tailieunhanh - On the Control Aspects of Semiactive Suspensions for Automobile Applications

The requirements are also needed for clearly distinguishing car-sharing from "fictive car- sharing" such as might be established for the sole purpose of taking advantage of special benefits that genuine car-sharing schemes should be eligible for. The requirement of the administrator of a car-sharing scheme being a legal entity (requirement 1) and of each vehicle being registered in the name of a legal entity (requirement 4) reduces the risk of misuse. Requirement 2 also reduces the possibilities of registering car-sharing schemes that fail to live up to the goals implicit in the definition of them presented here. The requirement of. | On the Control Aspects of Semiactive Suspensions for Automobile Applications by Emmanuel D. Blanchard Thesis submitted to the Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering Approved Mehdi Ahmadian Chairman Harry H. Robertshaw Donald J. Leo June 2003 Blacksburg Virginia Keywords Semiactive Skyhook Groundhook Hybrid Suspensions Vehicle Dynamics H2 On the Control Aspects of Semiactive Suspensions for Automobile Applications by Emmanuel D. Blanchard Mehdi Ahmadian Chairman Mechanical Engineering Abstract 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 H2 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.