coil to get experimental data. The data's consistency with the model curves verifies the correctness of the model.

Characterization of single point diamond machined single-crystal silicon

Volume 11, Issue 6, November 2013, Pages 485-491
Feifei Xu | Feifei Xu | Feifei Xu | Xiaodong Zhang | Xiaodong Zhang | Xiaodong Zhang | Fengzhou Fang | Fengzhou Fang | Fengzhou Fang

Tapper cutting and turning were conducted on single-crystal silicon by the ultra-precision machine tool. The machining induced subsurface damage layer was measured by Raman spectroscopy. The measured Raman spectra were precisely fitted by Gaussian and Lorentzian distributions so that the thickness of amorphous layer and the information of residual stresses could be derived. The results show that the cutting induced damage layer is different from the nanoscratch and grinding induced damage layer. In the cutting silicon surface, except amorphous silicon, no high pressure phase was measured. The thickness of amorphous silicon layer and the residual stress increase correspondingly as the cutting depth increases. The larger cutting depth will make the residual stress more in homogeneous, which makes the single-crystal Raman peak split into two or three peaks. Generally the cutting depth of ductile turning single-crystal silicon is relatively small, so the turned subsurface has a thin amorphous layer and small residual compressive stress. When the cutting depth increases, the fractures, thicker amorphous layer and larger residual compressive stress exist in the turned surface. In the turning process, the diamond is cutting the machined surface which has an amorphous silicon layer on it. As a high cutting speed is used, the temperature of the contact region between diamond tool and workpiece will raise the ductility of the amorphous silicon layer, and better silicon optical surface will be machined.

Determination of the mechanical properties of nano-pillars using the nanoindentation technique

Volume 12, Issue 3, January 2014, Pages 182-188
Zhi Li | Sai Gao | Pohlenz Frank | Brand Uwe | Koenders Ludger | Peiner Erwin

The measurement uncertainty of depth sensing indentation technique (also referred to as nanoindentation technique) for the determination of the mechanical properties of nano-objects is subject to plenty of error sources, including sample roughness, indentation size effect (ISE), etc. Regarding one-dimensional (1D) nano-objects with relatively large aspect ratio, it is revealed in this paper that the equivalent specimen stiffness of this kind of nano-objects becomes one of the main error sources for quantitative nanoindentation measurement. For the purpose of improvement of the measurement uncertainty of nanoindentation testing for 1D materials, the currently available Oliver-Pharr method is further extended to compensate for the negative influence of the specimen stiffness of 1D nano-objects. To verify the feasibility of this practical data interpretation method, nanoindentation tests on silicon nano-pillars with different pillar diameters were performed. The geometrical dimensions (i.e. vertical height and in-plane diameter, respectively) of these chemically etched nanopillars were quantitatively determined by atomic force microscopy (AFM). Experimental results indicate that the measurement error would amount to higher than 50% for nanopillars with actual diameter of 386 nm and an aspect ratio of about 1.3 in the case of Oliver-Pharr data evaluation method being applied. In contrast, with the proposed data interpretation method for nanoindentation testing, the measurement results are no longer sensitive to the geometrical dimensions of nanopillars.

Self-conditioning mechanism of hydrophilic fixed abrasive pad

Volume 12, Issue 6, January 2014, Pages 429-434
Jun Xu | Yongwei Zhu | Nannan Zhu | Jianbin Wang | Jun Li

©, 2014, Tianjin University. All right reserved. Self-conditioning is one of the key performances of fixed abrasive pad (FAP). In order to investigate implementation mechanism of its self-conditioning, PHL-350 high speed lapping and polishing machine was used for a Marathon experiment on K9 glass wafer. The influence of lapping pressure and pore on the self-conditioning performance of FAP was studied. Results show that the self-conditioning performance of FAP improves a lot with a rise of applied pressure from 0.15 MPa to 0.20 MPa and the material removal rate of Pad 1 and Pad 2 kept stable at above 10 μm/min and 8 μm/min after a certain period of time. Meanwhile, the slurry wear rate almost increased by 7 times with the addition of pore forming additive, improving the stability of material removal rate of FAP. Therefore, increasing applied pressure and weakening FAP matrix benefit the self-conditioning process of FAP.

