Abstract
KEYWORDS –Stepped automatic transmission, Driver’s intention, Identification, Gearshift rule, Optimization
ABSTRACT – A performance index weighted method has been proposed to reflect the significance of each performance in the optimization of gearshift rules to improve the comprehensive performance of vehicle equipped with stepped automatic transmission. In order to appropriately express the driver’s expectation on each individual performance and meanwhile build a link between the driver’s intention and the optimized gearshift rules, an inference method based on fuzzy logic has been used to map the driver’s manipulating behavior and the vehicle operating status to the weights corresponding to each performance such as power performance and fuel economy. The physical parameters that can describe driver’s manipulating behavior and vehicle operating status are used as the input of the inference system, and the weights for each performance are used as the output of the inference system. A set of fuzzy rules have been induced from the experience of experts, skilled drivers, as well as sampled test data, and these rules have been further used to calculate the weights, and the weights are used to reflect the driver’s preference in a comprehensive performance evaluation function. Two typical individualized gearshift rules for a 6-speed automatic transmission have been calculated via genetic algorithm (GA). The inference method and the vehicle performance corresponding to the optimized individualized gearshift rules have been evaluated and compared via simulation. Simulation results show that the proposed fuzzy inference method can express the driver’s performance preference, and the optimized individualized gearshift rules corresponding to different driver’s manipulating modes make the vehicle equipped with stepped automatic transmission get an acceptable comprehensive performance and meanwhile adapt to individual driving patterns.