Dimensional Measurement System Research Articles

Design and Evaluation of Two Dimensional Metrological Atomic Force Microscope using a Planar Nanoscanner

An atomic force microscope (AFM) using a laser interferometer is regarded as one of the best solutions for the standardization of two dimensional length measurement systems. We propose a new two dimensional (2D) metrological AFM system, which uses an orthogonally decoupled XY scanner and a commercial AFM head. We designed a decoupled planar scanner having minimal parasitic errors, particularly crosstalk errors. The parasitic tilt error was measured and evaluated using an autocollimator. Furthermore, we evaluated the uncertainty of the combined system according to the Guide to the Expression of Uncertainty in Measurement.

Development of a Small Two Axis Spherical Motor Type Laser Tracker with Submicron Measurement Accuracy

Recently, it is in great need for measurement of the three dimensional surface form of the car and the aircraft, the path of the industrial robot and the machine tool, and so on with a high degree of accuracy. We have proposed a novel laser tracking three dimensional position measurement system which can measure the 3D position with submicron accuracy at more than 1[m] by combining the oscillating lever mechanism with the spherical motor. Before making the full system, we made the first and the second prototype spherical motor type laser tracker unit and tested them. The average measurement error of the developed laser tracker 2 is 0.45[μm] and the standard deviation is 0.54[μm], which satisfy the specifications needed for the full system.

116 光学式三次元形状計測装置の開発(搬送・振動・計測)

116 光学式三次元形状計測装置の開発(搬送・振動・計測)

Laserforming of 3D Features

The aim of the research presented in this paper is to investigate the feasibility of generating 3D features in sheet metal blanks using laser forming techniques. Aiming for systematic process planning and a good process control capability, only the temperature gradient mechanism is considered for this purpose. The research has been performed on a 6 kW CO2 laser CNC platform. In a first part, bending along curved lines and bending close to edges are investigated. In a second part, these findings are applied for the creation of a louver. A dimensional measurement system is used for analyzing the geometric dimensional characteristics of the formed shapes. It is found that louvers can be made as a local 3D feature in a sheet metal blank. Based on these initial results, it can be concluded that form features, which are traditionally generated by means of form tools on a punching machine, can to some extend also be obtained by means of industrial lasers, widening the application range of these machine tools.

Robot Path Planning for Dimensional Measurement in Automotive Manufacturing

This paper addresses the robot path planning problem in our effort to develop a fully automated dimensional measurement system using an eye-in-hand robotic manipulator. First, the CAD-based vision sensor planning system developed in our lab is briefly introduced; it uses both the CAD model and the camera model to plan camera viewpoints. The planning system employs a decomposition-based approach to generate camera viewpoints that satisfy given task constraints. Second, to improve the efficiency of the eye-in-hand robot inspection system, robot path planning is studied, which is the focus of this paper. This problem is rendered as a Traveling Salesman Problem (TSP). A new hierarchical approach is developed to solve the TSP into its suboptimality. Instead of solving a large size TSP, this approach utilizes the clustering nature of the viewpoints and converts the TSP into a clustered Traveling Salesman Problem (CTSP). A new algorithm, which favors the intergroup paths, is proposed to solve the CTSP quickly. Performance of the new algorithm is analyzed. It is shown that instead of a fixed performance ratio as reported in some existing work, a constant bound can be achieved which is related to the diameter of the clusters. Experimental results demonstrate the effectiveness of the robot motion planning system. The proposed path planning approach can obtain sub-optimal solutions quickly for many large scale TSPs, which are common problems in many robotic applications.

