Static Calibration Research Articles

Improvement of Software for Dynamic Force Correction of Force Transducers

Software for correcting the dynamic error of the force sensor in the impact force measurement, which uses an output signal of the sensor itself, has been improved. The software corrects the output waveform of the sensor by using the output waveform itself and estimates its uncertainty. In the experiment, the dynamic error of the sensor is evaluated using the Levitation Mass Method (LMM). In the LMM, the impact force applied to the sensor is accurately determined as an inertial force of the moving part of the aerostatic linear bearing. The parameter for correcting the dynamic error is determined from the results of one set of impact measurements of the sensor. Then the validity of the parameter is evaluated by using the results of measurements of the sensor. The uncertainty of the un-corrected force and that of the corrected force are also estimated. In the previous version of the software, the user input “input text-file” which contains force that is calculated based on the static calibration results. On the other hand, the output signal from the sensor is not force. This time, the software has been modified to load input text-file which contains the output signal from the sensor.

Development of a new calibration procedure and its experimental validation applied to a human motion capture system.

Motion capture systems are often used for checking and analyzing human motion in biomechanical applications. It is important, in this context, that the systems provide the best possible accuracy. Among existing capture systems, optical systems are those with the highest accuracy. In this paper, the development of a new calibration procedure for optical human motion capture systems is presented. The performance and effectiveness of that new calibration procedure are also checked by experimental validation. The new calibration procedure consists of two stages. In the first stage, initial estimators of intrinsic and extrinsic parameters are sought. The camera calibration method used in this stage is the one proposed by Tsai. These parameters are determined from the camera characteristics, the spatial position of the camera, and the center of the capture volume. In the second stage, a simultaneous nonlinear optimization of all parameters is performed to identify the optimal values, which minimize the objective function. The objective function, in this case, minimizes two errors. The first error is the distance error between two markers placed in a wand. The second error is the error of position and orientation of the retroreflective markers of a static calibration object. The real co-ordinates of the two objects are calibrated in a co-ordinate measuring machine (CMM). The OrthoBio system is used to validate the new calibration procedure. Results are 90% lower than those from the previous calibration software and broadly comparable with results from a similarly configured Vicon system.

Integrative seismic safety evaluation of a high concrete arch dam

An integrative seismic safety evaluation of an arch dam should include all sources of nonlinearities, dynamic interactions between different components and the external loads. The present paper investigates the calibration procedure and nonlinear seismic response of an existing high arch dam. The first part explains the conducted analyses for the static and thermal calibrations of the dam based on site measurements. The second part investigates the nonlinear seismic analysis of the calibrated model considering the effect of joints, cracking of mass concrete, reservoir–dam–rock interaction, hydrodynamic pressure inside the opened joints and the geometric nonlinearity. Penetration of the water inside the opened joints accelerates the damage process. The integrative seismic assessment of a case study shows that the dam will fail under the maximum credible earthquake scenario. The dam is judged to be severely damaged with extensive cracking and the joints undergo opening/sliding. A systematic procedure is proposed for seismic and post-seismic safety of dams.

Underwater blast wave pressure sensor based on polymer film fiber Fabry-Perot cavity.

This paper describes the theoretical and experimental aspects of an optical underwater shock wave sensor based on a polymer film optical fiber Fabry-Perot cavity manufactured by vacuum deposition technology. The transduction mechanism of the sensor involves a normally incident acoustic stress wave that changes the thickness of the polymer film, thereby giving rise to a phase shift. This transient interferometric phase is interrogated by a three-phase-step algorithm. Theoretically, the sensor-acoustic-field interaction principle is analyzed, and the phase modulation sensitivity based on the theory of waves in the layered media is calculated. Experimentally, a static calibration test and a dynamic calibration test are conducted using a piston-type pressure calibration machine and a focusing-type electromagnetic shock wave. Results indicate that the repeatability, hysteresis, nonlinearity, and the overall measurement accuracy of the sensor within the full pressure range of 55MPa are 1.82%, 0.86%, 1.81%, and 4.49%, respectively. The dynamic response time is less than 0.767μs. Finally, three aspects that need further study for practical use are pointed out.

Metrological traceability of a system for measuring electrodermal activity

The paper presents a procedure for evaluation of system for measuring electrodermal activity of the skin. The proposed procedure was tested within a metrological evaluation of a low-cost wireless system. The procedure consists of static calibration by comparison, dynamic evaluation by means of generated sine signals and testing for functionality using of a simple psychophysiological experiment. Additionally, the quality and reliability of measured data transmission is evaluated. A low cost, low weight, ergonomically shaped and battery powered wireless (ZigBee protocol) portable wrist-type measuring system was designed and built and the proposed procedure used to evaluate it. Based on the results of the evaluation acceptance criteria for a reliable skin conductance meter used for skin conductance levels studies could be proposed. Devices conforming to these criteria would be reliable and sufficiently accurate for skin conductance level measurements, with an established metrological traceability and readings linked to the basic units of the international system of units SI.

