Advanced Modeling, Control, and Optimization Methods in Power Hybrid Systems - 2021

The climate changes that are becoming visible today are a challenge for the global research community. In this context, renewable energy sources, fuel cell systems and other energy generating sources must be optimally combined and connected to the grid system using advanced energy transaction methods. As this reprint presents the latest solutions in the implementation of fuel cell and renewable energy in mobile and stationary applications such as hybrid and microgrid power systems based on the Energy Internet, blockchain technology and smart contracts, we hope that they will be of interest to readers working in the related fields mentioned above

Modeling and Control for a Class of Tendon-Driven Continuum Mechanisms

This thesis contributes to the emerging field of soft material robots and treats modeling, state estimation and control for a special class of continuum mechanisms. The overall outcome of is a novel treatment of a continuum in robotics research. At first a description of the overall system as a tendon-driven multi-body system modeled by a nonlinear rigid-body dynamics is proposed. In combination with the introduced real-time pose and velocity estimation, nonlinear model-based control in real-time is possible. Furthermore, the structural properties of the model allow employing modern control methods for underactuated mechanical systems which are adapted to provide set point control for the upper platform. The developed methods in modeling, state estimation and control presented in this work are experimentally validated on a humanoid robot. Due to their promising results, this thesis lays the foundation for the use of tendon-driven continuum mechanisms as generic joint modules for modular robotic systems which may mark the beginning of a new generation of light-weight robots

Control techniques for mechatronic assisted surgery

The treatment response for traumatic head injured patients can be improved by using an autonomous robotic system to perform basic, time-critical emergency neurosurgery, reducing costs and saving lives. In this thesis, a concept for a neurosurgical robotic system is proposed to perform three specific emergency neurosurgical procedures; they are the placement of an intracranial pressure monitor, external ventricular drainage, and the evacuation of chronic subdural haematoma. The control methods for this system are investigated following a curiosity led approach. Individual problems are interpreted in the widest sense and solutions posed that are general in nature. Three main contributions result from this approach: 1) a clinical evidence based review of surgical robotics and a methodology to assist in their evaluation, 2) a new controller for soft-grasping of objects, and 3) new propositions and theorems for chatter suppression sliding mode controllers. These contributions directly assist in the design of the control system of the neurosurgical robot and, more broadly, impact other areas outside the narrow con nes of the target application. A methodology for applied research in surgical robotics is proposed. The methodology sets out a hierarchy of criteria consisting of three tiers, with the most important being the bottom tier and the least being the top tier. It is argued that a robotic system must adhere to these criteria in order to achieve acceptability. Recent commercial systems are reviewed against these criteria, and are found to conform up to at least the bottom and intermediate tiers. However, the lack of conformity to the criteria in the top tier, combined with the inability to conclusively prove increased clinical benefit, particularly symptomatic benefit, is shown to be hampering the potential of surgical robotics in gaining wide establishment. A control scheme for soft-grasping objects is presented. Grasping a soft or fragile object requires the use of minimum contact force to prevent damage or deformation. Without precise knowledge of object parameters, real-time feedback control must be used to regulate the contact force and prevent slip. Moreover, the controller must be designed to have good performance characteristics to rapidly modulate the fingertip contact force in response to a slip event. A fuzzy sliding mode controller combined with a disturbance observer is proposed for contact force control and slip prevention. The robustness of the controller is evaluated through both simulation and experiment. The control scheme was found to be effective and robust to parameter uncertainty. When tested on a real system, however, chattering phenomena, well known to sliding mode research, was induced by the unmodelled suboptimal components of the system (filtering, backlash, and time delays). This reduced the controller performance. The problem of chattering and potential solutions are explored. Real systems using sliding mode controllers, such as the control scheme for soft-grasping, have a tendency to chatter at high frequencies. This is caused by the sliding mode controller interacting with un-modelled parasitic dynamics at the actuator-input and sensor-output of the plant. As a result, new chatter-suppression sliding mode controllers have been developed, which introduce new parameters into the system. However, the effect any particular choice of parameters has on system performance is unclear, and this can make tuning the parameters to meet a set of performance criteria di cult. In this thesis, common chatter-suppression sliding mode control strategies are surveyed and simple design and estimation methods are proposed. The estimation methods predict convergence, chattering amplitude, settling time, and maximum output bounds (overshoot) using harmonic linearizations and invariant ellipsoid sets

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Three-Tether Wave Energy Converter: Hydrodynamic Modelling, Performance Assessment and Control

Hydro, wind and solar power have become major contributors to the global renewable energy market. However, ocean wave power is emerging as a strong contender in the renewable energy mix due to its high power density and minimal environmental impact. Wave energy has the potential to provide an off-grid electricity solution to remote island communities, and fulfil offshore power needs of small industrial projects. One of the best wave energy resources in the world is concentrated along the southern margin of Australia, and if harnessed, wave power could contribute up to 27 per cent of the country’s electricity demand by 2050. Over the past few decades, a large number of concepts and designs have been suggested to convert wave energy into electricity. Despite a huge effort made by industry and the scientific community, the technology for extracting power from ocean waves still remains at a pre-commercial stage of development. The main challenge is to design an economically viable wave energy converter (WEC) where its life-cycle costs (investments, operation and maintenance) can be justified by the amount of generated electricity. This thesis focuses on the performance improvement of a particular class of wave energy converters, namely, a bottom-referenced fully submerged point absorber, by means of the three-tether mooring configuration. The main contribution is made towards the design, optimisation and control of the converter in order to answer three research questions: (i) what distinctive features of the fully submerged WECs can be utilised to increase their power absorption efficiency; (ii) how geometric parameters of the converter, such as the tether arrangement, shape, and aspect ratio affect the system performance; and (iii) what factors influence the practical implementation of the optimal control strategies on the three-tether WEC. To explore these questions, numerical frequency- and time-domain models have been developed using state-of-the-art techniques based on linear hydrodynamic theory. In order to gain background knowledge and build a core understanding of the submerged systems, the difference between floating and fully submerged point absorbers is investigated. Attention is given to the distinctive features observed in the hydrodynamic properties, power production limits, and control performance. Recommendations are provided on the choice of the buoy size and shape, depending on the wave climate of the deployment site. The advantages of employing multiple degrees of freedom in energy harvesting, especially for submerged converters, are demonstrated. The design considerations of the three-tether WEC are investigated from a number of perspectives including the tether arrangement, mass, shape, and aspect ratio of the buoy. A clear correlation between an optimal tether inclination angle and the buoy aspect ratio is identified. The comparison of three-tether WECs with different buoy geometries is performed not only based on their power output, but also taking into account a range of cost-related performance metrics. Moreover, the benefits of the three-tether converter over its single-tether counterpart are demonstrated through the detailed techno-economic analysis of both prototypes. The final aspect of this dissertation is devoted to the development of the advanced control system for the three-tether WEC. The causal velocity tracking controller is taken as a basis and extended to the multivariable control problem. It is demonstrated that the designed controller is able to improve the power absorption of the three-tether WEC as compared to a quasi-standard control approach while imposing a series of technical requirements on the power take-off machinery.Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 201

Large space structures and systems in the space station era: A bibliography with indexes (supplement 05)

Bibliographies and abstracts are listed for 1363 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1991 and July 31, 1992. Topics covered include technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion and solar power satellite systems