Static Calibration Method Research Articles

Numerical Investigation on the Influence of Turbine Rotor Parameters on the Eddy Current Sensor for the Dynamic Blade Tip Clearance Measurement.

Eddy current sensors are increasingly being used to measure the dynamic blade tip clearance in turbines due to their robust anti-interference capabilities and non-contact measurement advantages. However, the current research primarily focuses on enhancing the performance of eddy current sensors themselves, with few studies investigating the influence of turbine rotor parameters on the measurements taken by these sensors for dynamic blade tip clearance. Hence, this paper addresses this gap by using COMSOL Multiphysics 6.2 software to establish a finite model with circuit interfaces. Additionally, the model's validity was verified through experiments. This model is used to simulate the voltage output of the sensor and the measurement of dynamic blade tip clearance under various rotor parameters. The results indicate that the length and number of blades, as well as the hub radius, significantly affect the sensor voltage output in comparison to rotation speed. Furthermore, we show that traditional static calibration methods are inadequate for measuring dynamic blade tip clearance using eddy current sensors. Instead, it is demonstrated that incorporating rotor parameters into the calibration of eddy current sensors can enhance the accuracy of dynamic blade tip clearance measurements.

Mechanism of Seebeck coefficient variation at the output of NiCr/NiSi thin film thermocouple with different wires

In this paper, by using magnetron sputtering to prepare NiCr/NiSi thin film thermocouples, the static calibration method is used for NiCr/NiSi thermocouples with rapid temperature calibration experiments. Different temperature calibration curves are obtained. The Seebeck coefficient of NiCr/NiSi thin film thermocouples connected to NiCr/NiSi wires is significantly higher (41.39 μV/°C) than that of NiCr/NiSi wires (0 μV/°C). The Seebeck coefficient (41.39 μV/°C) of the NiCr/NiSi thin-film thermocouple connected to copper wire is significantly higher than that of the thermocouple connected to copper wire (0 μV/°C). The problem of the Seebeck coefficient of the K-type thermocouple is analyzed by experimental data, which provides the relevant parameter basis for the use of the K-type thermocouple. The method has the advantages of simple equipment, convenient operation, accurate and reliable data, and provides a basis for the sensor to measure the temperature measurement.

Performance Testing of Micro-Electromechanical Acceleration Sensors for Pavement Vibration Monitoring.

Pavement vibration monitoring under vehicle loads can be used to acquire traffic information and assess the health of pavement structures, which contributes to smart road construction. However, the effectiveness of monitoring is closely related to sensor performance. In order to select the suitable acceleration sensor for pavement vibration monitoring, a printed circuit board (PCB) with three MEMS (micro-electromechanical) accelerometer chips (VS1002, MS9001, and ADXL355) is developed in this paper, and the circuit design and software development of the PCB are completed. The experimental design and comparative testing of the sensing performance of the three MEMS accelerometer chips, in terms of sensitivity, linearity, noise, resolution, frequency response, and temperature drift, were conducted. The results show that the dynamic and static calibration methods of the sensitivity test had similar results. The influence of gravitational acceleration should be considered when selecting the range of the accelerometer to avoid the phenomenon of over-range. The VS1002 has the highest sensitivity and resolution under 3.3 V standard voltage supply, as well as the best overall performance. The ADXL355 is virtually temperature-independent in the temperature range from -20 °C to 60 °C, while the voltage reference values output by the VS1002 and MS9001 vary linearly with temperature. This research contributes to the development of acceleration sensors with high precision and long life for pavement vibration monitoring.

