The application field of the pneumatic systems is limited comparing the electromotive system and the hydraulic one. Because control performance of the pneumatic systems is inferior to the other system. But the pneumatic system has the character which is not present in the electromotive system and the hydraulic system, i.e., high safety and excellent environmental preservation. If the control performance is improved, it will be possible to apply the pneumatic system to every industrial field. In the pneumatic system, the main factors that control performance is especially inferior because the character of the plant changes widely by air compressibility and the difference in the load mass. Therefore, pneumatic servo system cannot accomplish satisfactory control performance by using usual control methods (PID or optimal control methods). So an adaptive control system has been introduced to improve the control performance.
This paper presents a design scheme of an adaptive pole-placement control for pneumatic servo systems. In this design scheme, we used unique method for deciding control parameters. The effectiveness of the proposed design scheme is confirmed by experiments using the existent pneumatic servo system.

抄録全体を表示

A pneumatic regulator using a solenoid valve is more useful than a conventional diaphragm-type regulator, in view of output accuracy and response against the changes in the load. However, if solenoid valve is controlled using an ordinary control method such as the Bang·Bang control, the fluctuation of output pressure is inevitable due to the switching action of the solenoid valve.
In this paper, we propose a method capable of a continuous flow rate and pressure. It can be shown that the providing a high-speed operation pulse to a solenoid valve makes the plunger of the valve to be wafted in the middle of the stroke.

抄録全体を表示

Pneumatic cylinder systems design has been conducted treating pipes only as a restriction using the equivalent effective area method, neglecting the air temperature change in the pipes. According to this method, the cylinder velocity is the same when restrictions along the pneumatic line are the same. However, this paper shows different results using the same restrictions when only the position of the speed control valve along the outlet pipe is changed. These results are explained by the air temperature change in the outlet pipe and impossible to predict with the equivalent effective area method. To verify the air temperature change, air temperature is measured using thermocouples and experiments are simulated using a pipe model with consideration given to heat transfer. The influence of the air temperature change in the pipe on cylinder response is clarified. Simulation results using a previously proposed pipe model show that cylinder response can be predicted accurately.

抄録全体を表示

The pneumatic cylinder has internal rubber seals. When the piston moved toward the desired position, the seal sticks and slides and then attaches itselt to the cylinder wall or piston rod, near the final position. So the viscoelastic formation of the seal appears and has an affect on the control performances, such as positioning accuracy, stability and settling delay in this region.
In this report, the viscoelasticity of piston displacement caused by the seal when it attaches is examined and the effects of viscoelasticity regarding the control performance are analyzed. It is shown that the viscoelasticity becomes very large near the desired position such as within 0.02mm and as a result, piston displacement becomes very slow. The speed can not be improved using the ordinary control method. To improve the settling delay and ensure the control stability, the control method, taking account the viscoelasticity model, is induced and the various types of performance are specified. The control is composed of the feedback loops by using the response model of system including the viscoelasticity.

抄録全体を表示