In this paper, we propose a method for detecting concave and convex micro defects on three-dimensional small metal parts. Generally, because visibility of this defect type depends on imaging conditions, it is difficult to detect the small defect. Major factors of visibility changes are a lighting angle, a camera position, and so on. On the other hand, in some cases, not only defect detection but also quantitative evaluation of defects is required. In previous work, the microscopic shape measuring system using iterative photo-metric stereo techniques has been developed. This system is good for the measurement precision, but computing time is long. It is necessary to reduce calculation cost in order to introduce this system to a manufacturing line as in-line inspection. Therefore, we focus on the specificity of the visibility change and treat with a multi-illuminated image analysis, and we introduce an inspection system composed of a defect detection stage and a three-dimensional measurement stage. In first stage, multi-illuminated images are converted to “the blinking pattern image”, and some defect candidate regions are detected. And in next stage, by applying three-dimensional restoration only to the candidate regions, the inspection is completed in in-line time. As a result of experiments, it was confirmed that actual concave and convex defects were detected with required precision. In addition, the computational time of quantitative evaluation of defects decreased by about 96% compared with the conventional system measuring all surfaces of a metal part.
Distribution measurement of eyelid pressure is an important technology for diagnosis and treatment on corneal disorders, dry eyes etc. The measurement methods are limited because of the eyeball surface curvature, as well as the eyelid pressure itself is fairly small ranging from 10 to 30 mmHg. So far, MEMS fabricated contact lenses and strip pressure sensors have been proposed, however, distribution measurement are impossible except an average or a local pressure. In this study, we propose a new method for the pressure and abrasive distribution measurement, in which, a color film coated contact lens works as a sensing device for the film thickness decrease due to blinking. In the first report, we experimentally evaluated thickness reduction characteristics of sucrose films, using a newly developed friction tester. Experimental results show its sufficient potential as a sensing material for eyelid pressure measurement.
Selective laser sintering hybrid milling (SHM) is an advanced manufacturing technology that combines the advantages of additive manufacturing and traditional machining. This technology is used to fabricate extremely complicated and high-precision products. The key factor of SHM is the milling process that is performed during the depositing process. However, the thermal shrinkage during the cooling process when depositing new layers on the ones that were machined is a fundamental problem because it creates deformation errors which significantly reduce product accuracy. In this study, the thermal deformation error in SHM was investigated using finite element analysis (FEA) and confirmed experimentally. The mechanism involved in the shrinkage in SHM was studied using three shrinkage rules. Moreover, a compensation technique was proposed with the aim of reducing the thermal deformation error. The results proved that compensation could significantly reduce the deformation error in SHM.
This article deals with mathematical generalization of log-aesthetic curves (LAC). We generalized LAC in terms of similarity geometry. This generalized family of curves called quasi-aesthetic curves (QAC) contains LACs, parabolic arcs, typical curves of Mineur and some well-known plane curves in differential geometry. However, the well-used curves in the field of industrial shape design, for exsample, elliptical arcs and hyperbolic arcs are not contained in the family of QACs. As our viewpoint, we observed the similarity curvature of QAC. The similarity curvature of QAC satisfies the 2-th order Burgers equation. In the applied mathematical context, the 2-th order Burgers equation is a member of the family of the n-th order Burgers equations (Burgers hierarchy). By interpreting this result, we present aesthetic curve hierarchy.