A Generative Approach to Condition-Aware Score Calibration for Speaker Verification

In speaker verification, score calibration is employed to transform verification scores to log-likelihood ratios (LLRs) which are statistically interpretable. Conventional calibration techniques apply a global score transform. However, in condition-aware (CA) calibration, information conveying signal conditions is provided as input, allowing calibration to be adaptive. This paper explores a generative approach to condition-aware score calibration. It proposes a novel generative model for speaker verification trials, each which includes a trial score, a trial label, and the associated pair of speaker embeddings. Trials are assumed to be drawn from a discrete set of underlying signal conditions which are modeled as latent Categorical random variables, so that trial scores and speaker embeddings are drawn from condition-dependent distributions. An Expectation-Maximization (EM) Algorithm for parameter estimation of the proposed model is presented, which does not require condition labels and instead discovers relevant conditions in an unsupervised manner. The generative condition-aware (GCA) calibration transform is then derived as the log-likelihood ratio of a verification score given the observed pair of embeddings. Experimental results show the proposed approach to provide performance improvements on a variety of speaker verification tasks, outperforming static and condition-aware baseline calibration methods. GCA calibration is observed to improve the discriminative ability of the speaker verification system, as well as provide good calibration performance across a range of operating points. The benefits of the proposed method are observed for task-dependent models where signal conditions are known, for universal models which are robust across a range of conditions, and when facing unseen signal conditions.

Static Calibration Method for Line-Scan Cameras in 2D Space

Static Calibration Method for Line-Scan Cameras in 2D Space

A static and fast calibration method for line scan camera based on cross-ratio invariance

This paper presents a new calibration method of line scan camera model based on cross-ratio invariance using a calibration pattern on the top of the gauge block. Instead of using the 3D pattern, planner pattern with precise motion platform, or pre-calibrated matrix camera, only a planner pattern with gauge blocks is used in this new method. A group of data on the line scan camera projection plane is obtained by placing the planner pattern at a different height. Line scan camera parameters were calibrated through a derived mathematical model. This method is simple, inexpensive and easy to use. The experimental results demonstrated that the average reprojection error of this method is 0.0431, which is 62.2% lower than the traditional method, which proves the feasibility and effectiveness of this method.

Inertial-Based Human Motion Capture: A Technical Summary of Current Processing Methodologies for Spatiotemporal and Kinematic Measures.

Inertial-based motion capture (IMC) has been suggested to overcome many of the limitations of traditional motion capture systems. The validity of IMC is, however, suggested to be dependent on the methodologies used to process the raw data collected by the inertial device. The aim of this technical summary is to provide researchers and developers with a starting point from which to further develop the current IMC data processing methodologies used to estimate human spatiotemporal and kinematic measures. The main workflow pertaining to the estimation of spatiotemporal and kinematic measures was presented, and a general overview of previous methodologies used for each stage of data processing was provided. For the estimation of spatiotemporal measures, which includes stride length, stride rate, and stance/swing duration, measurement thresholding and zero-velocity update approaches were discussed as the most common methodologies used to estimate such measures. The methodologies used for the estimation of joint kinematics were found to be broad, with the combination of Kalman filtering or complimentary filtering and various sensor to segment alignment techniques including anatomical alignment, static calibration, and functional calibration methods identified as being most common. The effect of soft tissue artefacts, device placement, biomechanical modelling methods, and ferromagnetic interference within the environment, on the accuracy and validity of IMC, was also discussed. Where a range of methods have previously been used to estimate human spatiotemporal and kinematic measures, further development is required to reduce estimation errors, improve the validity of spatiotemporal and kinematic estimations, and standardize data processing practices. It is anticipated that this technical summary will reduce the time researchers and developers require to establish the fundamental methodological components of IMC prior to commencing further development of IMC methodologies, thus increasing the rate of development and utilisation of IMC.

Gait Phase Detection Based on Muscle Deformation with Static Standing-Based Calibration.

Gait phase detection, which detects foot-contact and foot-off states during walking, is important for various applications, such as synchronous robotic assistance and health monitoring. Gait phase detection systems have been proposed with various wearable devices, sensing inertial, electromyography, or force myography information. In this paper, we present a novel gait phase detection system with static standing-based calibration using muscle deformation information. The gait phase detection algorithm can be calibrated within a short time using muscle deformation data by standing in several postures; it is not necessary to collect data while walking for calibration. A logistic regression algorithm is used as the machine learning algorithm, and the probability output is adjusted based on the angular velocity of the sensor. An experiment is performed with 10 subjects, and the detection accuracy of foot-contact and foot-off states is evaluated using video data for each subject. The median accuracy is approximately 90% during walking based on calibration for 60 s, which shows the feasibility of the static standing-based calibration method using muscle deformation information for foot-contact and foot-off state detection.

