Gearshift Sequence Optimisation for Vehicles with Automated Non-Powershifting Transmissions

Journal article, 2003

Vehicle powertrains are increasingly automated. The gearshift strategy that is built into an automated manual (non-powershifting) transmission (AMT) has to determine when to shift and to which gear. AMT has the potential to reduce environmental impact and improve vehicle performance. However, the gearshift strategy is far from obvious, especially for heavy-duty trucks with many gears. This paper presents an analytic tool for finding the ultimate gearshift sequence for any given vehicle and driving situation. The paper includes some case studies that show credible results. These studies addressuphill acceleration and engine torque down control. The optimisation criterion used is minimum acceleration time. The tool is based on a trajectory optimisation method called dynamic programming. The cost function is formulated using simulations results from a dynamic system model, which can be implemented in Simulink. Comparisons with measurements secure a reasonably good practical relevance.