Abstract:Dynamic metrology has achieved initial effects after decades of development. However, due to the complexity of engineering dynamic measurement, existing metrology technology shows its limitations in terms of theoretical framework, characterization of metrological characteristics, and application in engineering measurement, and its future development direction is a problem worthy of study and discussion. Aiming at the high-precision dynamic measurement requirements for engineering applications, dynamic metrology technology is comprehensively reviewed from the perspective of the entire dynamic measurement technology chain, and several primary problems are discussed and analyzed combining domestic and foreign relevant researches. The problems include definition and scope, value reproduction and traceability, calibration method, and application method in measurement domestic and foreign. Suggestions are given from the aspects of thinking mode of research and analysis, requirements of technology and method innovation, and deep-level cooperation. These analyses are expected to provide some reference for the future development direction of dynamic metrology.

Abstract:The absolute gravity acceleration measurement based on the cold atom interference principle has the advantages of high sensitivity and long-term continuous measurements. It is of great significance in basic physics research, resource exploration, and inertial navigation, and is recognized as the next generation of absolute gravimeter. This article describes the principle of atomic interferometric gravimetry, summarizes the hardware system composition and performance requirements, points out the main factors limiting the capability of measurement and engineering applications, and summarizes the current situation and future trend of the engineering development of atomic gravimeter.

Abstract:Geometric digital measuring method has had a profound impact on the development of measuring equipment for manufacturing, as the measurement task are diverse and complicated, the demand for geometric digital measuring method and measuring equipment is higher and higher. This paper, taking a type of the key existing measurement system as an example, classifies the measuring systems according to the working principle of the sensor unit and respectively introduces the laser tracker, laser radar, laser tracking interferometer, mobile space coordinate measuring system, GPS and digital photogrammetry system, as well as the mathematical model of each typical measuring equipment, working principle, main parameters, the main representative products, application fields and current limitations of each measurement system. Combining with the current situation developing the automatic, digital and intelligent measuring equipment and the current requirement of complex environment for the on-site measurement task, the paper has summarized the following trends: the measurement parameters has developed from a single to the multiple, the measured object has developed from single point to the point cloud, the measurement way has progressed from static to dynamic measurement and the measurement scheme on how to solve the measurement task has advanced to be independently done by a single measurement system toward to be collaboratively completed by more measurement systems. It provides reference for the selection of geometric digital measurement methods and measuring equipment.

Abstract:The geometry measurement and control of large parts in the high-end equipment is the basis to ensure the quality of product delivery. The improvement of high-end equipment performance and productivity demands higher accuracy and efficiency for geometric dimension measurement. This paper introduces the working principles, typical instruments and application characteristics of six large-scale measurement technologies, including coordinate measurement, scanning measurement, attitude measurement, collaborative measurement, networking measurement and dynamic measurement, based on the measurement requirements of large-scale parts. The construction scheme and working characteristics of two special large-scale measurement systems, fixed measurement system and flexible measurement system, are analyzed. Furthermore, this paper summarizes the means and methods of laboratory calibration, on-site calibration and on-site verification of large-scale measurement system, and expounds the comprehensive development trend of large-scale, high precision, high efficiency, automation and intelligence of geometric dimension measurement of large-scale parts.

Abstract:The geometric parameters of aero-engine blades are defined and classified. Based on the importance of precise measurement of blade geometric parameters, the complexity of profile parameters measurement and the status quo of full parameter measurement and evaluation of blade geometric characteristics, the requirements of the construction of measurement and measurement guarantee system for aero-engine blade geometric parameters are introduced in detail. A test measurement guarantee system covering the parameters of aero-engine blade geometrical characteristics is proposed, and the connotation and architecture of the system are expounded, which can provide technical support for the construction of the integrated collaborative work platform for the digital design and manufacturing of aero-engine blade parts.

Abstract:The generation of residual stress and the influence on the performance of materials are summarized. The current measurement methods of residual stress are introduced. Their theory, application and features are analyzed, especially the methods of X-ray diffraction, neutron diffraction, nanoindentation and hole-drilling. The techniques of calibration for residual stress based on sample and instrument function are given. The importance of calibration for the residual stress measurement are emphasized. The future development of measurement and calibration methods on residual stress are prospected.

Abstract:Facing the challenge of extreme measurement conditions such as short time and high speed, the photonic Doppler velocimetry (PDV) system develops rapidly in four aspects: larger dynamic range, higher sensitivity, higher temporal resolution and multi-channel measurement ability. Firstly, the principle and background of photonic Doppler velocimetry is introduced in detail. Secondly, the classical improvement methods and development status of transient high-speed PDV system with measuring speed above 100m/s and recording time of nanoseconds are classified and summarized. Then, the application of time stretches and time lens in the PDV system is emphatically introduced, and the characteristics and potential of time amplification are discussed. Finally, the problems of the transient high speed PDV system are summarized and its future development is prospected.

