Robust Vehicle Speed Control Using Disturbance Observer in Hybrid Electric Vehicles

This paper presents a practical approach using disturbance observer (DOB)-based longitudinal vehicle speed control in hybrid electric vehicles (HEVs). Speed control law is derived from a linearized nominal plant model obtained assuming that the vehicle is a lumped mass. The plant uncertainty and external disturbance are lumped into a disturbance term and compensated for by the DOB. In addition, a feedforward term is designed to improve tracking performance when a target trajectory varies during acceleration and deceleration. The proposed control algorithm is validated by simulations. Vehicle experiments are performed on C-segment HEVs and D-segment plug-in HEVs. The validation results from both simulations and vehicle experiments, comparing a proportional-integral (PI) controller, show that the proposed controller is more robust to model uncertainty and external disturbance.