720 research outputs found

    Development of subsea robot nomad with a micro computer based intelligent control system

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    The goal of this PhD project was to design and develop a small inexpensive subsea robot with a micro computer based intelligent control system. The robot developed is called NOMAD. It could be the key element in a Distributed Marine Observation System(DMOS). Most Engineering PhDs are research oriented; this one has a design focus. -- NOMAD uses an air/water ballast tank instead of a battery/motor system to drive itself vertically. To facilitate mission requirements, great efforts were made to develop a high performance onboard micro computer based control system. To deal with the uncertainty and nonlinearity of the robot model, investigations were conducted to check the potential of strategies based on Neural Networks and Fuzzy Logic. A Real Time Kernel software and an onboard micro computer with a Z180 CPU were used to implement a Fuzzy Variable Structure Switching (FVSS) control scheme and a multiple-task, multiple-layered control structure. -- The design and development process for NOMAD are detailed in this thesis. The results of digital simulation, theoretical analysis and typical data recorded from tests in a deep water tank on the robot are presented. Successful tests and good agreement between data and analysis indicate great potential for industrial application of the technologies developed in this project

    Volume 1 – Symposium

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    We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group A: Materials Group B: System design & integration Group C: Novel system solutions Group D: Additive manufacturing Group E: Components Group F: Intelligent control Group G: Fluids Group H | K: Pumps Group I | L: Mobile applications Group J: Fundamental

    Odour discrimination in mice with perturbed granule cells, assayed by automated behavioural testing

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    Olfaction, the sense of smell, is one of the most important sensory stimuli for any organism, from unicellular bacteria to highly complex metazoans like humans. Volatile chemicals constituting olfactory cues can carry a vast range of information, enabling animals to detect and locate food, mates or shelter. The structure of the olfactory system has remained remarkably conserved, indicating that the precise anatomy is integral to the detection and discrimination of odours. Previous studies have shown that the connectivity of olfactory bulb mitral and granule cells plays a crucial role in odour discrimination in mice, yet several aspects of granule cell function remain unclear. To investigate the impact of modified granule cell function on odour discrimination in mice, we first established a novel automated operant conditioning setup. This setup allowed us to train large (>20 animals) groups of mice on a go/no-go odour discrimination task with minimal experimenter interference. It was used for detailed analysis olfactory behaviour by assessing parameters such as the discrimination time, the speed at which animals were able to discriminate and odour and initiate a corresponding behavioural response. As neurobiological function follows form, we focussed on the specialized dendrodendritic connection between the principal output neurons of the mammalian olfactory bulb, the mitral cells, and the most abundant inhibitory interneurons of the olfactory bulb, the granule cells. As inhibition of mitral cells from granule cell has been shown to directly affect the discrimination of odour mixtures, we sought to modulate the strength of this inhibition using two different approaches. The first strategy was based on increasing the inhibitory output through the overall increase of granule cells. Towards this end, a novel transgenic mouse line was used, in which the pool of neuronal stem cells can be temporarily increased resulting in an olfactory bulb specific increase of physiologically normal and functionally integrated granule cells. Utilizing the automated behaviour setup, we were able to show that discrimination accuracy, but not the discrimination time of highly similar mixtures of two enantiomers is increased in mice harbouring an increased number of granule cells. The second approach was based on reducing the inhibitory output of granule cells by reducing the global activation of granule cells following local dendritic activation, a feature which is thought to be gated by T-type calcium channels. Therefore, we established a simultaneous triple knock-down of all three T-type subunits using adeno-associated virus-based shRNA expression in granule cells. We found that mice with reduced T-type expression did not show the typical increase in discrimination times when comparing simple with complex odours, suggesting that a lack of global activation affects discrimination of simple odours. In summary, these findings highlight the importance of granule cell-derived inhibitory input onto mitral cells for the discrimination of highly similar odour stimuli. Taking into account the subtle nature of the molecular modifications and the flexibility of the novel approach to behavioural phenotyping, these results clearly outline the path to a large-scale, systematic investigation into the limits of olfaction

    Learning-based robotic manipulation for dynamic object handling : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Mechatronic Engineering at the School of Food and Advanced Technology, Massey University, Turitea Campus, Palmerston North, New Zealand

