METHOD AND APPARATUS FOR COMPENSATING PRESSURE FLUID CHARACTERISTIC OF SERVO VALVE IN ELECTROHYDRAULIC SERVO DEVICE

摘要

PURPOSE:To enhance the control ability of an electrohydraulic servo device by adjusting a loop gain to the maximum value (maximum permissible value) less than hunting limit in each load pressure corresponding to load pressure alteration. CONSTITUTION:A loop gain is made to be a total gain of loop running through an adder 8, a multiplier 101, an amplifier 5, a servo valve 3, a hydraulic cylinder 2, a pressure detector 11, and an amplifier 10, and becomes variable by the output (y) of a function generator 102 to the multiplier 101. In the vicinity of load pressure PL=0, the gain of the amplifier 5 is determined so as not to generate hunting in a servo system. In this case, the output (y) of the function generator 102 to the multiplier 101 is determined one (1). When the load pressure becomes PL=PS (the gradient between the pressure of the valve 3 and fluid amount becomes the maximum), the output (y) is determined to form the loop gain being limit not to generate hunching in a servo system.