Frictional torque compensation method and device as well as idle speed control method and system

The invention discloses a frictional torque compensation method and device as well as an idle speed control method and system and belongs to the field of automobile electronic control. The frictional torque compensation method comprises the following steps: inquiring an initial frictional torque from a prestored torque pulse spectrum table according to the current engine operating parameter; carrying out double integration on the D-value of the current revolving speed and a target revolving speed to obtain a frictional torque compensation value; and adding the initial frictional torque and the frictional torque compensation value together to obtain a final frictional torque. The frictional torque compensation system realizes the frictional torque compensation method, and the idle speed control method and an idle speed control system utilize the final frictional torque acquired by the compensation to carry out idle speed control; the D-value of the current revolving speed and the target revolving speed is subjected to double integration so as to obtain the frictional torque compensation value, thereby effectively reducing or eliminating the difference of the frictional torque obtained through searching the table and the actual frictional torque of an engine; and the final frictional torque after compensation is utilized to realize more stable idle speed control.