An equivalence graph cut method based on wavelet transform for SAR image registration

Volume 11, Issue 1, January 2013, Pages 14-19
Wei Xu | Chengcai Leng | Naigong Yu | Xiaogang Ruan

This paper proposes a novel equivalence graph cut method based on wavelet transform for SAR image registration in order to improve robustness and real-time performance. First, the equivalence graph cut model is constructed in low-frequency sub-images after wavelet transform of image, which can reduce speckle noise. The proposed model can not only avoid NP-complete problems but also provide a solution to the choice of mapping function. Then, scale invariant feature transform (SIFT) is exploited to find the feature matching in the object accurately segmented from the original image so as to reduce the feature point description of search space and improve real-time performance. Finally, the accurate SAR image registration is achieved based on the transformation parameters found by matching relationship. The experimental results show that the proposed method can achieve fast and accurate image registration.

Laser micromachining of polymer

Volume 13, Issue 3, May 2015, Pages 205-210
Wei Jia | Yiming Luo | Youjian Song | Bowen Liu | Minglie Hu | Lu Chai | Chingyue Wang

©, 2015, Nami Jishu yu Jingmi Gongcheng/Nanotechnology and Precision Engineering. All right reserved. This paper summarizes the research progress of laser induced refractive index modification, surface periodic structures and porous structures produced by laser ablation, and laser micromachining in bulk materials. The mechanisms of laser polymer modification and ablation, and the effects of laser wavelength and pulse duration are discussed. The mechanisms of laser ablation are not clear yet. Generally, the mechanism is a mixture of photochemical and photothermal features and is closely related to the polymer structure and properties. Through analysis of the characteristics of laser processed polymer materials, the application prospect of laser micromachining of polymer materials is explored.

Hysteresis compensation and decoupling control of piezoelectrically driven two-dimensional micro-positioning stage

Volume 11, Issue 3, May 2013, Pages 252-260
Yuansheng Chen | Jinhao Qiu | Hongli Ji

To improve the accuracy of piezoelectrically driven two-dimensional micro-positioning stage, a compound control system incorporating feedforward, decoupling and feedback controllers was designed to compensate for the hysteresis of piezoelectric actuator and attenuate the coupling effect between different actuating directions. With modified Prandtl-Ishlinskii hysteresis model, two feedforward controllers were designed to compensate for the hysteresis in the x and y directions, respectively. To attenuate the coupling effect, the decoupling controller was used to estimated the coupling shift and then manipulate the voltage to counteract this shift. The compound control system incorporating feedforward, decoupling and PID feedback controllers to reduce the tracking error. Experimental result shows that the maximum absolute values of tracking error were 4.16 μm in the x direction and 4.18 μm in the y direction without control, while they were reduced to 0.06 μm and 0.07 μm, respectively, with the compound control system. It indicates that the compound control system can well compensate for hysteresis and attenuate coupling effect without modifying the structure.

Precise micro-cutting fabrication of roller imprint cylindrical grating template

Volume 11, Issue 6, November 2013, Pages 473-478
Zongwei Xu | Gonghao Li | Wei Wu | Xiaodong Xing | Wanli Li | Hongzhong Liu | Ming Chen

As a core device of high precision computer numerical control (CNC) machine tools, large-scale micro-pitch grating directly determines the level of the manufacturing capacity of CNC machine tools. And it is a viable technology innovation to use nano-imprint roller technology to achieve high-precision large-scale micro-pitch grating. In this paper, a precision experiment machining platform was established for manufacturing the cylindrical grating template. And great efforts were made to improve the micro-fabricating process, and the parameters and materials were optimized during the experiments. With various factors, such as efficiency, quality of cutting, quality of nano-imprint, considered, the 20 μm, 10 μm and 4 μm pitch precision micro-cuttings of roller grating template in a full circle with the diameter of 110 mm were achieved. The number of the grooves is more than ten thousand, and the cutting time is over 62 h in the 4 μm pitch cutting process. The total splice error of the roller grating template is less than 300 nm. To solve the problem of insufficient filling during the nano-imprint, the V-shaped and trapezoid diamond tools were fabricated by focused ion beam (FIB) technology, and good nano-imprint re-suits were obtained.

