Fault Detection in Idle Speed Control of IC Engines

This paper presents a fault detection method for the idle speed control of an internal combustion (IC) engine. Two specific faults are addressed: throttle faults - actuator faults due to a mismatch between the throttle command and the actual throttle position, and manifold pressure sensor faults – faults due to an incorrect measurement of the manifold pressure. The main objective is to detect these two faults even in the presence of external torque loads varying from 5 up to 10Nm, and considering a modeling fault related to temperature variations. The proposed approach is based on residual generators using the parity equation and an active threshold calculation technique. An external torque observer is implemented, in order to simulate the external torque disturbances. Simulation results show 100% fault detection during nominal temperature conditions, and 89.6% fault detection during the initial operating stage of the engine.