(Dr. William Singhose, advisor)

"Command Generation in Control System Design for Systems with Parameter Variations"

Abstract

The need for the rapid movement and operation of flexible structures, coupled with the inherent ill effects of the flexibility, has led to the development of a wide array of control strategies intended to limit vibration.  If the vibration characteristics of the system are known a priori, commands can be generated that prevent energy from being injected into the system’s flexible modes.  Commands that will not induce vibration can be obtained with input shaping, a type of command generation that is implemented by convolving a sequence of impulses with the reference signal.

In the past, input shapers have been designed using the fundamental frequencies of the system on which they operate.  However, a system’s fundamental frequencies may vary as the result of changes in parameters such as mass or physical dimension.  A method is proposed in this thesis for designing input shapers directly from expected variations in the physical parameters.  Several advantages of the proposed design method are presented.  The method is applied to the control of cranes that behave like double pendulums and cranes with payloads that are hoisted during transport.