A laser displacement sensor based on the triangulation method is capable of high-speed measurement, has a long working distance, and has a wide measurement range, so it can be used for distance measurement, vibration measurement, positioning measurement, form measurement, etc. However, speckles are generated in the image spot because the laser, which is coherent light, is used as the light source. It is known that the center of gravity of the image spot changes due to this speckle pattern, resulting in a change in displacement. The displacement fluctuation due to speckle is considered to be related to the NA of the light receiving lens, the triangulation angle of the receiving lens, the wavelength of the light source, and the surface textures of the irradiation spot. In this study, we varied conditions of these elements and measured micro form. As a result, it was found that the displacement fluctuation decreased with increasing NA and triangulation angle. Regarding the wavelength of the light source, it was possible to reduce the displacement fluctuation by shortening the wavelength. It was also found that the displacement fluctuation differs depending on the submicro topograpy of the irradiation spot. These results are important in designing the laser triangulation sensor.
In this paper, a method for scale-reconstructible Structure from Motion to improve the robustness of three-dimensional (3D) reconstruction with a thin plate is proposed. Scale-reconstructible Structure from Motion is a 3D measurement method with an absolute scale using a single camera and a refractive plate. However, previous studies need a large thick refractive plate to achieve scale-reconstructible Structure from Motion. To solve this problem, a weighting factor according to the amount of refraction for optimization of 3D reconstruction was designed. It was confirmed that optimization using the weighting factor is effective for the robust 3D reconstruction method by simulation experiment.
A continuously variable transmission (CVT) consisting of slider-cranks, solid cams and non-invertible mechanisms is discussed in this paper. The conventional CVTs are mainly classified as belt-types or toroidal types in conduction mechanisms. Basically, these conventional CVTs are composed of frictional conduction components. However, the proposed CVT in this paper does not have any special friction conductions. Friction force which is being occurred in the conventional CVTs gives their energy transfer efficiency more inferior. The mechanism without any friction conductions provides a high function that creates no noise, is durable, and offers high transmission efficiency. The details of the fundamental design method for the new CVT are mainly explained in this paper. Four identical slider crank mechanisms as one of four-bar crank mechanisms are placed in parallel in the CVT. The proposed CVT does not generate any slip phenomena even if high power or torque is conducted in the mechanism. In particular, we analyze the geometry of the link mechanisms and three-dimensional cams, and design the shape of a solid cam in each gear ratio. Furthermore, we estimate the required number of all units consisting of slider-cranks, and takeover time of each unit in the CVT.
Laser sintering is one of the additive manufacturing technologies that used in product manufacturing. The mechanical property of the parts built by laser sintering is known to have anisotropy and design and building layout are limited by anisotropy. Stacking marks on surface is assumed in one of reason in anisotropy and it is expected that anisotropy is slacked off by removing stacking marks. In this study, difference of mechanical properties and anisotropy by whether post processed or not was investigated and to reveal effect of post processing was attempted. As post processed, specimen was cut out from laser sintering plate parts and was removed stacking marks. Tensile test was carried out and tensile properties and degree of anisotropy in post processed specimen and non-post processed specimen were compered. As a result, post processed specimen showed higher tensile strength and elongation at break than non-post processed specimen in build direction and anisotropy was became weaker in all tensile mechanical properties. This fact was suggested that post process by surface cutting is effective for making parts which have homogeneous mechanical properties.
This study proposes a new method of tool path generation with suppressing chatter vibration. To achieve the objective, a new cutting simulator has been developed in this study previously. The simulator is developed based on the Vatti clipping algorithm that can realize high speed and high accuracy, and can calculate chatter stability diagrams of each cutting point successively owing to its high speed property. Therefore, the tool path without chatter can be generated by tracing points in the stable region. In this paper, details of the generation algorithm of the tool path without chatter using the cutting simulator is presented. And the effectiveness is confirmed by pocket machining with a square endmill by comparing with the conventional tool path.