Robust Multivariable Idle Speed Control

The problem of a multivariable idle speed control with high robustness against variations of the load torque and against influences of unmodeled dynamics is considered. The control variables include the throttle position, the spark timing, and the air-to-fuel ratio. The objectives are both controlling the idle speed and preventing steady-state deviations of the spark timing and the A/F-ratio from their nominal values. Several controllers developed with the LQG/LTR method for the model based design of robust output feedback controls are presented. The responses of the control systems to steps of the load torque shown. Both simulation results and experimental data are displayed.