2π phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry （PSP） can be used to ...2π phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry （PSP） can be used to solve such an issue. In the measurement, two properchosen frequency gratings are utilized to synthesize an equivalent wavelength grating which ensures the computed phase in a principal phase range. Thus, the error caused by the phase unwrapping process with the conventional phase reconstruct algorithm can be eliminated. Finally, experimental result of a specimen with large plastic deformation is given to prove that the proposed method is effective to handle the phase discontinuity.展开更多
An optical technique for 3 D shape measurement is presented. This technique, based on a deformed projected grating pattern which carries 3 D information of the measured object, can automatically and accurately obtain ...An optical technique for 3 D shape measurement is presented. This technique, based on a deformed projected grating pattern which carries 3 D information of the measured object, can automatically and accurately obtain the phase map of a measured object by using one step phase shift algorithm.In comparison with traditional phase shift technique, the technique is much faster, with the equivalent accuracy. Only one frame image is sufficient for measuring. Experimental result of typical object is presented.展开更多
Automatically assessing fabric smoothness grade is very important in the evaluation of fabric appearance.A system for objectively evaluating the fabric smoothness grade based on a grating projection unit and double co...Automatically assessing fabric smoothness grade is very important in the evaluation of fabric appearance.A system for objectively evaluating the fabric smoothness grade based on a grating projection unit and double colored CCD(short form of charge coupled device) was constructed in this paper.Two images captured by different CCD compensated each other which reduced the influence of noises.The application of the four-step phase-shifting method enabled the calculation of the exact phase in a point easy and quick.A large amount of 3D points with three coordinates X,Y and Z were obtained precisely making the definition and calculation of fabric smoothness characters easy.Then four parameters which intuitively denoted the fabric smoothness degree were obtained.Finally,a proper neural network was built,which successfully performed the fabric smoothness classification.The experimental results show that the system is applicable for all the fabric whatever pattern or color.The experimental grades provided by this grating projection system are also highly consistent with the subjective results.展开更多
In the three-dimensional(3D) contour measurement,the phase shift profilometry(PSP) method is the most widely used one.However,the measurement speed of PSP is very low because of the multiple projections.In order to im...In the three-dimensional(3D) contour measurement,the phase shift profilometry(PSP) method is the most widely used one.However,the measurement speed of PSP is very low because of the multiple projections.In order to improve the measurement speed,color grating stripes are used for measurement in this paper.During the measurement,only one color sinusoidal fringe is projected on the measured object.Therefore,the measurement speed is greatly improved.Since there is coupling or interference phenomenon between the adjacent color grating stripes,a color correction method is used to improve the measurement results.A method for correcting nonlinear error of measurement system is proposed in this paper,and the sinusoidal property of acquired image after correction is better than that before correction.Experimental results show that with these correction methods,the measurement errors can be reduced.Therefore,it can support a good foundation for the high-precision 3D reconstruction.展开更多
底栏栅式渠首是新疆粗颗粒山溪性河流引水防沙枢纽的首选类型,但实践运用表明,当引水量超过30 m 3/s时,渠首冲沙有利、工程布置紧凑的优势逐渐丧失,后期运行管理效益大打折扣。为此在保留原有布置优势的情况下,以扩大底栏栅引水流量为目...底栏栅式渠首是新疆粗颗粒山溪性河流引水防沙枢纽的首选类型,但实践运用表明,当引水量超过30 m 3/s时,渠首冲沙有利、工程布置紧凑的优势逐渐丧失,后期运行管理效益大打折扣。为此在保留原有布置优势的情况下,以扩大底栏栅引水流量为目标,提出了“⊥”型廊道新结构及优化布置方案,新结构在原垂直水流方向“—”型廊道结构基础上增设了顺水流方向“|”型廊道(根据流量的大小可布置双排甚至多排“|”型廊道),并结合底栏栅水流动力方程及取水流量计算方法得到了“⊥”型廊道取水流量的计算方法。随后以新疆头屯河渠首为例,在保持原平面布置不变的情况下引入“⊥”型廊道新结构,其引水量可达48.96 m 3/s,提升了39.89%,工程造价降低了63.46%。“⊥”型廊道新结构及布置方案突破了传统底栏栅式渠首设计引水流量相对较小的限制,拓宽了底栏栅式渠首的适用范围,还提高了经济效益,可为此类工程提供新的工程方案。展开更多
A position sensor based on grating projection with spatial filtering and polarization modulation is presented. A grating is projected onto the object to be measured through a 4f optical system with a spatial filter. A...A position sensor based on grating projection with spatial filtering and polarization modulation is presented. A grating is projected onto the object to be measured through a 4f optical system with a spatial filter. After reflected by the object, the grating projection is imaged on a detection grating through another 4f optical system to form moiré fringes, The polarization modulated moiré signal is detected to obtain the position information of the object. In the position sensor, the moiré signal varies sinusoidally with the position of object. The measurement is independent of the incident intensity on the projection grating and the reflectivity of the object to be measured, In experiments, the effectiveness of the position sensor is proved, and the root mean square （RMS） error at each measurement position is less than 13 nm.展开更多
基金the National Natural Science Foundation of China(No.10672065).