Calibration accuracy of error model coefficients K2 and K3 of gyro accelerometer influenced by errors of centrifuge

Volume 11, Issue 2, March 2013, Pages 140-145
Shiming Wang | Shunqing Ren

In order to accurately calibrate second-order nonlinear error model coefficient K2 and third-order coefficient K3 of gyro accelerometer, firstly the coordinate systems were established on the centrifuge with a counter-rotating platform, and with error sources of centrifuge considered, accurate specific force input and angular velocity input of gyro accelerometer were derived. Then the contribution of each error of centrifuge to the calibration errors of K2, K3 were given according to the error model of gyro accelerometer. Through simulation, the practical impact of each error on the calibration accuracy of K2, K3 is shown quantitatively, and the calibration accuracy of error model coefficients K2, K3 of gyro accelerometer can be improved by error compensation. Meanwhile, the centrifuge errors which should be focused on when calibrating accelerometers with different accuracies are given. The simulation results also show that it is unnecessary to adjust the center of gyro accelerometer when centrifuge with the counter-rotating platform is used for its calibration. In addition, it has little effect on calibration when the magnitudes of the spindle speed and the angular velocity vector of reversal platform rotary axis are not exactly equal, and their directions are not completely opposite.

Preparation, photocatalytic properties and photogenerated hydroxyl radicals of TiO2nanoparticles

Volume 11, Issue 2, March 2013, Pages 111-117
Tao Xian | Tao Xian | Hua Yang | Hua Yang | Jianfeng Dai | Jianfeng Dai | Ruishan Li | Youcai Feng | Jinlong Jiang

A polyacrylamide gel route was used to prepare TiO2nanoparticles. X-ray diffraction(XRD), scanning electron microscope (SEM) and ultraviolet-visible diffuse reflectance spectrometer (UV-Vis DRS) were used to investigate the influences of calcining temperature on the crystalline phase, particle morphology and bandgap energy of products. The photocatalytic properties of the prepared TiO2samples were investigated by the degradation of methyl orange (MO) under UV irradiation. The results reveal that the sample prepared at 500°C exhibits the highest photocatalytic activity. With the increase of catalyst loading, the degradation rate of MO increases firstly and then decreases, with the optimal catalyst loading being 4.0 g/L. When the pH level is not very high (≤7.2), the MO degradation rate exhibits a decreasing trend with the increase of pH level. Hydroxyl radicals(·OH) formed on the catalyst under UV irradiation were detected by the photoluminescence (PL) spectroscopy using coumarin as a probe molecule, and the effects of calcining temperature, catalyst loading and pH value on the yield of ·OH were investigated. The results reveal that similar to the MO degradation rate, ·OH yield also depends on the above variables, indicating that the ·OH radical is likely to be the main active species responsible for dye degradation.

Key technologies for calibrating parameters of a bladed disk measuring machine

Volume 12, Issue 4, July 2014, Pages 235-241
Zurong Qiu | Zhikun Su | Guoxiong Zhang | Haitao Zhang | Xinghua Li

©, 2014, Tianjin University. All right reserved. To detect a bladed disk in-situ during its production, a dedicated articulated arm coordinate measuring machine (CMM) was developed. The structure of the machine was realized by a combination of linear-linear-rotational motions, which makes it possible for the machine to cover a large measurement range within limited room for mounting, so that the demands of the task can be met. To calibrate the parallelism between the linear and the rotational axes of the machine, a new method was put forward. In this method, a flat plate is used as the physical implementation of the horizontal plane, and a mechanical square serves as the vertical reference. After calibration and error compensation, the uncertainty of the machine is less than 0.01 mm, which can meet the design requirements. The method is easy to carry out, and its validity is proved by the good repeatability of calibration results.

