scholarly journals Thermal Drift Investigation of an SOI-Based MEMS Capacitive Sensor with an Asymmetric Structure

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3522 ◽  
Author(s):  
Haiwang Li ◽  
Yanxin Zhai ◽  
Zhi Tao ◽  
Yingxuan Gui ◽  
Xiao Tan
Keyword(s):  
Structural Parameters ◽  
Weighted Average ◽  
Capacitive Sensor ◽  
Expansion Ratio ◽  
Asymmetric Structure ◽  
Temperature Sensitive ◽  
Navigation Systems ◽  
Temperature Drift ◽  
Capacitive Accelerometer ◽  
Symmetric Structure

High-precision, low-temperature-sensitive microelectromechanical system (MEMS) capacitive accelerometers are widely used in aerospace, automotive, and navigation systems. An analytical study of the temperature drift of bias (TDB) and temperature drift of scale factor (TDSF) for an asymmetric comb capacitive accelerometer is presented in this paper. A five-layer model is established for the equivalent expansion ratio in the TDB and TDSF formulas, and the results calculated by the weighted average of thickness and elasticity modulus method are closest to the results of the numerical simulation. The analytical formulas of TDB and TDSF for an asymmetric structure are obtained. For an asymmetric structure, TDB is only related to thermal deformation and fabrication error. Additionally, half of the fixed electrode distance is not included in the expressions of Δ d and Δ D for asymmetric structures, thus resulting in the TDSF of the asymmetric structure being smaller compared to a symmetric structure with the same structural parameters. The TDSF of the symmetric structure is [−200.2 ppm/°C, −261.6 ppm/°C], while the results of the asymmetric structure are [−11.004 ppm/°C, −72.404 ppm/°C] under the same set of parameters. The parameters of the optimal asymmetric structure are obtained for fabrication guidance using numerical methods. In the experiment, the TDSF and TDB of the packaged structure and the non-packaged structure are compared, and a significant effect of the package on the signal output is found. The TDB is reduced from 3000 to 60 μg/°C, while the TDSF is reduced from 3000 to 140 ppm/°C.

Design, modeling, and simulation of an INS system using an asymmetric structure of six accelerometers and its error analysis in the ECEF frame

2016 ◽  
Vol 231 (13) ◽  
pp. 2345-2361 ◽  
Author(s):  
Vahid Ghasemzadeh ◽  
Mohammad M Arefi
Keyword(s):  
Error Analysis ◽  
Lower Cost ◽  
Inertial Navigation ◽  
Asymmetric Structure ◽  
Navigation Systems ◽  
Inertial Navigation Systems ◽  
Symmetric Structure ◽  
Angular Velocities ◽  
Dynamic Relations ◽  
Short Time

The inertial navigation system is one of the most important and common methods of navigation. In this system, accelerometers and gyroscopes are used to measure linear accelerations and angular velocities, respectively. Accelerometers have simpler manufacture techniques, lower cost, and smaller volume and weight in comparison with gyroscopes. Therefore, in some application of navigation systems, non-gyro inertial navigation systems based on accelerometers are used. In this paper, an asymmetric structure of six accelerometers is proposed. Then dynamic relations of this structure are extracted. This structure and its relations can determine linear accelerations and angular velocities, completely. Moreover, the algorithm of inertial navigation in earth centered earth fixed (ECEF) frame is suggested. Error analysis as of the most important issues in inertial navigation is discussed. Thus, bias, misalignment, sensitivity, and noise of accelerometers are modeled appropriately. In addition, a symmetric structure of accelerometers is proposed and its equations are derived. Finally, the designed system, error model of accelerometers, and algorithm of inertial navigation in ECEF frame are simulated. The results of simulation show that the designed system has suitable accuracy and applications for short time navigation. Furthermore, results confirm that the proposed asymmetric structure requires less accelerometer in comparison with symmetric structure.

