Type of Document	Master's Thesis
Author	Langdon, Justin David
Author's Email Address	jlangdon@vt.edu
URN	etd-02132007-112050
Title	Design and Adaptive Control of a Lab-based, Tire-coupled, Quarter-car Suspension Test Rig for the Accurate Re-creation of Vehicle Response
Degree	Master of Science
Department	Mechanical Engineering
Advisory Committee	Advisor Name Title Dr. Steve Southward Committee Chair Dr. Corina Sandu Committee Member Dr. John Ferris Committee Member
Keywords	vehicle response replication suspension system identification adaptive inverse control test rig quarter-car
Date of Defense	2007-01-31
Availability	unrestricted
Abstract The purpose of this study has two parts directed toward a common goal. First, a state-of-the- art quarter-car test platform has been designed and constructed to offer increased testing flexibility at a reasonable cost not found commercially. With this new test rig completed, the second objective is a proof-of-concept evaluation of a well known adaptive control algorithm applied to this new quarter-car test rig for the purpose of replicating the dynamic suspension response, such as a response that was recorded during a road test. A successful application of this control algorithm on the quarter-car rig is the necessary first step toward its application on an 8-post test rig for a direct comparison to current practices. Before developing a new test rig, the current state-of-the-art in quarter-car rigs was first evaluated as well as indoor vehicle testing in general. Based on these findings, a list of desired functional requirements was defined for this new design to achieve. The new test rig was built and evaluated to determine how these goals were met and what the next steps would be to improve the rig. The study then focused on evaluating control policies used for reproducing dynamic responses on vehicle road simulators such as 4- post and 7-post shaker rigs. A least-mean squares (LMS) adaptive algorithm is introduced and applied first in software using a linear two-mass quarter-car model, and then to the actual hardware-in-the-loop quarter-car rig. The results of the study show that the resulting quarter-car test rig design is quite flexible in its ability to test a multitude of suspension designs and also its ability to accommodate new hardware in the future such as a body loaders. The study confirms that this particular implementation of the LMS algorithm is a viable option for replicating test vehicle response on an indoor quarter-car test rig. Thus, a future study to compare the use of this algorithm to the current industry standard batch processing method is possible.
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