Abstract: Improper accelerating strategy is critical to deteriorate the fuel consumption of ground vehicles. In order to reduce fuel consumption during acceleration, the fuel optimized accelerating strategy of CVT-based vehicles under the framework of pseudo-spectral optimal control is studied quantitatively. The vehicle longitudinal dynamic model including engine fuel consumption is built first, and an equivalent fuel consumption index is proposed to eliminate the effect of the travelling distance. Further the identification of eco-accelerating strategy is then converted into a Bolza-typed optimal control problem. The state equation and performance index is strongly nonlinear, which makes it difficult to obtain theoretical optimal solution. So the Legendre pseudo-spectral method is adopted to obtain the numerical solution. The economical accelerating strategy is presented quantitatively and the mechanism of the numerical results is also analyzed by using differential element method. The simulation and analysis show that fuel-optimized accelerating strategy is the balance of increasing engine efficiency and decreasing air resistance, the optimal accelerating strategy is a dynamic strategy which is closely related to the engine characteristics and target end-state speed, both aggressive and mild acceleration are objectionable to good fuel consumption in accelerating process. The potential fuel benefit of the proposed strategy is evaluated by simulations.

Key words: accelerate, eco-driving, optimal control, pseudo-spectral method, vehicle