Laser triangulation theory was used to develop a novel contact-free method for measuring the coal level in a silo under harsh environmental conditions found in coal mines, such as the presence of dense dust, high humi...Laser triangulation theory was used to develop a novel contact-free method for measuring the coal level in a silo under harsh environmental conditions found in coal mines, such as the presence of dense dust, high humidity, and low illumination. A laser source and a camera were mounted at the top of the silo. The laser spot projected into the silo was imaged by the camera. The pinhole imaging principle allows the level to be found from the lateral shift of the spot image on the sensor. A pre-calibrated look-up table of the coal depth versus spot position was used to obtain the depth. The measurement accuracy depends on the step size used during pre-calibration. The actual application of a device designed according to these principles shows that it is easy to implement. The detection of the coal level in a silo at the low illumination level found in coal mines is demonstrated.展开更多
With the increasing miniaturisation and integration of electronic products and the increase of heat, it is necessary to design and introduce heat sinks and install fans. The volume of electronic components, especially...With the increasing miniaturisation and integration of electronic products and the increase of heat, it is necessary to design and introduce heat sinks and install fans. The volume of electronic components, especially the height, is very important for the structural and thermal design of electronic devices. This paper presents a design scheme of an online height measurement device based on laser triangulation and commercial charge coupled device(CCD). It analyzes the principles of electronic component height measurement, and expounds the composition and working principle of the laser measurement system. In addition, the commonly used methods to determine the center position are compared and analysed. These methods include circle fitting, gray centroid and extension method or Gaussian fitting. These methods usually lead to different results. The experimental results show that the fitting speed of the gray centroid is faster. The 3 D model of components is given through measurement, and the error factors affecting measurement are analysed.展开更多
Pavement roughness is one of the most important factors for appraising highway construction. In this paper, we choose the laser triangulation to measure pavement roughness. The principle and configuration of laser tri...Pavement roughness is one of the most important factors for appraising highway construction. In this paper, we choose the laser triangulation to measure pavement roughness. The principle and configuration of laser triangulation are introduced. Based on this technology, the pavement roughness of a road surface is measured. The measurement results are given in this paper. The measurement range of this system is 50 μm. The measurement error of this technology is analyzed. This technology has an important significance to appraise the quality of highway after completion of the workload.展开更多
A non contact three dimensional measurement method is presented in this paper.This system consists of a laser triangulation probe,a probe head and a coordinate measuring machine (CMM).The measurement principle of th...A non contact three dimensional measurement method is presented in this paper.This system consists of a laser triangulation probe,a probe head and a coordinate measuring machine (CMM).The measurement principle of the system is discussed,and a system calibration method employing a reference ball is proposed.The geometric model involving four frames is established to calculate the data points based on the reading of the laser probe and position information from the CMM.A measuring experiment for gesso free form surface using this system is carried out.展开更多
Mechanical characteristics of MO disk are vital for the designer of the drives and the manufacturers who provide the mass-product MO disks. So measuring mechanical characteristics is very significant. We compares the ...Mechanical characteristics of MO disk are vital for the designer of the drives and the manufacturers who provide the mass-product MO disks. So measuring mechanical characteristics is very significant. We compares the existing measuring methods and gives some novel measuring methods we adopted in details. The measuring system based upon these methods was introduced too. Some typical measuring results are also shown in this paper.展开更多
Inside the second experimental wave energy converter (WEC) launched at the Lysekil research site on the Swedish west coast in March 2009 a number of sensor systems were installed for measuring the mechanical performan...Inside the second experimental wave energy converter (WEC) launched at the Lysekil research site on the Swedish west coast in March 2009 a number of sensor systems were installed for measuring the mechanical performance of the WEC and its mechanical subsystems. One of the measurement systems was a set-up of 7 laser triangulation sensors for measuring relative displacement of the piston rod mechanical lead-through transmission in the direct drive. Two measurement periods, separated by 2.5 month, are presented in this paper. One measurement is made two weeks after launch and another 3 months after