Dynamic Calibration Method Research Articles

Dynamic calibration method of the laser beam for a non-orthogonal shaft laser theodolite measurement system.

The non-orthogonal shaft laser theodolite (N-theodolite) measurement system is a new kind of instrument applied to large-scale metrology. The system consists of two identical N-theodolites, each of which is made up of a two-dimensional rotary table and one collimated laser. The three axes of the N-theodolite have no strict requirements on their orthogonality and intersection conditions. A novel method, to the best of our knowledge, is proposed to calibrate the N-theodolite measurement system, and the calibration method of the laser beam for N-theodolite is the key innovation aspect of this paper. The laser beam is calibrated through dynamic rotation. Throughout the experiment, the straightness accuracy of the laser beam of the left N-theodolite is 0.08 mm and the right N-theodolite is 0.074 mm. The repeatability of the straightness accuracy is ${\pm 0.032}\,\,{\rm mm}$±0.032mm. The uncertainty of straightness accuracy is 0.040 mm. The measurement experiment results show that the maximum deviation of the measured value of this system is 0.34 mm at a range of 5 m, which is verified to be a feasible method for the calibration of the laser beam.

An On-Orbit Dynamic Calibration Method for an MHD Micro-Angular Vibration Sensor Using a Laser Interferometer.

The magnetohydrodynamic (MHD) micro-angular vibration sensor is a significant component of the MHD Inertial Reference Unit (MIRU) and measures micro-amplitude and wide frequency angular vibration. The MHD micro-angular vibration sensor must be calibrated in orbit since the ground calibration parameters may change after lift-off. An on-orbit dynamic calibration method for the MHD micro-angular vibration sensor is proposed to calibrate the complex sensitivity of the sensor in high frequency. An absolute calibration method that combines a homodyne laser interferometer and an angular retroreflector was developed. The sinusoidal approximation method was applied, and the calibration system was established and tested using a manufactured MHD sensor. Furthermore, the measurement principle and installation errors were analyzed, including the eccentric installation error of the retroreflector, the tilt installation error of the retroreflector, and the optical path tilt error. This method can be realized within a rotation range of and effectively avoid the installation error caused by mechanical errors. The results indicate that the calibratable angular vibration frequency range is 25–800 Hz, and the angular velocity range is –7590 mrad/s. The expanded uncertainties of the sensitivity amplitude and phase shift of the calibration system for the MHD micro-angular sensor are and .

Research on Calibration Method of Underwater Shock Wave Pressure Measurement Sensor Systemt

Underwater explosions are distinguished from explosions in the air, and their environment is complex, making sensor systems more difficult to calibrate. In this paper, the calibration method of underwater shock wave pressure sensor system is studied. The dynamic pressure calibration method based on water shock tube is proposed to calibrate the system. The propagation characteristics of the pulse pressure signal in the water shock tube are studied. The water shock tube device suitable for the calibration of the underwater shock wave pressure sensor system is designed. In the end, the advantages of the water shock tube in measuring the underwater shock wave pressure are summarized.

A traceable dynamic calibration research of the measurement system based on quasi-static and dynamic calibration for accurate blast overpressure measurement

To ensure measurement accuracy in blast tests, the blast overpressure measurement system with piezoelectric sensors needs to be calibrated. Due to the charge leakage on the piezoelectric crystal and the decrease in the service life of the piezoelectric sensor under static pressure loads, the static calibration is not suitable here. This paper presents a traceable dynamic calibration method combining the quasi-static calibration using a drop-weight device and the dynamic calibration using a shock tube. First, the normalized low-frequency and high-frequency characteristics of the measurement system can be derived by the quasi-static calibration and the dynamic calibration, respectively. Then, based on the quasi-static calibration, a calculation method is proposed to obtain the performance characteristics which can be traceable to the SI, including the sensitivity, the linearity and the repeatability of the measurement system. Therefore, this calibration method combining quasi-static and dynamic calibration can help to obtain the frequency characteristics and the performance characteristics of the measurement system with traceability. For accurate blast overpressure measurement, based on the frequency characteristics derived from the calibration, the dynamic modelling and compensation are implemented on the measurement system to make the compensated measurement system meet the so-called undistorted measurement requirements. As the measurement system is compensated, it can be proved that the performance characteristics calculated by the quasi-static calibration are consistent with that of the compensated measurement system. So, the blast overpressure can be accurately represented with the multiplication of the calculated sensitivity traceable to the SI and the output voltage of the measurement system in blast overpressure measurement. By combining the traceable dynamic calibration with dynamic modelling and compensation, the calibrated and compensated measurement system can realize accurate blast overpressure measurement. Finally, influence factors of the blast overpressure measurement uncertainty are analyzed and possible measures to further improve the measurement accuracy are illustrated.

