Pneumatic Fuzzy Controller Simulation vs Practical Results for Flexible Manipulator

Abstract

The flexible manipulators have many industrial applications; but most of the reported works are using electrical or hydraulic actuators. These actuators have a linear behaviour and the control is easier than pneumatic actuators; but the pneumatic position control is a highly non linear problem, due to the air compressibility behaviour and internal friction (Moore & Pu, 1993). Because of these conditions, there are certain difficulties in pneumatics cylinder control design. The main disadvantage of electrical actuators is the low powerweight rate, the high current related with its load and it is heavy. The hydraulic actuators are not ecological, needs hydraulic oil and return lines to the pump is needed. By the other hand, the pneumatic actuators are clean, economy, light, faster, have a great power-weight rate and return lines are not needed. However, pneumatic actuators are not used into flexible manipulators developed due to their highly non linear behaviour. It is important to note that research lines; such as pneumatic control, embedded systems and flexible manipulators, are used in separate way. As a matter of fact, most of manipulators robots use electric or hydraulic actuators; however, the pneumatic actuators are being used in recent years (Ramos at al, 2006a; Ramos et al, 2006b) to control a flexible manipulator arm. This is the beginning of a project which involves the use of a pneumatic cylinder to control a flexible manipulator robot. Our first approach is to use one degree of freedom, but the main goal is to have a two degree of freedom flexible manipulator. Several pneumatic controllers had been developed; for example, the Model Reference Adaptive Control, MRAC (Suarez & Luis, 2005); however, the pneumatic model used for the control design, have the next considerations; a lineal actuator, a lineal valve, without damping systems at the sides, ideal gas, adiabatic changes and constant viscous friction. Other works have been focused in friction parameter identification techniques of cylinder pneumatic (Wang & Wang, 2004), dynamic modelling and simulation (Jozsef & Claude,