Joint estimation of SOC and SOH for lithium-ion batteries based on EKF multiple time scales

PurposeThe operation state of lithium-ion battery for vehicle is unknown and the remaining life is uncertain. In order to improve the performance of battery state prediction, in this paper, a joint estimation method of state of charge (SOC) and state of health (SOH) for lithium-ion batteries based on multi-scale theory is designed.Design/methodology/approachIn this paper, a joint estimation method of SOC and SOH for lithium-ion batteries based on multi-scale theory is designed. The venin equivalent circuit model and fast static calibration method are used to fit the relationship between open-circuit voltage and SOC, and the resistance and capacitance parameters in the model are identified based on exponential fitting method. A battery capacity model for SOH estimation is established. A multi-time scale EKF filtering algorithm is used to estimate the SOC and SOH of lithium-ion batteries.FindingsThe SOC and SOH changes in dynamic operation of lithium-ion batteries are accurately predicted so that batteries can be recycled more effectively in the whole vehicle process.Originality/valueA joint estimation method of SOC and SOH for lithium-ion batteries based on multi-scale theory is accurately predicted and can be recycled more effectively in the whole vehicle process.

RESEARCH ON INTEGRATED STATIC AND DYNAMIC GEOMETRIC CALIBRATION TECHNOLOGY FOR OPTICAL SURVEYING AND MAPPING SATELLITES

Abstract. As the satellite latitude and camera temperature changes, temperature distortion in orbit makes the optical axis of the star sensor drifts slowly in the satellite body coordinate system, and the attitude measurement system contains low frequency errors that cannot be ignored. Low frequency errors are systematic in short periods, and occasional in long periods, which cause an error of a few minutes, so as to greatly reduce the positioning accuracy without control points of satellite photography. Traditional geometric calibration can only eliminate system errors caused by changes in optics in sensor platform and mechanical structures and etc., and cannot reduce the effect of low-frequency errors. An integrated static and dynamic geometric calibration method based on optical surveying and mapping satellites is proposed in this paper. The attitude system error and low frequency error are effectively detected by establishing a correction model of low frequency errors and analyzing the effective calibration process of traditional on-orbit calibration and dynamic calibration. Finally, relevant experiments are performed with image from satellite TIANHUI-1 in seven test fields, which verifies that this low-frequency error compensation method is correct and effective.

Dynamic calibration method for a trace moisture analyzer based on the quick response of a ball surface acoustic wave sensor

The measurement of trace moisture is important in industry to maintain the quality and yield of products, such as semiconductors, lithium-ion batteries, and organic electroluminescence devices. In the field, on-site calibration of a trace moisture analyzer is required to maintain its reliability. Given these circumstances, we previously developed a ball surface acoustic wave (SAW) sensor using SAW on spherical piezoelectric elements and reported its quick response as its advantage over other trace moisture analyzers. However, the ultimately short response time of less than 1 s has not been verified, and it has not yet been calibrated on-site. In this study, we developed a system for the injection of saturated water vapor to evaluate the quick response of a trace moisture analyzer, and we verified the quick response time of as short as 0.64 s. It is the shortest response time reported so far. In addition, to realize its on-site calibration, we developed a dynamic calibration method, which takes only 10 min, by the injection of saturated water vapor, in contrast to the presently available static calibration method that takes 10 h. Since this system consists of simple components, it can be downsized. Moreover, because it uses a small amount of saturated water vapor as the calibration gas, it is easy to prepare calibration gases in the field and may be applied to on-site calibration.