Network dynamic field calibration for micro inertial measurement unit

Calibration accuracy of micro inertial measurement unit (MIMU) will affect the navigation accuracy of micro strap-down inertial navigation system. Generally, when the application environment changes (i.e. environment temperature and humidity), the specific force and angular rate output by MIMU will be changed, which were influenced by the zero bias of accelerometers, the zero drift of gyroscopes and so on. Thus, it is necessary to carry out the field calibration for MIMU. Aiming at the application of multi MIMUs, the network dynamic field calibration method is proposed in this paper. According to the navigation attitude and velocity error models, the estimating model is established. Then, the observability for the parameters in the estimating model is analyzed. By fusing the output information of MIMUs and GPS, vehicle experiments are carried out with the designed maneuvers in order to estimate the parameters. The experiment result illustrated that the proposed network dynamic filed calibration can efficiently realize the calibration for the parameters in the model of several MIMUs simultaneously.

A Dynamic Calibration Method of Installation Misalignment Angles between Two Inertial Navigation Systems.

Generally, in order to ensure the reliability of Navigation system, vehicles are usually equipped with two or more sets of inertial navigation systems (INSs). Fusion of navigation measurement information from different sets of INSs can improve the accuracy of autonomous navigation effectively. However, due to the existence of misalignment angles, the coordinate axes of different systems are usually not in coincidence with each other absolutely, which would lead to serious problems when integrating the attitudes information. Therefore, it is necessary to precisely calibrate and compensate the misalignment angles between different systems. In this paper, a dynamic calibration method of misalignment angles between two systems was proposed. This method uses the speed and attitude information of two sets of INSs during the movement of the vehicle as measurements to dynamically calibrate the misalignment angles of two systems without additional information sources or other external measuring equipment, such as turntable. A mathematical model of misalignment angles between two INSs was established. The simulation experiment and the INSs vehicle experiments were conducted to verify the effectiveness of the method. The results show that the calibration accuracy of misalignment angles between the two sets of systems can reach to 1″ while using the proposed method.

Features calibration of the dynamic force transducers

The article discusses calibration methods of dynamic forces measuring instruments. The relevance of work is dictated by need to valid definition of the dynamic forces transducers metrological characteristics taking into account their intended application. The aim of this work is choice justification of calibration method, which provides the definition dynamic forces transducers metrological characteristics under simulation operating conditions for determining suitability for using in accordance with its purpose. The following tasks are solved: the mathematical model and the main measurements equation of calibration dynamic forces transducers by load weight, the main budget uncertainty components of calibration are defined. The new method of dynamic forces transducers calibration with use the reference converter “force-deformation” based on the calibrated elastic element and measurement of his deformation by a laser interferometer is offered. The mathematical model and the main measurements equation of the offered method is constructed. It is shown that use of calibration method based on measurements by the laser interferometer of calibrated elastic element deformations allows to exclude or to considerably reduce the uncertainty budget components inherent to method of load weight.

Dynamic behavior analysis of drug delivery devices using a dynamic gravimetric method

The calibration of drug delivery devices is essential for accurate dose control. In this study, drug delivery devices, namely infusion and syringe pumps, were assessed using a dynamic gravimetric method. The flow rates caused by the syringe pump, infusion pump, and pressure-based pump were measured at various flow rates (0.5–60 mL/h) by simultaneously using a dynamic gravimetric method and flow meter. The measurement error uncertainty of the pumps were obtained using the dynamic gravimetric calibration method. The pulsation period and amplitude were obtained with respect to the flow rate to analyze the pulsating flow of the syringe pump and infusion pump. The pump error increased in the following order: the pressure-based pump, syringe pump, and infusion pump based on the flow rate. The measurement error uncertainty of the syringe pump increased slightly when the flow rate decreased, whereas the infusion pump exhibited significant increases in the error and uncertainty when the flow rate decreased. The flow stability of the pulsating flow from each pump was analyzed according to the flow rate. Thus, we discussed the characteristics of the pulsating flow from each drug delivery device. We confirmed that the pumps had different flow stability, error, and measurement uncertainty because of their different working principles.

