Control Method Of Power-cycling Variable Transmission Based On Driver-Vehicle-Environment System

First of all, the whole mechanical structure of Power-cycling Variable Transmission(PCVT) system is introduced, and the similarities and differences between the PCVT system and other kinds of variable speed drive system are elaborated. Then the numerical model of vehicle engine, the dynamic models of the parts of hydraulic mechanical transmission with a new type of return flow resulting of double idler pulley hydraulic torque converter and the dynamic model of full vehicle are built. Based on the whole structure model, the vehicle transmission system basic shifting strategy is established. The strategy contains the optimal-power shifting strategy and the optimal fuel economy shifting strategy.In order to achieve the accurate recognition of driver’s style, the driver’s driving style can be divided into long-term and short-term driving style. And different driving style use different recognition methods: an exponential smoothing method is used to predict long-term driving style; by adopting the fuzzy clustering to identify the driver’s short-term driving style. The power demand coefficient can be identified to characterize of driver’s intention after the recognition of the driver’s driving style. According to the power demand coefficient, the basic dynamic shift strategy and economy shift strategy are interpolated for the best fit strategy that reflect the driver intention directly.The basic shift strategy will not have good control effect when a vehicle operates on the ramp. The vehicle will encounter cycle shift when climbing ramp; and the vehicle speed will rise with high gear ratio leading to inability to make full use of engine braking. The concept of degree of load is adopted to recognize the ramp slope of road. The slope of road can be quantified and presented by the degree of load. Through the quantitative slope, the vehicle driving conditions can be known clearly, thereby the gear control strategy can be modified with specific target to solve the problem of up and down hills.Based on the analysis of the lateral characteristics of the vehicle operating on curve, fuzzy reasoning based on wheel speed signal recognition model and gear decision method are established. Thus the problem of unreasonable curve shift and cyclic shift is solved when the vehicle operates on a given curve.The ramp and curves always appear at the same time when the vehicle operates on a actual road. It is needed to analyze the coupling condition to make driving environment logic priority for different priority to formulate appropriate control strategies.Through the above driver intention recognition and vehicle road environment recognition, the modified vehicle control strategy is obtained under different conditions. According to different driver’s intention and the combination of various operation conditions, the integrated control strategy is made for the coupling of the driver’s intentions, vehicle operation condition and the road environment. The simulations of full vehicle model in the ECE, EUDC and WLTC driving cycle are carried out to verify the rationality of the control strategy.