Suspension is the integral part of vehicle's body. Its main purpose is to reduce the vertical acceleration transferred from rough road conditions to passenger seat, so in returns offering better ride comfort. Passive suspension systems have been utilized for decades. In Passive suspension system, spring absorbs all the energy and the damper then dissipates this energy in the form of heat. However, the passive suspension system could not meet the conflicting requirements among the ride comfort and the road holding. The parameters of these kinds of suspension are in general fixed and they cannot be adapted to road surface. This in returns give very discomfort feeling to passenger if the stiffness is hard or it affects vehicles stability when stiffness is soft. The semi-active control strategy is effective than passive control strategy, the passive suspension spring is still involved in this strategy, whereas the force of damper can be controlled with respect to operating conditions. Active suspension systems have much better advantage of introducing external actuator force based on the feedback obtained from the sensors.

M. Umair Khan is a lecturer in the department of electrical engineeing COMSATS Abbottabad, Pakistan. Dr. Laiq Khan is a professor in the department of electrical engineeing COMSATS Abbottabad, Pakistan.