A calculation and uncertainty evaluation method for the effective area of a piston rod used in quasi-static pressure calibration

This paper describes the merits and demerits of different sensors for measuring propellant gas pressure, the applicable range of the frequently used dynamic pressure calibration methods, and the working principle of absolute quasi-static pressure calibration based on the drop-weight device. The main factors affecting the accuracy of pressure calibration are analyzed from two aspects of the force sensor and the piston area. To calculate the effective area of the piston rod and evaluate the uncertainty between the force sensor and the corresponding peak pressure in the absolute quasi-static pressure calibration process, a method for solving these problems based on the least squares principle is proposed. According to the relevant quasi-static pressure calibration experimental data, the least squares fitting model between the peak force and the peak pressure, and the effective area of the piston rod and its measurement uncertainty, are obtained. The fitting model is tested by an additional group of experiments, and the peak pressure obtained by the existing high-precision comparison calibration method is taken as the reference value. The test results show that the peak pressure obtained by the least squares fitting model is closer to the reference value than the one directly calculated by the cross-sectional area of the piston rod. When the peak pressure is higher than 150 MPa, the percentage difference is less than 0.71%, which can meet the requirements of practical application.

A dynamic machine tool circle test calibration method by R-test

With the continuous popularization of automation in the manufacturing industry and continuous improvement of production efficiency, new requirements have been put forward for the error detection of machine tool. As a new automated detection tool, R-test has been widely studied by scholars. This paper proposes a dynamic test method for R-test, and analyses the influence of three main error sources of servo error, pitch error and reading error. The corresponding elimination methods are also introduced. An experiment on a double turntable machine tool was conducted to verify the analysis. In addition, the selection of feed rate and initial position in circle test is also studied.

Dynamic calibration method of temperature sensor based on Quasi‐δ pulse temperature excitation

AbstractAiming at the existing problems in the dynamic calibration method of temperature sensor, Quasi‐δ pulse temperature dynamic calibration method is proposed. The Quasi‐δ pulse dynamic calibration principle was described, the characteristics of Quasi‐δ pulse function were analyzed, and the relationship among pulse width of Quasi‐δ signal, frequency range that can be calibrated, and calibration precision was obtained. Quasi‐δ pulse temperature dynamic calibration system was built using the laser as the heat source which generates the excitation temperature required for dynamic calibration. In the system, optical focusing system was designed using ellipsoidal mirror which has a better conjugate imaging property. Applying the dynamic calibration system, a K‐type armored thermocouple was calibrated dynamically, and mathematical model of the calibrated thermocouple was established by generalized least squares method based on a special whitening filter. Dynamic characteristics of the thermocouple in time domain and frequency domain were analyzed.

Measurement correction method for force sensor used in dynamic pressure calibration based on artificial neural network optimized by genetic algorithm

We present an optimization algorithm to obtain low-uncertainty dynamic pressure measurements from a force-transducer-based device. In this paper, the advantages and disadvantages of the methods that are commonly used to measure the propellant powder gas pressure, the applicable scope of dynamic pressure calibration devices, and the shortcomings of the traditional comparison calibration method based on the drop-weight device are firstly analysed in detail. Then, a dynamic calibration method for measuring pressure using a force sensor based on a drop-weight device is introduced. This method can effectively save time when many pressure sensors are calibrated simultaneously and extend the life of expensive reference sensors. However, the force sensor is installed between the drop-weight and the hammerhead by transition pieces through the connection mode of bolt fastening, which causes adverse effects such as additional pretightening and inertia forces. To solve these effects, the influence mechanisms of the pretightening force, the inertia force and other influence factors on the force measurement are theoretically analysed. Then a measurement correction method for the force measurement is proposed based on an artificial neural network optimized by a genetic algorithm. The training and testing data sets are obtained from calibration tests, and the selection criteria for the key parameters of the correction model is discussed. The evaluation results for the test data show that the correction model can effectively improve the force measurement accuracy of the force sensor. Compared with the traditional high-accuracy comparison calibration method, the percentage difference of the impact-force-based measurement is less than 0.6% and the relative uncertainty of the corrected force value is 1.95%, which can meet the requirements of engineering applications.

