Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xi, 96 p. : ill. (some col.), map. Includes abstract. Includes bibliographical references (p. 75).

The demand for unmanned aerial vehicles (UAVs) has increased dramatically in the last decade from reconnaissance missions to attack roles. As their missions become more complex, advances in endurance and manoeuvrability become crucial. Due to the advances in material fabrication, wing morphing can be seen as an ideal solution for UAVs to provide improvements by overcoming the weight drawback. This thesis investigates the area of aircraft design and simulation for low speed UAVs looking at performance enhancements techniques for low speed UAVs, and their effects on the aerodynamic capabilities of the wing. The focus is on both suitable control design and wing morphing techniques based on current research findings. The low speed UAV X-RAE1 is used as the test bed for this investigation and is initially analytically presented as three dimensional body where the equations relate to the forces and moments acting on the UAV. A linearised model for straight flight at different velocities is implemented and validated against a non-linear model. Simulations showed the X-RAE1 to have acceptable stability properties over the design operating range. Control design techniques, linear quadratic regulators (LQR) and H-infinity optimisation with Loop Shaping Design Procedure (LSDP), are used to design simple control schemes for linearised longitudinal model of the X-RAE1 UAV at different velocities. The effectiveness and limitations of the two design methods show that both designs are very fast, with settling times 2-3 seconds in the height response and remarkably low variation of the results at different velocities. Computational fluid dynamics is then used to investigate and simulate the impact of introducing smart effector arrays on a UAV. The smart effector array produces a form of active flow control by providing localised flow field changes. These induced changes have direct impact on the aerodynamic forces and showed a substantial increase of lift at low angles of attack. There was also a significant increase to the lift to drag ratio at high angles of attack which resulted to a delay in stall.

The subject of this thesis is the investigation of multibody system modelling and control analysis techniques for the development of advanced suspension systems in passenger cars. A review of the application of automatic control to all areas of automotive vehicles illustrated the important factors in such developments, including motivating influences, constraints and methodologies used. A further review of specific applications for advanced suspension systems highlighted a major discrepancy between the significant claims of theoretical performance benefits and the scarcity of successful practical implementations. This discrepancy was the result of idealistic analytical studies producing unrealistic solutions with little regard for practical constraints. The predominant application of prototype testing methods in implementation studies also resulted in reduced potential performance improvements. This work addressed this gap by the application of realistic modelling and control design techniques to practical realistic suspension systems. Multibody system modelling techniques were used to develop vehicle models incorporating realistic representations of the suspension system itself, with the ability to include models of the controllers, and facilitate control analysis tasks. These models were first used to address ride control for fully active suspension systems. Both state space techniques, including linear quadratic regulator and pole placement and frequency domain design methods were applied. For the multivariable frequency domain study, dyadic expansion techniques were used to decouple the system into single input single output systems representing each of the sprung mass modes. Both discretely and continuously variable damping systems were then addressed with a range of control strategies, including analytical solutions based on the active results and heuristic rule-based approaches. The controllers based on active solutions were reduced to satisfy realistic practical limitations of the achievable damping force. The heuristic techniques included standard rule-based controllers using Boolean logic for the discretely variable case, and fuzzy logic controllers for the continuously variable case.

