An overall framework to provide a complete tool management solution to an existing or specified manufacturing system is constructed, and prototype software provided, for a hierarchy of levels of tool flow automation. The work is targeted at the design and operation of tooling systems for prismatic parts flexible machining systems ranging from stand-alone unmanned machining stations to highly automated multi-machine multi-cell configurations. The research work moves from identification and category definition of a tool flow network appropriate for the manufacturing requirements, through the careful selection and definition of operating rules and strategies to the evaluation of the options available for tool issue and assignment. Two main computer aids (design facilities) to provide support in a systems thinking approach to tool flow management have been developed and tested with the aid of case studies. The essential role of these design facilities is the timely scheduling of tools to satisfy a short to medium term manufacturing task, and to examine the cost and number of captive tools under selected rules and strategies.

The work presented in this thesis attempts to improve the performance of industrial robot systems in a flexible manufacturing environment by addressing a number of issues related to external sensory feedback and sensor integration, robot kinematic positioning accuracy, and robot dynamic control performance. To provide a powerful control algorithm environment and the support for external sensor integration, a transputer based open architecture robot controller is developed. It features high computational power, user accessibility at various robot control levels and external sensor integration capability. Additionally, an on-line trajectory adaptation scheme is devised and implemented in the open architecture robot controller, enabling a real-time trajectory alteration of robot motion to be achieved in response to external sensory feedback. An in depth discussion is presented on integrating a stereo vision sensor with the robot controller to perform external sensor guided robot operations. Key issues for such a vision based robot system are precise synchronisation between the vision system and the robot controller, and correct target position prediction to counteract the inherent time delay in image processing. These were successfully addressed in a demonstrator system based on a Puma robot. Efforts have also been made to improve the Puma robot kinematic and dynamic performance. A simple, effective, on-line algorithm is developed for solving the inverse kinematics problem of a calibrated industrial robot to improve robot positioning accuracy. On the dynamic control aspect, a robust adaptive robot tracking control algorithm is derived that has an improved performance compared to a conventional PID controller as well as exhibiting relatively modest computational complexity. Experiments have been carried out to validate the open architecture robot controller and demonstrate the performance of the inverse kinematics algorithm, the adaptive servo control algorithm, and the on-line trajectory generation. By integrating the open architecture robot controller with a stereo vision sensor system, robot visual guidance has been achieved with experimental results showing that the integrated system is capable of detecting, tracking and intercepting random objects moving in 3D trajectory at a velocity up to 40mm/s.

The work presented in this thesis is aimed at improving the accuracy of one of the components of a flexible pavement design procedure commonly used in South Africa, namely the South African Mechanistic- Empirical Design Method. This is achieved through the development of a new design approach and permanent deformation model for the pavement subgrade. The new distress model for the pavement subgrade was developed from a comprehensive Accelerated Pavement Testing (APT) database on subgrade behaviour and permanent deformation that was generated by a fleet of Heavy Vehicle Simulators (HVSs) over 20 years of testing in South Africa. A literature review of the origin of the current subgrade design model that is used by the South African Mechanistic-Empirical Design Method revealed that that model is based on very little actual subgrade performance data. The model was also developed from the AASHO road test data and adjusted for South African conditions, based on general observations of subgrade behaviour without any calibration. Previous researchers have illustrated the potential of using Heavy Vehicle Simulator data to develop structural pavement design models and it was decided to apply a similar process to the permanent deformation of the pavement subgrade. The present investigation consisted of two components, namely, the evaluation of the resilient and the permanent deformation response of the pavement subgrade, the emphasis in this thesis being more on the permanent deformation response. A general, multi-dimensional empirical model was formulated for the permanent subgrade deformation and the characteristics of the model investigated based on previously published permanent deformation data and mathematical assessment. A set of 35 HVS tests for which suitable data were available was identified and additional field and laboratory tests were done on selected sites to improve the classification of the subgrade materials at these sites. Standard procedures were developed to present the pavement, instrumentation and load sequence data of each HVS test. A process for doing the initial analysis of the deflection and permanent MDD displacement data and presenting the data was also developed. In terms of the resilient response of the subgrade, it was shown that the vertical depth deflection and vertical strain could be modelled accurately if an appropriate set of resilient modulus values was selected for the pavement layers. A detailed investigation of the resilient response of selected HVS sections did, however, clearly illustrate the stress-dependent behaviour of subgrade material, resulting in resilient modulus values being determined, which were well outside the range that would normally be expected for natural gravel subgrade material. This research needs to be continued to enable the development of a comprehensive set of stress-dependent resilient modulus models for South African subgrade materials. The selection of an appropriate critical parameter that can be used as a predictor of permanent subgrade deformation was done by an investigation of the relationship between potential critical parameters and several permanent deformation parameters. It was found that the subgrade elastic deflection showed the best correlation with the subgrade bearing capacity (the number of load repetitions that can be sustained before a terminal rut condition is reached). The vertical subgrade strain that is currently used in the South African Mechanistic-Empirical Design Method in fact correlates poorly with subgrade bearing capacity and has to be replaced with subgrade elastic deflection. A set of subgrade bearing capacity or design models was developed for different levels of permanent subgrade deformation. These models are referred to as S-N models and form contour lines on the general permanent deformation model that was formulated. The subgrade design model accommodates loading conditions ranging from a 40 kN dual wheel load to a 100 kN dual wheel load as well as subgrade materials ranging from a material quality one class better than that which would normally be used for a subgrade, to the lowest possible material class. The model is therefore very flexible in terms of its application. / Prof. P. Pretorius