Abstract:Angular motion measurement is widely used in rotating machinery, aircraft, ship, vehicle, robot and so on. This paper introduces the basic principle and application field of angular motion measuring instruments, expounds the present situation and development of angular motion parameter measurement technology, and emphatically introduces the dynamic calibration method of angular motion parameters.

Abstract:Autonomous navigation is the core index to evaluate the intelligent degree of wheeled mobile robot, but the metrological evaluation of autonomous navigation performance is still in its infancy, and the metrological evaluation index system and evaluation method are seriously missing. Therefore, this paper investigates the existing wheeled mobile robot autonomous navigation architecture and path planning algorithm, analyzes the performance index of wheeled mobile robot autonomous navigation, and summarizes the research status of autonomous navigation metrological evaluation. On this basis, the key technical difficulties of metrological evaluation technology for wheeled mobile robot are summarized, further promote the development of metrological evaluation technology for wheeled mobile robots.

Abstract:In order to reduce the influence of inaccurate area function to the measurement results of mechanical properties of thin-film and other micro-sized materials, a method to improve the accuracy of the indenter area function at small indentation depth is proposed. This method links the projected contact area between the indenter and the sample with the tip radius and angle of the indenter, which can improve the reliability of the commonly used area function determination method in the measurement of shallow indentation below 50 nm. The experimental results show that the measurement accuracy of indentation hardness and reduced modulus at a small contact depth can be improved by using this area function determination method.

Abstract:In the wind tunnel calibration test of air temperature sensor, due to the high-test cost and the gap between the calibration test environment and the actual use environment, it is necessary to build the virtual wind tunnel for the numerical calibration of the air temperature sensor, and realize the error correction and virtual calibration of the air temperature sensor under the extremely abnormal calibration condition. The virtual calibration of the numerical wind tunnel of the air temperature sensor is obtained. The simulation results can lower the working conditions of the real calibration as much as possible, and provide a supplement for the design and calibration of the air temperature sensor from the theoretical level. The development of air temperature calibration at home and abroad is introduced. The realization idea and method of virtual wind tunnel for the numerical calibration of air temperature sensor are analyzed. How to establish virtual simulation wind tunnel on computer platform by Computational Fluid Dynamics (CFD) technology is discussed to simulate the real calibration environment, which provides technical reference for the establishment of the virtual wind tunnel for the numerical calibration of domestic air temperature sensor.

Abstract:Based on the concept and technology of precision measurement and intelligent measurement, combined with high-precision force loading technology, indentation measurement technology, automatic control technology and robot technology, an unattended intelligent Rockwell hardness testing platform was designed and developed. The platform includes PLC control system, automatic sample injection system, automatic measurement system and automatic marking system, etc. The test results show that the platform has good measurement accuracy and significant advantages in improving measurement efficiency. The completion of the device promotes the intelligent process of hardness measurement, and provides a good reference for the development of unattended precision measurement and calibration of other specialties.

Abstract:Tacho-Torque measuring instruments are often used in the measurement of mechanical power of engines and other equipment. The measured technical parameters include torque, speed and power. Currently, the calibration of torque and speed measuring instruments mostly use the method of calibrating static torque and speed seprartely, which deviates greatly from the state of use. This paper introduces a torque / power standard device for multi-parameter synchronous calibration of a tacho-torque and power measuring devices. The overall mechanical structure, the design principle of standard torque generation system, the establishment of torque measurement model and the influence factors of measurement uncertainty are introduced. Through influencing factor analysis and experimental verification, it is concluded that the measurement uncertainty of the device’s recurrence value is less than 0. 2% . The device is used to calibrate various types of tacho-torque measuring instruments, and the results show that the device can achieve the function of applying the standard torque in the rotating state, and achieve the expected technical indicators, It can provide a technical means for the multi parameter synchronous traceability of this type of measuring instruments in the way close to the working state.