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This thesis presents a new finite element analysis (FEA) method for calculating the critical stress in an aircraft wheel’s lock-ring. The lock-ring is used on many modern designs in place of the bolts that join the two main sections of the wheel. The lock-ring is a safety critical component of the wheel as a failure could lead to an explosive release of tyre pressure. The stress field in this wheel forms a fatigue cycle as the wheel rotates when the aircraft manoeuvres on the ground. The stress field at the critical location on the lock-ring is strongly dependent on the contacting surfaces of three structural components of the wheel: the main hub, the lock-ring and the freeflange. Until completion of this work no method existed to calculate the fatigue stress cycle at this design critical location. Modern wheel designs, to minimise aircraft weight and therefore fuel use, are of minimum weight designs. This means that the aluminium material in the latest wheel designs is subjected to greater stress than in previous designs, therefore the ‘margin of safety’ for the wheels is reduced. It is important that methods are developed to calculate the stress in all regions of the wheel, including the lock-ring. Lock-ring wheel designs were originally used on military aircraft and more recently they have become common on business jet aircraft. Very recently the feasibility of their use on large commercial aircraft that carry upwards of 100 passengers is being considered. The operating environment on large commercial aircraft is very harsh for wheels and the methodology developed in this work is required to correctly assess the use of these wheels in this harsh and safety critical environment. The calculation method is compared against physical test data measured on two wheels using strain gauges. The wheels, with tyres installed, were loaded and rolled on a road wheel dynamometer to simulate aircraft ground manoeuvres. Measuring the critical location is difficult as access to it is limited; it had not been measured before. The measured data are used to verify the new FEA method. The new FEA method was developed with the potential for use by both a nonspecialist engineer and use in a modern Concurrent Engineering environment as requirements. The FEA is linked directly to the CATIA 3D computer aided design (CAD) model, using CADNexus software. This link is made in such a way that a modification to the design, once included in the CAD model, can be easily and automatically followed by an update to the FEA. The FEA requires solution of a non-linear model because contact between three structural components is critical and therefore must be modelled in detail. The general perception in industry is that non-linear FEA is a complex subject and must be undertaken by an experienced FEA specialist – this work provides strong supportive evidence to contradict this general perception. The FEA itself is implemented using ANSYS® Workbench software. The new analysis method, including the model set-up parameters is stored in an analysis template. This analysis template effectively captures the knowledge of a specialist FEA engineer so that it can be used, for design purposes, by a non-special engineer. The final FEA method is useful not only to non-specialist engineers but also, because the specialist knowledge is contained within the ANSYS® Workbench template, for outsourcing this structural analysis work to lower cost economies. The works creates a new FEA method of specific use to manufactures and designers of weight optimised aerospace wheels. Furthermore, in a more general context, it demonstrates that even complex non-linear FEA can be defined within knowledge capturing templates. This makes it accessible to engineers without specialist expertise with FEA. Empowering the design engineer to structurally optimise their own designs will lead to leaner design teams, which will consequently reduce development costs. The new method can be competed as part of a Concurrent Engineering process. This is advantageous as it can expedite the design process, therefore allowing FEA results to be available early enough in the programme to be made use of.

This thesis reports the analysis and design of a hovering rotor equipped with both slotted and blended trailing-edge flaps. This was accomplished by combining a simple blade element method with 3D inviscid and RANS CFD that allowed for a robust sequence of design specification, analysis, and verification. Most modern helicopters have high levels of blade twist and various tip shape designs to help improve hover performance. However, such blade designs face problems due to compressibility effects on the advancing blade in forward flight. The twisted blade gives rise to negative incidence at the blade tip, which accelerates shock formation on the lower surface. The current work looks to evaluate the implementation of a low twist rotor for improved forward flight performance and recovering any potential losses in hover performance by deflecting fixed, trailing-edge flaps.

This thesis investigated the management of electric vehicle battery charging in distribution networks. Different electric vehicle fleet sizes and network locations were considered. The energy storage capacity and backup generator’s energy requirements were calculated to achieve daily energy balance in a low voltage distribution network with micro-generation. The effect of the electric vehicle battery demand as controllable loads on the backup generator energy requirements was assessed. It was found that the use of electric vehicles as controllable loads reduced the energy requirements from the backup generator or made it unnecessary to achieve energy balance. Two control algorithms for the battery charging management of electric vehicles clustered in battery charging facilities were designed and developed. One algorithm calculates electric vehicle battery charging profiles for vehicles located in a parking space. Different charging policies were investigated, showing the ability of the control algorithm to define the electricity profile of the parking space according to network constraints and the policies’ objectives. The second algorithm calculates the number of batteries and chargers that are required to satisfy the battery demand of electric vehicle battery swapping stations. The impact of the number of chargers and batteries on the swapping station’s electricity load profile were evaluated. An agent-based control system was designed and developed for the battery charging management of electric vehicles dispersed in distribution networks. The electric vehicle battery charging schedules are calculated according to electricity prices and distribution network technical constraints. The real-time operation of the agent-based control system was demonstrated in the laboratory of TECNALIA’s research centre in Bilbao, Spain. A series of experiments showed the ability of the control system to operate and manage the electric vehicle battery charging when the distribution network is operated within its loading capacity and when the network technical limits are violated.