launch. Comparisons and correlations are made between different sensors measuring simultaneously. Noise levels are investigated. Filtering is discussed for further refinement of the laser triangulation sensor signals in order to separate noise from actual physical displacement and vibration. Measurements are presented from the relative displacement of the piston rod mechanical lead-through, from magnetic flux in the air gap, mechanical strain in the WEC structure, translator position and piston rod axial displacement and active AC power. Investigation into the measurements in the time domain with close-ups, in the frequency domain with Fast Fourier transform (FFT) and with time-frequency analysis with short time Fourier transform (STFT) is carried out to map the spectral content in the measurements. End stop impact is clearly visible in the time-frequency analysis. The FFT magnitude spectra are investigated for identifying the cogging bandwidth among other vibrations. Generator cogging, fluctuations in the damping force and in the Lorenz forces in the stator are distinguished and varies depending on translator speed. Vibrations from cogging seem to be present in the early measurement period while not so prominent in the late measurement period. Vibration frequencies due to wear are recognized by comparing with the noise at generator standstill and the vibration sources in the generator. It is concluded that a moving average is a sufficient filter in the time domain for further analysis of the relative displacement of the piston rod mechanical lead-through transmission.展开更多
High precision manufacturing, e.g. milling and grinding, which have manufacturing tolerances in the range of <10 μm require microscopic measurement techniques for the inspection of the manufactured components. The...High precision manufacturing, e.g. milling and grinding, which have manufacturing tolerances in the range of <10 μm require microscopic measurement techniques for the inspection of the manufactured components. These measurement techniques are very sensitive to cooling liquids and lubricants which are essential for many manufacturing processes. Therefore, the measurement of the components is usually conducted in separate and clean laboratories and not directly in the manufacturing machine. This approach has some major drawbacks, e.g. high time consumption and no possibility for online process monitoring. In this article, a novel concept for the integration of high precision optical topography measurement systems into the manufacturing machine is introduced and compared to other concepts. The introduced concept uses a reservoir with cooling liquid in which the measurement object is immersed during the measurement. Thereby, measurement disturbance by splashing cooling liquids and lubricants can effectively be avoided.展开更多
基金supported by the National Natural Science Foun-dation of China (No. 51074169)
文摘Laser triangulation theory was used to develop a novel contact-free method for measuring the coal level in a silo under harsh environmental conditions found in coal mines, such as the presence of dense dust, high humidity, and low illumination. A laser source and a camera were mounted at the top of the silo. The laser spot projected into the silo was imaged by the camera. The pinhole imaging principle allows the level to be found from the lateral shift of the spot image on the sensor. A pre-calibrated look-up table of the coal depth versus spot position was used to obtain the depth. The measurement accuracy depends on the step size used during pre-calibration. The actual application of a device designed according to these principles shows that it is easy to implement. The detection of the coal level in a silo at the low illumination level found in coal mines is demonstrated.
文摘With the increasing miniaturisation and integration of electronic products and the increase of heat, it is necessary to design and introduce heat sinks and install fans. The volume of electronic components, especially the height, is very important for the structural and thermal design of electronic devices. This paper presents a design scheme of an online height measurement device based on laser triangulation and commercial charge coupled device(CCD). It analyzes the principles of electronic component height measurement, and expounds the composition and working principle of the laser measurement system. In addition, the commonly used methods to determine the center position are compared and analysed. These methods include circle fitting, gray centroid and extension method or Gaussian fitting. These methods usually lead to different results. The experimental results show that the fitting speed of the gray centroid is faster. The 3 D model of components is given through measurement, and the error factors affecting measurement are analysed.
文摘Pavement roughness is one of the most important factors for appraising highway construction. In this paper, we choose the laser triangulation to measure pavement roughness. The principle and configuration of laser triangulation are introduced. Based on this technology, the pavement roughness of a road surface is measured. The measurement results are given in this paper. The measurement range of this system is 50 μm. The measurement error of this technology is analyzed. This technology has an important significance to appraise the quality of highway after completion of the workload.