Abstract:Torque standard machine is a standard instrument for the transmission of torque value, which is mainly used to calibrate high precision torque sensors. The uncertainty of the repeatability value is an important guarantee for the application effect. At present, most of the lever parts of the torque standard machines in China and abroad adopt the knife-edge and knife-bearing support method or the integral air-bearing support based on small hole throttling principle. By analyzing the limitations of the two support structures, a new type of lever support is designed and optimized. The system adopts a combined static pressure air-bearing to support the lever, which effectively controls the friction torque while reducing the difficulty of realization and the failure rate, thereby realizing the improvement of the performance of the whole machine. At the same time, the combined structure can also improve the moment arm-lever into a single-beam double-arm symmetrical frame structure, so that the measurement accuracy of the moment arm-lever can be effectively guaranteed on the basis of reducing the difficulty of lever processing and assembly. Based on the Fluent software, this paper conducts fluid simulation of porous static pressure air bearings, studies the influence of air supply pressure, porous material permeability, and thickness of the bearing body on their static performance, and provides theoretical basis and data support for the selection of bearings.

Abstract:Based on the study of the calibration method of distortion signal in the characteristic parameters of 270VDC aircraft power supply, combined with the actual needs in the calibration process, a standard signal source of 270V aircraft DC distortion based on direct digital waveform synthesis (DDWS) technology is designed, and the hardware design is introduced in detail.

Abstract:The difficult point of dynamic calibration technology is the dynamic calibration method for non-electricity transducers. It is reasonable with some premise that the results from the static calibration are used to the dynamic one. The dynamic calibration of thermo-transducer is facing more problems than the dynamic calibration of pressure transducers. The realization and understand of the metrology concept are promoted and developed by the research on dynamic calibration technology. The system analysis of the characteristics of the calibrated object is more important than the measurement based on trace-to-source and will become the first concerned items of metrology.

Abstract:Several commonly navigation and positioning methods are briefly introduced, some navigation and positioning systems are described, and the characteristics of different navigation and positioning systems are summarized. A low-cost, high-precision, fast, global navigation and positioning framework based on base stations of mobile communication network is proposed, and its characteristics, advantages and technical feasibility are discussed. The navigation manifestation framework is expected to have good application prospects in the future intelligent transportation, intelligent robots, intelligent logistics, intelligent nation defense, port automation, military operations and other fields.

Abstract:There is no research on the traceability of airborne high sound pressure calibration currently. Based on laser piston-phone method, traceability of airborne high sound pressure up to 180dB is realized by the measurement of piston velocity in a piston cavity using laser interferometer. Experiment results show the good coherence to theoretic formulas. It can support the traceability of airborne high sound pressure calibration and provides accurate value to high sound pressure metrology.

Abstract:The continuous iteration of the manufacturing and measurement process is the key to improving product performance. The current shortage of high-end measuring instruments has restricted the development of high-end manufacturing technology in China. Geometric measurement instrument is the basis of manufacturing traceability. Taking the step gauge calibration device developed as an example, this paper introduces the specific applications of Abbe principle, minimum deformation principle and shortest measuring chain principle for high-end length measuring instruments design, so as to provide technical reference for the development of high-end length measuring instruments and promote the improvement of China's independent development ability of high-end instruments.

Abstract:In order to obtain more realistic frequency response characteristics of the sensors, in this paper, the laser interferometer is used to dynamically calibrate the sensors. Based on the input and output data of the sensors, the structure and order of the system model are determined. Based on the output error model, the system identification experiment method is adopted to identify the parameters of the sensor model, so as to establish the mathematical equivalent model of the calibrated impact acceleration sensors. Then the model equation is converted into the transfer function, and the amplitude-frequency and phase-frequency characteristic curves of the sensors are plotted. Finally, the impact frequency domain calibration of the calibrated sensor is realized.

Abstract:Based on the theoretical model analysis of differential pressure flowmeter under pulsating flow condition, the algorithm of eliminating the influence of flow derivative term based on the double-channel differential pressure is given. The flow field in Venturi tube is simulated by FLUENT software, and then the calculation method of pulsating flow is verified. The simulation results show that the maximum error can be up to 100% when calculating the fluctuating flow using single-channel pressure, and the maximum error can be reduced to about 5% when calculating the fluctuating flow using double-channel differential pressure. The results show that the calculation method of double-channel differential pressure method can effectively improve the accuracy of pulsating flow measurement, and has the value of further popularization and application.

Abstract:In the field of dynamic pressure measurement, the pressure measurement system with transmission pipe is often used for the pressure measurement in narrow space and bad working conditions. The pressure signal through transmission pipe was often distorted, which becomes an important factor to decrease the frequency response of pressure measurement system. In this paper, the physical structure model of pressure measurement system with transmission pipe is introduced, and the dynamic measurement mechanism affected by the dynamic characteristics of transmission pipe is explained at first. Secondly, the calibration devices of transmission pipe and methods are introduced, a new calibration device and method is studied, and a static pressure and temperature adjustable calibration device is developed. Finally, the calibration device is used to test the pressure measurement system with transmission pipe, which can be used as a reference to the development of dynamic measurement and compensation technology of pressure measurement system with transmission pipe.

