Advisor(s)

Nader Jalili

Contributor(s)

Rifat Sipahi, Bahram Shafai

Date of Award

2012

Date Accepted

4-2012

Degree Grantor

Northeastern University

Degree Level

M.S.

Degree Name

Master of Science

Department or Academic Unit

College of Engineering, Department of Mechanical and Industrial Engineering

Keywords

mechanical engineering, engineering, adaptive, continuous, control, flexible, robust, vibration

Disciplines

Mechanical Engineering

Abstract

More advanced technology and materials in industry lead to the implementation of lightweight components in order for miniaturization and efficiency. Lightweight components and certain materials however, are susceptible to vibrations. The flexible structures that make up these systems pose a great problem for vibration control. The detailed modeling of such systems greatly reduces the complexity of the control law. It is this reason that an analysis of the model as a continuous system was done. The distributed-parameters system was then effectively reduced to an equivalent lumped-parameters model. The use of this discrete system was the basis for controller design of these flexible structures.

However, even the best model of a system is not able to overcome the need of an advanced controller for vibration suppression. Flexible structures, which are a common problem in robotics, represent nonlinear terms such as damping. Piezoelectric actuators or transmissions using gears can often be subject to nonlinear effects such as hysteresis or backlash. Even a mutli-part system could be subject to frictions or other conditions that could be found at boundary conditions of individual pieces. Thus, a controller is proposed that will account for unmodeled dynamics of the system.

This controller will also have the ability to reject external disturbances while accounting for varying parameters. It is rare that the properties of a structure do not change over time or with environmental factors such as temperature or humidity. Therefore, the controller must be able to account for these changes whether the change comes within the materials or in the joints of a structure.

A robust adaptive controller with perturbation estimation will guarantee stability for all of the noted effects. It will be robust enough to account for completely unmodeled dynamics while rejecting unknown disturbances. The adaptive law within the controller will be an on-line estimation of the parameters modeled within the system. The simulations of this advanced controller show the stability of the system and prove its robust and adaptive features when subject to varying internal or external conditions and disturbances. A proposed experimental setup is also discussed.

Document Type

Master's Thesis

Rights Information

copyright 2012

Rights Holder

Matthew Thomas Jamula


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