A Case based Online Trajectory Planning Method of Autonomous Unmanned Combat Aerial Vehicles with Weapon Release Constraints

As a challenging and highly complex problem, the trajectory planning for unmanned combat aerial vehicle (UCAV) focuses on optimising flight trajectory under such constraints as kinematics and complicated battlefield environment. An online case-based trajectory planning strategy is proposed in this study to achieve rapid control variables solution of UCAV flight trajectory for the of delivery airborne guided bombs. Firstly, with an analysis of the ballistic model of airborne guided bombs, the trajectory planning model of UCAVs is established with launch acceptable region (LAR) as a terminal constraint. Secondly, a case-based planning strategy is presented, which involves four cases depending on the situation of UCAVs at the current moment. Finally, the feasibility and efficiency of the proposed planning strategy is validated by numerical simulations, and the results show that the presented strategy is suitable for UCAV performing airborne guided delivery missions in dynamic environments

Application of nonlinear control theory in weapon guidance and control

This thesis considers the application of nonlinear control theory in two subjects pertinent to weapon applications. Initially, Section 2 considers the development of a simple nonlinear autopilot for a Laser Guided Bomb (LGB). Later a nonlinear autopilot design is developed using a Pulse-Width Modulated (PWM) controller derived from the method developed by Bemelli-Zazzera et al4. This is applied to an LGB utilising a “bang-bang” actuator, enabling the control surfaces to achieve a pseudo-proportional response. The PWM design stems from an equivalent Pulse Amplitude Modulated controller, which required a design technique to be developed for a linear autopilot and, in addition, simulation of an electro-mechanical actuator. Simulation demonstrated that the PWM controller can achieve the desired response but the design must incorporate actuator dynamics. Section 3 considers the use of nonlinear control theory to examine the nonlinear intercept equations using a Proportional Navigation (PN) guidance law. Using a simple heuristic example, PN is introduced and vector algebra used to develop a simple model of the intercept. The model is then used to illustrate the importance of the kinematic gain. Using the method pioneered by Ha et al16, Lyapunov theory is used to demonstrate that PN is a robust guidance law. Although generally derived assuming the target maintains rectilinear flight, Lyapunov theory is used to demonstrate interception is always possible provided the pursuer has sufficient manoeuvre advantage over the target. Noting that many missiles incorporate a 1 directional warhead, Lyapunov theory is used to design a time-varying rate bias that controls the direction of approach to the target. Simulation demonstrates that the guidance requirements are indeed achieved by this law but additional effort is required by the control system. In Section 3 it is demonstrated that the PN guidance law will always ensure an intercept, i.e. it does not by itself generate miss-distance. In the final part of Section 3, using adjoint software designed by Zarchan42, it is demonstrated that miss-distance develops in practical systems as the result of sub-system dynamicsMPhi

Airborne laser sensors and integrated systems

The underlying principles and technologies enabling the design and operation of airborne laser sensors are introduced and a detailed review of state-of-the-art avionic systems for civil and military applications is presented. Airborne lasers including Light Detection and Ranging (LIDAR), Laser Range Finders (LRF), and Laser Weapon Systems (LWS) are extensively used today and new promising technologies are being explored. Most laser systems are active devices that operate in a manner very similar to microwave radars but at much higher frequencies (e.g., LIDAR and LRF). Other devices (e.g., laser target designators and beam-riders) are used to precisely direct Laser Guided Weapons (LGW) against ground targets. The integration of both functions is often encountered in modern military avionics navigation-attack systems. The beneficial effects of airborne lasers including the use of smaller components and remarkable angular resolution have resulted in a host of manned and unmanned aircraft applications. On the other hand, laser sensors performance are much more sensitive to the vagaries of the atmosphere and are thus generally restricted to shorter ranges than microwave systems. Hence it is of paramount importance to analyse the performance of laser sensors and systems in various weather and environmental conditions. Additionally, it is important to define airborne laser safety criteria, since several systems currently in service operate in the near infrared with considerable risk for the naked human eye. Therefore, appropriate methods for predicting and evaluating the performance of infrared laser sensors/systems are presented, taking into account laser safety issues. For aircraft experimental activities with laser systems, it is essential to define test requirements taking into account the specific conditions for operational employment of the systems in the intended scenarios and to verify the performance in realistic environments at the test ranges. To support the development of such requirements, useful guidelines are provided for test and evaluation of airborne laser systems including laboratory, ground and flight test activities

