Demand of energy saving in various industrial fields is becoming increasingly important in recent years. The evaluation of the consumption energy in pneumatic piping systems is also becoming important. Energy losses in pneumatic piping systems are caused by pipes and various fittings that include screwed elbows, connectors, etc. Although the loss coefficient of screwed elbows in steady flow is well studied, very few studies have been made for its evaluation in unsteady flow. This paper examines the dynamic characteristics of the loss coefficient of a screwed elbow (nominal size: 1/2 B) in pneumatic unsteady flow, experimentally. This study confirmed the pressure change of a screwed elbow in turbulent pulsating flow up to 300 of dimensionless pulsatile frequency agree well with the calculation result assuming a steady-state loss coefficient.

View full abstract

In a constant pressure valve-controlled hydraulic servo system, the response is good but the efficiency is deteriorated. In a load-sensing pump-controlled hydraulic servo system, the efficiency is good but the response needs improvement. In this study, an N-level pressure hybrid power supply is proposed to realize high efficiency and high response simultaneously. In this paper, the characteristics and the working principle are described. An experimental setup of a 2-level pressure hybrid power supply is used to conduct the experiments. Experimental results show that the position response and force response of the proposed system followed the references quite well, while the efficiency is improved greatly compared with a conventional constant pressure valve-controlled hydraulic servo system.

View full abstract

The purpose of this study is to evaluate an operation system with virtual reality that is built in a virtual environment system in computer using computer graphics, and a control method of feedback in a master-slave system previously proposed by our Lab, by not only behavioral measures but also subjective measures and physiological measures. This study deals with a master-slave system for a tele-operated construction robot. The master in this system corresponds to two joysticks, which are used to operate the object from a remote location, and the slave corresponds to the construction robot with four degrees of freedom consisting of a fork glove, swing, boom and arm. In this study, the authors evaluated operability when the control method was adapted to an actual task that included transportation and piling up blocks using concrete block, based on behavioral measures (work efficiency and indexes expressing the danger level of an operation), subjective measure (measurement of mental strain using NASA-TLX), and physiological measure (measurement of physiology strain using heart rate variability). As a result, we verified that using the control method in this system could contribute to improving efficiency and safety in tele-operation work, and alleviate the operator’s mental strain.

View full abstract