Browsing by Author "Padayachee, Jared."

Now showing 1 - 9 of 9

The design and analysis of a novel 5 degree of freedom parallel kinematic manipulator.
(2019) Dharmalingum, Wesley Emile.; Padayachee, Jared.; Bright, Glen.
Abstract available in PDF.
Design and development of a low-cost high-performance vehicle mounted UHF RFID system for tracking goods and inventory.
(2019) Hoskins, Gareth Oregan.; Bright, Glen.; Padayachee, Jared.
Abstract available in the PDF.
Design and optimisation of a composite space frame chassis including experimental and computational analysis.
(2017) Narsai, Mikhail.; Adali, Sarp.; Padayachee, Jared.; Veale, Kirsty Lynn.
Composites are used in lightweight structural designs. In this dissertation, a robust carbon fibre reinforced polymer (CFRP) space frame chassis for a lightweight electric tricycle is produced. In large, most composite research is directed toward flat laminates rather than closed sections. This dissertation addresses the complexities of stresses at joints and buckling (local and global). The space frame design consists of two segments of iterations. The second and more important segment is based on optimisation using NX Nastran finite element analysis (FEA). The final design incorporates the use of steel sleeves to address stress concentrations at joins and local buckling. The design and execution of a new test method was developed to validate FEA results. The test method involves applying compressive stress on tubes fabricated using unidirectional (UD) fibre set at 35°, to induce compressive and shear stresses along the primary fibres. In this way, four major failure criteria were compared: Tsai-Wu, Hoffman, Hill and Maximum Strain. The Hoffman and Tsai-Wu criteria were shown to be accurate and conservative. The Hill criteria showed inaccuracy by having incorrectly high strength ratios, while the Maximum Strain criteria had the highest strength ratio, proving to be the least conservative and most inaccurate. This dissertation shows that certain failure criteria may be used confidently in applications such as filament winding and continuous pulComposites are used in lightweight structural designs. In this dissertation, a robust carbon fibre reinforced polymer (CFRP) space frame chassis for a lightweight electric tricycle is produced. In large, most composite research is directed toward flat laminates rather than closed sections. This dissertation addresses the complexities of stresses at joints and buckling (local and global). The space frame design consists of two segments of iterations. The second and more important segment is based on optimisation using NX Nastran finite element analysis (FEA). The final design incorporates the use of steel sleeves to address stress concentrations at joins and local buckling. The design and execution of a new test method was developed to validate FEA results. The test method involves applying compressive stress on tubes fabricated using unidirectional (UD) fibre set at 35°, to induce compressive and shear stresses along the primary fibres. In this way, four major failure criteria were compared: Tsai-Wu, Hoffman, Hill and Maximum Strain. The Hoffman and Tsai-Wu criteria were shown to be accurate and conservative. The Hill criteria showed inaccuracy by having incorrectly high strength ratios, while the Maximum Strain criteria had the highest strength ratio, proving to be the least conservative and most inaccurate. This dissertation shows that certain failure criteria may be used confidently in applications such as filament winding and continuous pultrusion methods, which are widely used in producing closed sections.trusion methods, which are widely used in producing closed sections.
Development of a modular reconfigurable machine for reconfigurable manufacturing systems.
(2010) Padayachee, Jared.; Bright, Glen.
The Reconfigurable Manufacturing Systems (RMSs) paradigm has been formulated to encapsulate methodologies that enable manufacturing systems to effectively cope with changes in markets and products. RMSs are systems which are envisioned to be capable of a rapid change in manufacturing layouts, process configurations, machines and control components to provide a quick response to changes in the master production schedule. This research was initiated due to the necessity for new forms of production machinery to be design for RMSs, which can aid manufacturers in the adjustment of system capacity and functionality at lower costs. This thesis presents the development of Modular Reconfigurable Machines (MRMs), as a novel machining solution within the scope of RMSs. MRMs are characterized by modular mechanical structures that enable the flexibility of the machine to be adjusted in response to changes in products. The concept of adjustable flexibility implies that the flexibility of the machines may be balanced to exactly match the requirements of the system when changes in production plans occur. Product changes are managed by a variation of machining processes and Degrees of Freedom (DOF) on a platform. The modular nature of these machines permits this to be done easily and cost effectively. MRMs therefore possess an advantage over traditional machining systems, where an adjustment of system functionality would require the procurement of new machinery. Manufacturers will also have the option to purchase machines with flexibility that may be increased as needed, instead of investing in highly flexible and expensive CNC systems, with features that are often excessive and unused. Main points of this research included the development of mechanical modules for assembly into complete machines. The number and types modules used in an assembly could be changed to provide the kinematic and process optimization of the mechanical hardware according to production requirements. In conjunction to the mechanical development, a suitable Mechatronic control system will be presented. The focus of control development was the facilitation of seamless system integration between modular mechanical hardware and the controller at both hardware and software levels. The control system is modular and distributed and characterised by a “plug-in” approach to control scalability. This is complimented by a software architecture that has been developed with a focus on hardware abstraction for the management of a reconfigurable mechanical and electronic architecture. A static and dynamic analysis of the MRM system is performed for a selected mechanical configuration. The performance of the mechanical and control system is also evaluated for static and dynamic positioning accuracy for different modes of motion control. The implications for MRMs are then analysed, which include system functionality and capacity scaling, manufacturing expansion flexibility and system life spans. The research was concluded with an analysis of the challenges and problems that must be addressed before MRMs become industrially acceptable machines.