Silicon dioxide film deposited by plasma enhanced chemical vapor deposition at low temperature

Volume 11, Issue 2, March 2013, Pages 185-190
Dongling Li | Dongling Li | Dongling Li | Zhengguo Shang | Zhengguo Shang | Zhengguo Shang | Zhiyu Wen | Zhiyu Wen | Zhiyu Wen | Shengqiang Wang | Shengqiang Wang | Shengqiang Wang

To meet the demand of inter-metal dielectric (IMD) layers and micro electro mechanical systems (MEMS), silicon dioxide (SiO2) films were deposited by plasma enhanced chemical vapor deposition (PECVD) at low temperature with silane(SiH4) and nitrous oxide (N2O) as precursor gases. The ellipsometer and stress measurement system were used to test the thickness, refractive index, uniformity and stress of the SiO2 film fabricated, and the effects of ratio frequency (RF) power, chamber pressure and N2O/SiH4 flow ratio on the properties of SiO2 film were studied. The results show that the refractive index of SiO2 film is mainly determined by N2O/SiH4 flow ratio and the uniformity of the film is influenced by the distance between electrodes and the chamber pressure. Moreover, by optimizing the process parameters, the SiO2 films were deposited at 260°C, with the refractive index measured as 1.45-1.52, the uniformity of ±0.64%, and the stress effectively controlled within -350--16 MPa. The deposited SiO2 films have good uniformity, compact structure, high deposition rate, low deposition temperature and controllable stress, which can be widely used in integrated circuit(IC) and MEMS devices.

Traceable calibration system for the normal spring constant of atomic force microscope probe

Volume 12, Issue 4, July 2014, Pages 249-257
Yunpeng Song | Sen Wu | Xinyu Geng | Xing Fu

©, 2014, Tianjin University. All right reserved. The spring constant of atomic force microscope (AFM) cantilever probe is of great significance in measurement of mechanical properties at micro-and nano-scale, which influences the reliability of mechanical measurement directly. Therefore, the spring constant must be precisely calibrated. Since the traceability of balance method, a new calibration setup based on the balance method is presented which combines ultra-precise electromagnetic balance with AFM test head. When the micro cantilever is approaching the balance by the precision stage, the deflection of the micro cantilever is under servo control and is detected by optical lever. Meanwhile, the contact force is directly measured by the balance. Finally, the spring constant of the micro cantilever is calculated using the Hooke's Law. Calibration results of normal spring constants of four types of commercial cantilever probes by the system proposed show that the system has good measurement repeatability. According to strict uncertainty analysis, the relative standard uncertainty of the calibration results obtained by the proposed system is less than 2%.

Tool tip arc measurement and characterization of micro-arc diamond tools

Volume 11, Issue 4, July 2013, Pages 334-340
Jingbo Zhou | Zengqiang Li | Yaqi Wang | Tao Sun | Wenjun Zong

To measure and characterize the tool tip arc of micro-arc diamond tools, an evaluation method based on high resolution scanning electron microscope image was brought out, and the edge extraction, edge fitting and the roundness characterization algorithms were also discussed. Firstly, Canny edge extraction method was adopted to detect the 2D edge profile of tool tip and moving least square algorithm was used to smooth edge profile. After that the arc characterization model of tool tip was established, and the characterization model was solved using sequential quadratic programming method. Finally, the factors affecting tool tip arc characterization results were analyzed including profile fitting error and nonper-pendicularity error, and the uncertainties of tool tip radius and tool tip roundness were also calculated. Experimental results show that the tool tip radius of micro-arc diamond tools is 30.213 μm with the uncertainty of 351 nm; the roundness is 0.114 μm with the uncertainty of 24 nm. From the characterization results it can be seen that the proposed method can measure and characterize the tool tip arc of micro-arc diamond tools with nano-meter precision.