Dynamic Calibration for Measurement System of Form Measuring Instruments Based on Elliptical Standard

A dynamic calibration method based on elliptical standard was put forward to further improve the calibration repeatability of measurement system of form measuring instruments. In this method, the radius difference of the major axis to the minor axis of elliptic contour acts as the standard value to calibrate the measuring system, and a low pass filter is used to filter the roughness, electrical noise and high frequency vibration signal which mixed into measurement data, the elliptic contour feature can be obtained accurately based on the low order harmonic properties. Compared with the traditional calibration method of flick standard, the proposed method ensure the calibration state is well consistent with the normal measuring state of the measuring system. Experimental results indicate that the calibration repeatability with 10nm can be achieved by measuring an elliptical standard. This method has been used in the calibration of measurement system of self-made ultra-precision cylindricity measuring instrument.

Does the roller pump adjustment in cardiopulmonary bypass settings influence hemolysis?

Roller pumps are widely used in procedures involving cardiopulmonary bypass (CPB) due to their ease of operation and maintenance, safety, and cost. Several studies in the literature have compared the use of roller pumps with centrifugal pumps, but the influence of the roller pump adjustment on hemolysis has been poorly explored. Measurements of hemolysis rates were carried out in 86 patients. The pump was adjusted by the dynamic calibration method, which was performed by an auxiliary device, and the patients were grouped according to the pump calibration: Group 1 (n = 20) 75 mmHg; Group 2 (n = 24) 150 mmHg; Group 3 (n = 22) 300 mmHg and Group 4 (n = 21) 450 mmHg. The hemolysis rates were measured at 4 different times during CPB (T0: before the surgical procedure; T1: 5 minutes after the start of CPB; T2: 30 minutes of CPB; and T3: 5 minutes after the CPB procedure). Hemolysis rates were calculated between the time intervals T0-T1, T1-T2, and T0-T3. No difference in hemolysis rates was observed between the groups (p>0.31). During the first 5 minutes of CPB, hemolysis represented 35.5% of the total hemolysis and no significant difference was found between groups (p>0.60). Calibration of roller pumps by the dynamic method did not influence the hemolysis rates. Additionally, the hemolysis during the first 5 minutes of CPB accounted for ~1/3 of the total hemolysis.

Comprehensive Calibration of Strap-Down Tri-Axis Accelerometer Unit

This paper proposes a comprehensive calibration method to improve the precision of a strap-down tri-axis accelerometer unit, in which parameters are divided into static and dynamic ones. The contribution of the manuscript is that it solves the problem of inappropriate installation and the size effect error for tri-axis accelerometer unit at high speed by using static and dynamic calibration method, respectively. The experiment results show the measuring accuracy of accelerometers is increased by more than one order of magnitude, and the navigation precision is increased by more than two orders of magnitude.

Empirical mode decomposition-adaptive least squares method for dynamic calibration of pressure sensors

In this paper, an approach combining empirical mode decomposition (EMD) with adaptive least squares (ALS) is proposed to improve the dynamic calibration accuracy of pressure sensors. With EMD, the original output of the sensor can be represented as sums of zero-mean amplitude modulation frequency modulation components. By identifying and excluding those components involved in noises, the noise-free output could be reconstructed with the useful frequency modulation ones. Then the least squares method is iteratively performed to estimate the optimal order and parameters of the mathematical model. The dynamic characteristic parameters of the sensor can be derived from the model in both time and frequency domains. A series of shock tube calibration tests are carried out to validate the performance of this method. Experimental results show that the proposed method works well in reducing the influence of noise and yields an appropriate mathematical model. Furthermore, comparative experiments also demonstrate the superiority of the proposed method over the existing ones.