Adaptive calibration of Diesel engine injection for minimising fuel consumption with constrained NOx emissions in actual driving missions

This article proposes a method for fuel minimisation of a Diesel engine with constrained [Formula: see text] emission in actual driving mission. Specifically, the methodology involves three developments: The first is a driving cycle prediction tool which is based on the space-variant transition probability matrix obtained from an actual vehicle speed dataset. Then, a vehicle and an engine model is developed to predict the engine performance depending on the calibration for the estimated driving cycle. Finally, a controller is proposed which adapts the start-of-injection calibration map to fulfil the [Formula: see text] emission constraint while minimising the fuel consumption. The calibration is adapted during a predefined time window based on the predicted engine performance on the estimated cycle and the difference between the actual and the constraint on engine [Formula: see text] emissions. The method assessment was done experimentally in the engine test set-up. The engine performace using the method is compared with the state-of-the-art static calibration method for different [Formula: see text] emission limits on real driving cycles. The online implementation of the method shows that the fuel consumption can be reduced by 3%–4% while staying within the emission limits, indicating that the estimation method is able to capture the main driving cycle characterstics.

A Simple Calibration Method for Ratio Error and Phase Error of Electronic Energy Meter

The ratio errors of resistance divider network and current transformer, and the phase error introduced by current transformer, which are the main error sources, greatly affect the measurement accuracy of actual electronic energy metering equipment. Because the fairness of energy metering system has a significant influence on the energy market, a digital calibration method for ratio error and phase error of electronic energy meter is proposed to deal with this problem in this paper. By establishing the equivalent models of the analog front-end circuit of static meter, a simple and high accuracy digital calibration method for reducing ratio error and phase error of static meter is given. Firstly, the DC bias of each channel is subtracted from its corresponding channel. After that, correction coefficients are used to correct the ratio errors of voltage and current channels. Finally, a piecewise Lagrange quadratic interpolation method is used to realize phase error calibration. The proposed approach has the features of simplicity and high efficiency. The experimental results validate the accuracy and effectiveness of the proposed algorithm.

Real-time calibration algorithm of magnetometer for spinning projectiles

Purpose In spite of the vehicle, magnetic field interference can be reduced by some measures and techniques in ammunition design and manufacturing stage, the corruption of the vehicle magnetic field can still reach hundreds to thousands of nanoteslas. Besides, the magnetic field that the ferromagnetic materials generate in response to the strong magnetic field in the vicinity of the body. So, a real-time and accurate vehicle magnetic field calibration method is needed to improve the real-time measurement accuracy of the geomagnetic field for spinning projectiles. Design/methodology/approach Unlike the past two-step calibration method, the algorithm uses a linear model to calibrate the magnetic measurement error in real-time. In the method, the elliptical model of magnetometer measurement is established to convert the coefficients of hard and soft iron errors into the parameters of the elliptic equation. Then, the parameters are estimated by recursive least square estimator in real-time. Finally, the initial conditions for the estimator are established using prior knowledge method or static calibration method. Findings Studies show the proposed algorithm has remarkable estimation accuracy and robustness and it realizes calibration the magnetic measurement error in real-time. A turntable experiments indicate that the post-calibration residuals approximate the measurement noise of the magnetometer and the roll accuracy is better than 1°. The algorithm is restricted to biaxial magnetometers’ calibration in real-time as expressed in this paper. It, however, should be possible to broaden this method’s applicability to triaxial magnetometers' calibration in real-time. Originality/value Unlike the past two-step calibration method, the algorithm uses a linear model to calibrate the magnetic measurement error in real-time and the calculation is small. Besides, it does not take up storage space. The proposed algorithm has remarkable estimation accuracy and robustness and it realizes calibration the magnetic measurement error in real time. The algorithm is restricted to biaxial magnetometers’ calibration in real-time as expressed in this paper. It, however, should be possible to broaden this method’s applicability to triaxial magnetometers’ calibration in real-time.

“Dynamic knee valgus” – Are we measuring what we think we’re measuring? An evaluation of static and functional knee calibration methods for application in gait and clinical screening tests of the overhead squat and hurdle step

