Papers by Keyword: Velocity Measurement

Abstract: The article presents the process of determining the speed of an unmanned rescue vehicle.The conducted investigations involved a measurement system developed for testing dynamic lorries. The application of a test system for low-speed all-terrain vehicles was possible due to a wide measurement range of sensors. Speed was tested employing two following methods:an indirect method consisting of the measurement of the instantaneous rotational speed of the wheel;a direct method consisting of the measurement of speed against the ground, taken with an optical speed sensor.The authors also describe the sources of interferences characteristic of both methods that include:the wheelspin affecting the correctness of speed determination in the indirect measurement;the unevenness of the surface (ground) hindering the correct operation of the optical speed sensor.The paper also presents the characteristics of the rotational speed of the wheels obtained in road and off-road conditions. Based on the obtained signals, linear speed was determined. Additionally, the article discusses methods for eliminating measurement disturbances.

Abstract: Electrostatic sensor is based on the principle of electrostatic induction. It is widely used for gas/solid two-phase flow measurement because it has the advantages of simple structure, high sensitivity, low cost, etc. In this paper, a velocity measurement system of gas/solid flow based on electrostatic sensor and cross-correlation algorithm is discussed. Electrostatic sensor with circular electrode is adopted. By COMSOL optimum simulation, the axial length of the electrode is designed. The signal conditioning circuits are discussed and cross-correlation algorithm is analyzed. The initial experimental results demonstrate that the velocity measurement system of gas/solid flow designed in this paper is feasible.

Abstract: High voltage switch mechanical parameters include time parameters, travel parameters and velocity parameters. In this paper, a standard device is developed which use liner motor to simulate switch motion that realize time parameters, travel parameters and velocity parameters calibration. This article describes the working principle of the standard device and core technology. The calibration data verify the device performance parameters meet the design requirements.

Abstract: A micro ball supersonic impact test system was developed for the study of dynamic fracture of ceramic materials. This system consists of (1) low pressure gas gun, (2) sabot assembly and stopper block for velocity multiplication system, (3) velocity measurement device for sabot and ball, and (4) enclosed target box for final impact test. The principle of velocity multiplication system is similar to two stage gun. The plastic sabot assembly houses steel plunger and the void filled with silicone rubber. The sabot is stopped by the stopper block then the steel plunger inside the sabot compress the silicon rubber to high pressure to rupture the plastic membrane. Then the compressive energy of the silicon rubber is transferred to the ball. More than ten times of initial speed was attained. Non-contact velocity measurement system uses two set of ribbon laser with optical array sensor to measure the supersonic speed of the micro ball. Maximum speed up to 1200m/s for plastic and 600m/s for steel ball was attained. Perforation test of plastic film laminated glass window was successfully done by the developed impact system.

Abstract: According to the process of PD radar target tracking, the radial motion of target has a significant impact on velocity measurement. Simulation shows that there is an apparent relation between radial velocity and non-coherent accumulated waveform. Based on the calculation of the entropy of non-coherent accumulated waveform, a method based on waveform entropy in velocity measurement is proposed. Experiments show that the new method can achieve high measurement accuracy, and is insensitive to velocity. At the same time, a rough estimation of velocity is used to shorten the running time.

Abstract: Optical velocimeter has been an important experimental installation in many labs. In this letter, an improved fiber-optic velocimeter that can be used to measure dynamic velocity of a moving object is described. The key parameters of the system are analysed.

Abstract: A PXI-based microwave interferometer system is constructed to measure the velocity of interior ballistic ammunition. The hardware and software structure of the system is introduced. Wavelet denoising and polynomial chirplet transform is used to process motion signals. Finally, experiments are conducted aiming at the launching process of a certain object, and results show that the proposed system is of high efficiency to calculate the velocity-time, displacement-time and acceleration-time curve of the ammunition. As an experimental case study, the proposed system has been applied to interior ballistic measurement.

Abstract: Cross correlation techniques have been proved to be a valuable tool for online continuous velocity measurement of particulate solids in pneumatic pipelines. In order to reduce computational complexity the sampling frequency is usually kept as low as possible, and the peak in the correlation function is found by interpolating the correlation function. Parabola functions are commonly used as parametric models of the cross correlation function in time delay estimation. However, the parabolic-fit interpolation method introduces a bias at low sampling rate to the center frequency ratio of input signal. In this paper, a combined interpolation method is proposed to improve the estimation accuracy. Experiments are carried out to evaluate the performance of the proposed interpolation method for low sampling rate. The experimental results have been promising and have shown the potential of the proposed method for particle flow velocity measurements.

Abstract: Aimed at the measurement of kinetic energy for swarm of flying fragments, a measuring method of kinetic energy for the flying fragment using six-light-screen array was presented in this paper. When a fragment pass through the six light screens, the six-time sequences, can be gathered in turn. Lots of fragments can generate some sequence of six-times. The algorithm that can distinguish the sequence from a group of sequences of time is put forward in this paper. According to the coordinates of fragment position on a position indicator as well as all the sequences of the fragments, the real time sequence can be distinguished and recognized. Then the real velocity and accurate location of the fragment can be calculated with the algorithm designed, and the kinetic energy of fragments can be measured. The algorithm is proved accurate and effective by the simulation.

Abstract: Local shear wave velocity measurements are effective to obtain tissue elasticity map. We have proposed novel wave number spectrum based shear wave velocity measurement system. However, the accuracy and resolution of this technique should be optimized and sophisticated in future clinical application for breast cancer diagnosis. We propose a simulator of RF signal in shear wave velocity measurement system which can consider arbitrary shear wave propagation. We demonstrate the usefulness of this simulator by experimental result. Moreover, accuracy and resolution of small object is discussed for breast cancer application.