In this paper, we describe Point-to-Point control of a pneumatic cylinder using μ synthesis. So far, the pneumatic cylinders have been controlled by PID or I-PD controller, etc. The pneumatic cylinders are difficult to control owing to the delay of the pressure dynamics caused by the compression of the air, the friction force, the changes of the loading mass and so on. Therefore, we must re-tune the control gains. A robust control system must be designed considering modeling error caused by the changes of these characteristic values. A robust controller is designed by μ synthesis in which the changes of these characteristics are considered as the uncertainty of a nominal model. Moreover, the transient response is not perfect in the controller using μ synthesis. A two-degree-of-freedom control system is constructed to improve the transient response. Experimental results show the control effects.

抄録全体を表示

As charging time is greater than exhausting time in a pneumatic resistance-capacitance circuit, the step-up and step-down response behaviors of the pressure feedback system are also different. This paper proposes a method of using an asymmetric pneumatic servovalve with software compensation, whose downstream portwidth is bigger than upstream one, for equalizing the rise time and step-down time with almost the same satiability instead of using a symmetric valve with software compensation for the high-speed force control of a pneumatic system in a spot welding machine. Using mathematical models of the pneumatic force control system, simulations of fuzzy control and proportional control systems with symmetric and asymmetric servovalve were carried out. When rise time is kept constant to be 3ms and the valve operates in linear and saturation ranges, step-down time is improved and reduced from 18ms for the symmetric servovalve with software compensation method to 5.6ms for the asymmetric servovalve with software compensation method.

抄録全体を表示

The purpose of this research is to get pressure-flow characteristics of V-notch machined on the valve plate of hydraulic pumps and motors. The changes of discharge coefficient are investigated with a basic test device by using the shape of the notch, the openings, the direction of flow, the pressure difference, the back pressure and the like as a parameter. The occurrence of cavitation is observed by means of a transparent apparatus to consider the relation with the discharge coefficient.

抄録全体を表示

An electro-hydraulic manipulator using hydraulic actuators consists of many nonlinear elements with its parameter fluctuations being much greater than those of an electrically driven manipulator. So it is quite difficult to obtain stable control perfomance.
In this report, we have applied a disturbance estimation and compensation type robust control to all the axes in a 3-link electro-hydraulic manipulator. From the results, it was confirmed that the perfomance of trajectory tracking and attitude regulating was greatly improved by the disturbance observer, the model of which is the same for each axis.
On the other hand, for autonomous assembly tasks, it is said that compliance control is one of the most available methods. Therefore, we have proposed a compliance control based on the position control by a disturbance observer for our manipulator system. To realize more stable contact work, the states in the compliance loop are fedback, where not only displacement but also the velocity and acceleration are considered. We have also applied this compliance control to the Peg-in-Hole insertion task and analyzed the mechanical relation between the peg and hole. Moreover we have proposed a new method of shifting the position of the end-effector periodically for the purpose of a smoother insertion. As a result of using this method, it could be experimentally confirmed that the Peg-in-Hole insertion task with a clearance of 0.05 [mm] could be achieved.

抄録全体を表示