A reduced-order nonlinear clutch pressure observer for automatic transmission using ISS

For a new kind of automatic transmissions using proportional pressure valves to control the clutches directly, a clutch pressure observer design method is suggested in the concept of input-to-state stability (ISS). Model uncertainties including steady state errors and unmodelled dynamics are considered as additive disturbance inputs and the observer is designed such that the error dynamics is input-to-state stable. Lookup tables, which are widely used to represent complex nonlinear characteristics of engine systems, appear in their original form in the designed reduced-order observer. Finally, the designed pressure observer is tested on an AMESim powertrain simulation model.