Set terrain-based optimal speed limits for heavy trucks energy saving

Abstract

In this paper, the benefit of setting optimal speed limits according to roadway geometry in minimising heavy truck fuel consumption is investigated and is proposed to replace constant speed limits. The optimal speed limits are set with reference to the truck’s optimal speed trajectory, which is calculated by using a constrained Nonlinear Programming (NLP) solver to minimise the truck fuel consumption and travel time based on the road geometry. The developed truck model has a standard weight-to-power ratio for highway control design and performs the speed trajectory calculated by the NLP solver for real roads. Simulation results show that truck driving at the optimal speed velocity is able to significantly reduce fuel consumption with small travel time increases, when compared to constant speed cruise driving. Thus, the implementation of the optimal speed limits based on terrain variation could save heavy trucks’ fuel consumption.