AFIT School of Engineering Contributions to Air Force Research and Technology Calendar Year 1973

This report contains abstracts of Master of Science Theses, Doctoral dissertations, and selected faculty publications completed during the 1973 calendar year at the School of Engineering, Air Force Institute of Technology, at Wright-Patterson Air Force Base, Ohio

AFIT School of Engineering Contributions to Air Force Research and Technology Calendar Year 1973

This report contains abstracts of Master of Science Theses, Doctoral dissertations, and selected faculty publications completed during the 1973 calendar year at the School of Engineering, Air Force Institute of Technology, at Wright-Patterson Air Force Base, Ohio

Dynamic Response of a Collidant Impacting a Low Pressure Airbag

There are many uses of low pressure airbags, both military and commercial. Many of these applications have been hampered by inadequate and inaccurate modeling tools. This dissertation contains the derivation of a four degree-of-freedom system of differential equations from physical laws of mass and energy conservation, force equilibrium, and the Ideal Gas Law. Kinematic equations were derived to model a cylindrical airbag as a single control volume impacted by a parallelepiped collidant. An efficient numerical procedure was devised to solve the simplified system of equations in a manner amenable to discovering design trends. The largest public airbag experiment, both in scale and scope, was designed and built to collect data on low-pressure airbag responses, otherwise unavailable in the literature. The experimental results were compared to computational simulations to validate the simplified numerical model. Experimental response trends are presented that will aid airbag designers. The two objectives of using a low pressure airbag to demonstrate the feasibility to 1) accelerate a munition to 15 feet per second velocity from a bomb bay, and 2) decelerate humans hitting trucks below the human tolerance level of 50 G\u27s, were both met

The development of a warhead into an integrated weapon system to provide an advanced battlefield capability

This thesis addresses the topic of integration of weapons systems into communication networks to provide an advanced battlefield capability, with particular application to air launched and long range crew served weapon systems which may also be vehicle mounted. It considers the use of 'Military off-the-shelf' seeker, navigation and communication systems coupled with a novel tandem warhead system. This combination of 'low risk' technologies and a novel warhead system is intended to demonstrate a greater flexibility in weapon systems which could be exploited to reduce development risk, integration risk, qualification costs and increase target defeat capability across the wider more current target set. The use of a suitable communication and navigation system enabling integration of such a weapon system into a networked force was also investigated. This thesis is based on one area of research; Multiple Effects Weapons. Research is being undertaken by several nations on Multiple Effects Weapons. The aim of this research is not to provide a one weapon fits all solution, a panacea, the aim is to widen the utility of one system which could be employed in many roles. As yet no warhead system has achieved the types of effects that are being sought, although research and product development – particularly in the United States of America - continues. Therefore the United Kingdom government has sought to understand what technologies would be required to achieve a truly flexible warhead system which would enable defeat of large Main Battle Tanks, heavily armoured Infantry Fighting Vehicles, Soft Skinned Vehicles, infantry and urban structures. To this end numerical modelling, design and a demonstration programme of a MEW warhead system was performed. MEW systems are not only reliant on 'Smart' warhead systems, the application of sensors, fuzing and communication systems are crucial to enable suitable employment of a 'one size fits most' approach. The other important sub-systems which provide the link to the battlefield network are also discussed in this thesis, the inclusion of these well developed low risk technologies make it is possible to bring such systems into service in the near term with increased system flexibility. The integration of such a system relies on the current United States Department of Defense procurement strategy which includes development of the Joint Tactical Radio System radio system which will allow Ad-Hoc networking between platforms, weapons systems and commanders. Airframe and propulsion technologies are not discussed; they are outside of the scope of this thesis. The use of proprietary data from suppliers other than QinetiQ has been avoided as suitable permissions are not in place, this has limited the systems engineering aspects of this thesis to high level block diagrams which provide guidance on integration issues