The development of methods for the design and evolution of reconfigurable cellular manufacturing systems.
(2016) Padayachee, Jared.; Bright, Glen.
The concept of reconfigurable manufacturing is presently being researched due to the need for production systems that are able to economically respond to changes in markets and the rapid introduction of new products. Cellular Manufacturing Systems (CMS) are a central concept in just-in-time and lean manufacturing. Although CMS are able to provide a strategic operating advantage, machine cell clusters do not remain optimal over an extended period of time. The concept of a Dynamic CMS (DCMS) has received attention in recent years; a DCMS is a system where the layout of machines change in order to improve the responsiveness of CMS to changing production requirements. A deficiency in existing DCMS methods is that reconfiguration plans are generated without the consideration of an initial design of the factory floor space for future change. This research distinguishes Reconfigurable CMS (RCMS) from DCMS, as a system that is designed at the outset for changes to system layout and cell configurations. The concept of a Factory Configuration Template (FCT) is proposed in this research; the FCT is a design of the factory floor space to ensure the feasible implementation of reconfiguration plans generated by mathematical models. A nine step method for FCT design is presented that uses a Simultaneous Fuzzy Clustering Heuristic to develop manufacturing cells and part families. A Tabu Search algorithm was develop to generate the optimal arrangement of machine sites in cells. Three multi-period machine assignment models were developed that determine reconfiguration plans based on changing product demand and the introduction of new products. The models that were developed included two integer linear programs that determine the distribution of machine resources among cells over multiple periods. A quadratic zero-one programming model was developed that distributes machines among available sites in cells to promote unidirectional part flow. The results show that RCMS is able to provide a more economical solution than traditional CMS with the added advantage of improved part flow in the system.
Multi-point static dexterous posture manipulation for the stiffness identification of serial kinematic end-effectors.
(2020) Singh, Akshay Pradeep.; Bright, Glen.; Padayachee, Jared.
The low stiffness inherent in serial robots hinders its application to perform advanced operations due to its reduced accuracy imparted through deformations within the links and joints. The high repeatability, extended workspace, and speed of serial manipulators make them appealing to perform precision operations as opposed to its alternative, the CNC machine. However, due to the serial arrangement of the linkages of the system, they lack the accuracy to meet present-day demands. To address the low stiffness problem, this research provided a low-cost dexterous posture identification method. The study investigated the joint stiffness of a Fanuc M10-iA 6 Degree of Freedom (DOF) serial manipulator. The investigation involved a multivariable analysis that focused on the robot’s workspace, kinematic singularity, and dexterity to locate high stiffness areas and postures. The joint stiffness modelling applied the Virtual Joint Method (VJM), which replaced the complicated mechanical robot joints with one-dimensional (1-D) springs. The effects of stress and deflection are linearly related; the highest stress in a robot’s structure is distributed to the higher load-bearing elements such as the robot joints, end-effector, and tool. Therefore, by locating optimal postures, the induced stresses can be better regulated throughout the robot’s structure, thereby reducing resonant vibrations of the system and improving process accuracy and repeatability. These aspects are quantifiably pitched in terms of the magnitude differences in the end-effector deflection. The unique combination of the dexterity and the stiffness analyses aimed to provide roboticists and manufacturers with an easy and systematic solution to improve the stiffness, accuracy, and repeatability of their serial robots. A simple, user-friendly and cost-effective alternative to deflection measurements using accelerometers is provided, which offers an alternative to laser tracking devices that are commonly used for studies of this nature. The first investigation focused on identifying the overall workspace of the Fanuc M-10iA robot. The reachable workspace was investigated to understand the functionality and potential of the Fanuc robot. Most robotic studies stem from analysing the workspace since the workspace is a governing factor of the manipulator and end-effector placement, and its operations, in a manufacturing setting. The second investigation looked at identifying non-reachable areas and points surrounding the robot. This analysis, along with the workspace examination, provided a conclusive testing platform to test the dexterity and stiffness methodologies. Although the research focused on fixing the end-effector at a point (static case), the testing platform was structured precisely to cater for all robotic manufacturing tasks that are subjected to high applied forces and vibrations. Such tasks include, but are not limited to, drilling, tapping, fastening, or welding, and some dynamic and hybrid manufacturing operations. The third investigation was the application of a dexterous study that applied an Inverse Kinematic (IK) method to localise multiple robot configurations about a user-defined point in space. This process was necessary since the study is based on a multi-point dexterous posture identification technique to improve the stiffness of Serial Kinematic Machines (SKMs). The stiffness at various points and configurations were tested, which provided a series of stiff and non-stiff areas and postures within the robot’s workspace. MATLAB®, a technical computing software, was used to model the workspace and singularity of the robot. The dexterity and stiffness analyses were numerically evaluated using Wolfram Mathematica. The multivariable analyses served to improve the accuracy of serial robots and promote their functionality towards high force application manufacturing tasks. Apart from the improved stiffness performance offered, the future benefit of the method could advance the longevity of the robot as well as minimise the regular robot maintenance that is often required due to excessive loading, stress, and strain on the robot motors, joints, and links.