Analysis of 109 Japanese children's lip and nose shapes using 3-dimensional digitizer

We assessed lip and nose shapes, which played an important role in performance evaluations, before and after cleft lip and nose surgery. We used a noncontact-type semiconductor laser 3-dimensional measurement system on normal Japanese children to obtain 3-dimensional images of noses and lips, which were accurate enough to measure facial shapes. We could rotate these images on the computer, therefore we measured the following points: the distance between the peaks of the Cupid's bow and the width of the labial fissure (frontal view), and the width of the nose and the nasal tip protrusion (basal view). Lip and nose shapes were evaluated for each gender. Additionally, nasolabial angles (NLA) were measured on the lateral views of faces. We classified the morphology of the philtral columns into four types; (1) triangular type, (2) parallel type, (3) concave type, and (4) flat type. We also classified nostril shapes into four types: (1) teardrop type, (2) heart shaped type, (3) round type, and (4) triangular type. We calculated the average of the 3-dimensional coordinate values for each landmark, and created standard facial models of normal Japanese children. Moreover, we invented a new morphological evaluation method before and after cleft lip and nose surgery, using the 3-dimensional data converting and editing software. The method was more feasible to evaluate the assessment cleft lip and nose surgery, by quantifying the surface areas of right and left nostrils and the surface areas of upper and lower vermilions, even now by measuring with the eyes and comparing them.

Three-dimensional analysis of the effects of the treatment on anterior crossbite in the primary dentition

We performed measurement using a 3-dimensional measurement system in study models of children with anterior crossbite in the primary dentition treated using a chin cap and lingual arch, and evaluated changes in the dentition and occlusion after treatment based on measurement values and also using wire frame models. Comparing with the situation before treatment, the overbite of anterior teeth shows improvement to become shallow and the terminal plane becomes vertical type and the occlusal plane becomes flatter. Labioclination of upper anterior teeth, linguoclination of lower anterior teeth and backward movement of lower dentition are observed. Occlusal view shows that both upper and lower dental arch become semicircular configuration. The width, depth and height of the post-treatment dentition became closer to the standard values. Chin cap and lingual arch treatment for anterior crossbite during early childhood is effective, and also helpful in the normal development of occlusion in children.

Three-dimensional level-curve scanning based on intersection of laser lines

A dimensional measurement system that also tracks object movements is presented here. The method directly yields the level curves of an object. It is an extension of collimation methods, coupled with the use of structured lighting with features formed from several luminous planes intersecting in a single line. This line defines a set of points of the space at a fixed distance Z0 from the measuring head. The locus of the points of the object where the lighting is reduced to a single line is the level curve sought. The introduction of an asymmetry into the lighting structure permits one to determine the direction as well as an approximate value of the value of the distance to the level curve from a point on the illuminated object. The experiments performed permit one to evaluate the performance of such a system, and suggest future applications.

335 光学式三次元計測システムの高機能化(センサー関連技術, OS-18 計測・評価・診断)

335 光学式三次元計測システムの高機能化(センサー関連技術, OS-18 計測・評価・診断)

Asymmetry of the sphenoid bone and its suitability as a reference for analyzing craniofacial asymmetry

The purposes of this study were to evaluate the asymmetry of the sphenoid bone and to determine its suitability as a reference for analyzing asymmetry of the skull. Thirty-seven dry skulls from India were divided into group A (n = 18), with a right-left length discrepancy of less than 2 mm for both the external acoustic meatus-frontozygomatic suture and external acoustic meatus-subspinale, and group B (n = 19), with a right-left length discrepancy of more than 2 mm for either of these 2 parameters. The skulls were then examined with regard to the percentage of asymmetry of the sphenoid bone, the angles between the cranial base and the facial axis, and the distance between reference surfaces of the sphenoid bone and facial landmarks by 3-dimensional measurement system. The following results were obtained: 1. Asymmetry of the sphenoid bone, while slight, was found in both groups. There were no significant differences between the 2 groups. 2. The cranial base and the facial axis did not form a right angle in group A, and there were no significant differences between the 2 groups. 3. The distances between reference surfaces of the sphenoid bone and the lower landmarks of the facial bone were greater than those of the upper landmarks. 4. The external acoustic meatus was the most suitable reference for analysis of craniofacial asymmetry.

