morteza farrokhnia - Mechanical Engineering, College of E ngineering, University of Tehran, Tehran, Iran;
mohammadreza farrokhnia - Chemical Engineering,callege of Engineering, University of Tehran, Tehran, Iran
alireza roudbari - Assistant Professor, Aerospace Engineering, Sattari Aerial University, Tehran, Iran;

Vibration control of structures and mechanical systems have been of interest to engineers and researchers for a long time. In this study, the principles of semi-active control and rapid changes of damping coefficient are taking into account. Controller improves suspension system’s performance criteria including passenger comfort and handling that are significant for the vehicle passengers and handling standards. To express the governing control law on damping at any moment the calculus of variations is utilized and an optimal controller is designed for semi-active suspension system. Another application of this study can be used in airplane to provide a means of maneuvering the aircrafl on the ground. to support the aircraft at a convenient height to give clearance for propellers and flaps, etc., to facilitate loading and to absorb the kinetic energy of landing and provide a means of controlling deceleration. Simulations results confirm that proposed optimal control law improves the performance of semi-active suspension.

Suspension Performance, Landing Gear, Se1ni-active Optimal Controller, Simulation