Evaluation of torque estimation using gray-box and physical crankshaft modeling

In-cylinder pressure and combustion torque provide feedback information that can be utilized in advanced control and diagnosis strategies for combustion engines. One challenge in torque estimation is the compensation of the torsional effects of the crankshaft. This paper presents a novel torque estimation method using a gray-box model (motivated from a physical model) of the crankshaft in combination with one in-cylinder pressure and one engine speed measurement. The MISO system inversion is described and the approach is benchmarked against an existing method. The results using a four-cylinder spark ignition engine encourage the further investigation of the approach.