ADMISSIBLE, SIMILAR TESTS: A CHARACTERIZATION

2019 ◽  
Vol 36 (2) ◽  
pp. 347-366 ◽  
Author(s):  
José Luis Montiel Olea
Keyword(s):  
Weight Function ◽  
Instrumental Variables ◽  
Structural Parameters ◽  
Average Power ◽  
Nuisance Parameter ◽  
Weighted Average ◽  
Necessary Condition ◽  
Ratio Test ◽  
Finite Sample ◽  
Characterization Result

This article studies a classical problem in statistical decision theory: a hypothesis test of a sharp null in the presence of a nuisance parameter. The main contribution of this article is a characterization of two finite-sample properties often deemed reasonable in this environment: admissibility and similarity. Admissibility means that a test cannot be improved uniformly over the parameter space. Similarity requires the null rejection probability to be unaffected by the nuisance parameter.The characterization result has two parts. The first part—established by Chernozhukov, Hansen, and Jansson (2009, Econometric Theory 25, 806–818)—states that maximizing weighted average power (WAP) subject to a similarity constraint suffices to generate admissible, similar tests. The second part—hereby established—states that constrained WAP maximization is (essentially) a necessary condition for a test to be admissible and similar. The characterization result shows that choosing an admissible, similar test is tantamount to selecting a particular weight function to report weighted average power. This result applies to full vector inference with a nuisance parameter, not to subvector inference.The article also revisits the theory of testing in the instrumental variables model. Specifically—and in light of the relevance of the weighted average power criterion in the main theoretical result—the article suggests a weight function for the structural parameters of the homoskedastic instrumental variables model, based on the priors proposed by Chamberlain (2007). The corresponding test is, by construction, admissible and similar. In addition, the test is shown to have finite- and large-sample properties comparable to those of the conditional likelihood ratio test.

scholarly journals DEVELOPMENT OF THE BASIC CAPACITIVE ACCELEROMETERS MODELS BASED ON THE VHDL-AMS LANGUAGE FOR THE CIRCUIT LEVEL OF COMPUTER-AIDED DESIGN

2020 ◽  
Vol 2 (1) ◽  
pp. 15-20
Author(s):  
V. M. Teslyuk ◽  
◽  
P. Yu. Denysyuk ◽  
T. V. Teslyuk ◽  
◽  
...  
Keyword(s):  
Differential Equations ◽  
Computer Aided Design ◽  
Structural Parameters ◽  
Software Systems ◽  
Mems Devices ◽  
Electric Circuits ◽  
Capacitive Accelerometer ◽  
Level Of Automation ◽  
Electric Parameters ◽  
Physical Principles

In the article, the basic VHDL-AMS models of MEMS-based capacitive accelerometers were developed. The models were designed for two basic types of capacitive accelerometers, namely lamellar and counter-pivotal. The developed models allow us to determine the source of electrical capacitive accelerometers depending on the incoming mechanical and structural parameters and were constructed for MEMS CAD at the circuit level. The circuit level of MEMS development requires an analysis of the total integrated device electric circuits. For this purpose, all the MEMS components should be written in the specific software systems, which would be understandable for the software system. Taking into account that MEMS devices operate on different physical principles, certain difficulties may arise during the electrical analysis, that is, the work of mechanical or other devices need to be described with the help of electric parameters. In the general case, the method for building the VHDL-AMS model of the MEMS-based capacitive accelerometer is needed construction of the simplified mechanical model, and then a simplified electrical model. On the basis of the simplified models, the VHDL-AMS model of electromechanical MEMS devices has been developed. In the article, the method of automated synthesis and mathematical models using the VHDL-AMS language, which is based on the method of electrical analogies were described. They use systems of ordinary differential equations and partial differential equations to determine the relationships between input and output parameters. The sequence and quantity of used differential equations are determined by the physical principles of operation of the MEMS element and the number of energy transformations, which allows increasing the level of automation of synthesis operations compared to existing methods. The results of the basic lamellar and counter-pivotal capacitive accelerometers are also shown. This enables to conduct research and analysis of its parameters and investigate the output electric parameters dependence on the input mechanical ones.

