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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Design of a low cost, high speed robot for poultry processing

Anderson, Eric William 10 August 2004 (has links)
In poultry plants in the United States, a water chiller is used to chill WOGs (de-feathered birds without giblets). After exiting the chiller these birds are manually transferred from a conveyor belt to shackles for further processing. The current process is less than ideal. The labor pool for jobs such as these is continuing to shrink and labor turnover is a constant problem. The rates of repetitive motion injury reported are high and are continuing to rise. In addition, many poultry producers see this as a bottleneck in the process. Automation has the potential to alleviate these problems. The high variability of this task, cost restrictions, and special design considerations associated with meat handling equipment make automation of this task challenging. Industrial robots have traditionally been limited to tasks with low variability. This task has high variability. They are presented on the conveyor belt in a wide variety of positions and orientations. Most robotic automation systems consist of a commercially available industrial robot, a specialized end effector and a control scheme. The economics of this task prohibit the use of a commercially available industrial robot, as there are no industrial robots on the market that will offer a short enough payback. Robots have not yet been adapted to meat handling processes, and existing robotic designs are not well suited to the task. In designing a low cost, high-speed robot for poultry processing the requirements of the robot are defined and a variety of robot architectures, constructions, and materials are explored. Simple modifications to the existing shackle and conveyor setup to make the task easier for a robot are also explored. After the robot requirements are defined a large group of possible designs are developed. The possible designs are systematically evaluated and/or eliminated until a single design is selected. The forward and reverse kinematics for this robot are developed. A singularity analysis is carried out. A proof of concept model is built. A prototype is modeled and a dynamic analysis of that prototype is carried out. The design is finalized based on the results of the dynamic analysis.
2

Measuring Closeness to Singularities of Parallel Manipulators with Application to the Design of Redundant Actuation

Voglewede, Philip Anthony 16 April 2004 (has links)
At a platform singularity, a parallel manipulator loses constraint. Adding redundant actuation in an existing leg or new leg can eliminate these types of singularities. However, redundant manipulators have been designed with little attention to frame invariant techniques. In this dissertation, physically meaningful measures for closeness to singularities in non-redundant manipulators are developed. Two such frameworks are constructed. The first framework is a constrained optimization problem that unifies seemingly unrelated existing measures and facilitates development of new measures. The second is a clearance propagation technique based on workspace generation. These closeness measures are expanded to include redundancy and thus can be used as objective functions for designing redundant actuation. The constrained optimization framework is applied to a planar three degree of freedom redundant parallel manipulator to show feasibility of the technique.

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