Application of a 3-dimensional measurement system to complete denture impressions

Statement of Problem. Little is known about tissue displacement at the tissue/denture base interface during impression making. Purpose. This study used a new 3-dimensional measurement system to analyze and compare 2 complete denture reline impression techniques (1 occluding and 1 digital) to determine which resulted in less displacement of the tissue/denture base interface during impression making. Material and Methods. The experiment included 10 completely edentulous subjects. For each subject, 3 mandibular casts were obtained: (1) a reference cast of the existing denture base, (2) a cast made with an occluding reline impression technique, and (3) a cast made with a digital reline impression technique. With the use of an optical 3-dimensional measurement system, the corresponding casts in a common coordinate system were analyzed geometrically. For each cast, the coordinates of the barycentric point and the high point were determined. For the same subject, the differences between the coordinates of the barycentric points of the 3 casts were calculated 2-by-2. The same calculation was performed for the high points. To determine whether these differences, which represent the displacements of the barycentric points and the high points, were statistically significant, the Wilcoxon signed-rank test for paired group comparisons was applied (P<.05). Cartographic differences among the casts from the same subject also were compared. Results. The uncertainty of measurement for the location of the barycentric and highest point was ±57 μm. The uncertainty in the differences among the cartographic displays was ±0.1 mm. Vertically, the mean distance that separated the barycentric points obtained with the 2 impression methods was 0.04 mm. Cartography data showed that the greatest dimensional differences between the 2 impression techniques (minimum 0.25 mm; maximum 1.5 mm) were located near the retromolar pad and along the lingual flange. Conclusion. Within the limitations of this 3-dimensional in vivo study, displacement of the tissue/denture base interface was essentially equivalent with the use of an occluding and a digital mandibular impression technique. (J Prosthet Dent 2002;87:603-12.)

Synthesis of the measurement system on the machine tool

The design methodology of a 2½-dimensional measurement and inspection system realized on a machine tool using a touch trigger probe and measuring G codes is studied in this paper. The reliability of measuring results, the agility of measurement, and user friendliness are synthesized in the design process. Algorithms for calibration and compensation of measuring errors are proposed to ensure the measuring accuracy by using a laser interferometer and ring gauges. Classification of probing feedrates and a collision-check algorithm can reduce measuring time and implement stylus-fracture-free measurements. To improve the previous onmachine measurement processes, all functions required for measurement and inspection processes are constructed as measuring G codes with similar forms of machining G codes. The interactive measuring program generating tool, which can automatically generate measuring G codes, is developed and potted in a ROM of a CNC, and can be called to perform an operation by the CNC without interfacing with personal computers. The validity and effectiveness of the developed system are verified on a horizontal machining centre with a Fanuc 15MA.

Topology of six degrees of freedom magnetic bearing

A novel magnetic topology has been designed for a six degrees of freedom, magnetically levitated and driven mirror, to be used in a three dimensional (3D) measurement system based on laser interferometry. The translations of the mirror are to be kept small, whereas the rotations are to be controlled over a large range with a high bandwidth and high accuracy. Finite element modelling (FEM) is used to analyze the proposed topology. For computational load reduction, a 2D FEM model has been derived from the actual 3D topology, which incorporates most of the magnetic subsystems. Simulations show that cross-influence between the actuators is small, that the forces and torques are proportional to the applied currents and that the angle of the rotor is of little influence. This allows the multiple in multiple out system to be regarded as multiple linear single in single out systems.

New Three Dimensional Measurement System for Tooth and Dentition Size by Extreme Close up Photographing

New Three Dimensional Measurement System for Tooth and Dentition Size by Extreme Close up Photographing

Self-ratings of ADHD symptoms in adults I: Factor structure and normative data

Background: Although well-standardized behavior rating scales are routinely utilized in children for evaluations of Attention Deficit Hyperactivity Disorder (ADHD), comparable measures for adults with ADHD symptomatology have been sparse. Based on current literature and clinical experience, nine aspects of adult ADHD functioning provided initial hypotheses regarding factor structure and scale items for a new scale for self-rating of symptoms by adults suspected of having ADHD. Method: A normative sample of 839 subjects and a clinical sample of 167 subjects completed ratings of an initial pool of 93 items. Results: Exploratory and confirmatory factor analyses suggested a four-factor structure involving 42 items. These factors include Inattention/Cognitive Problems, Hyperactivity/Restlessness, Impulsivity/Emotional Lability, and Problems with Self-Concept. Conclusion: The scale appears to cover the core features of ADHD as seen in children and adolescents, while adding content unique to adult expression of the ADHD syndrome. The new scale (Conners' Adult ADHD Rating Scale, or CAARS) may provide a useful dimensional measurement system for research and clinical applications.

