Development of a Simplified Model of Speed-Specific Vehicle-Specific Power Distribution Based on Vehicle Weight for Fuel Consumption Estimates

Abstract

The vehicle-specific power (VSP) distribution, as one of the fundamental inputs of VSP-based emission models such as the motor vehicle emission simulator model, is sensitive to vehicle weight. Developing field VSP distributions requires extensive vehicle type-specific trajectory data, which is expensive and time-consuming. On the other hand, estimating fuel consumption accurately by employing VSP distributions for various vehicle types is computationally highly complex. This study aims to develop a simplified model of speed-specific VSP distribution based on vehicle weight for fuel consumption. First, field speed-specific VSP distributions of eight types of vehicles are developed. Second, the Gaussian function is employed to fit the field speed-specific VSP distributions to “change” the discrete VSP distributions into continuous distributions to facilitate quantifying the relationship between VSP distributions and vehicle weights. Third, the relationship between VSP distributions and vehicle weights is quantified by employing polynomial functions. The results indicate the acceptable accuracy of the simplified model, with 93.8% of R2 of the Gaussian function being greater than 0.90. The error in estimating fuel consumption using the simplified model is acceptable. For vehicles weighing 1.5 t (1.5 metric tons), the average error is 6.3%. Besides the “hole filling” of VSP distributions of inaccessible vehicles, the simplified model will reduce the computational complexity of estimating fuel consumption by about 50%, which is beneficial for the realization of real-time online estimates of fuel consumption.