Abstract
The work aims to study the root mean square (RMS) responses to acceleration input for four state variables: the msvertical acceleration, the mspitch angular acceleration and the front and rear deflections of the suspensions. A half-car two degree-of-freedom model of semi-active control scheme is analyzed and compared with the conventional passive suspension system. Frequency response of the transfer function for the heave, pitch of the sprung mass and suspension deflections are initially compared and then mean square analysis is utilized to see the effect of semi-active scheme. Results indicate that significant improvements were achieved in the sprung mass heave and pitch responses using semi-active control scheme. However results for the rear and front suspension deflection show that there are limiting values of damping coefficient beyond which, the semi-active scheme becomes disadvantageous than the passive system.
Highlights
Suspension systems are often used to control response of various rigid and flexible multi-body systems [1,2]
The most common area of application of suspension systems is in vehicular applications, where they are used to control the tire deflection or wheelhop for handling performance and vehicle body deflection and acceleration for passenger ride comfort [3]
Since first introduced by Crosby and Karnopp [4,5], semiactive suspension systems continue to gain considerable attention in vehicle applications. This is due to its advantageous characteristics over passive system in overcoming the traditional conflict between vehicle safety and handling, and ride comfort, as well as its significantly less in complexity and power requirement than active suspension system [6,7,8]
Summary
Suspension systems are often used to control response of various rigid and flexible multi-body systems [1,2]. It is assumed that reducing the overall response (rms value) of the system generally reduce the discomfort level of passengers, improving the ride comfort This mean squares approach is utilized by many, including Asami and Nishihara [11] in their work in reducing the overall vibration transfer and later used by Blanchard [10] as the performance criteria in improving the ride comfort of a quarter-car model system. The comparison between different semi-active suspensions systems have been extensively covered by Ihsan et al [12,13] but without using RMS as a performance criteria and the main objective of these papers were to look into the dynamics of the systems under different controllers. The semi-active control system of this model can be regarded as closely resemble a skyhook control scheme
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