Robots have been developed to assist in the manufacturing of goods.However, as regards humans, safety must be always maintained during use. This study describes a control method to promote the practical application of pneumatic robots. Generally, pneumatic robots can easily carry out force control, but satisfactory position control performance can not easily be obtained. Especially, the autonomous control of robot is not capable of coping with the rapid changes in the task required. In this study, we have proposed a master-slave type hybrid position and force control, which is effective in overcoming this deficiency. This control method consists of both autonomous control of robots as well as human control. The position control is left to the master control carried out by operators and the force control is achieved using autonomous control.
To examine the practical use of the proposed control approach, the contacting tasks are executed with a vertical standing object wall. As a result, we were able to confirm that master-slave type control can easily overcome the inherent problems existing in pneumatic robots.

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A vane pump is being widely used in hydraulic systems. The vane pump for automotive power steering should be compact in size, low in cost and to have low frictional torque for savings in energy. The power steering pump is used at a wide range of pump speeds, pressures and oil temperatures. Although such working conditions affect the friction torque, its characteristics have yet to be revealed.
Influences of working conditions such as pump speed, pressure and oil temperature regarding the friction torque characteristics of the vane pump have been investigated in this research. As a result, it became clear that friction torque in the high pressure range reduces with an increase in pump speed when the pump speed is less than 1000 rpm. Also, the friction torque at high temperatures is higher than that at low temperatures when the pressure is high. This tendency is quite the opposite when the pressure is low. On the basis of these experimental results, a mathematical model for the friction torque could be constructed. The agreement between the calculated values and the experimental ones was excellent.
In addition, it could be verified that the larger the vane stroke and the thinner the vane thickness, the less the friction torque.

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In previous reports, the vane jumping phenomenon caused by excess precompression in an entrapment region and one of its prevention techniques by means of an additional chamber to the region have been studied.
This paper reports that installation of a spring loaded accumulator to the pumping chamber is useful for preventing vane detachment and reducing the peak pressure in the compression process. It was experimentally found that the improved new method is more effective in extensive pump operating conditions than the additional chamber method. Analyses and experiments were conducted on the response time of the pumping chamber pressure, and on a dimensionless parameter calculated from a steady pressure state. Design criteria of the accumulator were established by using the dimensionless parameter so as to protect the vane detachment against excessive pressure.

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For more efficient use of micro-machines, micro-actuators using fluid power were investigated. An in-pipe mobile machine is one of practical micro-mechanisms and a simple machine using the bellows actuators was constructed previously. The machine is able to move like an inchworm due to the three actuators, however, it has to pull three power supply tubes using a large load force.
To overcome this problem, this report attempted to reduce the number of tubes. After examining the performances of the bellows actuators, based on the analysis of the inchworm motion, the required characteristics were derived and a new supporting mechanism and small-size sequence valves were constructed. The newly constructed in-pipe mobile machine with a diameter of 25mm uses phosphor bronze bellows with a diameter of 8.3mm and length of 13mm. The mobile experiments show that the machine is able to lift a load of 5.9N at a speed of 1.5mm/s with an output power of 9.0mW. Also, a theoretical analysis of the mobile performance shows that the machine is able to produce a maximum output power of 120mW due to the improved conditions.

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