文摘2π phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry （PSP） can be used to solve such an issue. In the measurement, two properchosen frequency gratings are utilized to synthesize an equivalent wavelength grating which ensures the computed phase in a principal phase range. Thus, the error caused by the phase unwrapping process with the conventional phase reconstruct algorithm can be eliminated. Finally, experimental result of a specimen with large plastic deformation is given to prove that the proposed method is effective to handle the phase discontinuity.
文摘An optical technique for 3 D shape measurement is presented. This technique, based on a deformed projected grating pattern which carries 3 D information of the measured object, can automatically and accurately obtain the phase map of a measured object by using one step phase shift algorithm.In comparison with traditional phase shift technique, the technique is much faster, with the equivalent accuracy. Only one frame image is sufficient for measuring. Experimental result of typical object is presented.
文摘Automatically assessing fabric smoothness grade is very important in the evaluation of fabric appearance.A system for objectively evaluating the fabric smoothness grade based on a grating projection unit and double colored CCD(short form of charge coupled device) was constructed in this paper.Two images captured by different CCD compensated each other which reduced the influence of noises.The application of the four-step phase-shifting method enabled the calculation of the exact phase in a point easy and quick.A large amount of 3D points with three coordinates X,Y and Z were obtained precisely making the definition and calculation of fabric smoothness characters easy.Then four parameters which intuitively denoted the fabric smoothness degree were obtained.Finally,a proper neural network was built,which successfully performed the fabric smoothness classification.The experimental results show that the system is applicable for all the fabric whatever pattern or color.The experimental grades provided by this grating projection system are also highly consistent with the subjective results.
基金supported by the National Natural Science Foundation of China(Nos.60808020 and 61078041)the National Science and Technology Support(No.2014BAH03F01)+1 种基金the Tianjin Research Program of Application Foundation and Advanced Technology(No.10JCYBJC07200)the Technology Program of Tianjin Municipal Education Commission(No.20130324)
文摘In the three-dimensional(3D) contour measurement,the phase shift profilometry(PSP) method is the most widely used one.However,the measurement speed of PSP is very low because of the multiple projections.In order to improve the measurement speed,color grating stripes are used for measurement in this paper.During the measurement,only one color sinusoidal fringe is projected on the measured object.Therefore,the measurement speed is greatly improved.Since there is coupling or interference phenomenon between the adjacent color grating stripes,a color correction method is used to improve the measurement results.A method for correcting nonlinear error of measurement system is proposed in this paper,and the sinusoidal property of acquired image after correction is better than that before correction.Experimental results show that with these correction methods,the measurement errors can be reduced.Therefore,it can support a good foundation for the high-precision 3D reconstruction.
文摘底栏栅式渠首是新疆粗颗粒山溪性河流引水防沙枢纽的首选类型,但实践运用表明,当引水量超过30 m 3/s时,渠首冲沙有利、工程布置紧凑的优势逐渐丧失,后期运行管理效益大打折扣。为此在保留原有布置优势的情况下,以扩大底栏栅引水流量为目标,提出了“⊥”型廊道新结构及优化布置方案,新结构在原垂直水流方向“—”型廊道结构基础上增设了顺水流方向“|”型廊道(根据流量的大小可布置双排甚至多排“|”型廊道),并结合底栏栅水流动力方程及取水流量计算方法得到了“⊥”型廊道取水流量的计算方法。随后以新疆头屯河渠首为例,在保持原平面布置不变的情况下引入“⊥”型廊道新结构,其引水量可达48.96 m 3/s,提升了39.89%,工程造价降低了63.46%。“⊥”型廊道新结构及布置方案突破了传统底栏栅式渠首设计引水流量相对较小的限制,拓宽了底栏栅式渠首的适用范围,还提高了经济效益,可为此类工程提供新的工程方案。
文摘A position sensor based on grating projection with spatial filtering and polarization modulation is presented. A grating is projected onto the object to be measured through a 4f optical system with a spatial filter. After reflected by the object, the grating projection is imaged on a detection grating through another 4f optical system to form moiré fringes, The polarization modulated moiré signal is detected to obtain the position information of the object. In the position sensor, the moiré signal varies sinusoidally with the position of object. The measurement is independent of the incident intensity on the projection grating and the reflectivity of the object to be measured, In experiments, the effectiveness of the position sensor is proved, and the root mean square （RMS） error at each measurement position is less than 13 nm.
