Vibration Control Of Semi-active Suspension Integrated With Magnetorheological Fluid Damper

Semi-active vehicle suspension system integrated with Magneto-rheological fluid(MRF)dampers are becoming more and more popular due their superior performance over passive suspension system.MRF damper uses a type of smart fluid known as magneto-rheological fluid whose rheological properties can be adjusted with the application of voltage/current.They are adaptive devices that combines the effect of both passive and active suspension system with low power requirement.The performance and power requirement of such systems are highly dependent on the used control methods.The aim of this study is to design a control technique in order to achieve desired suspension performance and to investigate the effect of different control techniques on power requirement of MRF damper.This study presents the application of a fractional order control technique for a semiactive suspension system integrated with magneto-rheological fluid damper.Fractional order proportional-integral-derivative(FOPID)controllers are generalized form of classical proportional integral derivative(PID)using fractional calculus.The fractional order of derivative and integral of FOPID controller offers more flexibility in succeeding the control objective function.In this study,a Nelder-Mead optimization technique is adopted to optimize the FOPID controller gains to enhance the ride comfort and stability according to the desired performance criteria.The developed control system has two nested controllers.A continuous state controller is employed as a damper controller and a FOPID controller is used as a system controller.A two degree of freedom quarter car semi-active suspension model integrated with MRF damper has been investigated using proposed control system.For simplicity,only vertical dynamics of the suspension system is considered.Simulations results clearly shows the effectiveness of the proposed controller system in comparison with a conventional passive suspension system.The proposed system also shows superior performance in comparison with conventional PID controller.This study also investigates the effect of different control methods on power requirement of a semi-active MRF suspension system.For this purpose,a skyhook on-off,skyhook linear,conventional PID and proposed FOPID controller are compared in terms of their power requirement of MRF damper.The results showed that different applied voltage is required in different control strategies.The very small amount of power required for MRF damper can show its potential for it to be self-powered.