Title page for ETD etd-08142001-105010

Type of Document Master's Thesis
Author Goncalves, Fernando D.
Author's Email Address nando@vt.edu
URN etd-08142001-105010
Title Dynamic Analysis of Semi-Active Control Techniques for Vehicle Applications
Degree Master of Engineering
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Ahmadian, Mehdi Committee Chair
Inman, Daniel J. Committee Member
Robertshaw, Harry H. Committee Member
  • suspensions
  • vehicle dynamics
  • experimental
  • groundhook
  • magneto-rheological
  • semi-active
  • skyhook
Date of Defense 2001-08-07
Availability unrestricted
This experimental study evaluates the dynamic response of five semi-active control policies as tested on a single suspension quarter-car system. Incorporating a magneto-rheological damper, the full-scale 2DOF quarter-car system was used to evaluate skyhook, groundhook, and hybrid control. Two alternative skyhook policies were also considered, namely displacement skyhook and relative displacement skyhook. As well as exploring the relative benefits of each of these controllers, the performance of each semi-active controller was compared to the performance of conventional passive damping.

Each control policy is evaluated for its control performance under three different base excitations: chirp, step, and pure tone. Corresponding to the chirp input, transmissibilities and auto spectrums are considered for each control policy. Specifically, transmissibilities between the sprung mass displacement and the unsprung mass displacement are generated relative to the input displacement. Further, the ratio between the relative displacement across the damper and the input displacement is evaluated for each control technique. The chirp input also reveals the results of the auto spectrums of the sprung and unsprung mass accelerations. Both the step input and the pure tone input were used to generate time domain values of RMS and peak-to-peak displacements and accelerations.

This study shows that semi-active control offers benefits beyond those of conventional passive damping. Further, traditional skyhook control is shown to outperform the less conventional alternative skyhook policies.

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