The work presented in this thesis aims to make contribution to the understanding and application of six-legged statically stable walking machines in both theoretical and practical levels. In this thesis five pieces of work, performed with and for the three-joint six-legged Robot-EA308, are presented: 1) Standard gaits, which include the well-known wave gaits, are defined and a stability analysis, in the sense of static stable walking, is performed on an analytical level. Various definitions are given / theorems are stated and proved. 2) A free gait generation algorithm with reinforcement learning is developed. Its facilities of stability improvement, smooth speed changes, and adaptation in case of a rear-leg deficiency with learning of five-legged walking are experimented in real-time on the Robot-EA308. 3) Trajectory optimization and controller design is performed for the protraction movement of a three-joint leg. The trajectory generated by the controller is demonstrated with the Robot-EA308. 4) The full kinematic-dynamic formulation of a three-joint six-legged robot is performed with the joint-torques being the primary variables. It is demonstrated that the proposed torque distribution scheme, rather than the conventional force distribution, results in an efficient distribution of required forces and moments to the supporting legs. 5) An analysis of energy efficiency is performed for wave gaits. The established strategies for determination of gait parameters for an efficient walk are justified using the Robot-EA308.

In this thesis, an unmanned air vehicle (UAV) is used to develop a prototype base test platform for flight testing of new control algorithms and avionics for advanced UAV system development applications. A control system that holds the UAV at a fixed altitude above the ground is designed and flight tested. Only the longitudinal motion of the UAV is considered during the controller design, hence its lateral motions are controlled manually by a remote control unit from the ground. UAV&amp / #8217 / s altitude with respect to the mean sea level and position are obtained by an onboard global positioning system (GPS) and this information is transmitted to the ground computer via radio frequency (RF) communication modules. The altitude of the UAV above the ground is calculated by using the digital terrain elevation data (DTED). A controller is designed and its gains are tuned to maintain this flight altitude at a desired value by using the mathematical model developed to represent the longitudinal dynamics of the UAV. Input signals generated by the controller for elevator deflections are transmitted back to the UAV via RF communication modules to drive onboard servomotors to generate desired elevator deflections. All controller computations and RF communications are handled by a MATLAB&reg / based platform on a ground computer. UAV flight tests are carried out at two different autopilot modes / namely, mean sea level (MSL) altitude hold mode and above ground level (AGL) altitude hold mode. The developed platform worked properly during flight tests and proved to be reliable in almost every condition. Moreover, the designed controller system is demonstrated to be effective and it fulfills the requirements.

A cruise missile is a guided missile that uses a lifting wing and a jet propulsion system to allow sustained flight. Cruise missiles are, in essence, unmanned aircraft and they are generally designed to carry a large conventional or nuclear warhead many hundreds of miles with excellent accuracy. In this study, navigation and control studies on cruise missiles are performed. Due to the variety and complexity of the subsystems of the cruise missiles, the main concern is limited with the navigation system. Navigation system determines the position, velocity, attitude and time solutions of the missile. Therefore, it can be concluded that an accurate self-contained navigation system directly influences the success of the missile. In the study, modern radar data association algorithms are implemented as new Terrain Aided Navigation (TAN) algorithms which can be used with low-cost Inertial Measurement Units (IMU&rsquo / s). In order to perform the study, first a thorough survey of the literature on mid-course navigation of cruise missiles is performed. Then, study on modern radar data association algorithms and their implementations to TAN are done with simple simulations. At the case study part, a six degree of freedom (6 DOF) flight simulation tool is developed which includes the aerodynamic and dynamic model of the cruise missile model including error model of the navigation system. Finally, the performances of the designed navigation systems with the implemented TAN algorithms are examined in detail with the help of the simulations performed.