Study on Calibration Method for Explosion Pressure Test System

The segment sensitivity for various pressure sensors is obtained by implementing the static and dynamic calibrations for three types of pressure sensors, i.e., CY-YD-202, CY-YD-205 and CY-YD-203T, and the average absolute value of relative errors for sensors is obtained by measuring the dynamic high-frequency signal, which provides the basis for correct selection of pressure sensor during the test.

Tuned Forest Fire Prediction: Static Calibration of the Evolutionary Component of ‘ESS’


 
 
 Forest fires are a major risk factor with strong impact at eco-environmental and socio- economical levels, reasons why their study and modeling are very important. However, the models frequently have a certain level of uncertainty in some input parameters given that they must be approximated or estimated, as a consequence of diverse difficulties to accurately measure the conditions of the phenomenon in real time. This has resulted in the development of several methods for the uncertainty reduction, whose trade-off between accuracy and complexity can vary significantly. The system ESS (Evolutionary- Statistical System) is a method whose aim is to reduce the uncertainty, by combining Statistical Analysis, High Performance Computing (HPC) and Parallel Evolutionary Al- gorithms (PEAs). The PEAs use several parameters that require adjustment and that determine the quality of their use. The calibration of the parameters is a crucial task for reaching a good performance and to improve the system output. This paper presents an empirical study of the parameters tuning to evaluate the effectiveness of different configurations and the impact of their use in the Forest Fires prediction.
 
 

An IMU Static Attitude Angle Calibration Method Based on Total Station

This paper proposes a non-magnetic framework to calibrate the Inertial Measurement Unit (IMU) based on Total Station. The IMU consists of magnetometer, accelerator and gyroscope. The potential errors are analyzed and raw data of the IMU is preprocessed effectively. The IMU attitude mathematical models are constructed based on the collected spatial coordinate data, marked points, quaternion coordinate transformation, and geographical magnetic compensation. The causations which may affect the accuracy of experimental results are analyzed and technique supports are provided to calibrate the IMU dynamic attitude angle.

A Dynamic Calibration Method for Pirani Gauges Embedded in Fluidic Networks

This paper describes in situ dynamic calibration of microfabricated Pirani gauges, which are commonly used to measure vacuum levels in microsystems that may include pumps, valves, and other pressure modulation elements. Calibration is accomplished with a configuration where two sides of the supporting membrane of a Pirani gauge are at different pressures: an interior pressure within the microsystems and an exterior ambient pressure that can be directly controlled. This particular configuration is increasingly common as Pirani gauges are embedded in complex fluidic pathways such as those found in micro-gas chromatographs and multistage gas pumps. In the dynamic calibration the ambient pressure is rapidly modulated, while the interior pressure in the sense gap of the Pirani gauge remains relatively unchanged. The exterior pressure that is equal to the interior pressure is determined by a regression model. The dynamic calibration procedure and subsequent error analysis are illustrated by application to a 162-stage monolithic Knudsen vacuum pump. For this device, dynamic calibration improves the estimated upstream pressure from 30 (as suggested by uncorrected static calibration) to 0.9 Torr, with a 95.4% confidence interval from 0.7 to 1.1 Torr, assuming normal (Gaussian) distribution. These results demonstrate that dynamic calibration can be significantly more accurate than conventional static calibration for certain types of devices.

Development of Piezoelectric Three-Dimensional Dynamometer for Φ300mm Wafer Grinder

Due to the requirements of on-line detection of grinding force in the grinding process, this paper utilizes the structural characteristics of ultra-precision grinder with double-spindle and single-workstation, and then presents a grinding dynamometer based on piezoelectric effect of quartz crystals. Besides, the grinder dynamometer can measure grinding force in three directions, and the static properties of dynamometer are experimentally tested in a special experiment table. Moreover, the on-line static calibration and the actual grinding experiment of dynamometer installed in the silicon wafer grinder are performed. The results indicate that the grinding dynamometer has satisfactory static properties, that is, the linearity and repeatability are less than 1%, and the cross-talks are also less than 5%. As a result, each indicator has full reached the operating requirements in using of large diameter silicon wafer grinding force measuring.

