Application of fuzzy control for a hydraulic forging machine

Most metal-forming processes are non-linear, non-stationary and time-varian t. Nonetheless, linear controllers or LTI-control systems are used for many of these processes. Because of their simplicity of application, fuzzy cont rollers have recently been implemented for many industrial processes in Eur ope, in Japan and in the USA. Fuzzy control may be characterized as an appr oach using controllers which can be designed without a mathematical model o f the process and which are inherently non-linear. Fuzzy control is based o n a priori expert knowledge which can be described in the form of a languag e. This paper discusses one application of fuzzy control, an adaptive fuzzy co ntroller for a hydraulic forging machine which minimizes geometrical and ma terial defects of the workpiece by controlling the servo valve and the pump power. The paper describes the use of the fuzzy controller with two proces ses, upsetting and thixoforging. The design procedure for the controller an d experimental results are discussed. (C) 2001 Elsevier Science B.V. All ri ghts reserved.