Fuzzy logic positioning system of electro-pneumatic servo-drive

Development of automation and robotization in manufacturing process stimulates interest in pneumatic servo-systems whose advantages include low manufacturing costs, high dynamics and reliability (Situm et al., 2004). Unsatisfactory positioning accuracy of multiaxis pneumatic servosytems considerably reduces their application in manipulating machines, manipulators and robots. Rapid advance in parallel pneumatic manipulators imposes a lot of demands on controllers of pneumatic servo-drive concerning positioning accuracy, resistance to alternating parameters of state and disturbing signals (Dindorf et al., 2005; Takosoglu & Dindorf, 2005; Schulte & Hahn, 2004). The problem of positioning accuracy of servo-pneumatic systems is difficult to solve when no sufficient information on the process of conversion of the compressed gas energy into mechanical energy of pneumatic cylinder is available (Zhu, 2006; Takosoglu, 2005). Because of that, new control methods based on artificial intelligence, for example, fuzzy logic are introduced (Schulte & Hahn, 2004; Renn & Liao, 2004; Dindorf & Takosoglu, 2005). In traditional control systems of pneumatic servo-drives control algorithms are designed intuitively on the basis of operator’s experience. In fuzzy control the knowledge coded in knowledge base is the result of experience, intuition as well as theoretical and practical understanding of control system dynamics which in this case is the dynamics of pneumatic servosystems. Thanks to fuzzy logic the operator’s knowledge can be represented by means of mathematical operations. Fuzzy control enables moving from qualitative to quantitative control of pneumatic servodrive. Application of fuzzy controller makes control of multiaxial pneumatic sevosystems possible in manipulators and robots of various kinematic structures: series, parallel or hybrid series/parallel. Advancements in software for rapid prototyping in real time and in hardware-in-the-loop simulations enable to construct and test positioning fuzzy control (Bucher & Balemi, 2006) of pneumatic servo-drives in laboratory conditions. Such an approach minimizes the design costs of control systems of pneumatic servo-drives. Pneumatic servo-drives with teaching/playback control system have considerable practical significance, especially in the control of manipulating machines, manipulators, industrial robots as well as rehabilitation and physiotherapy manipulators. 13