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The thesis describes original work that has developed a novel climbing robot system for the Non-Destructive Testing (NDT) of aircraft fuselage and wings, and the processing and compression ofNDT image data based on the Wavelet Transform. The work establishes the functional requirements for a wall climbing robotic NDT system for aircraft inspection. A climbing robot has been designed and prototyped that can climb on all surface curvatures presented by the fuselage and wings. The novelty in the design is the use of a hierarchy of universal joints to allow flexible adaptation of the robot to varying surface curvatures while at the same time making the structure rigid when suction cups are activated. The structure of the flexible climbing robot has been analysed to establish its intrinsic stability. The hybrid electric and pneumatic control system obtains X-Y movement of the robot and is able to correct off-course errors. The control system tests cylinder rod positions and vacuum pressure before allowing movement of the robot. The climbing robot has been tested successfully on a real aircraft fuselage section. The robot can climb reliably and deploy wet or dry ultrasound transducers with a four axes Cartesian scanner mounted on the climbing robot. The development is reported of a new invention called a regional NDT image compression tool based on the Wavelet Transform. The development includes feature extraction of NDT images and Regional Set Partitioning in Hierarchical Trees (RSPIHT) coding algorithm. With this tool, the NDT image compression showed that the tested images could be compressed at ratios of up to 1000:1, and when the compressed images were reconstructed, the defects could be still observed clearly. This proves that the initial idea of using the regional Wavelet Transform based image compression technique is correct. The results of the work can be used as a general guideline for design and development of other new types of wall-climbing robotic NDT instrumentation and image data processing.

In this thesis novel numerical algorithms are developed to solve some problems of analysis and control design for unstable linear dynamical systems having their input constrained by maximum amplitude and rate of the control signals. Although the results obtained are of a general nature, all the problems considered are induced by flight control applications. Moreover, all these problems are stated in terms of geometry, and because of this their solution in the thesis was effectively achieved by geometrically-oriented methods. The problems considered are mainly connected with the notions of the controllable and stability regions. The controllable region is defined as the set of states of an unstable dynamical system that can be stabilized by some realizable control action. This region is bounded due to input constraints and its size can serve as a controllability measure for the control design problem. A numerical algorithm for the computation of two-dimensional slices of the region is proposed. Moreover, the stability region design is also considered. The stability region of the closed-loop system is the set of states that can be stabilized by a particular controller. This region generally utilizes only a part of the controllable region. Therefore, the controller design objective may be formulated as maximizing this region. A controller that is optimal in this sense is proposed for the case of one and two exponentially unstable open-loop eigenvalues. In the final part of the thesis a linear control allocation problem is considered for overactuated systems and its real-time solution is suggested. Using the control allocation, the actuator selection task is separated from the regulation task in the control design. All fault detection and reconfiguration capabilities are concentrated in one special unit called the control allocator, while a general control algorithm, which produces 'virtual' input for the system, remains intact. In the case of an actuator fault, only the control allocation unit needs to be reconfigured and in many cases it can generate the same 'virtual' input using a different set of control effectors. A novel control allocation algorithm, which is proposed in the thesis, is based on multidimensional interval bisection techniques.

For all types of aircraft (civil, military, manned, unmanned) the aircraft designer specifies a safe range for the centre of gravity (cg) of the aircraft and designs the aircraft to operate safely within these limits. Changes to the cg may affect aircraft stability, performance and fuel economy so it is an important system parameter. Changes to the in-flight cg position have traditionally been estimated by calculating fuel burn and from that calculating the change in weight and hence change in cg. Other techniques to estimate in-flight aircraft cg are included in the literature review. The motivation for additional cg estimation techniques arise from the potential benefits they offer to a Flight Control System (FCS). These benefits include the potential for improved fault detection and an improved FCS design with better aircraft performance and fuel economy. State estimation using Kalman filters has been used since the 1960 s in many fields of application including the aerospace industry. This thesis will introduce the concept of using state estimation to detect the unexpected angular acceleration associated with a cg change. This state estimation concept is applied to a linear Phantom aircraft model and then to a complex non-linear aircraft model of a delta-canard military aircraft, called ADMIRE. The most common state estimation approach used with non-linear systems is the Extended Kalman Filter (EKF), but an alternative approach is proposed in which the pitching and roll moment coefficient derivatives are selectively modified based upon the aircraft angle of attack, speed and altitude. Both longitudinal and lateral cg estimators are described and examples of their performance are provided and compared with an EKF version of the estimator. A discrete version of the estimator is also described and used with a hardware fuel rig. Faults are applied to the fuel rig and it is proposed that the estimator could aid the fault diagnosis. In a real implementation the aircraft will not be precisely modelled, therefore a sequence of robustness tests are included to identify the critical aircraft parameters affecting the estimator. The results show that a cg estimator based upon a Kalman filter, and using a selective coefficient correction approach, can satisfy the performance requirements specified by the industrial sponsor, BAE Systems.