Pixel equivalent calibration method for vision measurement

Volume 12, Issue 5, January 2014, Pages 373-380
Yongping Hao | Yongping Hao | Yongjie Wang | Yongjie Wang | Jiayi Zhang | Jiayi Zhang | Zhoulin Liu | Zhoulin Liu

©, 2014, Tianjin University. All right reserved. Pixel equivalent is an important measurement parameter for visual system and it critically affects the final measurement accuracy. A pixel equivalent calibration object was designed which is noise immune and easy to manufacture. The error caused by the height difference between measuring surface and calibration surface was analyzed. With the introduction of sub-pixel technology, a pixel equivalent calibration method was proposed based on shape matching. Through experiments, the influences of univariate changes or coupled changes of object distance, light intensity and posture of calibration object on the pixel equivalent calibration result was analyzed. Results show that this shape matching-based pixel equivalent calibration method is robust and practical.

SiC-SiC bonding methods for ultra high-temperature pressure sensors

Volume 12, Issue 4, July 2014, Pages 258-262
Deyuan Zhang | Yiju Zhao | Yonggang Jiang

©, 2014, Tianjin University. All right reserved. To produce the high-temperature pressure sensor cavity by SiC, this paper describes a SiC-SiC bonding process using high-performance ceramic adhesive, spin-on glass and Ni, respectively. Test results show that the three materials can all be used in SiC-SiC bonding by scanning electron microscope and tensile test for bonding strength. The thickness of the high-performance ceramic adhesive layer falls in the range of 20-30 μm, and its maximum bonding strength is approximately 4 MPa. The thickness of the spin-on glass layer is approximately 2 μm, and its maximum bonding strength is characterized as 1.5 MPa. The thickness of the Ni layer is approximately 1 μm, and its maximum bonding strength is 0.5 MPa. The three types of bonding processes show potential application in SiC based high-temperature pressure sensor.

A novel online oil debris monitoring sensor with three coils

Volume 13, Issue 2, January 2015, Pages 154-159
Zhijuan Wang | Zhijuan Wang | Junhong Zhao | Junhong Zhao | Guifu Ding | Guifu Ding

©, 2015, Nami Jishu yu Jingmi Gongcheng/Nanotechnology and Precision Engineering. All right reserved. Lubricating oil is the life blood of rotating and reciprocating machines and it carries a lot of wear debris. Such debris contains information that can reflect the working state of engines, and monitoring the metallic debris in lubricating oil is very important for early fault diagnosis, maintenance decision-making and accident prevention. In order to achieve real-time monitoring of oil debris, sensors based on inductive measurement technique was researched by finite element analysis method. According to the analysis results, a micro-channel oil debris monitoring sensor composed of a planar coil and two solenoids was designed, with the planar coil located in the middle of the two solenoids functioning as induction coil and the two solenoids as excitation coils. The sensor detects metallic debris passing through its center by monitoring induced electromotive force of the planar coil. A prototype was made to test the sensitivity of the sensor. The test results show that the sensor can detect ferromagnetic metal particles under 100 μm and, meanwhile, can distinguish ferromagnetic and non-ferromagnetic particles.

Structure optimization of connection frame in macro/micro motion platform based on frequency sensitivity analysis

Volume 12, Issue 3, January 2014, Pages 202-207
Lufan Zhang | Lufan Zhang | Zhili Long | Longsheng Nian | Longsheng Nian | Jiwen Fang | Jiwen Fang

Resonance usually results from similar frequency between connection frame and machine body, which will affect the realization of stability and ultra-precision positioning of macro/micro motion platform. In order to avoid resonance, this paper establishes a frequency model of connection frame using finite element method which is verified experimentally. And then, based on sensitivity method, perturbation of structure parameters in the model was investigated to obtain structure parameter sensitivity of stiffness and the first order natural frequency respectively, and design variables were selected. At last, an optimization model of connection frame was built comprising the objective function which is reciprocal of natural frequency and is verified by experiment, constraint conditions which are the weight of connection frame, and design variables which are results of sensitivity of structural parameters. Through optimization of the connection frame, the first order natural frequency is improved effectively, avoiding resonance between the connection frame and other parts. These results provide theoretical support for steady work and ultra-precision positioning of macro/micro motion platform.

