On the Control Aspects of Semiactive Suspensions for Automobile Applications

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.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Mechanical Engineering

Department dc:contributor.department

Mechanical Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2003

Author dc:creator

• Blanchard, Emmanuel

Chair dc:contributor.committeechair

• Ahmadian, Mehdi

Committee members dc:contributor.committeemember

• Leo, Donald J.
• Robertshaw, Harry H.

• Vehicle Dynamics
• H2
• Skyhook
• Hybrid
• Groundhook
• Suspensions
• Semiactive

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-07032003-150548

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/33876