While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,du...While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,due to continuously varied geometries of laser-matter incidence.In the present work,we propose a novel manufacturing system of 7-axis on-the-fly LST for complex curved surface,based on the integrated synchronization of 5-axis linkage motion platform with 2-axis galvanometer.Specifically,the algorithm for decomposing spatial texture trajectory on curved surface into low-frequency and high-frequency parts is established,based on which the kinematic model of synchronized 7-axis system is developed to derive the motion of each axis in both 5-axis linkage motion platform and 2-axis galvanometer simultaneously.Subsequently,the synchronized 7-axis LST system is experimentally realized,including the setup of mechanical stages integrated with optical path,the configuration of numerical control unit,and the development of processing software.Finally,case study of 7-axis on-the-fly LST of freeform aluminum surface is performed,and the advantages in terms of processing efficiency and texturing accuracy over 5-axis linkage LST are demonstrated.The correlation of reduced following errors between mechanical stages with the promoted performance of curved surface texturing by the 7-axis on-the-fly LST is further analyzed.Current work provides a feasible solution for establishing the manufacturing system for high performance LST of complex curved surface.展开更多
Based on the development of the non-contact measurement system of free-formsurface, NURBS reconstruction of measurement points of freeform surface is effectively realized bymodifying the objective function and recursi...Based on the development of the non-contact measurement system of free-formsurface, NURBS reconstruction of measurement points of freeform surface is effectively realized bymodifying the objective function and recursive procedure and calculating the optimum number ofcontrol points. The reconstruction precision is evaluated through Ja-cobi's transformation method.The feasibility of the measurement system and effectiveness of the reconstruction algorithm aboveare proved by experiment.展开更多
Developing CNC measuring method on the base of coordinate machine can makethe best of the hardware resource of CNC system and realize the integration of CAD/CAM/CAT. Based onthe evenly spaced parallel planes scanning,...Developing CNC measuring method on the base of coordinate machine can makethe best of the hardware resource of CNC system and realize the integration of CAD/CAM/CAT. Based onthe evenly spaced parallel planes scanning, a new adaptive digitizing approach for freeform surfacenamely arc length extrapolation is put forward. By this way, the digitizing approach can be addedto the CNC system, while the system's hardware and software are not changed.展开更多
Heavy-haul locomotives operate in complex and dynamic environments.Drivers are required to frequently monitor numerous displays within the cab and track conditions,and switching the line of sight will result in drivin...Heavy-haul locomotives operate in complex and dynamic environments.Drivers are required to frequently monitor numerous displays within the cab and track conditions,and switching the line of sight will result in driving blind for a certain distance.This can easily lead to visual fatigue and safety incidents over extended periods.In this paper,we propose a dual-focal-plane augmented reality head-up display(AR-HUD)system adapted for heavy-haul locomotives,integrating dual picture generation units(PGUs)with two freeform surfaces to achieve the display of near-field and far-field.Due to the large inclination angle of the windshield in heavy-haul locomotives,there are significant aberrations of the optical system and the virtual image quality of the far-field needs to be improved.To address this issue,we introduce two freeform surfaces into the optical path of the far-field to reduce aberration.The increased structural degrees of freedom facilitate subsequent optimization.Following optimization of the system,the maximum root mean square(RMS)radius within the eyebox regions E1 to E5 was smaller than the Airy disk radius,and the modulation transfer function(MTF)value at the cutoff frequency exceeded 0.3.Grid distortion was less than 5%,and at the cutoff frequency of 4.31 line pairs per millimeter(lp/mm),over 98%of the MTF was greater than 0.3.The image quality and overall imaging performance were excellent,with reasonable tolerance distribution,demonstrating the feasibility of this design.This configuration allows for the simultaneous display of both far-field and near-field images,enhancing its applicability in rail transport.The feasibility of this innovative AR-HUD system has been validated through user interface(UI)simulation.展开更多
Chinese-German sculptor Zhou Xiaoping has been traveling between China and Germany,creating sculptures,since 2003.She has created more than 80 large,urban sculptures,each of which has become a vivid carrier of urban m...Chinese-German sculptor Zhou Xiaoping has been traveling between China and Germany,creating sculptures,since 2003.She has created more than 80 large,urban sculptures,each of which has become a vivid carrier of urban memories.During the past decade,she has focused on creating freeform sculptures,and she has launched a global,cross-disciplinary-artist-collaboration project,which has involved the preservation of archives for contemporary artistic creation.展开更多
Freeform optics has become the most prominent element of the optics industry. Advanced freeform optical designs supplementary to ultra-precision manufacturing and metrology techniques have upgraded the lifestyle, thin...Freeform optics has become the most prominent element of the optics industry. Advanced freeform optical designs supplementary to ultra-precision manufacturing and metrology techniques have upgraded the lifestyle, thinking, and observing power of existing humans.Imaginations related to space explorations, portability, accessibility have also witnessed sensible in today’s time with freeform optics. Present-day design methods and fabrications techniques applicable in the development of freeform optics and the market requirements are focussed and explained with the help of traditional and non-traditional optical applications. Over the years,significant research is performed in the emerging field of freeform optics, but no standards are established yet in terms of tolerances and definitions. We critically review the optical design methods for freeform optics considering the image forming and non-image forming applications. Numerous subtractive manufacturing technologies including figure correction methods and metrology have been developed to fabricate extreme modern freeform optics to satisfy the demands of various applications such as space, astronomy, earth science, defence,biomedical, material processing, surveillance, and many more. We described a variety of advanced technologies in manufacturing and metrology for novel freeform optics. Next, we also covered the manufacturing-oriented design scheme for advanced optics. We conclude this review with an outlook on the future of freeform optics design, manufacturing and metrology.展开更多
Intersections and discontinuities commonly arise in surface modeling and cause problems in downstream operations. Local geometry repair, such as cover holes or replace bad surfaces by adding new surface patches for de...Intersections and discontinuities commonly arise in surface modeling and cause problems in downstream operations. Local geometry repair, such as cover holes or replace bad surfaces by adding new surface patches for dealing with inconsistencies among the confluent region, where multiple surfaces meet, is a common technique used in CAD model repair and reverse engineering. However, local geometry repair destroys the topology of original CAD model and increases the number of surface patches needed for freeform surface shape modeling. Consequently, a topology recovery technique dealing with complex freeform surface model after local geometry repair is proposed. Firstly, construct the curve network which freeform surface model; secondly, apply freeform surface fitting method determine the geometry and topology properties of recovery to create B-spline surface patches to recover the topology of trimmed ones. Corresponding to the two levels of enforcing boundary conditions on a B-spline surface, two solution schemes are presented respectively. In the first solution scheme, non-constrained B-spline surface fitting method is utilized to piecewise recover trimmed confluent surface patches and then employs global beautification technique to smoothly stitch the recovery surface patches. In the other solution scheme, constrained B-spline surface fitting technique based on discretization of boundary conditions is directly applied to recover topology of surface model after local geometry repair while achieving G~ continuity simultaneously. The presented two different schemes are applied to the consistent surface model, which consists of five trimmed confluent surface patches and a local consistent surface patch, and a machine cover model, respectively. The application results show that our topology recovery technique meets shape-preserving and Gt continuity requirements in reverse engineering. This research converts the problem of topology recovery for consistent surface model to the problem of constructing G1 patches from a given curve network, and provides a new idea to model repairing study.展开更多
基金the support by the Harbin Manufacturing Science and Technology Innovation Talent Project(No.2023CXRCGD035)the Open Research Foundation of State Key Laboratory of Digital Manufacturing Equipment and Technology in Huazhong University of Science and Technology,China(No.IMETKF2023012).
文摘While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,due to continuously varied geometries of laser-matter incidence.In the present work,we propose a novel manufacturing system of 7-axis on-the-fly LST for complex curved surface,based on the integrated synchronization of 5-axis linkage motion platform with 2-axis galvanometer.Specifically,the algorithm for decomposing spatial texture trajectory on curved surface into low-frequency and high-frequency parts is established,based on which the kinematic model of synchronized 7-axis system is developed to derive the motion of each axis in both 5-axis linkage motion platform and 2-axis galvanometer simultaneously.Subsequently,the synchronized 7-axis LST system is experimentally realized,including the setup of mechanical stages integrated with optical path,the configuration of numerical control unit,and the development of processing software.Finally,case study of 7-axis on-the-fly LST of freeform aluminum surface is performed,and the advantages in terms of processing efficiency and texturing accuracy over 5-axis linkage LST are demonstrated.The correlation of reduced following errors between mechanical stages with the promoted performance of curved surface texturing by the 7-axis on-the-fly LST is further analyzed.Current work provides a feasible solution for establishing the manufacturing system for high performance LST of complex curved surface.
基金This project is supported by Provincial Natural Science Foundation of Zhejiang of China (No.599026).
文摘Based on the development of the non-contact measurement system of free-formsurface, NURBS reconstruction of measurement points of freeform surface is effectively realized bymodifying the objective function and recursive procedure and calculating the optimum number ofcontrol points. The reconstruction precision is evaluated through Ja-cobi's transformation method.The feasibility of the measurement system and effectiveness of the reconstruction algorithm aboveare proved by experiment.
基金This project is supported by Provincial Key Science and Technology Planning of Zhejiang(No.971111198).
文摘Developing CNC measuring method on the base of coordinate machine can makethe best of the hardware resource of CNC system and realize the integration of CAD/CAM/CAT. Based onthe evenly spaced parallel planes scanning, a new adaptive digitizing approach for freeform surfacenamely arc length extrapolation is put forward. By this way, the digitizing approach can be addedto the CNC system, while the system's hardware and software are not changed.
基金supported by the Key R&D Plan Projects in Zhejiang Province(No.2023C01243)China and the National Natural Science Foundation of China(Nos.52472422,52293424,and 52477065).
文摘Heavy-haul locomotives operate in complex and dynamic environments.Drivers are required to frequently monitor numerous displays within the cab and track conditions,and switching the line of sight will result in driving blind for a certain distance.This can easily lead to visual fatigue and safety incidents over extended periods.In this paper,we propose a dual-focal-plane augmented reality head-up display(AR-HUD)system adapted for heavy-haul locomotives,integrating dual picture generation units(PGUs)with two freeform surfaces to achieve the display of near-field and far-field.Due to the large inclination angle of the windshield in heavy-haul locomotives,there are significant aberrations of the optical system and the virtual image quality of the far-field needs to be improved.To address this issue,we introduce two freeform surfaces into the optical path of the far-field to reduce aberration.The increased structural degrees of freedom facilitate subsequent optimization.Following optimization of the system,the maximum root mean square(RMS)radius within the eyebox regions E1 to E5 was smaller than the Airy disk radius,and the modulation transfer function(MTF)value at the cutoff frequency exceeded 0.3.Grid distortion was less than 5%,and at the cutoff frequency of 4.31 line pairs per millimeter(lp/mm),over 98%of the MTF was greater than 0.3.The image quality and overall imaging performance were excellent,with reasonable tolerance distribution,demonstrating the feasibility of this design.This configuration allows for the simultaneous display of both far-field and near-field images,enhancing its applicability in rail transport.The feasibility of this innovative AR-HUD system has been validated through user interface(UI)simulation.
文摘Chinese-German sculptor Zhou Xiaoping has been traveling between China and Germany,creating sculptures,since 2003.She has created more than 80 large,urban sculptures,each of which has become a vivid carrier of urban memories.During the past decade,she has focused on creating freeform sculptures,and she has launched a global,cross-disciplinary-artist-collaboration project,which has involved the preservation of archives for contemporary artistic creation.
基金the UK’s Engineering and Physical Sciences Research Council(EPSRC)funding of Future Metrology Hub(Ref.:EP/P006930/1)the UK’s Science and Technology Facilities Council(STFC)Innovation Partnership Scheme(IPS)project under Grant Agreement No.ST/V001280/1the European Union’s Horizon 2020research and innovation programme under Grant Agreement No.767589。
文摘Freeform optics has become the most prominent element of the optics industry. Advanced freeform optical designs supplementary to ultra-precision manufacturing and metrology techniques have upgraded the lifestyle, thinking, and observing power of existing humans.Imaginations related to space explorations, portability, accessibility have also witnessed sensible in today’s time with freeform optics. Present-day design methods and fabrications techniques applicable in the development of freeform optics and the market requirements are focussed and explained with the help of traditional and non-traditional optical applications. Over the years,significant research is performed in the emerging field of freeform optics, but no standards are established yet in terms of tolerances and definitions. We critically review the optical design methods for freeform optics considering the image forming and non-image forming applications. Numerous subtractive manufacturing technologies including figure correction methods and metrology have been developed to fabricate extreme modern freeform optics to satisfy the demands of various applications such as space, astronomy, earth science, defence,biomedical, material processing, surveillance, and many more. We described a variety of advanced technologies in manufacturing and metrology for novel freeform optics. Next, we also covered the manufacturing-oriented design scheme for advanced optics. We conclude this review with an outlook on the future of freeform optics design, manufacturing and metrology.
基金supported by China Postdoctoral Science Foundation(Grant No. 20110490376)National Natural Science Foundation of China (Grant No. 50575098)
文摘Intersections and discontinuities commonly arise in surface modeling and cause problems in downstream operations. Local geometry repair, such as cover holes or replace bad surfaces by adding new surface patches for dealing with inconsistencies among the confluent region, where multiple surfaces meet, is a common technique used in CAD model repair and reverse engineering. However, local geometry repair destroys the topology of original CAD model and increases the number of surface patches needed for freeform surface shape modeling. Consequently, a topology recovery technique dealing with complex freeform surface model after local geometry repair is proposed. Firstly, construct the curve network which freeform surface model; secondly, apply freeform surface fitting method determine the geometry and topology properties of recovery to create B-spline surface patches to recover the topology of trimmed ones. Corresponding to the two levels of enforcing boundary conditions on a B-spline surface, two solution schemes are presented respectively. In the first solution scheme, non-constrained B-spline surface fitting method is utilized to piecewise recover trimmed confluent surface patches and then employs global beautification technique to smoothly stitch the recovery surface patches. In the other solution scheme, constrained B-spline surface fitting technique based on discretization of boundary conditions is directly applied to recover topology of surface model after local geometry repair while achieving G~ continuity simultaneously. The presented two different schemes are applied to the consistent surface model, which consists of five trimmed confluent surface patches and a local consistent surface patch, and a machine cover model, respectively. The application results show that our topology recovery technique meets shape-preserving and Gt continuity requirements in reverse engineering. This research converts the problem of topology recovery for consistent surface model to the problem of constructing G1 patches from a given curve network, and provides a new idea to model repairing study.