In the present scenario, as advances in research, technology and engineering application have been on a rise , thus persuading researchers and engineers to employ new computer modelling techniques for the design and analysis, mainly due to time, environmental and economic constraints. Moreover it also forms a basis for any observed anomalies, when comparing with the simulated and experimental results and taking steps to develop optimum design strategies. The present research work deals with the development of novel ftlter designs when employed in aeronautical hydraulic systems. These pleated cartridge ftlters would be fabricated using eco-friendly fIltering media supported by unconventional disposable or reusable solid components. The primary focus of the present research work to develop a robust cost-effective simulating tools for simulating the results in the hydrodynamic behaviour of the fluid in pleated cartridge ftlters. As observed in any ftltration process, it comprises of two flow regimes namely free flow and porous flow regimes. For over five decades, it had been a subject of intense research and investigation for researchers, scientist and engineers to resolve some of the critical and vital issues related to filtration process. The main problems, when compared to others, that are associated with such processes are the free/porous interfacial constraints along with boundary conditions and their mathematical representation with respect to the industrial applications. A three dimensional model has been developed to represent the momentum and mass conservation for creeping incompressible flow in coupled free/porous flow regimes. In order to take into consideration the rheological behaviour of the fluid, power law model has been included, which forms the constitutive equation, and the viscosity of the fluid has been updated for the highly viscous specially formulated hydraulic fluid. For any numerical technique of analysis, on vital aspect is the boundary conditions that are imposed on the surface/volume/edge of the domain under consideration. The free (Stokes) and porous flow (Darey) regimes have been linked and solved in conjunction with continuity equations on a perturbed continuity scheme based on the standard Galerkin weighted residual finite element method. The perturb continuity UVWP finite element scheme is based On the equal order interpolation approximations and the discretized working equations are then transformed into the local coordinate system using iso-parametric mapping. The elements used are linear (8 nodded) hexahedral elements. The integrals in the elemental stiffness equations were calculated using Gauss-Legendre quadrature. After evaluation of the members of the elemental stiffness matrix, they are assembled over the common nodes in the computational grid to obtain a system of algebraic equations. After substituting the boundary conditions, the system becomes determinate and the algebraic equations can be solved using a frontal solution method. The described simulations are carried out using an in-house developed lnte! Visual FORTRAN code. The time stepping technique used here is second order Taylor-Galerkin method. The concept of compression permeability model developed by Nassehi et aL Nassehi et aL, 2005J ( developed for two dimensional case and now extended to three dimensional case) has been used to into the flow model to take into account the effects arising due to the mtration area loss in pleated cartridge filters and degree or extent of compression of the fUter medium. Significant over-use of media material or the need for changes to the geometric or mechanical design can be identified using the procedures described.

Unmanned aerial vehicles (UAV) have been receiving unprecedented development during the past two decades. Among different types of UAVs, unmanned helicopters exhibit promising features gained from vertical-takeoff-and-landing, which make them as a versatile platform for both military and civil applications. The work reported in this thesis aims to apply advanced control techniques, in particular model predictive control (MPC), to an autonomous helicopter in order to enhance its performance and capability. First, a rapid prototyping testbed is developed to enable indoor flight testing for miniature helicopters. This testbed is able to simultaneously observe the flight state, carry out complicated algorithms and realtime control of helicopters all in a Matlab/Simulink environment, which provides a streamline process from algorithm development, simulation to flight tests. Next, the modelling and system identification for small-scale helicopters are studied. A parametric model is developed and the unknown parameters are estimated through the designed identification process. After a mathematical model of the selected helicopter is available, three MPC based control algorithms are developed focusing on different aspects in the operation of autonomous helicopters. The first algorithm is a nonlinear MPC framework. A piecewise constant scheme is used in the MPC formulation to reduce the intensive computation load. A two-level framework is suggested where the nonlinear MPC is combined with a low-level linear controller to allow its application on the systems with fast dynamics. The second algorithm solves the local path planning and the successive tracking control by using nonlinear and linear MPC, respectively. The kinematics and obstacle information are incorporated in the path planning, and the linear dynamics are used to design a flight controller. A guidance compensator dynamically links the path planner and flight controller. The third algorithm focuses on the further reduction of computational load in a MPC scheme and the trajectory tracking control in the presence of uncertainties and disturbances. An explicit nonlinear MPC is developed for helicopters to avoid online optimisation, which is then integrated with a nonlinear disturbance observer to significantly improve its robustness and disturbance attenuation. All these algorithms have been verified by flight tests for autonomous helicopters in the dedicated rapid prototyping testbed developed in this thesis.