Design And Research Of Three-Dimensional Scanner For Plantar

The main purpose of a three-dimensional scanner is to create point-clouds on the geometric surface of an object.These points can be used to interpolate the surface shape of an object.And the more dense the point-clouds are,the more accurate the model can be created(the process is called three-dimensional reconstruction).With the development of society and the enrichment of material culture,the needs of people for personalized customization has become more and more intense.Among them,customized insoles for posture correction are quite popular.In order to meet the needs of the public and meet the current research hotspots,a low-cost and high-precision sole-specific three-dimensional scanner(based on the principle of monocular triangulation)is designed to obtain the threedimensional point cloud data of human sole surface and provide data support for the three-dimensional printer.In addition,a supporting software is developed to display the three-dimensional point cloud data of human sole in real time.At the design and manufacture time in this paper,the mechanical structure of plantar scanner is optimized by referring to the existing scanners and its own scanning characteristics.In the process of image acquisition and handle,a neighborhood filtering method which can refine the laser band well is used(using a 3*3 filtering window),then the image points on the laser band are extracted by gray centroid method.The plantar point-clouds images acquired have good display effect and high accuracy.The planter three-dimensional scanner has many error sources in scanning measurement.In order to improve the accuracy of point-clouds data and the display of detail features,the error of scanner is studied in this paper.At present,there are many research directions for the error analysis of scanners,which vary from one scanner to another.In order to improve the accuracy of ZW direction measurement,this paper chooses to analyze,measure and calibrate the plane perpendicularity error of laser.The plane deviation angle θ of the laser is estimated experimentally,which provides a basis for accurate calibration of the measured data in the ZW direction.In the meantime,the main work is to produce highprecision step standard parts,with coordinate measuring machine,to achieve high-precision error analysis under simple experimental conditions.Aiming at the good continuity accuracy of measurement data,the additional calibration error e is defined and analyzed and the systematic method and correction formula of error correction are given successfully.According to the verification of the measurement and correction results,the error can reach ±0.06 mm,and the correction is fairly successful.It can be concluded that the plantat threedimensional scanner designed can accurately provide the three-dimensional information of human plantar surface with simpler hardware and software design.Three-dimensional reconstruction,which is the most critical data handle,is needed after obtaining accurate plantar three-dimensional point-clouds data.Three-dimensional reconstruction can be understood as curve and surface fitting.Rapid development and reconstruction of complex surface characterized by triangulation is widely used in various fields.Referring to the latest literature,this paper proposes a detail triangulation method based on the depth characteristics of point-clouds.The reconstruction process of plantar point-clouds data based on line laser scanning is introduced in detail.Firstly,the strip data points are processed by segments,and the threshold is set to supplement the leak points and delete the useless segments.Secondly,the 8-neighborhood method is used to find the boundary points to connection to form a closed curve.Then,the strip data points are filtered by Savitzky-golay filter.Finally,a quadrilateral network is constructed according to the topological relationship of two-dimensional mesh form of data,and the proposed method of detail triangulation is used to segment the patches.Experiments show that the proposed surface reconstruction method responds quickly and exhibits boundary and internal details obviously.All in all,the plantar three-dimensional scanner has been designed and manufactured twice to meet the original purpose of the research.After structural design optimization,measurement and correction,and subsequent targeted data processing,the use of scanner has been stable enough;foot arch coefficient with multiple measurements waves range within 0.01 having high repetition accuracy;generated foot pathological analysis report is rich in content having high use value,and in medicine,it can make some feasible suggestions and contributions for the correction of patients’ posture.However,the shortcomings of the plantar threedimensional scanner still exist.In order to better match the 3D printer designed and manufactured by the team in the later stage,continuous improvement is still needed.