Design of fluxgate CMOS interface circuit

Volume 11, Issue 2, March 2013, Pages 146-151
Changchun Dong | Weiping Chen | Mingyuan Ren | Mingyuan Ren | Xiaowei Liu | Zhiping Zhou

A novel CMOS interface circuit that has driving and detecting functions is presented to achieve the integration of interface circuit of fluxgate with three tips. The driving circuit adopts the switch network and negative feedback loop for fully differential drive in substitution for traditional centertapped transformer, balances the voltage signal on driving electrodes in real time and suppresses the influence of power supply drift and temperature variation. The detecting circuit uses switched demodulation based on the double frequency of driving signal to extract the second harmonics and adopts closed loop detection to improve the linearity of system. The whole circuitry is realized with 0.5 μm CMOS technology and its testing results show that this kind of miniature fluxgate magnetometer (the fluxgate with three tips and CMOS interface circuit) has a sensitivity of 30.8 μV/nT and a linearity error of 0.62%, in which the power supply is 10 V and the power consumption is 100 mW. The area of the chip is merely 15.54 mm2.

Influence of multiple piezoelectric effects on physical parameters of piezoelectric quartz

Volume 11, Issue 1, January 2013, Pages 45-50
Zhonghua Zhang | Shuyun Wang | Guangming Cheng | Junwu Kan | Hongyun Wang

To improve the performance of quartz devices and products to adapt to and to promote the development of micro/nano electromechanical systems, the influence of multiple piezoelectric effects on elastic coefficient, piezoelectric coefficient and electromechanical coupling factor of piezoelectric quartz crystals was theoretically and experimentally studied. The theoretical analysis shows that the influence of multiple piezoelectric effects on elastic coefficient and piezoelectric coefficient is caused by multiple direct piezoelectric effects and multiple converse piezoelectric effects, respectively. The influence of multiple effects on physical parameters of piezoelectric quartz crystal was tested by connecting piezoelectric quartz in parallel with a capacitor whose capacity is much greater than that of the quartz. Tertiary piezoelectric coefficient of piezoelectric quartz is obtained through the experiment, which is 0.04 pC/N. The experimental results indicate that multiple effects cause both piezoelectric coefficient and electromechanical coupling factor to increase by 1.75%.

Analysis of feasible design region for right-angle flexure-hinge based on stiffness error

Volume 12, Issue 1, January 2014, Pages 15-21
Longsheng Nian | Longsheng Nian | Zhili Long | Lufan Zhang | Lufan Zhang | Jiwen Fang | Jiwen Fang

When pseudo rigid body (PRB) method is employed in the design of right-angle flexure-hinged double parallel four-bar mechanism, the thickness of support arm bar should be much larger than that of flexure-hinge in order to meet the assumption that the support arm bar is a rigid rod. The design is usually based on the experience and there is no authentic theoretical principle for the design of this mechanism. In this paper, through the stiffness error analysis of right-angle flexure-hinged double parallel four-bar mechanism, the feasible design region where the support arm bar can be equivalent to rigid rod is derived. First, the precise stiffness of the mechanism is derived by the integral method. Then, taking the deformation of support arm bar into account, the stiffness is validated as the precise theoretical stiffness by finite element analysis (FEA) method. Finally, the relative error between the stiffness derived by virtual work principle and that by integral method is analyzed and its change laws with structural parameters are investigated, and the feasible design region where the support arm bar can be equivalent to a rigid rod is derived.

Share this page: