Clutch control reference value setting method

A method comprising:

• measuring a hydraulic pressure applied to a clutch;
• applying a first ramp current to a solenoid valve;
• generating a current-hydraulic pressure model by acquiring a slope of the measured hydraulic pressure according to a current increase due to applying the first ramp current to the solenoid valve;
• setting a temporary volumetric kiss point (VKP) to a current causing a maximum difference between a model hydraulic pressure calculated from the current-hydraulic pressure model and the measured hydraulic pressure;
• determining validity of the temporary VKP by setting a pressure to a first target pressure that is lower than a temporary VKP pressure by a designated percent, the temporary VKP pressure being the model hydraulic pressure at the temporary VKP;
• determining that the temporary VKP is valid when a deflection amount calculated from a pressure difference integral value acquired by integrating differences between the model hydraulic pressure and the measured hydraulic pressure while increasing the current is greater than a designated first reference value when the first target pressure is applied to the clutch;
• determining that the temporary VKP is appropriate by setting the temporary VKP pressure determined to be valid to a second target pressure, wherein the temporary VKP is determined to be appropriate when a deflection amount calculated from a pressure difference integral value is greater than a designated second reference value and is less than a designated third reference value when the second target pressure is applied to the clutch, the pressure difference integral value being acquired by integrating differences between the model hydraulic pressure and the measured hydraulic pressure while increasing the current;
• using the temporary VKP as a control VKP after determining that the temporary VKP is appropriate;
• and
• controlling the clutch with the control VKP.