Osamu Oyama

Model reference adaptive control for a pneumatic cylinder servo system.

It seems to be useful to apply the model reference adaptive control (MRAC) method for pneumatic servo systems. Since pneumatic servo systems are easily effected by the change in system parameters such as the load mass or supply pressure, etc.The MRAC method for the pneumatic cylinder position servo system using a diaphragm-type electro-pneumatic converter is proposed in this paper. The converter acts with a very short lag time and has a simple first order transfer function. So the total transfer function of the servo system can be represented to the lower order system and this is suitable for the execution of MRAC.The experimental tests were carried out by using a 200-mm stroke and 40-mm bore single rod-type air cylinder. The reference model was set to the second order system which has an optimal dumping factor. Also, the response of the MRAC was tested under the various input conditions such as a rectangular signal, sinusoidal signal or triangular signal was yielded, respectively.As a result, the accommodations for the change in load mass, supply pressure or magnification of servo amplifier could be clarified.

Development of walking assist equipment with pneumatic cylinder

We have developed the human walking assist system for the people who have handicap of are injured. This system is composed by a pair of orthosis actuated by the pneumatic liner cylinders and a pair of shoe having a weight sensor. The reason why we decide to use the pneumatic actuators is that the pneumatic flexible characteristic caused by air compliance is soft for human and also fits for environment. This assist system supports the lift of legs and stretch of knees when the human walks on ground or stairs. The weight sensor attached in shoes measures the weight of user at the thernar and the heel. By using the data, the walking states, i.e., walk on ground, climb, and decend the stairs, are discriminated. However, only with this weight sensor, there is a limitation to recognize the walk states. So we make the new orthosis which have an additional inclination sensor to lead an angle of a thigh into the controller for an index of new discrimination.

Development of pneumatically assist walking system

We have developed a pneumatic assistance system for a human walker, who has a handicap or damage. The assistance system supports the human leg force by using pneumatic linear actuators when he desires to stretch his knee. The supportable angles of knee are large enough and the system can be widely used in the range of walking on ground or up/down stairs. This system consists of two outfits of each leg actuated by pneumatic linear cylinder and a pair of shoes having the weight sensors on the sole. When the human tries to walk, the force change is detected by sensors on shoes and the feature of signal forms in the appropriate conditions, i.e. walking on the ground or up/down the stairs are used to decide the assist timing of each assist control mode. The usefulness of this system is evaluated by the power reducing factor of human and his impression for usage.

Development and Application of Alternate Direction Air Compressor

This paper deals a new type of compressor that can deliver the air directions alternatively. This compressor is made by replacing the location of inhalation/exhalation air port into proper position of ordinary vane type air compressor. By using the compressor the direction or speed of cylinder can be selected changing the clockwise/counterclockwise rotational direction and the rotational speed of compressor and the extensional solenoid valves are not needed. In this report, we choose components of this compressor. The air motor that composes this compressor is paid to attention, and a new sample is examined.

Development of tendon-driven assistance manipulator system by air pressure control

We suggest to develop the tendon-driven 2-link manipulator driven by pneumatic cylinder as the assist care lift for the rising and sitting on a chair of elderly people, disabled people or wheelchair users. The tendon-driven manipulator system developed in this subject makes use of the pneumatic cylinder as an actuator. By means of the flexible action caused by the compressibility of the air, the welfare system using pneumatic actuators can be expected as the human-friendly assist. This system is constructed by two parts, i.e., one is the tendon-driven manipulator and the other is actuator part using pneumatic cylinder, and they are separated. The pneumatic cylinder and each link are connected by the tendon through the pulley. In this research, taking account of using the manipulator as care lift, we verified the effect of pneumatic drive, in the view point of the precision of manipulator trajects in case of actual human care.

Integral Compensation on pneumatic Cylinder position Servo System Driven with Solenoid Valve.

In this report, usefulness of seal elasticity for high accuracy positioning in a pneumatic cylinder is shown. When piston moves to desired position, the seal slides and attaches to cylinder wall. If the elastic seal attaches near the desired position, the slight displacement is corrected by its compliance with increasing or decreasing cylinder pressure, before the seal slides again. The slightly displaced operation is suitable for executing a integral compensation to reduce steady positioning error. The usefulness of seal elasticity for integral compensation to high accuracy positioning is tested in a pneumatic servo system which uses solenoid valves and the valve opening duration is operated by integrating the position error, theoretically and experimentally.