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Rp-Vibration Control of Automobile Suspension System Using a Smart Damper. pdf

This thesis presents a development of smart damper to control the vibrations of automobile when cruised on irregular road profiles; thereby the ride comfort is enhanced. The development of the smart damper includes the design of control valve inserted in the hydraulic circuit outside the main damper. The control valve controls the flow rate of the hydraulic oil, while the direction of flow of the hydraulic oil is controlled by a simple check valve.
The mathematical formulation includes two parts; the first represent the formulation of the suspension system, while the second represent the formulation of the control valve as a separable part. The formulation of the suspension system depends on a quarter automobile model which is taken as a two degrees of freedom. This model represented by two second order differential equations. The model of control valve also represented by second order differential equations, which characterized the dynamics of the control valve. The two models are matched and solved by Matlab/ Simulink package.
The optimum values of control valve parameters are according to time response of the valve nose for each parameter (minimum overshoot, minimum error, and minimum settling time). The optimized values of the control valve parameters are used in the overall mathematical model which is a result of matching the suspension system and the control valve. The solution of the overall model gives the response of automobile body (sprung mass).
The response of the sprung mass is tested by applying step and impulse inputs through the automobile tire. The two inputs represent an automobile passing over a sudden change in the road level as a step or an obstacle as an impulse.
Some experimental are performed by manufacturing mass- spring –smart damper subjected to impulse input. The square bump input with 3,5 cm height is performed by a cam builtin on a wheel driven by an electrical motor. The response is measured by an indicator attached to the sprung mass and the output of the indicator is fed to the computer to save the data.
The theoretical results are compared with some published works and the present experiments to validate the confidence of the mathematical analysis. The very important results is that the very short time required for steady state response which is about 0.25 sec, as well as the acceptable overshoot which is about 35%. The values represent a good enhancing to the vibration control of the sprung mass, and the experimental results with sprung mass 80 kg, 100kg are approximately identical with that simulation results for the same masses. In general and far away from numerical language, a fast attenuation of vibration induced by disturbance excitations due to irregular road surface. A total elimination of the system oscillation is approved by using the smart damper, which leads to ride comfort to the driver and passengers. A very important point is worth of mention is that the damping which is controlled by the control valve is a function of disturbance excitation in contrast to the traditional passive damper which has a constant damping at all time. Another input point is the very low cost of this damper, nearly the same as traditional passive damper, in comparison with active damper.