Title page for ETD etd-07032003-150548

Type of Document Master's Thesis
Author Blanchard, Emmanuel Dominique
URN etd-07032003-150548
Title On the Control Aspects of Semiactive Suspensions for Automobile Applications
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Ahmadian, Mehdi Committee Chair
Leo, Donald J. Committee Member
Robertshaw, Harry H. Committee Member
  • Vehicle Dynamics
  • H2
  • Skyhook
  • Hybrid
  • Groundhook
  • Suspensions
  • Semiactive
Date of Defense 2003-06-19
Availability unrestricted
This analytical study evaluates the response characteristics of a two-degree-of freedom quarter-car model, using passive and semi-active dampers, along with a seven-degree-of-freedom full vehicle model. The behaviors of the semi-actively suspended vehicles have been evaluated using skyhook, groundhook, and hybrid control policies, and compared to the behaviors of the passively-suspended vehicles. The relationship between vibration isolation, suspension deflection, and road-holding is studied for the quarter-car model. Three main performance indices are used as a measure of vibration isolation (which can be seen as a comfort index), suspension travel requirements, and road-holding quality. After performing numerical simulations on a seven-degree-of-freedom full vehicle model in order to confirm the general trends found for the quarter-car model, these three indices are minimized using optimization techniques.

The results of this study indicate that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for typical passenger cars. The results also indicate that for typical passenger cars, the hybrid control policy results in a better compromise between comfort, road-holding and suspension travel requirements than the skyhook and groundhook control policies. Finally, the numerical simulations performed on a seven-degree-of-freedom full vehicle model indicate that the motion of the quarter-car model is not only a good approximation of the heave motion of a full-vehicle model, but also of the pitch and roll motions since both are very similar to the heave motion.

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