An Effective Method for Determining Finite Element Model Parameters of Rotor Elastic Support System

2011 ◽  
Vol 141 ◽  
pp. 191-197
Author(s):  
Yong Xing Wang ◽  
Jiang Yan ◽  
Sheng Ze Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Support System ◽  
Structural Parameters ◽  
Element Model ◽  
Elastic Support ◽  
Asymmetric Structure ◽  
Model Parameters ◽  
Equivalent Stiffness ◽  
Rolling Ball

A finite element model of the elastic support rotor system based on the corresponding experimental model was established. According to the principle of two types of model with an equal first order critical speed, the equivalent stiffness and damping of a rolling ball bearing support system with rubber rings determined by experiment were transferred into the finite element model. Then, the dynamic behavior of rotor systems with symmetric and asymmetric structure, different support system stiffness and support span were calculated and analyzed respectively. At last, the influence of the rotor structural parameters on the equivalent stiffness of elastic bearing support system obtained by experiment was pointed out.

scholarly journals Investigation on Inertial Sorter Coupled with Magnetophoretic Effect for Nonmagnetic Microparticles

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 566 ◽  
Author(s):  
Jiayou Du ◽  
Long Li ◽  
Qiuyi Zhuo ◽  
Ruijin Wang ◽  
Zefei Zhu
Keyword(s):  
Magnetic Field ◽  
Structural Parameters ◽  
Expansion Ratio ◽  
Numerical Results ◽  
Lateral Migration ◽  
Sheath Flow ◽  
Micro Particles ◽  
Micro Piv ◽  
Sorting Efficiency ◽  
Good Agreement

The sizes of most prokaryotic cells are several microns. It is very difficult to separate cells with similar sizes. A sorter with a contraction–expansion microchannel and applied magnetic field is designed to sort microparticles with diameters of 3, 4 and 5 microns. To evaluate the sorting efficiency of the designed sorter, numerical simulations for calculating the distributions of microparticles with similar sizes were carried out for various magnetic fields, inlet velocities, sheath flow ratios and structural parameters. The numerical results indicate that micro-particles with diameters of 3, 4 and 5 microns can be sorted efficiently in such a sorter within appropriate parameters. Furthermore, it is shown that a bigger particle size and more powerful magnetic field can result in a greater lateral migration of microparticles. The sorting efficiency of microparticles promotes a lower inlet velocity and greater sheath flow ratios. A smaller contraction–expansion ratio can induce a greater space between particle-bands. Finally, the micro particle image velocity (micro-PIV) experiments were conducted to obtain the bandwidths and spaces between particle-bands. The comparisons between the numerical and experimental results show a good agreement and make the validity of the numerical results certain.

scholarly journals Interactive model of magnetic field reconstruction stand for mobile robot navigation algorithms debugging which use magnetometer data

ACTA IMEKO ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 47
Author(s):  
Stanislaw Goll ◽  
Alexander Borisov
Keyword(s):  
Magnetic Field ◽  
Mobile Robot ◽  
Electrical Equipment ◽  
Reference Points ◽  
Mobile Robot Navigation ◽  
Navigation Systems ◽  
Temperature Drift ◽  
Simulink Model ◽  
Working Space ◽  
Magnetometer Data

An important addition to inertial navigation systems is the magnetometer. Areas with magnetic field anomalies serve to determine the reference points. However, magnetometers can be influenced by both the robot’s configuration and its electrical equipment. Compensation for the robot’s self-influence on the readings of the magnetometers is carried out by computer tools. In order to obtain the initial data, live experiments are required in a natural environment. To simplify data acquisition concerning the behaviour of the magnetometric systems of a mobile robot, a special facility that allows for the local compensation of the Earth’s magnetic field is used, and an artificial magnetic field that varies according to a predetermined algorithm is created. Using this facility, we can also simulate the magnetic field that will be present in the intended environment of the application of the robot. The facility features are a working space that is sufficient to place the mobile robot; a coil temperature drift correction; uniformity of the frequency response in operating frequency range; compensation for the power supply interference and similar disturbances; sensitivity equalisation of control channels; compensation for the misalignment of the sensor’s and coil system’s coordinate systems. An interactive Simulink model is designed and evaluated. The automated stand is created as an experimental facility, its parameters proving the proposed model’s adequacy.

