Online ISSN : 1349-7022
Print ISSN : 1880-3121
ISSN-L : 1349-7022
Volume 49 , Issue 3
Showing 1-3 articles out of 3 articles from the selected issue
  • Shuce ZHANG, Hiromu IWASHITA, Kazushi SANADA
    2018 Volume 49 Issue 3 Pages 65-71
    Published: 2018
    Released: November 12, 2018

    In this paper, a Soave-Redlich-Kwong adiabatic equation of real gas charged in accumulators is proposed. The Soave-Redlich-Kwong equation is the most accurate real gas model for representing accumulator behavior, but it is relatively complex mathematical equation. For simulating accumulator dynamic behavior, it has been used by combining with a thermal time constant model. The mathematical procedure for the Soave-Redlich-Kwong equation for the adiabatic equation is described in this paper. The Soave-Redlich-Kwong adiabatic equation is discussed by comparing the van der Waals adiabatic equation. By comparing representative gas models, the Soave-Redlich-Kwong adiabatic equation is found to be valid.

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  • Ryo YAGISAWA, Kazuhisa ITO, PHAM Ngoc Pha, Shigeru IKEO
    2018 Volume 49 Issue 3 Pages 72-79
    Published: 2018
    Released: November 12, 2018

    Water hydraulic systems are an outstanding driving source because they have no risk of environmental pollution and fire hazard. However, conventional water hydraulic systems, as well as oil hydraulic systems, have larger energy loss for pressure loss through mainly control valves. Here, there are two solutions to achieve the energy-saving: reducing the restriction loss through control valves, and applying the energy recovery module with an accumulator. In oil hydraulic systems, the independent metering system which includes two control valves for one actuator to reduce the restriction loss through valves has been proposed. This system applies a variable displacement pump to control the pump supply flow. However, variable displacement pumps have been still at the stage of research and development in the field of water hydraulics because of the internal leakage and the difficulty of selecting materials on sliding parts. In contrast, the energy recovery module can reduce the energy consumption and be applied to water hydraulic systems.

    This paper proposes two circuits which achieve each energy-saving solution for water hydraulic motor systems with a fixed displacement pump and compares the control and energy performances of these circuits. According to the experimental results, the pump supply energy of the proposed circuit which reduces the restriction loss could be reduced 40% of that of the conventional system. In contrast, the pump supply energy of the proposed circuit which applies the energy recovery module could be reduced 10% of that of the conventional system.

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  • Toshihiro YOSHIMITSU, Kousuke OHSHITA, Chihiro HAGIWARA, Osamu OYAMA
    2018 Volume 49 Issue 3 Pages 80-88
    Published: 2018
    Released: November 12, 2018

    Personal care robots are expected to be valuable labor force in Japan that is entering an aging society. When using the personal care robot in the same space as humans, there are many safety issues. Personal care robots are actively researched, and flexible pneumatic actuators are used there. Collecting environmental information is necessary for robots and humans to coexist safely. Research on the tactile field of the robot does not reproduce the human skin sensation and the like but utilizes data obtained from contact sensors and the like as a physical quantity different from human skin sensation. However, there are many problems that have not yet been elucidated for the mechanism of human material recognition. Tactile sensation is a sense that it is possible to detect the hardness, surface roughness, temperature of an object for the first time by touching and moving an object unlike vision and hearing, and it is a sensation that it is important to actively move a finger.

    In this study, artificial fingers with joints for detecting the surface condition, hardness and temperature are fabricated using a strain gauge and a thermocouple, and by introducing active tactile perception using a pneumatic actuator, Develop pneumatic artificial fingers with near tactile sensory function. To make the texture factor equivalent to that obtained from humans by these, a material recognition system capable of discriminating the material equivalent to human by optimizing a neural network that simulates the connection structure of nerve cells in human brain.

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