An on-demand fixture manufacturing cell for mass customisation production systems.
(2017) Naidoo, Enrico.; Padayachee, Jared.; Bright, Glen.
Increased demand for customised products has given rise to the research of mass customisation production systems. Customised products exhibit geometric differences that render the use of standard fixtures impractical. Fixtures must be configured or custom-manufactured according to the unique requirements of each product. Reconfigurable modular fixtures have emerged as a cost-effective solution to this problem. Customised fixtures must be made available to a mass customisation production system as rapidly as parts are manufactured. Scheduling the creation/modification of these fixtures must now be treated together with the production scheduling of parts on machines. Scheduling and optimisation of such a problem in this context was found to be a unique avenue of research. An on-demand Fixture Manufacturing Cell (FxMC) that resides within a mass customisation production system was developed. This allowed fixtures to be created or reconfigured on-demand in a cellular manufacturing environment, according to the scheduling of the customised parts to be processed. The concept required the research and development of such a cell, together with the optimisation modelling and simulation of this cell in an appropriate manufacturing environment. The research included the conceptualisation of a fixture manufacturing cell in a mass customisation production system. A proof-of-concept of the cell was assembled and automated in the laboratory. A three-stage optimisation method was developed to model and optimise the scheduling of the cell in the manufacturing environment. This included clustering of parts to fixtures; optimal scheduling of those parts on those fixtures; and a Mixed Integer Linear Programming (MILP) model to optimally synchronise the fixture manufacturing cell with the part processing cell. A heuristic was developed to solve the MILP problem much faster and for much larger problem sizes – producing good, feasible solutions. These problems were modelled and tested in MATLAB®. The cell was simulated and tested in AnyLogic®. The research topic is beneficial to mass customisation production systems, where the use of reconfigurable modular fixtures in the manufacturing process cannot be optimised with conventional scheduling approaches. The results showed that the model optimally minimised the total idle time of the production schedule; the heuristic also provided good, feasible solutions to those problems. The concept of the on-demand fixture manufacturing cell was found to be capable of facilitating the manufacture of customised products.
Research and development of a reconfigurable robotic end-effector for machining and part handling.
(2020) Reddy, Clydene Emmanual.; Padayachee, Jared.; Bright, Glen.
Abstract available in PDF.
A state communication and software switching module and thin middleware layer for reconfiguration management in reconfigurable manufacturing systems.
McLean, Roscoe Roy Peter.; Padayachee, Jared.; Bright, Glen.
Reconfigurable Manufacturing Systems are a new area of operations and manufacturing research. The global need for production systems which can react rapidly to dynamic markets has increased in the last decade and will continue to drive changes in the manufacturing industry. The further development of RMS technologies is therefore highly important for future industries. The Reconfiguration Management and Middleware System (RMMS) developed in this research aimed to form a hardware-supported middleware technology which allows for the fast and seamless ramp-up of heterogeneous machine controllers on a newly reconfigured factory floor. The goal was to allow for the autonomous assignment and switching of software routines on machine controllers after a physical reconfiguration, thereby speeding up the ramp-up of the system. The technology was based on a recorded literature review and fits into the paradigm of RMS. The RMMS was developed not as a traditional software-heavy layer, but as a thin layer of software assisted by interactive mechatronic hardware, designed to remove heterogeneity in the control software. The system design was based on research into areas of engineering and operations management and followed the Mechatronic design approach. The literature led to a technology that takes the entire RMS paradigm into account and the development was conducted in conjunction with experiments to verify the individual functionality of each sub-system and ensure the overall system’s success. The RMMS uses hardware to handle heterogeneity and uses a positioning system (developed by the author) along with an intelligent processing system (a clustering algorithm and artificial intelligence engine) to construct data into a factory floor model. The positioning system, when assisted by the intelligence, operates at an accuracy of over 90%, which is comparable to commercial positioning techniques which cost over ten times more. The RMMS used the developed model to, autonomously and wirelessly, assign new programs to machine controllers after a physical reconfiguration, to complete a factory reconfiguration. The system was verified through practical scenarios constructed in the Mechatronics laboratory. Realistic reconfiguration operations were performed and the RMMS was required to detect changes in the factory floor and respond by assigning new, appropriate, software routines to each machine controller in the system. Experiments have proved that the system was capable of re-establishing operations in under half an hour, as opposed to a full day using manual techniques. The system has accurately switched between control routines based on the physical state of the factory floor, which amounts to control reconfiguration. The reconfiguration of factory floor control was successful in four out of four factory layouts tested and therefore successfully does a job no commercially available system can do.