Estimation of engine rotational dynamics using a closed-loop estimator with stroke identification for engine management systems

Abstract

In order to study the effect of the crank sensor noise on the engine management system (EMS), an algorithm using a closed-loop estimator with stroke identification is proposed to estimate the engine rotational dynamics. Estimated crank angle and engine speed are used for fuel injection and ignition control systems. The closed-loop estimator design is based on a linear model by assuming that the engine rotational inertia is constant. Since the effective inertia actually varies with different crank angles, the stability of the proposed algorithm is assessed using the Lyapunov stability theorem. Performances of the proposed and traditional algorithms are evaluated using a non-linear engine model with a four-plus-one-tooth crankshaft wheel in Matlab/Simulink. The estimated crank angle and engine speed of the traditional algorithm can be significantly affected by large sensor noises resulting from the poorly grounded ignition coil. It was found that the proposed algorithm can mitigate the noise impact and thus maintain the desired engine control performance.