In this study, the implementation of modern control techniques, that can be used both for the stable recovery of the aircraft from the undesired high angle of attack flight state (stall) and the agile maneuvering of the aircraft in various air combat or defense missions, are performed. In order to accomplish this task, the thrust vectoring control (TVC) actuation is blended with the conventional aerodynamic controls. The controller design is based on the nonlinear dynamic inversion (NDI) control methodologies and the stability and robustness analyses are done by using robust performance (RP) analysis techniques. The control architecture is designed to serve both for the recovery from the undesired stall condition (the stabilization controller) and to perform desired agile maneuvering (the attitude controller). The detailed modeling of the aircraft dynamics, aerodynamics, engines and thrust vectoring paddles, as well as the flight environment of the aircraft and the on-board sensors is performed. Within the control loop the human pilot model is included and the design of a fly-by-wire controller is also investigated. The performance of the designed stabilization and attitude controllers are simulated using the custom built 6 DoF aircraft flight simulation tool. As for the stabilization controller, a forced deep-stall flight condition is generated and the aircraft is recovered to stable and pilot controllable flight regimes from that undesired flight state. The performance of the attitude controller is investigated under various high angle of attack agile maneuvering conditions. Finally, the performances of the proposed controller schemes are discussed and the conclusions are made.

In this thesis, a simulation package for the Six Degrees of Freedom (6DOF) motion of an underwater vehicle is developed. Mathematical modeling of an underwater vehicle is done and the parameters needed to write such a simulation package are obtained from an existing underwater vehicle available in the literature. Basic equations of motion are developed to simulate the motion of the underwater vehicle and the parameters needed for the hydrodynamic modeling of the vehicle is obtained from the available literature. 6DOF simulation package prepared for the underwater vehicle was developed using the MATLAB environment. S-function hierarchy is developed using the same platform with C++ programming language. With the usage of S-functions the problems related to the speed of the platform have been eliminated. The use of Sfunction hierarchy brought out the opportunity of running the simulation package on other independent platforms and get results for the simulation.

This thesis documents the studies conducted in deriving a mathematical model representing the dynamics of a maneuvering ship to be implemented as part of an interactive real-time simulation system, as well as the details and results of the implementation process itself. Different effects on the dynamics of ship motions are discussed separately, meaning that the effects are considered to be applied to the system one at a time and they are included in the model simply by the principle of superposition. The model is intended to include the hydrodynamic interactions between the ship hull and the ocean via added mass (added inertia), damping and restoring force concepts. In addition to these effects, which are derived considering no incident waves are present on the ocean, the environmental disturbances, such as wind, wave and ocean current are also taken into account for proposing a mathematical model governing the dynamics of the ship. Since the ultimate product of this thesis work is a running computer code that can be integrated into an available simulation software, the algorithm development and code implementation processes are also covered. Improvements made on the implementation to achieve &ldquo / better&rdquo / real-time performance are evaluated comparatively in reference to original runs conducted before the application of improvement under consideration. A new method to the computation of the wave model that allows faster calculation in real-time is presented. A modular programming approach is followed in the overall algorithm development process in order to make the integration of new program components into the software, such as a new hull or propulsion model or a different integrator type possible, easily and quickly.

Active vehicle safety systems for road vehicles play an important role in accident prevention. In recent years, rapid developments have been observed in this area with advancing technology and electronic control systems. Active yaw control is one of these subjects, which aims to control the vehicle in case of any impending spinning or plowing during rapid and/or sharp maneuver. In addition to the development of these systems, integration and cooperation of these independent control mechanisms constitutes the current trend in active vehicle safety systems design. In this thesis, design methodology and simulation results of an active yaw control system for two axle road vehicles have been presented. Main objective of the yaw control system is to estimate the desired yaw behavior of the vehicle according to the demand of the driver and track this desired behavior accurately. The design procedure follows a progressive method, which first aims to design the yaw control scheme without regarding any other stability parameters, followed by the development of the designed control scheme via taking other stability parameters such vehicle sideslip angle into consideration. A two degree of freedom vehicle model (commonly known as &ldquo / Bicycle Model&rdquo / ) is employed to model the desired vehicle behavior. The design of the controller is based on Fuzzy Logic Control, which has proved itself useful for complex nonlinear design problems. Afterwards, the proposed yaw controller has been modified in order to limit the vehicle sideslip angle as well. Integration of the designed active yaw control system with other safety systems such as Anti-Lock Braking System (ABS) and Traction Control System (TCS) is another subject of this study. A fuzzy logic based wheel slip controller has also been included in the study in order to integrate two different independent active systems to each other, which, in fact, is a general design approach for real life applications. This integration actually aims to initiate and develop the integration procedure of the active yaw control system with the (ABS). An eight degree of freedom detailed vehicle model with nonlinear tire model is utilized to represent the real vehicle in order to ensure the validity of the results. The simulation is held in MATLAB/Simulink environment, which has provided versatile design and simulation capabilities for this study. Wide-ranging simulations include various maneuvers with different road conditions have been performed in order to demonstrate the performance of the proposed controller.