基金Supported by"863"High Technology Development Comittee ofChina (No."863"- 51 1 - 942 - 0 2 4 ) National Natural Science Foun-dation of China (No.50 0 750 64)
文摘A non contact three dimensional measurement method is presented in this paper.This system consists of a laser triangulation probe,a probe head and a coordinate measuring machine (CMM).The measurement principle of the system is discussed,and a system calibration method employing a reference ball is proposed.The geometric model involving four frames is established to calculate the data points based on the reading of the laser probe and position information from the CMM.A measuring experiment for gesso free form surface using this system is carried out.
基金Supported by the State Key Technology Program in the Ninth 5 -year Plan( No.96 -E0 1-0 4-0 3)
文摘Mechanical characteristics of MO disk are vital for the designer of the drives and the manufacturers who provide the mass-product MO disks. So measuring mechanical characteristics is very significant. We compares the existing measuring methods and gives some novel measuring methods we adopted in details. The measuring system based upon these methods was introduced too. Some typical measuring results are also shown in this paper.
基金supported by The Swedish Energy AgencyThe Gothenburg Energy Research Foundation,The Goran Gustavsson Research Foundation,Angpanneforeningen’s Foundation for Research and Development,The Olle Engkvist Foundation,The J.Gust.Richert Foundation,CF Environmental Fund,Vargons Research Foundation,The Swedish Research Council grant No.621-2009-3417 and the Wallenius Foundation.
文摘Inside the second experimental wave energy converter (WEC) launched at the Lysekil research site on the Swedish west coast in March 2009 a number of sensor systems were installed for measuring the mechanical performance of the WEC and its mechanical subsystems. One of the measurement systems was a set-up of 7 laser triangulation sensors for measuring relative displacement of the piston rod mechanical lead-through transmission in the direct drive. Two measurement periods, separated by 2.5 month, are presented in this paper. One measurement is made two weeks after launch and another 3 months after launch. Comparisons and correlations are made between different sensors measuring simultaneously. Noise levels are investigated. Filtering is discussed for further refinement of the laser triangulation sensor signals in order to separate noise from actual physical displacement and vibration. Measurements are presented from the relative displacement of the piston rod mechanical lead-through, from magnetic flux in the air gap, mechanical strain in the WEC structure, translator position and piston rod axial displacement and active AC power. Investigation into the measurements in the time domain with close-ups, in the frequency domain with Fast Fourier transform (FFT) and with time-frequency analysis with short time Fourier transform (STFT) is carried out to map the spectral content in the measurements. End stop impact is clearly visible in the time-frequency analysis. The FFT magnitude spectra are investigated for identifying the cogging bandwidth among other vibrations. Generator cogging, fluctuations in the damping force and in the Lorenz forces in the stator are distinguished and varies depending on translator speed. Vibrations from cogging seem to be present in the early measurement period while not so prominent in the late measurement period. Vibration frequencies due to wear are recognized by comparing with the noise at generator standstill and the vibration sources in the generator. It is concluded that a moving average is a sufficient filter in the time domain for further analysis of the relative displacement of the piston rod mechanical lead-through transmission.
文摘High precision manufacturing, e.g. milling and grinding, which have manufacturing tolerances in the range of <10 μm require microscopic measurement techniques for the inspection of the manufactured components. These measurement techniques are very sensitive to cooling liquids and lubricants which are essential for many manufacturing processes. Therefore, the measurement of the components is usually conducted in separate and clean laboratories and not directly in the manufacturing machine. This approach has some major drawbacks, e.g. high time consumption and no possibility for online process monitoring. In this article, a novel concept for the integration of high precision optical topography measurement systems into the manufacturing machine is introduced and compared to other concepts. The introduced concept uses a reservoir with cooling liquid in which the measurement object is immersed during the measurement. Thereby, measurement disturbance by splashing cooling liquids and lubricants can effectively be avoided.
