Three-dimensional shape measurement of a transparent object using a rangefinding approach

This paper describes a non-contact optical measuring approach by which to measure the three-dimensional (3D) shape of a transparent object such as a glass panel or an acrylic plate. In conventional approaches to obtain the 3D shape of a transparent object, contact-type sensors have been widely used. However, the measurement accuracy of contact-type sensors is susceptible to the influence of various factors. In this paper, we propose a novel triangulation-based rangefinding approach that can be applied to the 3D shape of a transparent object or to an opaque object. The rangefinder is based on the fact that the light projected onto the surface of a transparent object is in part reflected by the surface, though the majority of the projected light is transmitted through the surface. From the experimental results, the proposed rangefinding approach has the advantage that it can easily measure the 3D-shape of an object if the object reflects or transmits light, depending on its location. As a result, we conclude that the proposed approach has great potential for a wide range of industrial applications.</p

Constraint satisfaction on dynamic environments by the means of coevolutionary genetic algorithms

We discuss adaptability of evolutionary computations in dynamic environments. We introduce two classes of dynamic environments which are utilizing the notion of constraint satisfaction problems: changeover and gradation. The changeover environment is a problem class which consists of a sequence of the constraint networks with the same nature. On the other hand, the gradation environment is a problem class which consists of a sequence of the constraint networks such that the sequence is associated with two constraint networks, i. e., initial and target, and all constraint networks in the sequence metamorphosis from the initial constraint network to the target constraint network. We compare coevolutionary genetic algorithms with SGA in computational simulations. Experimental results on the above dynamic environments confirm us the effectiveness of our approach, i.e., coevolutionary genetic algorithm</p

Range imaging system with multiplexed structured light by direct space encoding

Since practical multiplexed structured light systems currently available use plural light patterns or different illumination conditions to ensure a high reliability, their fast performance is impaired. This paper describes a fast, highly reliable range imaging system with a multiplexed structured light system that uses a direct space encoding approach while using only a single light pattern. Unlike a conventional encoding approach, the proposed approach is unique in that it encodes object space through the use of a special optical system which consists of field stops, plural lenses, and shield masks, rather than a light pattern. The theoretical considerations and experimental results demonstrate that the proposed approach is effective for a highly reliable, fast, accurate range imaging system </p

Film Continuity Problem on Journal Bearing Design

Pressure distribution has been measured and analyzed to clarify the fundamental characteristics of "continuous oil-film" formed in a transparent journal bearing, into which oil in general use is supplied. Measured pressure mostly shows quasi-Sommerfeld distribution, which is characterized by downstream shift of pressure profile and underdevelopment of pressure trough compared with Sommerfeld distribution for perfect oil-film. Sommerfeld distribution is approximately observed only under limited conditions : low eccentricity and low speed. Quasi-Sommerfeld state is rather common in "continuous oil-film", unruptured film formed by using practical lubricants, than Sommerfeld state. Continuous oil-film is accompanied by fine bubbles and is controlled by the growing up or down of the bubbles

A new fast rangefinding method based on a non-mechanical scanning mechanism and a high-speed image sensor

In this paper, we present a new fast rangefinding method based on a non-mechanical scanning mechanism and a high-speed image sensor. Although the light stripe rangefinding method often is utilized to measure three dimensional shape of an object, it is difficult to acquire dense range data at high-speed with conventional light stripe rangefinders. We proposed a fast rangefinding method based on two new ideas unlike conventional methods: (1) to move a parabolic light pattern onto the object by means of a non-mechanical mechanism; (2) to detect a true peak value using a high-speed image sensor. We have designed and built a prototype rangefinder. The rangefinder was able to acquire three-dimensional position at 500 ns which is faster than conventional rangefinders. As a result, the proposed method is effective for high-speed three-dimensional measurement </p

A new method for 3-D shape measurement and surface reflectance of an object with rangefinder

An object for computer graphics application requires the following two information: the three dimensional (3D) shape and surface reflectance property of the object. We proposed a 3D shape and surface reflectance measurement system using the new sensor, which can detect the incidence position and the angle of the light simultaneously. Experimental results successfully demonstrate the efficacy of the method.</p

A new sensor system for simultaneously detecting the position and incident angle of a light spot

The present paper describes a newly devised sensor, which has the ability to detect the two-dimensional position and the one-dimensional angle of a light spot simultaneously. Ordinary laser-based measurement systems utilize CCD or PSD sensors. These conventional sensors can detect only a light spot's position. When the sensor can detect the incident angle of a light spot as well as the position, the sensor has a wide range of applicability. The sensor consists of two linear array-type sensors whose depth positions are slightly different. We have designed and built a prototype sensor system. We experimentally verified the practicable accuracy of the present sensor system. We also applied the present sensor system to two typical laser-based measurement systems: 2-D position measurement, and 3-D shape measurement for specular objects. Experimental results show that the sensor system was applicable to a laser-based measurement system. </p

A new method of measuring the 3-D shape and surface reflectance of an object using a laser rangefinder

The present paper describes a newly proposed method for simultaneously measuring 3D shape and surface reflectance of an object using a laser rangefinder. The original work of this method lies in the advantage that the proposed method measures the surface reflectance using the object itself that is used for the 3D shape measurement. Experimental results show that the proposed method was applicable to noncontact industrial inspection, robot vision in automatic assembly, and reverse engineering.</p

Preparation of nanoparticles by the self-organization of polymers consisting of hydrophobic and hydrophilic segments: Potential applications

AbstractThis review describes the preparation of core-corona type polymeric nanoparticles and their applications in various technological and biomedical fields. Over the past two decades, we have studied the synthesis and clinical applications of core-corona polymeric nanoparticles composed of hydrophobic polystyrene and hydrophilic macromonomers. These nanoparticles were utilized as catalyst carriers, carriers for oral peptide delivery, virus capture agents, and vaccine carriers, and so on. Moreover, based on this research, we attempted to develop novel biodegradable nanoparticles composed of hydrophobic poly(γ-glutamic acid) (γ-PGA) derivatives (γ-hPGA). Various model proteins were efficiently entrapped on/into the nanoparticles under different conditions: encapsulation, covalent immobilization, and physical adsorption. The encapsulation method showed the most promising results for protein loading. It is expected that biodegradable γ-hPGA nanoparticles can encapsulate and immobilize various biomacromolecules. Nanoparticles consisting of hydrophobic and hydrophilic segments have great potential as multifunctional carriers for pharmaceutical and biomedical applications, such as drug, protein, peptide or DNA delivery systems