Type of Document	Master's Thesis
Author	Nayfeh, Nader Ali
Author's Email Address	nnayfeh@vt.edu
URN	etd-12172002-160627
Title	Adaptation of Delayed Position Feedback to the Reduction of Sway of Container Cranes
Degree	Master of Science
Department	Electrical and Computer Engineering
Advisory Committee	Advisor Name Title William T. Baumann Committee Co-Chair Ziyad N. Masoud Committee Co-Chair Daniel J. Stilwell Committee Member
Keywords	gantry crane delayed feedback control Container cranes sway reduction
Date of Defense	2002-12-04
Availability	unrestricted
Abstract Cranes are increasingly used in transportation and construction. Increasing demand and faster requirements necessitate better and more efficient controllers to guarantee fast turn-around time and to meet safety requirements. Container cranes are used extensively in ship-to-port and port-to-ship transfer operations. In this work, we will extend the recently developed delayed position feedback controller to container cranes. In contrast with traditional work, which models a crane as a simple pendulum consisting of a hoisting cable and a lumped mass at its end, we have modeled the crane as a four-bar mechanism. The actual configuration of the hoisting mechanism is significantly different from a simple pendulum. It consists typically of a set of four hoisting cables attached to four different points on the trolley and to four points on a spreader bar. The spreader bar is used to lift the containers. Therefore, the dynamics of hoisting assemblies of large container cranes are different from that of a simple pendulum. We found that a controller which treats the system as a four-bar mechanism has an improved response. We developed a controller to meet the following requirements: traverse an 80-ton payload 50 m in 21.5 s, including raising the payload 15 m at the beginning and lowering the payload 15 m at the end of motion, while reducing the sway to 50 mm within 5.0 s at the end of the transfer maneuver. The performance of the controller has been demonstrated theoretically using numerical simulation. Moreover, the performance of the controller has been demonstrated experimentally using a 1/10th scale model. For the 1/10th scale model, the requirements translate into: traverse an 80 kg payload 5 m in 6.8 s, including raising 1.5 m at the beginning and lowering 1.5 m at the end of motion, while reducing the sway to 5 mm in under 1.6 s. The experiments validated the controller.
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