ANALYSIS OF THE PRECISE RASTER-FORMING SYSTEMS / PRECIZINIŲ RASTRŲ FORMAVIMO SISTEMŲ ANALIZĖ

The precision raster-forming systems creation and development must be based on research in the specific work environment. In not ideal metrological conditions the precision raster-forming system allows to achieve high accuracy of the calibration, when used dynamic calibration method. The article discusses about mechanical design of precision raster-forming systems. According to the scientists’ works describes the precision systems, which working in the dynamic mode. Atliekant tikslumo tyrimus padaryta didelė pažanga, tačiau precizinės rastrų formavimo sistemos dažnai yra per daug sudėtingos ir skirtingos, todėl sunku ar beveik neįmanoma perkelti ir pritaikyti joms šių tyrimų pasiekimų tiesiogiai. Tokių sistemų kūrimas ir tobulinimas turi remtis tyrimais specifinėje darbo aplinkoje. Precizinė rastrų formavimo sistema leidžia neidealiomis metrologinėmis sąlygomis dinaminiu kalibravimo būdu pasiekti didelį kalibravimo tikslumą. Straipsnyje nagrinėjamos problemos, susijusios su precizinės rastrų formavimo sistemos mechaninės struktūros projektavimu ir jo metu kylančiais sunkumais. Remiantis mokslininkų atliktais darbais aprašomos tikslios precizinės sistemos, dirbančios dinaminiu režimu.

Proposal of a New Dynamic Calibration Method for Transthoracic Admittance Cardiogram Using an Electrical Thoracic Simulator

Proposal of a New Dynamic Calibration Method for Transthoracic Admittance Cardiogram Using an Electrical Thoracic Simulator

The dynamic finite element model calibration method of concrete dams based on strong-motion records and multivariate relevant vector machines

In this work, a new finite element (FE) model calibration method of concrete dams based on strong-motion records and multivariate relevant vector machines (MRVM) is proposed. The modal features of a dam are extracted using second order blind identification (SOBI) based method at first. For some selected combinations of uncertain parameters of the FE model using the Latin hypercube design, the corresponding structural modal features are calculated using the finite element method (FEM). With these data, a procedure to calibrate the uncertain parameters of a dam’s dynamic FE model is developed. By taking the uncertain parameters as inputs and the calculated structural modal features using FEM as outputs, the MRVM model is trained to record the complex relationship between them. Then, the genetic algorithm (GA) is adopted to solve the optimization problem corresponding to the dynamic FE model calibration problem, and the trained MRVM model, instead of FEM, is used to obtain the modal parameters of a dam for different feasible solutions during the optimization search process to improve the computational efficiency. Using the simulated seismic response records of a numerical example the accuracy, robustness and computation efficiency of the proposed dynamic FE model calibration method is verified. The analysis result using the strong-motion records of a realistic concrete dam indicates that the proposed dynamic FE model calibration method has good performance.

A Study on the Improving Inspection Method for Production Quality of the HIGH-Ra LED Lighting Based on Dimming Control

Complaints of HIGH-Ra LED lighting based on dimming control are steadily occurred by the quality degradation due to the luminance deviation. Consequently, constructors and electrical contractors currently avoid the sales and distribution of this lighting.BR This problem was appeared because the characteristics of each electronic device such as wavelength band, linearity, gain characteristic, off-set and cut-off of the HIGH-Ra LED lighting that CRI value is improved by phosphor or mixed LED light sources are not considered. It can be sufficiently improved by an inspection method in a whole range of dimming level. However, the present inspection methods are only conducted by lighting test, actinography or aging test.BR Therefore, the paper proposes the dynamic calibration method, considering the functions of dynamic check equipment and interlocking․calibration based on dimming level, for the production quality of the HIGH-Ra LED lighting in order to overcome the disadvantages of the present inspection. This method offers the sequential areal inspection and narrow range auto calibration, to detect the defective parts and analyze the corresponding causes. At the same time, it can improve not only production quality and productivity, but also reduce the inspection time and production costs.