Advent of passenger cars has caused people to use them for more efficiency in their performance and wasting less time. Problems, however, still exist in them. For instance, since people travel with cars, their human bodies undergo in fatigue, restlessness, and sometimes health problems. Human body reaction under external vibration depends on the amplitude, frequency, and acceleration of the applied external excitation. These limitations which are usually announced by the bureau of standards imply the necessity of control of amplitude, vibration, frequency, and acceleration received by human body due to cars passing humps and bumps. In this paper, a quarter car model with active suspension system is considered and three control approaches namely optimal control, fuzzy control, and adaptive fuzzy optimal control (AFOC) are applied. Moreover, the performance of different controllers is compared. Application of three different methods indicate that adaptive fuzzy optimal control results in a higher performance in time, acceleration, amplitude, and consequently lower hazards to human body.
H∞ optimal control of vehicle active suspension systems in two time scales