Abstract:Device and method of recovery characteristic calibration of temperature sensors under transonic and supersonic conditions are introduced in this paper. By method such as inverse series connection and local mutual correction at low flow speed, several typical temperature sensors are calibrated under conditions of Mach 0.95 to Mach 2.0, and the calibration results are compared with NASA's. Comparison results show that relative deviation between them ranges from 0.1%~2.8%. Some laws on recovery characteristic of temperature sensors under transonic and supersonic conditions are revealed through calibration, which can provide basis for precise measurement of high-speed gas temperature.

Abstract:p.V.T.t gas flow; positive pressure; normal pressure; uncertainty

Abstract:Surge measurement system is used to accurately identify the surge when the aero-engine is about to surge or at the early stage of surge. It is an important means to avoid the serious accidents, such as the air shutdown and blade fracture caused by aerodynamic instability of aero-engine. In this paper, based on an existing dynamic pressure calibration device, the high temperature characteristic of the surge differential pressure sensors and the dynamic characteristic of the surge measurement system are tested, which will greatly decrease the chance of misjudgment and missed judgment of the aero-engine surge measurement system. The dynamic calibration of surge measurement system is of great significance to the study of aero-engine instability and the improvement of engine reliability.

Abstract:This article introduces a high precision and low impact acceleration standard device based on ISO international standard. The high precision calibration of the acceleration sensor with half sinusoidal waveform is realized in the range of the peak acceleration (20~10000) m/s2 and pulse width (0.5~10) ms. This paper introduces the structure and working principle of standard device. It can realize the uncertainty of 0.5% (k=2) impact acceleration measurement through comparison with the national benchmarks for impact acceleration in the National Institute of Metrology (NIM). The device improves the accuracy of the standard device of impact acceleration. It meets the need of high precision calibration of impact accelerometers in aerospace, transportation and automobile industry.

Abstract:This paper introduces in detail the development of a micro pressure standard device for liquid pressure gauge calibration. Using ultrasonic liquid level positioning technology to realize accurate liquid level positioning, the height of liquid column is accurately measured by laser interference technology. At the same time, the temperature control, displacement control, data acquisition and processing subsystem design are introduced. Finally, the measurement uncertainty of the micro pressure standard device is analyzed and verified. The standard device fills the nonexistence of the standard below 5kPa micro pressure value and solves the traceability problem of high accuracy micro pressure instruments in national defense system.

Abstract:This paper summarizes the development trend of civil aircraft power supply system, aiming at the variable frequency AC power supply system, the significance of the research on calibration technology of the test system for civil aircraft variable frequency AC power supply characteristic is expounded. According to the technical requirements of the test system for the characteristics of variable frequency AC power supply, the calibration method is studied and the calibration specification is written; Based on the technologies of Direct Digital Frequency Synthesis (DDFS), Direct Digital Waveform Synthesis (DDWS), broadband signal amplification and filtering, the calibrating signal source for the characteristics of variable frequency AC power supply is developed; According to the workflow and signal setting in the calibration method, the calibration program is made and the automatic calibration system is formed. Finally, the above calibration system is applied to the power supply test systems of several main engine plants and institutes, and the field test verification is completed. Through the above research process, a complete calibration capability of civil aircraft power supply characteristics test system is established, which lays a solid foundation for the future research of civil aircraft power supply characteristics and power supply adaptability of electrical equipment.

Abstract:As a measurement tool of wind speed environmental noise, surface microphone is widely used in aerospace and vehicle fields. It is a flat structure and has no cavity in the front end, so it can only be calibrated by conventional means. In this paper, a kind of surface microphone calibration technology is studied. The methods of a flat asymmetric short coupling cavity and a large diameter flat surface microphone mounting gland are adopted. Through simulation analysis and test verification, the surface microphone can be calibrated effectively.

Abstract:In the in-situ calibration of rotor balance, the calibration uncertainty is the most important technical factor. First, the environment according to the actual working condition and in-situ calibration method is studied. Then, the in-situ calibration device was developed, mainly introducing the mechanical structure design and ascertaining the sources of uncertainty. Finally, for the first time in-situ calibration test of the rotor balance was completed and for in-situ calibration uncertainty was evaluated in accordance with the standard method. The results showed that the standard calibration device has achieved that the relative force-component calibrating uncertainty is better than 0.1%, the relative torque component calibrating uncertainty is better than 0.3%.