In the early phase of the design of a space mission it is generally desirable to investigate as many feasible alternative solutions as possible. Traditionally a system margin approach is used in order to estimate the correct value of subsystem budgets. While this is a consolidated and robust approach, it does not give a measure of the reliability of any of the investigated solutions. In addition the mass budget is typically overdimensioned, where a more accurate design could lead to improvements in payload mass. This study will address two principal issues typically associated with the design of a space mission: (i) the effective and efficient generation of preliminary solutions by properly treating their inherent multi-disciplinary elements and (ii) the minimisation of the impact of uncertainties on the overall design, which in turn will lead to an increase in the reliability of the produced results. The representation and treatment of the uncertainties are key aspects of reliable design. An insufficient consideration of uncertainty or an unadapted mathematical representation leads to misunderstanding of the real issues of a design, to delay in the future development of the project or even potentially to its failure. The most common way to deal with uncertainty is the probabilistic approach. However, this theory is not suitable to represent epistemic uncertainties, arising from lack of knowledge. Alternative theories have been recently developed, amongst which we find Evidence Theory which is implemented in this work. Developed by Shafer from Dempster's original work, it is regarded by many as a suitable paradigm to accurately represent uncertainties. Evidence Theory is presented and discussed from an engineering point of view and special attention given to the implementation of this approach. Once mathematically represented, the uncertainties can be taken into account in the design optimisation problem. However, the computational complexity of Evidence Theory can be overwhelming and therefore more efficient ways to solve the reliable design problem are required. Existing methods are considered and improvements developed by the author, to increase the efficiency of the algorithm by making the most of the available data, are proposed and tested. Additionally, a new sample-based approximation technique to tackle large scale problems, is introduced in this thesis. Assuming that the uncertainties are modelled by means of intervals, the cluster approximation method, and especially implemented as a Binary Space Partition, appears to be very well-suited to the task. The performance of the various considered methods to solve the reliable design optimisation problem in the frame of Evidence Theory is tested and analysed. The dependency on the problem characteristics, such as dimensionality, complexity, or multitude of local solutions are carefully scrutinised. The conclusions of these tests enables the author to propose guidelines on how to tackle the problem depending on its specificity. Finally, two examples of preliminary space mission design are used to illustrate how the proposed methodology can be applied. Using realistic and current mission designs, the results show the benefits that could be achieved during the preliminary analyses and feasibility studies of space exploration.

This document is the executive summary of the author's Engineering Doctorate portfolio. It is entitled "Key Challenges in the Development of Automotive Software-based Electronic Control Systems", and presents the main results from two distinct but interrelated projects, each of which addresses a different challenge. It begins with an introduction to automotive software-based electronic control systems, and emphasises the problems associated with the use of software. The first project was concerned with using software in a safety-related control system, and addressed the issue of how to demonstrate that it was sufficiently safe, i.e. that there was sufficient confidence that the software would behave as expected, even under fault conditions. The second project was concerned with the investigation and introduction of a new simulation technology for developing electronic control systems. It sought to address the challenge presented by the need to develop ever more complex systems, whilst at the same time reducing dependence on prototype testing, and reducing the time available for development. The projects ran concurrently throughout, and both were perfonned within the ElectricallElectronic Engineering department at Jaguar Cars, who are responsible for the development of all the control systems within Jaguar's products. This summary concludes with a section which hypothesises on the future direction for automotive software-based electronic control system technology, against a context of the business environment in which the industry operates.

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