Debating Space Security: Capabilities and Vulnerabilities

The U.S. position in the debate on space security has been that (1) space-based systems could be developed and used to obtain decisive warghting superiority over an adversary, and (2) these space-based systems, because they might give such an inordinate advantage over any adversary, will be attacked. The Russians and Chinese, in contrast, claim to be threatened by U.S. aspirations in space but deny that they pose a serious threat to U.S. space-based systems. They view the development of advanced military space systems by the United States as evidence of a growing gap of military capabilities limited only by technological--not political--constraints. They argue that U.S. missile defense systems operating in coordination with advanced satellite sensors would weaken their nuclear retaliatory potential. This dissertation argues that the positions held by both of these parties are more extreme than warranted. An analytical evaluation quickly narrows the touted capabilities and assumed vulnerabilities of space systems to a much smaller set of concerns that can be addressed by collaboration. Chapter 2: Operationally Responsive Space (ORS): Is 24/7 Warghter Support Feasible? demonstrates the infeasibility of dramatically increasing U.S. warfighting superiority by using satellites. Chapter 3: What Can be Achieved by Attacking Satellites? makes the case that although U.S. armed forces rely extensively on its satellite infrastructure, that does not immediately make them desirable targets. The functions performed by military satellites are diffused among large constellations with redundancies. Also, some of the functions performed by these satellites can be substituted for by other terrestrial and aerial systems. Chapter 4: The Limits of Chinese Anti-Satellite Missiles demonstrates that anti-satellite (ASAT) intercepts are very complex under realistic conditions and that a potential adversary with space capabilities comparable to China's has very limited capability to use ASATs in a real-world battle scenario. Finally, in order to evaluate the chief concern raised by the Russians and Chinese, chapter 5: Satellites, Missile Defense and Space Security simulates a boost-phase missile defense system cued by the advanced Space Tracking and Surveillance (STSS) sensors. It demonstrates that even under best case assumptions, the STSS sensors are not good enough for the boost-phase missile defense system to successfully intercept and destroy an ICBM. Together, these chapters aim to narrow the contentions in the debate on space security thereby fostering the international colloboration and data sharing needed to ensure safe operations in space

PROFESSIONAL ENGLISH AVIATION ACTIVITIES

Навчальний посібник з англійської мови професійного спрямування. Складається з тематичних розділів, що містять базову термінологію, автентичні тексти, комплекс комунікативних лексико-граматичних вправ, передтекстовий термінологічний англо-український вокабуляр та додаткові тексти для самостійного опрацювання. Призначений для студентів вищих авіаційних навчальних закладів

Integrated influential factors of internal stakeholder that negatively affecting project successful completion in Yemen

Development construction projects in Yemen are encountering a huge delays in time, cost invade, surrendered and disappointment. Because of an emotional movement in the limit and volume of the Yemeni development part in the course of the most recent decade, the need of a deliberate investigation of the reasons that adversely influencing negatively the project successful completion and building up an unmistakable comprehension among the stakeholder experts is profoundly urgent. The fundamental objective of this study is to recognize and rank the causes that contrarily influencing the project successful completion in Yemen. Utilizing a chose set of 55 qualities, this exploration initially distinguished the key elements affecting project completion in Yemen development industry. A survey has framed the premise of this examination and dispersed to proprietor, advisor and temporary worker. The outcome covers that the 10 major delay factors including money cash flow and financial difficulties faced by contractors, conflict between owners and other parties, delay in progress payment by owner, poor project management, slow decision from owner, escalation of prices of materials, lack of contractor experience, design errors made by designers, shortages of materials and poor site management and supervision. These findings are expected to be significant contributions to Yemen construction industry in controlling the time and cost overruns in construction. The effect of (IIF) is negatively influences to project successful completion regarding to time overrun, cost overrun, negatively affect to satisfaction of the stakeholder, negatively affect to technical specification and negatively affecting to fulfillment all meeting all the project objectives/requirements. These findings are required to be noteworthy commitments to Yemen development industry in controlling the time and cost invades in development