Two-degree-of-freedom damping control of driveline oscillations caused by pedal tip-in maneuver

Driveline oscillations caused by pedal tip-in maneuvers are uncomfortable for the passenger and stressing for the mechanical parts of the powertrain. In a drive-bywire vehicle, the engine torque can be used as a control input signal to reduce driveline oscillations. Approaches based on feedback control alone are often insufficient to provide tracking performance in the presence of measurement delays. We design a feedforward controller using differential flatness that complements the feedback controller to improve tracking performance. For generality, our proposed feedforward control design is for an n-th order powertrain model. We show that the phase difference between the last two inertias is a flat output when the powertrain is undamped. Using this flat output, we design a feedforward control law to prevent oscillation during pedal tip-in. Simulation results show the improved tracking performance of our proposed approach in comparison to a feedback controller with a static prefilter.