Background"Dynamic knee valgus” has been identified as a risk factor for significant knee injuries, however, the limits and sources of error associated with existing 3D motion analysis methods have not been well established. Research questionWhat effect does the use of differing static and functional knee axis orientation methods have on the observed knee angle outputs for the activities of gait, overhead squatting and a hurdle step? MethodsA pre-existing dataset collected from one season (September 2015–May 2016) as part of a prospective observational longitudinal study was used. A secondary analysis of data for 24 male footballers, from a single British University football team, was conducted in order to evaluate the effect of static (conventional gait model) and dynamic (constrained and unconstrained mDynaKAD) methods on knee joint kinematics for flexion-extension and valgus-varus angles. ResultsNo single calibration method consistently achieved both the highest flexion and lowest valgus angle for all tests. The constrained and unconstrained mDynaKAD methods achieved superior alignment of the knee medio-lateral axis compared to the conventional gait model, when the movement activity served as its own calibration. The largest mean difference between methods for sagittal and coronal plane kinematics was less than 4° and 14° respectively. Cross-talk could not account for all variation within the results, highlighting that soft tissue artefact, associated with larger muscle volumes and movements, can influence kinematics results. SignificanceWhen considering the trade-off between achieving maximum flexion and minimal valgus angle, the results indicate that the mDynaKAD methods performed best when the selected movement activity served as its own calibration method for all activities. Clinical decision making processes obtained through use of these methods should be considered in light of the model errors associated with cross-talk and effect of soft tissue artefact.

Transport tracking through communication in WDSN for smart cities

In this paper, an efficient method for transport tracking through a Wireless Dynamic Sensor Network (WDSN) is developed based on the measurement of the Received Signal Strength Indicator (RSSI) in a real urban environment. WDSN deployment is supported by at least two nodes: node-mode-fixed and node-mode-mobile as the unknown node. The estimation of the arrival of university transport bus is by measuring the RSSI to determinate the distance between nodes on a star topology using IEEE 802.15.4. The proposed method consists of de-encapsulating the received frame at the fixed node to obtain the RSSI and the travel time information sent by the mobile node through WDSN. The algorithm to detect the location of the node is based on the static calibration method of the normal logarithmic shadowing (LNSM) parameters. The measurement results show that the proposed method is useful to determinate the location between nodes in smart cities.

Dynamic sine calibration of pressure transducers

Pressure transducers are frequently used in dynamic environments such as combustion engines, aerospace applications or industrial process control. Like for every measurement task it is essential to know the uncertainty of the obtained measurement result, even in a dynamic environment. But most pressure sensors are only calibrated by static calibration methods. So the frequency response of the transducer and the uncertainty for the dynamic measurement result cannot be quantified. Furthermore it is remarkable that there is no standardized method to quantify the frequency response of a pressure transducer. Hence no national standard or traceability for periodic, dynamic pressure calibration exists. Due to this lack of investigation methods the author has made an effort to develop a primary method to calibrate pressure transducers dynamically. This method allows to measure the frequency response with sufficient dynamic pressure amplitudes up to 1.2 MPa. Due to the construction of the pressure generator frequencies up to 10 kHz can be reached. In the paper the pistonphone based apparatus is presented.

The Comparison Of In-Flight Pitot Static Calibration Method By Using Radio Altimeter As Reference with GPS and Tower Fly By Methods On CN235-100 MPA

The new proposed In-Flight Pitot Static Calibration Method has been carried out during Development and Qualification of CN235-100 MPA (Military Patrol Aircraft). This method is expected to reduce flight hours, less human resources required, no additional special equipment, simple analysis calculation and finally by using this method it is expected to automatically minimized operational cost. At The Indonesian Aerospace (IAe) Flight Test Center Division, the development and updating of new flight test technique and data analysis method as specially for flight physics test subject are still continued to be developed as long as it safety for flight and give additional value for the industrial side. More than 30 years, Flight Test Data Engineers at The Flight Test center Division work together with the Air Crew (Test Pilots, Co-Pilots, and Flight Test Engineers) to execute the flight test activity with standard procedure for both the existance or development test techniques and test data analysis. In this paper the approximation of mathematical model, data reduction and flight test technique of The In-Flight Pitot Static Calibration by using Radio Altimeter as reference will be described and the test results had been compared with another methods ie. By using Global Position System (GPS) and the traditional method (Tower Fly By Method) which were used previously during this Flight Test Program (Ref. [10]). The flight test data case are using CN235-100 MPA flight test data during development and Qualification Flight Test Program at Cazaux Airport, France, in June-November 2009 (Ref. [2]).

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.

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.