Adaptive closed loop material testing using fuzzy logic control

One of the major difficulties in the design of control systems for the hydraulic electromechanical systems, is presented by the fact that the specimen stiffness may change, especially, during the low cycle fatigue tests. Thus, there is a need for frequent tuning of the existing controller. Typically, an operator will change the controller´s parameters if the performance deteriorates during testing. This problem may be circumvented with adaptive techniques but also, as shown in this paper, an approach using fuzzy logic can be as successful. Further, a fuzzy compensator can overcome this structural disturbance, and still retain a simple controller configuration which is readily applicable in real time