A morphing aircraft can be defined as an aircraft that changes configuration to maximize its performance at radically different flight conditions. Morphing structures require a large aspect ratio and area change during flight in order to optimise operational performance. Morphing wings are being developed to mimic bird’s wing movements. Birds have different wing profiles at different points in their flight, where swept wings reduce the drag at higher speeds at flight lift-off and long straight wing profile is better for performance at low loitering speed. Hyper-extensible braided cords have been developed to be used within morphing ‘skin’ materials. The cords use a low-modulus elastomeric core braided around with high-modulus yarns. These cords can be produced with various braid angles, which influence the extensibility of the cords. The higher the braid angle, the greater the extension The braid angle is controlled by the precision pre-tension of the elastomeric component. A computational model for predicting the load-strain behaviour of these hyper-extensible cords has been developed. Opposite to hyper-extensible cords are inextensible cord reinforcement composites, such as toothed timing belts used in car engines, which utilise a combination of reinforcement techniques to guarantee a high quality high strength product. Braiding is an alternate technology for producing cords with potentially superior performance in terms of improved ability to resist unravelling as well as superior interface due to ‘Chinese finger-trap effect.’ Carbon core with varying glass fibre braid have been developed. This led to various braid patterns being formed. A system for mapping braid pattern/topology has been developed. Aswel as the braid pattern, the braid colour patterns can also be produced. This mathematical model involves basic matrix manipulations, which have been proved using the MatLab program. The predicted braid patterns have been compared with actual samples. Being able to model braid patterns is a time and cost effective compared to previous trial and error methods.

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Large, ``rigid'' structures made of interconnecting beams and tendons represent a type of construction that has many engineering benefits. Lightweight, strong, and generally constructed of standard-shaped metal framework, they also incur significant challenges to control vibration. The construction that makes them strong, light, and ``rigid'' also makes them have very small inherent structural damping, and highly-complex modal structure. A myriad of control techniques have been developed to work on this problem with success usually in very small bandwidths related to a specific frequency ``hot-spot'' around a few specific modes. This work describes the design, analysis, and implementation of a novel controller configuration applicable to broadband vibration suppression on a large, uncertain resonant structure. The measurement, identification, characterization, and modeling of a large, flexible, lightly-damped test structure with in excess of 1000 modes in 50-5000Hz range was used as the basis for choosing a control configuration. This choice leverages the relative benefits of different control types to obtain one with a combination of the best features of all of them. High-order and low-order feedback, and feed-forward controller configurations were all used in different frequency ranges. Real design tradeoffs such as computation complexity, model accuracy, and available actuator technologies were fundamental to the design choices. Measured individual modal reduction was as much as 15dB for feedback control, 20dB for feed-forward control, and 4dB broadband over the range of 50-5000Hz. / Ph. D.

Approved for public release; distribution is unlimited / Today's demand for a high speed, low weight and large load capable manipulator has spurred the research on flexible manipulators. This thesis centers on an implementation of dynamic control on a single-link flexible arm utilizing a general purpose micro-computer. This research also studies the dynamic behavior of the control system with a brief comparison of the derived flexible-body-model controller to a rigid-body-model controller. / http://archive.org/details/implementationof00kirk / Lieutenant, United States Navy