Calibration system in hydraulic system

A calibration system for a hydraulic system of a working machine, comprising:

• a hydraulic actuator;
• a control valve for controlling a supply flow rate of the hydraulic actuator, including:
• a spool valve for supplying the hydraulic actuator, which opens an opening with an opening area corresponding to a pilot pressure,
• a pressure compensation valve connected to an inlet side and an outlet side of the spool valve, and configured to keep a differential pressure between an inlet side pressure and an outlet side pressure constant, and
• an electromagnetic proportional valve which outputs the pilot pressure to the spool valve proportional to a current;
• an operator input for driving the hydraulic actuator;
• a pressure sensor for detecting the pilot pressure from the electromagnetic proportional valve to the spool valve;
• an output current control unit for outputting the current to the electromagnetic proportional valve;
• a controller for controlling the control valve based on an operation of the operator input, the controller configured to detect the operator input, and direct the output current control unit to output the current to the electromagnetic proportional valve based on a corresponding data representing a corresponding relationship between the operator input and the supply flow rate of the hydraulic actuator;
• and
• a calibration control unit configured to:
• set a calibration point of the operator input,
• reference a setting data to determine the supply flow rate at the calibration point,
• set a target pilot pressure at the calibration point,
• measure the pilot pressure from the electromagnetic proportional valve via the pressure sensor,
• direct the output current control unit to adjust the current to a calibrated output current where the pilot pressure is the same as the target pilot pressure at the calibration point, and
• adjust the corresponding data stored in the controller.