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    Figures are re-used in this thesis with permission of their respective publishers or under a Creative Commons licence.Recent trends have shown that the lifecycles and production volumes of modern products are shortening. Consequently, many manufacturers subject to frequent change prefer flexible and reconfigurable production systems. Such schemes are often achieved by means of manual assembly, as conventional automated systems are perceived as lacking flexibility. Production lines that incorporate human workers are particularly common within consumer electronics and small appliances. Artificial intelligence (AI) is a possible avenue to achieve smart robotic automation in this context. In this research it is argued that a robust, autonomous object handling process plays a crucial role in future manufacturing systems that incorporate robotics—key to further closing the gap between manual and fully automated production. Novel object grasping is a difficult task, confounded by many factors including object geometry, weight distribution, friction coefficients and deformation characteristics. Sensing and actuation accuracy can also significantly impact manipulation quality. Another challenge is understanding the relationship between these factors, a specific grasping strategy, the robotic arm and the employed end-effector. Manipulation has been a central research topic within robotics for many years. Some works focus on design, i.e. specifying a gripper-object interface such that the effects of imprecise gripper placement and other confounding control-related factors are mitigated. Many universal robotic gripper designs have been considered, including 3-fingered gripper designs, anthropomorphic grippers, granular jamming end-effectors and underactuated mechanisms. While such approaches have maintained some interest, contemporary works predominantly utilise machine learning in conjunction with imaging technologies and generic force-closure end-effectors. Neural networks that utilise supervised and unsupervised learning schemes with an RGB or RGB-D input make up the bulk of publications within this field. Though many solutions have been studied, automatically generating a robust grasp configuration for objects not known a priori, remains an open-ended problem. An element of this issue relates to a lack of objective performance metrics to quantify the effectiveness of a solution—which has traditionally driven the direction of community focus by highlighting gaps in the state-of-the-art. This research employs monocular vision and deep learning to generate—and select from—a set of hypothesis grasps. A significant portion of this research relates to the process by which a final grasp is selected. Grasp synthesis is achieved by sampling the workspace using convolutional neural networks trained to recognise prospective grasp areas. Each potential pose is evaluated by the proposed method in conjunction with other input modalities—such as load-cells and an alternate perspective. To overcome human bias and build upon traditional metrics, scores are established to objectively quantify the quality of an executed grasp trial. Learning frameworks that aim to maximise for these scores are employed in the selection process to improve performance. The proposed methodology and associated metrics are empirically evaluated. A physical prototype system was constructed, employing a Dobot Magician robotic manipulator, vision enclosure, imaging system, conveyor, sensing unit and control system. Over 4,000 trials were conducted utilising 100 objects. Experimentation showed that robotic manipulation quality could be improved by 10.3% when selecting to optimise for the proposed metrics—quantified by a metric related to translational error. Trials further demonstrated a grasp success rate of 99.3% for known objects and 98.9% for objects for which a priori information is unavailable. For unknown objects, this equated to an improvement of approximately 10% relative to other similar methodologies in literature. A 5.3% reduction in grasp rate was observed when removing the metrics as selection criteria for the prototype system. The system operated at approximately 1 Hz when contemporary hardware was employed. Experimentation demonstrated that selecting a grasp pose based on the proposed metrics improved grasp rates by up to 4.6% for known objects and 2.5% for unknown objects—compared to selecting for grasp rate alone. This project was sponsored by the Richard and Mary Earle Technology Trust, the Ken and Elizabeth Powell Bursary and the Massey University Foundation. Without the financial support provided by these entities, it would not have been possible to construct the physical robotic system used for testing and experimentation. This research adds to the field of robotic manipulation, contributing to topics on grasp-induced error analysis, post-grasp error minimisation, grasp synthesis framework design and general grasp synthesis. Three journal publications and one IEEE Xplore paper have been published as a result of this research

    Sensors Fault Diagnosis Trends and Applications

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    Fault diagnosis has always been a concern for industry. In general, diagnosis in complex systems requires the acquisition of information from sensors and the processing and extracting of required features for the classification or identification of faults. Therefore, fault diagnosis of sensors is clearly important as faulty information from a sensor may lead to misleading conclusions about the whole system. As engineering systems grow in size and complexity, it becomes more and more important to diagnose faulty behavior before it can lead to total failure. In the light of above issues, this book is dedicated to trends and applications in modern-sensor fault diagnosis

    Volume 3 – Conference

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    We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group 8: Pneumatics Group 9 | 11: Mobile applications Group 10: Special domains Group 12: Novel system architectures Group 13 | 15: Actuators & sensors Group 14: Safety & reliabilit

    Sliding Mode Control

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    The main objective of this monograph is to present a broad range of well worked out, recent application studies as well as theoretical contributions in the field of sliding mode control system analysis and design. The contributions presented here include new theoretical developments as well as successful applications of variable structure controllers primarily in the field of power electronics, electric drives and motion steering systems. They enrich the current state of the art, and motivate and encourage new ideas and solutions in the sliding mode control area
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