A non-contact end effector for robotic handling of non-rigid materials

Abstract

The handling and packaging of food products are generally very labour intensive processes
\nwhere the risk of product contamination is high. Cost-effective automatic handling of such
\nproducts is becoming an increasingly important issue, particularly for ready-meals, in order
\nto eliminate the risk of contamination via human contact and to reduce the unit cost of the
\nfinal product. A major handicap associated with using automation in the food sector is a
\nlack of suitable robot end effectors. The majority of end effectors used for electromechanical
\nparts are not applicable, because, non-rigid food products have somewhat
\nunpredictable and unstable behaviour characteristics which arises from their natural physical
\nproperties.
\nThe main aim of this project was to develop a novel non-contact end effector that can
\nhandle non-rigid products. A range of novel end effectors have been designed, developed
\nand tested. These end effectors use compressed air and take advantage of the radial air
\noutflow phenomena. These end effectors have advantages over the conventional end
\neffectors of lifting flat, thin, porous materials with viscous or slippery surfaces without
\nmechanical contact.
\nThis thesis discusses hygiene, mechanical properties and delicacy of food products from the
\nhandling point of view. A literature survey on the radial air outflow and the application fields
\nof the radial air outflow is discussed in detail. The end effectors (grippers) which have been developed and used in the assembly of electro-mechanical parts are discussed with regards
\nto their usage in handling non-rigid food products.
\nThe theoretical analysis of the radial air outflow phenomena and lifting equilibrium of a flat
\nobject, by using lifting forces created by the radial air outflow, is given in detail. The design
\nconsiderations for the radial air outflow nozzles and the number and configuration of these
\nnozzles are described regarding the shape, compliance and weight of the materials to be
\nlifted. The experimental program and procedures carried out during this research are also
\npresented.
\nThe results of the experimentation, using rigid and non-rigid materials, are comprehensively
\ndiscussed from an applications point of view in terms of a practical handling environment.
\nDuring experimentation materials such as aluminium (as a rigid material) and jelly, sliced
\nmeat and fabric (as non-rigid and porous materials) have been used. The mechanical
\nproperties of rigid and non-rigid materials to be lifted are also discussed for handling
\npurposes. For the first time, the design considerations of a novel radial outflow nozzle for
\nporous and delicate materials are introduced. The advantages and disadvantages of the noncontact
\nend effector over conventional end effectors are discussed from the non-rigid
\nmaterial handling point of view. An operational sequence and a conceptual application of
\nsuch a novel non-contact end effector in a practical handling environment are introduced.
\nIn the final part of this thesis, conclusions are made and recommendations given, both
\ntheoretically and practically, to further extend the research.