In these years, demand for 3D measurement technology is increasing. However, in many of the conventional 3D measurement methods, such as phase-shift patterns projection method, it is difficult to measure shape of specular reflective and transparent objects. This is because power of reflected light is too high from specular reflective objects or too low from transparent objects, so that reflected light cannot be captured accurately by digital camera. Digital Holography has been used for resolving this problem. In digital holography, interference fringe of object wave and reference wave is recorded by digital camera. Phase of object wave can be calculated using Fresnel diffraction, and shape of object can be calculated using interferometry. Although shape of specular reflective and transparent objects can be measured using digital holography, DC and virtual term exist in single interference fringe as noises, decreases measurement accuracy. For higher accuracy measurement, phase-shift digital holography has been developed. However, for generating four phase-shift interference fringes, measurement system is expensive and complex. Moreover, phase-shift interference fringes are instable due to vibration of measurement environment. For these reasons, conventional phase-shift digital holography is difficult to apply. We propose a new method of generating phase-shift interference fringes using wave detection principle, and developed a low price measurement system using the proposal method to solve the problem. This paper uses a measuring method of phase-shift digital holography using single interference fringe. The experimental result shows how the stable 3D measurement system using single-shot phase-shift digital holography can achieve with low-cost and high accuracy.
For micro-system technology such as MEMS, techniques for handling micro-parts are the recent arisen issue. The laser trapping is one of the most expected techniques because it is non-contact method. However, the laser trapping in air condition has not matured especially in terms of method for the initial picking up phase, since the optical force by the laser trapping is relatively small compared to the adhesion forces. Therefore this study aims to develop the laser trapping method by reducing the adhesion forces, using a periodic structured substrate. The analysis shows that the van der Waals force, electrostatic force and capillary force can be decreased with the periodic structured substrate. The laser trapping experiments revealed that the substrate fabricated by the femto-second laser was effective for the laser trapping. It was found that the laser trapping on the 2-dimensional LIPSS was succeeded with a high possibility.
These days, with the advancement of an aging society, the number of people who need rehabilitation is increasing and it is desired that robotics be applied to rehabilitation. However, considering interactions between humans and robots, problems involving safety of humans are concerned. Therefore, up to the present, passive systems that are constructed of controllable fluids have been developed. Passive systems are load systems, and then they generate reaction force only when external force acts on them. So, they are stable, safe and secure systems for people. But, they have not been controlled robustly. Modeling errors of actuators cause the deterioration of controllers. In this research, the passive system is constructed using magnetorheological (MR) fluids and the robust velocity constraint control based on the disturbance observer is proposed. The proposed method will be applied to rehabilitation trainings about an isokinetic contraction of specific types of muscle contraction. Compared to the conventional method, the validity of the proposed method is verified by experiments and safe and secure trainings using robots will be achieved.
Since the energy consumption of production facilities occupies the great portion of the energy consumption in the manufacturing, the energy saving of the production facilities is important. Thus, this study focuses onto the energy consumption of the feed drive system and aims at reduction of its energy consumption. Feed drive systems are widely used for various industrial facilities such as NC machine tools, hence the energy consumption of feed drive systems are directory related with the energy consumption in the manufacturing. In order to achieve the purpose, the energy consumption of the feed drive system is clarified by using the experimental apparatus single axis feed drive system and the energy usages are also estimated by simple mathematical models. The measurement tests are carried out with both of ball-screw and linear motor drives, under several friction characteristics, and several driven mass to investigate the influence of the factors to the energy consumption of the feed drive system. As the results, it is clarified that the energy consumption is influenced by the drive system, friction characteristics of linear guide and velocity loop gain.
Silicon carbide bodies are prepared by electric current activated sintering at lower temperatures with the aid of carbon onion. Sintering process is monitored in terms of compaction rate of silicon carbide particles. The variations of relative density and hardness of sintered bodies are related to carbon onion content. As a result, the addition of 8 mass% of carbon onion provides silicon carbide sintered body with 94% of relative density and 2800HV at as low sintering temperature as 1850°C. Carbon onion is found to contribute to smaller void formation caused by inhibition of grain growth and to peak shift of the highest compaction rate to lower sintering temperatures. Furthermore, the inclusion of carbon onion influences little effect on hot hardness and improves lubricity and electrical conductivity of silicon carbide sintered bodies.
This study presents a surface treatment method that involves dipping sintered cutting tools into a high-pressure, high-temperature processing liquid. These treated tools have already been introduced in some industries, and it is obvious that tool life has improved by this treatment. Furthermore, this treatment rarely had an adverse influence on tool life. The treated carbide tools were worn by the turning experiments that involved turning a SUS304 stainless steel specimen. Results show that this treatment not only helped reduce tool wear but also required less cutting force. However, this limits the applications of treated carbide tools, e.g., they become unsuitable for heavy duty cutting. The existence of cutting oil on the tool surface was verified by FT-IR. Microscopic analysis indicated that the surface of the treated tools was rougher than that of the untreated tools, the reason for which was revealed by EPMA analysis.
In this study, we propose the new equations which predict cutting forces under the conditions of a small feed (2.5μm) and negative approach angle. They are based on Nakayama's equations. According to our previous research, the experimental cutting forces were larger than the calculated forces with Nakayama's equations. The differences were caused by size effect. One of the causes of size effect was a cutting edge radius. Therefore, the new equations were formulated with taking into account the cutting edge radius. The cutting force calculated by the new equations were approximately equal to the experimental results. The accuracy of the new equations is validated under the conditions of thrust force free cutting.
In micro-welding of aluminum alloy, its low melting point and high thermal conductivity make it difficult to obtain the large penetration depth with the good surface integrity. In order to perform the stable key-hole welding with little defects, it is important to understand the processing phenomenon near the boundary between heat conduction and key-hole type welding. Therefore, the boundary condition of key-hole generation in micro-welding of aluminum alloy was experimentally and numerically investigated with hybrid Nd:YAG laser system, in which a continuous diode laser (LD) of 808nm in wavelength was superposed in a pulsed Nd:YAG laser of 1064nm in wavelength. It became clear that the keyhole generation became stable when the continuous LD was superposed with pulsed Nd:YAG laser, and the shorter pulse interval time and higher continuous LD power led to the generation of the key-hole. The results of numerical analysis made it clear that the superposition of continuous diode laser is effective to stabilize the key-hole generation in micro-welding of aluminum alloy by pulsed Nd:YAG laser, since the continuous diode laser could keep the temperature near the boundary condition of key-hole generation appeared at the time when the temperature of welded bead was around the boiling point.