To grip various objects indoors by a robot, it was investigated how many kinds of object on a desk are handled and how they are gripped in a human life, in which a subject with wearable camera records images for 30 days. It was proven that not more than hundred kinds of objects are handled in gripping ways corresponding to the shape and size of each object. They were classified to 9 categories. Hands of human subject were restricted so that they only act like parallel grippers. According to the gripping way of restricted hands, categorization was revised to 12 categories. To cope with all categorized objects, the gripping methods were proposed for dual robot arms equipped with parallel grippers. It was preliminarily proven that the proposed method has potential for practical robot arms to grip all categories of objects mentioned above.
In this study it is proposed the new measurement method of diameter for a microsphere based on whispering gallery mode (WGM) resonances. WGMs are the light propagation mode, which is occurred inside a spherical shape. Diameter is estimated based on measurement of a circumference that is equivalent to optical path length of WGMs, for which resonant wavelengths and the mode numbers are necessary to be determined. Resonant wavelengths are measured experimentally. In this paper, how to determine the mode numbers are mainly discussed. There are three kinds of modes; radial, azimuthal and angular mode. Resonant wavelengths are discrete number with these mode numbers. Free spectrum ranges (FSRs) of the resonant wavelengths include information about the mode, so focused on FSRs, the radial mode number and the azimuthal mode numbers can be determined. The determination methods were experimentally confirmed. Angular mode numbers are estimated using different two resonant wavelengths. Firstly, certain angular mode numbers are allocated to the resonant wavelengths, and then the diameter is estimated. For proper angular mode numbers, the estimated diameters are agreed with each other. After such mode analysis, the diameter measurement was performed. Variation of the measured diameters was within 30 nm, which validates a feasibility of the proposed method.
We present single-shot three-wavelength digital holography using spatial frequency-division multiplexing, spatial bandwidth enhancement, and three reference arms to generate spatial carrier frequencies. Recordable spatial frequency bandwidth is extended by utilizing signal theory. Intentional aliasing makes use of the recordable space-bandwidth product of a monochromatic image sensor. Three reference arms generates different spatial carrier frequencies for respective wavelengths. We demonstrate its feasibility by three-wavelength and lens-less recording of a metallic object with a single-shot exposure.
A novel planetary gear train (PGT) as a mechanical continuous varying gear ratio transmission is introduced and tested in this paper. The novel PGT has a novel shaft which connects planet gear rotation axis and revolution axis on it by universal joint.Although PGT has been using in many kinds machines, noise and vibration problem is still critical and it is yet to be done, especially in advanced transmission such as Toyota hybrid system and geared turbo fan engine. The new PGT can reduce meshing frequency less than one third compared to ordinary 2K-H PGTin the same gear ratio and the noise level in the new PGT is also less than that of 2K-H PGT. Furthermore, the new PGT can provide wider gear ratio than 2K-H PGT in the same meshing frequency level. Although it can achieve development goals, it also has several serious problems due to tilting axis. Problems and solutions for them are discussed in the last paper of this paper, and further PGT is introduced.
This paper presents the experimental analysis for the fluctuation of rolling friction force, which deteriorates high precision motion in linear ball guideways. A simple drive with four tracks and four balls was used to investigate the influence of contact surface and contact load on the friction force fluctuation. To provide different surface integrity, ground, polished, and shot-peened surfaces were prepared. Experimental results showed that the friction force fluctuation was dependent on position change and influenced by the inclination angle of the rolling contact surface. The fluctuation of friction coefficient was inversely proportional to the cube root of the contact load. The wavelength analysis on the friction coefficient showed that friction coefficient was suppressed as the contact load increased. An empirical formula for estimating the friction force fluctuation was proposed based on these experimental results and a single ball friction model proposed by Ishikawa and Suda.
Laser shrink fitting for pipe coupling was developed as an application of laser forming. The coupling of the pipe of stainless steel and bar of hardened oxygen-free copper is made by laser shrink fitting. A bar is inserted into a pipe, and the pipe surface of the bar-inserted-part is irradiated and heated by 1kw class laser. Metallographic structure of the laser irradiated part of the pipe is not changed. Metallographic structure of the bar is changed into recrystallization structure. The fitted part of the pipe is shrunk in both circumferential and axial direction. The residual stress on the surface of the fitted pipe is compressive in both circumferential and axial direction. The tensile strength of the fitted part is 53% to the tensile strength of base metal of hardened oxygen-free copper bar.
In end milling operations, undesired tool approach marks may occur due to the tool deflection by transient cutting force change in the tool approach motion. The tool approach marks have a particularly big influence on the machined surface quality in case of the smooth and continuous surfaces are highly required. Therefore, in this study, a method to reduce the tool approaching mark due to the tool deflection by cutting force in ball end-milling operation is proposed. The influence of the tool deflection onto the machined surface is investigated. Characteristics of the tool approach mark are investigated based on the measured machined surfaces profile. As a result, it is confirmed that the behavior of the tool approach mark can be evaluated by using the proposed machining test. It is also confirmed from the results that the tool approach mark is generated by the difference of tool deflection by changing the actual radial depth of cut during the tool approach motion. A method to reduce the tool approach marks by the tool motion paths with the offset between the retract and approach paths is adopted, and the equation of the offset for effective compensation is proposed. It is experimentally confirmed that the proposed method can effectively eliminate the tool approach marks on the finished surface.