Title page for ETD etd-02132007-112050

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
Southward, Steve C. Committee Chair
Ferris, John B. Committee Member
Sandu, Corina Committee Member
  • vehicle response replication
  • suspension
  • system identification
  • adaptive inverse control
  • test rig
  • quarter-car
Date of Defense 2007-01-31
Availability unrestricted
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


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