A Conductance Ring Coupled Cone Meter for Oil-Water Two-Phase Flow Measurement

Simultaneous measurement on the phase fraction and flow rate of oil-water two-phase flow is of significance in process industries. A compact flow meter conductance ring coupled cone meter (CRCC) is presented to measure these two parameters by combining a long-waist cone meter (LWC) for flow rate measurement and a pair of conductance rings at the annular channel of the LWC for phase fraction measurement. The CRCC utilizes the spatial characteristics of LWC and conductance rings to achieve more reliable estimations on flow rate and phase fraction. The sizes of the LWC (diameter ratio β and waist length L) and conductance rings (separation Le between electrodes) are jointly optimized considering the overall pressure drop and sensitivity of electrical sensing field. A CRCC of β = 0.65, L=50 mm, and Le=15 mm is fabricated for static calibration and dynamic oil-water two-phase flow measurement tests. The dynamic experimental results demonstrate that the proposed CRCC is capable of delivering inferences on phase fraction and individual flow rate with an associated average relative error below 5% after easy calibration.

A systematic sensitivity analysis of constrained cellular automata model for urban growth simulation based on different transition rules

Cellular automata (CA) have emerged as a primary tool for urban growth modeling due to its simplicity, transparency, and ease of implementation. Sensitivity analysis is an important component in CA modeling for a better understanding of errors or uncertainties and their propagation. Most studies on sensitivity analyses in urban CA modeling focus on specific component such as neighborhood configuration or stochastic perturbation. However, sensitivity analysis of transition rules, which is one of the core components in CA models, has not been systematically done. This article proposes a systematic sensitivity analysis of major operational components in urban CA modeling using a stepwise comparison approach. After obtaining transition rules, three stages (i.e. static calibration of transition rules, dynamic evolution with varied time steps, and incorporation with stochastic perturbation) are designed to facilitate a comprehensive analysis. This scheme implemented with a case study in Guangzhou City (China) reveals that gaps in performance from static calibration with different transition rules can be reduced when dynamic evolution is considered. Moreover, the degree of stochastic perturbation is closely related to obtain urban morphology. However, a more realistic (i.e. fragmented) urban landscape is achieved at the cost of decreasing pixel-based accuracy in this study. Thus, a trade-off between pixel-based and pattern-based comparisons should be balanced in practical urban modeling. Finally, experimental results illustrate that models for transition rules extraction with good quality can do an assistance for urban modeling through reducing errors and uncertainty range. Additionally, ensemble methods can feasibly improve the performance of CA models when coupled with nonparametric models (i.e. classification and regression tree).

Study on Measurement of Six-DOF Force/Torque for Loading Experiment on Heavy Load Equipment

According to the requirements of fatigue test of aircraft cabin, large engine and mining machinery for heavy-duty six dimensional generalized force sensors, a new method of using piezoelectric quartz as force-sensitive element on the basis of the theory of heavy force division and equivalent capacity compression is proposed in this study. Furthermore, in order to minimize the force-coupling for the six-dimension force sensor, the optimization objective function is devised and the calculation method for decoupling is also proposed, on the basis of which, the generalized force sensor with high sensitivity, high stiffness, high linearity but light in its weight is designed. At last, the static calibration experiment is carried out the result shows that the sensor has a good ability of heavy force division and capacity for equivalent compression it can be well used in large tonnage six component force loading device and fatigue test system.

Experiment on Static Characteristics of the Braking Signal Transmitter

The braking signal transmitter is a major component of the EBS. The structure and working principle of a braking signal transmitter were introduced. The test bed of the braking signal transmitter was designed and built. The static characteristics of the braking signal transmitter were obtained by analyzing the test data. The inflection points and the slope of each segment curve obtained by the bed test are basically identical to the static characteristic calibration curve. The pressure does not reach the maximum pressure of the static characteristic calibration curve because the gas source pressure does not reach the required test pressure. Keywords: Braking signal transmitter, EBS, static characteristics, bed test.

PROSAD: A powerful platform for instrument calibration and quantification

There is critical need for instrument calibration and correction procedures that can improve the quality of mass spectral quantitative results. Currently, mass spectrometry (MS) technologies suffer from certain biases related to instrumental responses, which tend to restrict its application. To overcome these biases, we developed the PROgressive SAmple Dosage (PROSAD) platform and tested it. PROSAD, an optimized sample preparation and data analysis method, is used in conjunction with a liquid chromatography (LC)/MS system and a low-voltage ionization source (e.g., no-discharge atmospheric pressure chemical ionization (ND-APCI)). The mass spectrometers used for this report were an HCT Ultra ion trap, a LTQ XL Orbitrap, and a TSQ Vantage triple-stage quadrupole. The PROSAD elaborative system, because of its dedicated mathematical algorithm, provided a dynamic linear calibration check and correction. We tested PROSAD using a leucomalachite green-fish homogenate assay. Atrazine in tea matrix samples were also quantified. Better quantification was achieved using PROSAD compared with the classic linear, static calibration procedure in both test cases. PROSAD provides a dynamically optimized calibration curve that affords increased stability, accuracy, and precision for the quantification of MS data.

