The design of the conventional passive suspension has always been a compromise between vehicle handling and comfort, which led to the development of the modern active and semi active suspension systems. Amongst these, semi-active suspension has been focus of research in recent years owing to its lesser complexity and less power consumption as compared to active suspension.
Semi active suspension uses real time variation in damping coefficient which can be achieved by using various control strategies. It is observed from available literature that Skyhook (for better ride comfort), Groundhook (for better vehicle handling) and Hybrid are most widely used strategies. These strategies use ‘On-Off’ control strategy (i.e. two preset values of damping co-efficient) but a better control over damping coefficients can be achieved using Continuous Control strategy. This paper aims to implement Continuous control strategy using Fuzzy logic for the semi active suspension. For the analysis, Two degree of freedom Quarter car model is used which is excited by three road profiles namely Bump, Sine Wave and Swept Sine wave. Comparison is done on the basis of vehicle parameters: Body displacement, Wheel displacement, Suspension working space and Dynamic tire deflection. Also frequency response of system is analysed using Fast Fourier Transform. Simulation is done using MATLAB SIMULINK and results of ‘Continuous control strategy’ are compared with the results of ‘On-Off control strategy’ and ‘Passive suspension’. Continuous control strategy using Fuzzy Logic control was found to provide better overall performance with 22.1% reduction in body displacement, 11.66% reduction in dynamic tire deflection and 31.77% reduction in suspension working space. Also Fuzzy logic control retained its stability over whole frequency range.