ESTIMATION OF INSTANTANEOUS INDICATED TORQUE IN MULTICYLINDER ENGINES

A method and apparatus for estimating instantaneous torque in an internal combustion engine includes a comprehensive model of internal combustion engine dynamics. Instantaneous net torque is estimated using a model which describes the relationship between engine indicated torque and crankshaft angular velocity. The first method and apparatus perform an explicit model inversion to solve for individual cylinder combustion torques. The second method and apparatus perform an implicit model inversion for reconstructing combustion torques produced by individual combustion events in an internal combustion engine. Unknown input observers are used in the implicit model inversion. The individual cylinder combustion torques are monitored as an indication of engine performance.