SUBJECT: Ph.D. Dissertation Defense
BY: Joshua Vaughan
TIME: Tuesday, June 24, 2008, 1:00 p.m.
PLACE: MARC Building, 114
TITLE: Dynamics and Control of Mobile Cranes
COMMITTEE: Dr. William Singhose, Chair (ME)
Dr. Kok-Meng Lee (ME)
Dr. Rhett Mayor (ME)
Dr. John-Paul Clarke (AE)
Dr. Patricio Vela (ECE)


The rapid movement of machines is a challenging control problem because it often results in high levels of vibration. As a result, flexible machines are typically moved relatively slowly to avoid such vibration. Input shaping is one method that eliminates motion-induced vibrations by intelligently designing the reference command such that system vibration is cancelled. It has been successfully implemented on a number of systems, including bridge and tower cranes. The implementation of input shaping on cranes provides a substantial increase in the operational efficiency. Unfortunately, most cranes, once erected, have limited or no base mobility, limiting their workspace. The addition of base mobility could help extend the operational effectiveness of cranes and may also expand crane functionality. Mobile cranes may also be better suited for use in harsh and/or distant environments. Teleoperation of oscillatory systems, such as cranes, then becomes another avenue for advancement of crane functionality. Toward advancing mobile crane control techniques, new multi-input shaping methods have been developed and applied to a mobile, portable tower crane. During this development, a firm understanding of robust input shaping techniques and the compromises inherent to input shaper design was formed. In addition, input shaping was compared to other command generation techniques, namely lowpass and notch filtering, and proven to be superior for vibration reduction in mechanical systems. Another, new class of input shapers was also introduced that limit the input shaper induced overshoot in human operated systems. Finally, a series of crane operator studies investigate the application of input shaping techniques to teleoperated cranes. These studies suggest that input shaping is able to dramatically improve remote crane operator performance.