PROJECT TITLE :

Fuel-Optimal Cruising Strategy for Road Vehicles With Step-Gear Mechanical Transmission

ABSTRACT:

This paper studies the principles and mechanism of a fuel-optimal strategy in cruising scenarios, i.e., the heart beat and glide (PnG) operation, for road vehicles equipped with a step-gear transmission. In the PnG strategy, the control of the engine and therefore the transmission determines the fuel-saving performance, and it is obtained by solving an optimal control problem (OCP). Because of a discrete gear ratio, sturdy nonlinear engine fuel characteristics, and completely different dynamics in the pulse/glide mode, the OCP could be a switching nonlinear mixed-integer downside. This difficult downside is converted by a knotting technique and the Legendre pseudospectral methodology to a nonlinear programming downside, which then solves the optimal engine torque and transmission gear position. The optimization results show the numerous fuel saving of the PnG operation as compared with the constant-speed cruising strategy. The underlying fuel-saving mechanism of the PnG strategy is explained graphically. For a real-time implementation, a close to-optimal practical rule that permits a driver and/or an automatic control system to fast select gear positions and engine torque profile is proposed with only slightly deteriorated fuel saving.