MATERIAL TESTING APPARATUS AND CONTROL METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To increase a servo valve input signal to the utmost and to enable stable operation. SOLUTION: Load is applied to a material test piece 9 by a hydraulic actuator 9 operated by a servo valve 7 and this load is detected by a sensor 11 and the difference signal to a control target input signal Ei. The detection signal Ef from the sensor is multiplied by a proportion constant Kp and this multiplication signal is inputted to the servo valve 7. The proportion constant is changed so as to become large as the absolute value of the difference signal increases, and a product of the proportion characteristic of input/output in a combination of the servo valve and the hydraulic actuator and the proportion constant becomes almost constant regardless of the change of the difference signal.