Reducing automotive engine speed fluctuation at idle

This paper concerns an automotive idle speed control problem. Specifically, a problem of reducing engine idle speed fluctuations is considered. The authors develop an engine model for the instantaneous engine speed containing quasi-AC component. When there are different torque variations in the cylinders of the engine, the periodic variation of the engine speed fluctuates, which causes more vibration of the vehicle. The authors develop a control strategy to reduce this fluctuation with only engine speed as the measured variable by using four spark advances as control inputs.