Powertrain control strategy determination for computer–controlled transmissions

An analytical method has been developed for determining the optimal power–train control strategy (engine calibration and shift strategy) on a second–by–second basis through a user specified drive cycle. The optimisation process is subject not only to emission constraints, but also permits the introduction of transmission dynamics and driveability considerations, such as shift frequency, as further operating constraints. With the inclusion of new constraints in the program, the fuel economy projection, the shift strategy, and therefore, the engine speed/road trajectory and the engine calibration are automatically altered by the simulation to reflect the impact of the imposed constraints. The methodology can be applied to both discrete ratio and continuously variable transmissions. In this paper, the optimisation algorithm is detailed and a graphical technique is described for deriving vehicle implementable shift strategies from the optimum. The effects on shift strategy and fuel economy of variation of dri...