3D Profile measurement using a multi-gray scale compared with reference projections

Using a three dimensional measurement system with a gray code projection, this paper proposes a novel technique for improving the reliability of the space encoding method. This space encoding method can measure a colored object under a normal illuminated environment. The measurement space is separated into 256 sub-spaces by four gray level patterns. These patterns are projected by a liquid crystal display projector, and are observed by a CCD camera. When the measurement area is 160 mm × 130 mm, the measurement accuracy of this system is approximately 0.5 mm, and the standard deviation is 0.35 mm in a dark room environment and 0.39 mm in a normal illuminated environment. It is shown that this method can be used to measure a colored object by measuring a colored plaster figure in a dark room environment and under a normal illuminated environment.

Method for Ball Screw Generation without Form-Dressing. Development of Dimensional Measurement and Shape Analysis System for Ball Screw.

In a previous report, a method for ball screw generation using a standard-shape grinding wheel instead of a form-dressed grinding wheel was proposed. The result of the shape analysis of the generated ball screw performed using a conventional contour analysis system contains some errors, because in the system the cross section of the ball screw groove is assumed to be a gothic arch, a combination of circular arcs, while the actual profile of the ball screw generated by the present generation method is not always a gothic arch. In this paper, an advanced dimensional measurement and shape analysis system for a ball screw which can be applied to any cross-sectional shape is presented. The dimensional measurement method of the system, named the six ball method, similar to the three wire method for measurement of normal thread, and is more exact than the three wire method. In the shape analysis method in the present system the shape of the cross section is not assumed to be a circular arc, but the contact point of a steel ball is determined directly through the simulation of the contact between the groove surface and the steel balls. Using this system a detailed examination of a ball screw profile was performed.

岩盤開発設計のための予測とモニタリング （その７） 長大残壁の安全監視へのＧＰＳ変位計測システムの応用に関する現場実験

Open pit quarries often form large slopes after a long-term excavation. In early 1990s, some large failures of those slopes in Japan occurred. Therefore a method for monitoring the slope stability is necessary and should be established immediately.The Global Positioning System, a surveying system using artificial satellites, is a promising method for monitoring long-term stability of large slopes. The GPS offers several advantages which include: it is a three dimensional measurement system with high accuracy for a long baseline, and measurement can be taken during night and day under varying weather condition with portable equipment. The first and third authors have developed a new system by using the GPS for monitoring ground displacements at real-time.In this paper, the GPS displacement monitoring system is outlined and a field experiment to investigate the applicability of the system at a practical slope is described and the results are discussed.

多値パターン投影による3次元形状測定 (第2報)

In three dimensional measurement system using the gray code projection, this paper proposes the technique for improving the reliability of the space encoding method. This space encoding method can measure the object under the illumination, the colored surface of object. The measurement space is encoded to 256 spaces by four gray level patterns. These patterns are projected by liquid crystal color projector, and are taken by CCD camera. When measurement area is 160 mm × 130 mm, measurement accuracy of this system is 1 mm, and the standard deviation is 0.41 mm in the horizontal cross-section, 0.34 mm in the vertical cross-section. It is shown that this method can measure colored object, by measuring the colored plaster figure in the dark and under the illumination.

High Resolution Still Video Camera for Industrial Photogrammetry

Still video cameras are easy to handle, portable, digital image acquisition devices for close range photogrammetry. They allow fast object recording without being connected to a computer. As an example of the new camera type, the high resolution Kodak DCS200 is presented in this paper, combined with the DPA digital photogrammetric station used for image measurement and object reconstruction. The performance of this three dimensional measurement system is illustrated by calibration results as well as applications to high precision dimensional inspection in industry.