A study of discrete-time sliding mode control for SI engine idle speed control

This paper investigates the application to the provision of integral discrete sliding mode tracking control with input constraint for engine idling speed control because the control logic are always implemented in discrete-time by microprocessors. The subject of this experiment is to improve the stability of the system against disturbances such as fuel purges and torque loads. A discrete Sliding mode control based on servo system is employed that effectively remove the steady-state error when the bias power disturbance occurs. The control logic also concluded a design of feedback compensation gain, derived from the control input difference, to compensate for control input constraint. A mean-value engine model combined with dead time and superimposed disturbances was constructed in Matlab/Simulink. The simulation results showed the issue relating to steady-state deviation was successfully solved under the disturbances having bias power, and also robustness was maintained during engine speed fluctuations.