Torque estimation based on nonlinear engine model considering crankshaft torsion

This paper discusses a torque estimation method for combustion engines by utilizing nonlinear modeling. In the proposed method a precise nonlinear engine model is described, and is used to estimate the engine torque based on a crankshaft angle. Especially the torsional effect of the crankshaft is considered in the proposed framework to improve the estimation accuracy. The model requires derivatives of the crankshaft angle, and a high-gain observer plays an important role to differentiate the angle. The proposed method with the precise engine model is verified through some numerical simulations. The simulation results show that the method can improve the torque estimation even with unignorable crankshaft torsion.