Multibody Mechatronic Systems

Abstract

The vehicle longitudinal dynamics is responsible for calculating the vehicle power consumption to attend a specific route, estimating, by the equations, the forces acting on the system such as aerodynamic drag, rolling resistance, climbing resistance and the driver behavior. The gear shifting strategies influence significantly in the vehicle acceleration performance and fuel consumption because it changes the powertrain inertia and the engine speed. The literature presents gear shifting strategies based on the engine power and torque. A fuel economy strategy is more difficult to determine, because it depends on a large number of factors like the engine efficiency, vehicle speed, transition ratio and required acceleration. This paper presents a study based on the US06 standard velocity profile, in which the high speeds and acceleration stretches create a situation where the vehicle performance is limited by the engine available power and by the tire-ground traction limit. Because of the many factors involved in the vehicle behavior, it was developed an algorithm to optimize the gear shifting process to choose the more adequate strategy to each stretch. The analysis were performed by co-simulation between the multibody dynamics software Adams™ and Matlab/Simulink™, where is defined the vehicle power demand.