In this thesis, a test platform based on real-time facilities and embedded software is designed to verify the performance of a controller model in real time. By the help of this platform, design errors can be detected earlier and possible problems can be solved cost-effectively without interrupting the development process. An unmanned combat air vehicle (UCAV) model is taken as a plant model due to its importance in current and future military operations. Among several autopilot modes, the altitude hold mode is selected since it is an important pilot-relief mode and widely used in aviation. A discrete PID controller is designed in MATLAB/Simulink environment for using in verification studies. To control the dynamic system in wide range, a gain scheduling is employed where the altitude and velocity are taken as scheduling variables. Codes for plant and controller model are obtained by using real time workshop embedded coder (RTWEC) and downloaded to two separate computers, in which xPC kernel and VxWorks operating system are run, respectively. A set of flight test scenarios are generated in Simulink environment. They are analyzed, discussed, and then some of them are picked up to verify the platform. These test scenarios are run in the setup and their results are compared with the ones obtained in Simulink environment. The reusability of the platform is verified by using a commercial aircraft, Boeing 747, and its controller models. The test results obtained in the setup and in Simulink environment are presented and discussed.

This thesis reports the identification of linear and nonlinear handling models for road vehicles starting from structural identifiability analysis, continuing with the experiments to acquire data on a vehicle equipped with a sensor set and data acquisition system and ending with the estimation of parameters using the collected data. The 2 degrees of freedom (dof) linear model structure originates from the well known linear bicycle model that is frequently used in handling analysis of road vehicles. Physical parameters of the bicycle model structure are selected as the unknown parameter set that is to be identified. Global identifiability of the model structure is analysed, in detail, and concluded according to various available sensor sets. Physical parameters of the bicycle model structure are estimated using prediction error estimation method. Genetic algorithms are used in the optimization phase of the identification algorithm to overcome the difficulty in the selection of initial values for parameter estimates. Validation analysis of the identified model is also presented. Identified model is shown to track the system response successfully. Following the linear model identification, identification of 3 dof nonlinear models are studied. Local identifiability analysis is done and optimal input is designed using the same procedure for linear model structure identification. Practical identifiability analysis is performed using Fisher Information Matrix. Physical parameters are estimated using the data from simulated experiments. High accuracy estimates are obtained. Methodology for nonlinear handling model identification is presented.

Active safety systems for road vehicles make a crucial preventive contribution to road safety. In recent years, technological developments and the increasing demand for road safety have resulted in the integration and cooperation of these individual active safety systems. Traction control system (TCS) is one of these individual systems, which is capable of inhibiting wheel-spin during acceleration of the vehicle on slippery surfaces. In this thesis, design methodology and simulation results of a traction control system for four wheeled road vehicles are presented. The objective of the TCS controller is basically to improve directional stability, steer-ability and acceleration performance of vehicle by controlling the wheel slip during acceleration. In this study, the designed traction control system based on fuzzy logic is composed of an engine torque controller and a slip controller. Reference wheel slip values were estimated from the longitudinal acceleration data of the vehicle. Engine torque controller determines the throttle opening angle corresponding to the desired wheel torque, which is determined by a slip controller to track the reference slip signals. The wheel torques delivered by the engine are compensated by brake torques according to the desired wheel torque determined by the slip controller. Performance of the TCS controller was analyzed through several simulations held in MATLAB/Simulink for different road conditions during straight line acceleration and combined acceleration and steering. For simulations, an 8 DOF nonlinear vehicle model with nonlinear tires and a 2 DOF nonlinear engine model were built.