The problem of optimal guidance design for the low altitude, subsonic, vertical plane approach maneuver of an air vehicle constrained to maintain view of a fixed final position is studied using a nonlinear, constrained, optimal control problem formulation. Multiple, competing optimization criteria are included separately as performance goals and in combination as state equality constraints for design tradeoff analysis. In conjunction with vehicle flight constraints, a sensor line-of -sight (LOS) angle limit is imposed as a control variable inequality constraint to provide a sensor field of regard influence on the guidance design. Numerical results are provided that illustrate the optimal guidance for different performance criteria, the sensor LOS profile along the optimal maneuvers, and the influence of the sensor limit on the guidance law design. A near-optimal, closed-loop feedback guidance law that incorporates the sensor constraint is developed based on neighboring extremals. / Ph. D.

A design method for a multi-loop mixed discrete/continuous trajectory following pitch control algorithm for a generic aerospace vehicle is presented. This design methodology is facilitated by a time scale separation observed in the dynamical system. Two variations of this algorithm are considered, with features and drawbacks of both evaluated. The algorithm is then tested by simulations with two vehicles flying arbitrary trajectories. Results are presented for a thrust-vector controlled high-performance missile without atmospheric effects, and for a single-stage-to-orbit hypersonic vehicle with both elevator and thrust-vector control. It is shown that the control algorithm results in a pitch loop feedback controller that is robust and very stable, and is at least near optimal for the class of trajectories considered. No claims of optimality are made for the outer loop, but it is shown in the simulations that the outer loop tracker can do a reasonable job of following the prescribed nominal trajectory. / Ph. D.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006. / A real time attitude and heading reference system (AHRS) was successfully implemented for use on an airship. The AHRS was tested on board a small airship (blimp) with real data supplied from the inertial measurement unit and GPS receiver. The inertial measurement unit was built with lower grade sensors, resulting in significant reductions in component cost. To ensure accurate navigation results, the high rate inertial measurements were complemented with low rate GPS velocity and position updates in an extended Kalman filter configuration. A study was made of various Kalman filter configurations, especially the possibility of splitting a big Kalman filter into smaller Kalman filters. It was found that the best trade-off between accuracy and processing power was achieved by having two smaller Kalman filters running in sequence. The first extended Kalman filter estimates the attitude of the airship, while the second extended Kalman filter estimates the velocity and position of the airship. The two smaller Kalman filters were implemented on an onboard computer to provide real time estimates of the attitude, velocity and position of the airship.

Modern commercial air travel is considered by most transportation specialists to be the safest of all forms of transportation. While safe, any loss of life is tragic and the only really acceptable state of commercial air transport safety is that of 'zero-tolerance' where no accident is acceptable. Research has demonstrated that the largest single causal component for airline accidents is the flightcrew. In addition, the recent automation of these machines has created many new safety concerns involving flightcrew situational awareness, human-machine interfacing, workload, attention, and complexity, to name a few. These concerns led to a series of studies developing, refining, and testing numerous aspects of this issue. The studies incorporated ASRS (Aviation Safety Reporting System) incident reports, NTSB (National Transportation Safety Board) and other accident reports, and the development of a CTM (cockpit task management) system. The information gained from this research led to the development of an agent-based cockpit task aiding system termed the AgendaManager. A traditional text-based display similar to that used in the CTMS study was developed, optimized, and integrated with existing systems like EICAS (Engine Indicating and Crew Alerting System) using a visual display development guide developed from a literature review. An alternate display incorporating graphics and located on the primary flight display (PFD) was also developed in an effort to improve pilot agenda management performance. Both of the interfaces were developed using a comprehensive visual display design guide compiled through a literature review. The Agenda Manager displays were tested in order to determine if the PFD enhancements improved agenda management performance. Eleven general aviation pilots participated in the study, three in the pilot study and eight in the main study. Results from the main study indicate little, if any, difference in agenda management performance in regards to the display format used. In general, the study demonstrated the usefulness of the display guidelines, importance of tracking instrument rating when using general aviation pilots in an experiment, and the equivalence of 'round-trip' scenarios. / Graduation date: 1998

No description available.

