On-line Estimation of Net Engine Torque from Crankshaft Angular Velocity Measurement using Repetitive Estimators

The need for improvements in the on-line estimation of automotive engine performance variables and model parameters pertaining to the fueling and emission control subsystems is greater nowadays as a result of more stringent emission controls and fuel economy requirements. There is also a concurrent requirement for improved on-board diagnostics to detect different types of malfunctions. The inherent periodicity of engine processes with respect to crank angle has not been fully exploited for these diagnostic and estimation tasks. The objective of the work described here is to fully recognize the advantages which are potentially afforded by this property. In particular, we focus on the on-line estimation of the torque generated in a single-cylinder CFR engine from the measured crankshaft angular velocity and a model of the rotational dynamics of the engine. On-line estimation of the torque produced by each cylinder in a multi-cylinder engine has great potential application both in engine feedback control and diagnostic strategies. The ability to recursively estimate engine torque can lead to individual cylinder control strategies, and to instantaneous detection of engine misfires. In addition, the torque estimate can also be utilized for general health monitoring purposes.