Simplified Method for Pushover Curves of Asymmetric Structure with Displacement-Dependent Passive Energy Dissipation Devices

2007 ◽  
Vol 10 (5) ◽  
pp. 537-549 ◽  
Author(s):  
Hong-Nan Li ◽  
Gang Li
Keyword(s):  
Energy Dissipation ◽  
Analytical Method ◽  
Numerical Results ◽  
Asymmetric Structure ◽  
Engineering Analysis ◽  
Passive Energy Dissipation ◽  
Symmetric Structure ◽  
Simplified Method ◽  
Pushover Curve ◽  
Energy Dissipation Devices

This paper presents a simplified method to calculate pushover curves for an asymmetric structure with displacement-dependent passive energy dissipation devices (DDPEDDs). The deformations of a symmetric structure are analyzed in translation and torsion, respectively. These results are then combined in order to calculate the pushover curve for an asymmetric structure with DDPEDDs. The numerical results obtained by using the simplified analytical method are then compared to those obtained from the analysis of the models using the software SAP2000. The results show that the simplified analytical method can be an effective tool for engineering analysis of an asymmetric structure.

Temperature drift modeling and compensation of capacitive accelerometer based on AGA-BP neural network

Measurement ◽  
2020 ◽  
Vol 164 ◽  
pp. 108019 ◽  
Author(s):  
Zhiming Han ◽  
Li Hong ◽  
Juan Meng ◽  
Yanan Li ◽  
Qiang Gao
Keyword(s):  
Neural Network ◽  
Bp Neural Network ◽  
Temperature Drift ◽  
Capacitive Accelerometer

scholarly journals An Active and Soft Hydrogel Actuator to Stimulate Live Cell Clusters by Self-folding

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 583
Author(s):  
Jun Woo Lim ◽  
Hee-jin Kim ◽  
Yechan Kim ◽  
Sung Gyu Shin ◽  
Sungwoo Cho ◽  
...  
Keyword(s):  
Growth Factor ◽  
Expansion Ratio ◽  
Live Cell ◽  
Radius Of Curvature ◽  
Temperature Sensitive ◽  
Vascular Endothelial ◽  
Cell Clusters ◽  
New Strategy ◽  
Response To Temperature ◽  
Endothelial Growth Factor

The hydrogels are widely used in various applications, and their successful uses depend on controlling the mechanical properties. In this study, we present an advanced strategy to develop hydrogel actuator designed to stimulate live cell clusters by self-folding. The hydrogel actuator consisting of two layers with different expansion ratios were fabricated to have various curvatures in self-folding. The expansion ratio of the hydrogel tuned with the molecular weight and concentration of gel-forming polymers, and temperature-sensitive molecules in a controlled manner. As a result, the hydrogel actuator could stimulate live cell clusters by compression and tension repeatedly, in response to temperature. The cell clusters were compressed in the 0.7-fold decreases of the radius of curvature with 1.0 mm in room temperature, as compared to that of 1.4 mm in 37 °C. Interestingly, the vascular endothelial growth factor (VEGF) and insulin-like growth factor-binding protein-2 (IGFBP-2) in MCF-7 tumor cells exposed by mechanical stimulation was expressed more than in those without stimulation. Overall, this new strategy to prepare the active and soft hydrogel actuator would be actively used in tissue engineering, drug delivery, and micro-scale actuators.

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