Automatic Drive Train Management System for 4WD Vehicle Based on Road Situation Identification

The slip ratio of vehicle driving wheels is easily beyond a reasonable range in the complex and changeable driving conditions. In order to achieve the adaptive acceleration slip regulation of four-wheel driving (4WD) vehicle, a fuzzy control strategy of Automatic Drive Train Management (ADM) system based on road situation identification was proposed in this paper. Firstly, the influence on the control strategy of ADM system was analyzed from two aspects, which included the different road adhesion coefficients and the vehicle’s ramp driving state. In the meantime several quantitative expressions of relevant control parameters were derived. Secondly, the fuzzy logic control algorithm was adopted to design a road situation identification subsystem and a ramp driving state identification subsystem respectively. The former was based on the μ-S curve model, and the latter was based on the vehicle driving equilibrium equation. Thirdly, the physical model of limited slip differential was simplified appropriately and a spring damping model of the torque distribution was established. Finally, two typical working tests were carried out on the Matlab/Simulink-CarSim co-simulation platform to verify the proposed fuzzy control algorithm. The results show that 4WD vehicle equipped with ADM system can keep driving wheels’ slip ratio in the reasonable range rapidly by using the proposed control strategy, when its driving conditions are terrible such as low road adhesion coefficient. And so the vehicle trafficability is effectively enhanced.