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Since the nonlinearity which inherently exists in vehicle system need to be considered in active suspension control law design, a new control strategy is proposed for active vehicle suspension systems by using a combined control scheme, i.e., respectively using a PID controller and a fuzzy logic controller in two loops. In this paper, the investigation is mainly focused on vehicle ride comfort performance and simulations in straight running operating condition are presented. The control goal is to minimize vehicle body vertical and pitch accelerations for passenger comfort. The control system consists of two parallel control loops. One loop, using PID control, is to minimize vehicle body vertical acceleration; and the fuzzy logic controller is to minimize pitch acceleration and meanwhile to attenuate vehicle body vertical acceleration further by tuning weighting factors.

A nonlinear controller for electronically controlled clutches of Automatic Mechanical Transmission (AMT) vehicle is designed based on the variable structure control strategy. During the automatic clutch engagement, influence of dynamic characteristics of clutch on the longitudinal driving comfort and fuel economy of the vehicle is examined and discussed. It is difficult to control the engaging process of the automatic clutch because there exist nonlinearities and uncertainties due to variation of vehicle characteristics, driving condition and the driver's intention. Good performance of the system requires high standards in design of the control system, which are dependent on an accurate model of the dynamic system, a robust controller and so on. In this paper, a nonlinear controller is proposed based on variable structure control (VSC) for the purpose of improving dynamic responses for engagements of the automated clutches at vehicle start-up and shift.