This paper presents the motor vehicle velocity control that, under certain well-defined conditions, ensures a minimum fuel consumption. To this purpose, a vehicle with a stepped mechanical transmission is considered, assuming that the gear is unchanged during the movement. This optimal control problem is formulated for different cases and solved by applying Pontryagin's maximum principle. Whenever there is a singular solution, it is shown to correspond to the uniform motion law. The optimal velocity controls include the following phases that may be combined in different ways: deceleration without engine shut-off (null engine power), strong decelerative braking, constant speed movement and full-throttle acceleration. Examples are presented by using the experimental data on engine fuel consumption. The stress falls on the significant reductions in fuel consumption that can be achieved compared to uniform motion. (A)
Abstract