Thesis (M.S.)--University of Florida, 2005. / Title from title page of source document. Document formatted into pages; contains 42 pages. Includes vita. Includes bibliographical references.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, April 2016 / A Rotary Wing Unmanned Aerial Vehicle (RW UAV) as a platform and its payload consisting of sophisticated sensors would be costly items. Hence, a RW UAV in the 500 kg class designed to fulfil a number of missions would represent a considerable capital outlay for any customer. Therefore, in the event of an engine failure, a means should be provided to get the craft safely back on the ground without incurring damage or causing danger to the surrounding area. The aim of the study was to design a controller for autorotative landing of a RW UAV in the event of engine failure. In order to design a controller for autorotative landing, an acceleration model was used obtained from a study by Stanford University. FLTSIM helicopter flight simulation package yielded necessary RW UAV response data for the autorotation regimes. The response data was utilized in identifying the unknown parameters in the acceleration model. A Differential Dynamic Programming (DDP) control algorithm was designed to compute the main and tail rotor collective pitch and the longitudinal and lateral cyclic pitch control inputs to safely land the craft. The results obtained were compared to the FLTSIM flight simulation response data. It was noted that the mathematical model could not accurately model the pitch dynamics. The main rotor dynamics were modelled satisfactorily and which are important in autorotation because without power from the engine, the energy in main rotor is critical in a successful execution of an autorotative landing. Stanford University designed a controller for RC helicopter, XCell Tempest, which was deemed successful. However, the DDP controller was designed for autonomous autorotative landing of RW UAV weighing 560 kg, following engine failure. The DDP controller has the ability to control the RW UAV in an autorotation landing but the study should be taken further to improve certain aspects such as the pitch dynamics and which can possibly be achieved through online parameter estimation. / MT 2017

This thesis discusses the creation of an object-oriented method to facilitate the creation and specification of aircraft mission profiles. Mission profiles are detailed descriptions of an aircraft's flight path and its inflight mission activities. They are a vital aspect of the conceptual design process of an aircraft. The Mission Profile Input System (MPIS) created is general in nature and can be customized to be compatible with existing aircraft CAD systems. All data associated with the mission—phase parameters, phases, and mission parameters, are defined to be objects. Each data type can therefore be customized individually to meet any requirements which may be necessary to make the MPIS compatible with a host system. Customization of the MPIS is further enhanced by the nature of the design upon which it is based. An object-oriented design provides the system with a high degree of extendibility. The encapsulation and inheritance features of object-oriented design allow new types of phases and phase parameters to be simply "plugged" into the existing system. The MPIS provides the user with an interactive, Motif-like interface which is conducive to manipulating the large quantities of data inherent in specifying mission profiles. The system is based on the ISO graphics standard, PHIGS, and hence is device-independent. Moreover, the system has been implemented using the hybrid object-oriented language, C++, which is supported by a large number of computer systems. / Master of Science

Optimal midcourse guidance is examined for an air-to-air missile featuring boost-coast-sustain propulsion. A vertical plane, point-mass model is studied with load factor as a control variable. Time-range-energy optimal trajectories are computed, open-loop, via the usual necessary conditions and a multiple-shooting algorithm. A requirement on terminal velocity magnitude is examined for its effect on firing range. Next, a study of the optimal midcourse guidance problem with reduced-order models is presented. The models under study, in addition to the point-mass model, are: - Singularly perturbed model with y as fast variable; - Point mass model with approximation of the induced-drag; - Energy model. One of the major results in this study is that the reduced-order models are not accurate enough to approximate the optimal trajectories and so are of limited use as reference trajectories in an on-board scheme. Thus, optimal trajectories, computed by using the point-mass model, are selected as the reference trajectories for a closed-loop guidance scheme. Finally, an approach to on-board real-time calculations for an optimal guidance approximation is derived. Extremal fields and neighboring extremal theory ideas are used together with pre-calculated Euler solutions to construct a closed-loop guidance algorithm. The method is applied to the midcourse guidance of an air-to-air missile and was found to perform quite well. / Ph. D.

A real-time computer algorithm to control and optimize aircraft flight profiles is described and applied to a three-dimensional minimum-time intercept mission. The proposed scheme has roots in two well-known techniques: singular perturbations and neighboring-optimal guidance. Use of singular-perturbation ideas is made in terms of the assumed trajectory-family structure. A heading/energy family of prestored point-mass-model state-Euler solutions is used as the baseline in this scheme. The next step is to generate a near-optimal guidance law that will transfer the aircraft to the vicinity of this reference family. The control commands fed to the autopilot consist of the reference controls plus correction terms which are linear combinations of the altitude and path-angle deviations from reference values, weighted by a set of precalculated gains. In this respect the proposed scheme resembles neighboring-optimal guidance. However, in contrast to the neighboring-optimal guidance scheme, the reference control and state variables as well as the feedback gains are stored as functions of energy and heading in the present approach. A detailed description of the feedback laws and of some of the mathematical tools used to construct the controller is presented. The construction of the feedback laws requires a substantial preflight computational effort, but the computation times for on-board execution of the feedback laws are very modest. Other issues relating to practical implementation are addressed as well. Numerical examples, comparing open-loop optimal and approximate feedback solutions for a sample high-performance fighter, illustrate the attractiveness of the guidance scheme. Optimal three-dimensional flight in the presence of a terrain limit is studied in some detail. / Ph. D. / incomplete_metadata