GLUE based marine X-band weather radar data calibration and uncertainty estimation

The Generalized Likelihood Uncertainty Estimation methodology (GLUE) is investigated for radar rainfall calibration and uncertainty assessment. The method is used to calibrate radar data collected by a Local Area Weather Radar (LAWR).In contrast to other LAWR data calibrations, the method combines calibration with uncertainty estimation. Instead of searching for a single set of calibration parameters, the method uses the observations to construct distributions of the calibration parameters. These parameter sets provide valuable knowledge of parameter sensitivity and the uncertainty.Two approaches are analyzed; the static calibration approach, where the LAWR is calibrated once for a long period and the dynamic approach, where the estimate is continuously adjusted based on ground observations.The analysis illustrates that the static calibration performs insufficiently, whereas the dynamic adjustment improves the performance significantly.It is found that even if the dynamic adjustment method is used the uncertainty of rainfall estimates can still be significant.

An Evaluation of the Calibration Process of a Neutron-Gamma Ray Online Coal Analyzer

Samples of a thermal coal were analyzed by the conventional methods and the online analyzer. The results obtained in static calibration tests and the online analysis showed high correlations of 89.9%, 98.6%, and 98.2%, respectively for volatile matter, ash, and calorific value. However, the results obtained for the dynamic tests correlate poorly with reproducible conventional tests, particularly at the initial stages of the calibration study. It was observed that the results of the real-time analyses gradually get closer to the conventional static results as the online analyzer accumulated more data on the varying nature of the coal deposit.

目标捕获能力检测装置静动态目标源对比度的标定

In order to realize the static and dynamic contrast calibration of the adjustable contrast optical target device for measuring the low-contrast target capture capability of photoelectric tracker, a target sources contrast measurement system is established for researching the relationship between image contrast and optical contrast. The static target sources image contrast is analyzed and the static calibration curve based on the least squares method is obtained. The military standard rules and the static calibration method, according to the dynamic target sources unique deformation effect and gray gradual change effect, which leads to the problem of lacking uniform and accurate target gray extraction method; discriminant analysis based on mathematical statistical methods is used to classify target gray extraction frame dimensions by different gray values. Then, the scatterplots are applied to visualize the relationship between the extraction frame size and gray distribution, which makes the extraction frame size clear and exclude harmful effects from the above two effects on calibration. Dynamic contrast calibration curves are mapped out under different rates conditions. Experimental results indicate that the accuracy of extraction frame selected is more than 94% and the evaluation parameters of the static and dynamic calibration fitting equations: R2 and Radj2 are both better than 99%, calibration precision S is better than 0.006, which demonstrates that the method is feasible and can satisfy contrast calibration demands in the equipment.

Research on the characteristics of a piezoelectric balance for the dynamic motion device

Wind tunnel balance is one of the most important measurement instruments in the aerodynamic field. In this paper, a new type of piezoelectric wind tunnel balance is developed to measure the dynamic six-component force in the case of the hatch open motion device in the subsonic flow field. This mechanical device mainly consists of a novel piezoelectric balance and a rotary encoder. The piezoelectric balance assembled with four triaxial piezoelectric load cells is developed as the core force measurement of the device. According to the electric charges output of the load cells which are proportional to the airloads, the six-component force and moment can be inversely calculated and the measuring model of the dynamic are presented. The characteristics of the piezoelectric balance have been performed by the static calibration and the dynamic test. The experimental results show that the non-linearity and repeatability error is within 0.06% and 0.19%, the maximum crosstalk error is 1.94%. The first natural frequency of the mechanical device is 163.57 Hz. The piezoelectric balance has a good performance of dynamic response and following feature. It is appropriate for the piezoelectric balance to be used to measure the dynamic airloads in the wind tunnel.

Measurement Performance Assessment: Dynamic Calibration Compared with Static Calibration Method for Roller Tester of Vehicle Brake Force

The measurement performance of the roller tester for the vehicle brake force is evaluated by both proposed dynamic calibration and traditional static calibration to find an effective way for ensuring the vehicle safety. Three static parameters, brake force error of a single bench, difference of the left and right benches, and measurement repeatability, are verified to be eligible in the experiments. However, the experimental results of the dynamic calibration prove that the same brake tester fails on the repeatability with a 10.4% error. The dynamic calibration method improves the measurement performance of the brake tester in practical applications.