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Optimal Trajectory Reconfiguration And Retargeting For The X 33 Reusable Launch Vehicle
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Book Synopsis Optimal Trajectory Reconfiguration and Retargeting for the X-33 Reusable Launch Vehicle by : Patrick J. Shaffer
Download or read book Optimal Trajectory Reconfiguration and Retargeting for the X-33 Reusable Launch Vehicle written by Patrick J. Shaffer and published by . This book was released on 2004-09-01 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis considers the problem of generating optimal entry trajectories for a reusable launch vehicle following a control surface failure. The thesis builds upon the work of Dr. David Doman, Dr. Michael Oppenheimer and Dr. Michael Bolender of the Air Vehicles Directorate, Air Force Research Lab Dayton Ohio. The primary focus of this work is to demonstrate the feasibility of inner loop reconfiguration and outer loop trajectory retargeting and replanning for the X-33 reusable launch vehicle (RLV) following the imposition of a control surface failure. The trajectory generation model employs path constraints generated by an AFRL trim deficiency algorithm coupled with an inner loop control allocator and aerodynamic database that captures the full 6-DOF vehicle aerodynamic effects while utilizing an outer loop 3-DOF model. The resulting optimal trajectory does not violate the trim deficiency constraints and provides additional margins for trajectories flown during failure conditions. The footprints generated by the thesis show that contemporary footprint analysis for vehicles experiencing control surface failures are overly optimistic when compared to those footprints that consider vehicle aerodynamic stability and realistic landable attitudes at the threshold of the landing runway. The results of the thesis also show the performance reductions resulting from decoupling the inner and outer loop and that trajectories can be generated to the landing runway without using a region of terminal area energy management.
Book Synopsis Optimal Trajectory Reconfiguration and Retargeting for a Reusable Launch Vehicle by :
Download or read book Optimal Trajectory Reconfiguration and Retargeting for a Reusable Launch Vehicle written by and published by . This book was released on 2005 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Autonomous reusable launch vehicles (RLV) are being pursued as low-cost alternatives to expendable launch vehicles and the Shuttle. The employment of autonomous reusable launch vehicles requires additional guidance and control robustness to fulfill the role of an adaptive human pilot, in the event of failures or unanticipated conditions. The guidance and control of these vehicles mandate new guidance strategies that are able to identify and adapt to vehicle failures during the flight and still return to earth safely. This work utilizes an online trim algorithm that provides the outer loop with the feasible range of Mach number and angle of attack, for which the vehicle can be rotationally trimmed. The algorithm allows one to include 6-degree-of-freedom (DOF) trim effects and constraints in a reduced order dynamical model which is used in the solution of an optimal control problem. A direct pseudospectral method is used to solve a two-point-boundary-value problem which determines the optimal entry trajectory subject to appropriate constraints such as normal load, dynamic pressure limits, heat load limits, and state dependent constraints.
Book Synopsis Fault Tolerant Optimal Trajectory Generation for Reusable Launch Vehicles by : Patrick J. Shaffer
Download or read book Fault Tolerant Optimal Trajectory Generation for Reusable Launch Vehicles written by Patrick J. Shaffer and published by . This book was released on 2006 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reconfigurable inner-loop control laws improve the fault tolerance of a vehicle to control effector failures; however, in order to preserve stability, the unfailed effectors may be deployed to off-nominal positions to compensate for undesirable perturbations caused by the failed effectors. The effectors acting under the influence of a reconfigurable control law can produce significant perturbations to the nominal forces produced by the wing and body and can also affect the range of flight conditions over which the vehicle can be controlled. Three degree-of-freedom (3 DOF) dynamical models used in trajectory optimization for aerospace vehicles typically include wing-body aerodynamic force effects but ignore the aerodynamic forces produced by the control surfaces. In this work, a method for including these trim effects as well as control induced trajectory constraints in a 3 DOF model is presented.
Book Synopsis Optimal Trajectory Designs and Systems Engineering Analyses of Reusable Launch Vehicles by : Hung-i Bruce Tsai
Download or read book Optimal Trajectory Designs and Systems Engineering Analyses of Reusable Launch Vehicles written by Hung-i Bruce Tsai and published by . This book was released on 2003 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: Realizing a reusable launch vehicle (RLV) that is low cost with highly effective launch capability has become the "Holy Grail" within the aerospace community world-wide. Clear understanding of the vehicle's operational limitations and flight characteristics in all phases of the flight are preponderant components in developing such a launch system. This dissertation focuses on characterizing and designing the RLV optimal trajectories in order to aid in strategic decision making during mission planning in four areas: 1) nominal ascent phase, 2) abort scenarios and trajectories during ascent phase including abort-to-orbit (ATO), transoceanic-abort-landing (TAL) and return-to-launch-site (RTLS), 3) entry phase (including footprint), and 4) systems engineering aspects of such flight trajectory design. The vehicle chosen for this study is the Lockheed Martin X-33 lifting-body design that lifts off vertically with two linear aerospike rocket engines and lands horizontally. An in-depth investigation of the optimal endo-atmospheric ascent guidance parameters such as earliest abort time, engine throttle setting, number of flight phases, flight characteristics and structural design limitations will be performed and analyzed to establish a set of benchmarks for making better trade-off decisions. Parametric analysis of the entry guidance will also be investigated to allow the trajectory designer to pinpoint relevant parameters and to generate optimal constrained trajectories. Optimal ascent and entry trajectories will be generated using a direct transcription method to cast the optimal control problem as a nonlinear programming problem. The solution to the sparse nonlinear programming problem is then solved using sequential quadratic programming. Finally, guidance system hierarchy studies such as work breakdown structure, functional analysis, fault-tree analysis, and configuration management will be developed to ensure that the guidance system meets the definition of vehicle design requirements and constraints.
Book Synopsis Optimal Guidance Command Generation and Tracking for Reusable Launch Vehicle Reentry (Preprint). by :
Download or read book Optimal Guidance Command Generation and Tracking for Reusable Launch Vehicle Reentry (Preprint). written by and published by . This book was released on 2006 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this work is to develop a robust guidance and control architecture for autonomous reusable launch vehicles that incorporates elements of recent advances in the areas of optimal trajectory generation and reconfigurable control. This work integrates three separately developed methods to form a coherent architecture with the potential to manage control effector failures, vehicle structural/aerodynamic degradation, uncertainty, and external disturbances. Outer-loop guidance commands in the form of body-frame angular rates (roll, pitch, and yaw) are generated from an optimal reference trajectory that is computed off-line with a direct pseudospectral method and then tracked by a reconfigurable inner-loop control law. The appropriate open-loop state histories from the pseudo-four-degree-of-freedom reference trajectory are converted using a modified backstepping approach that complements the inner-loop control law in a six-degree-of-freedom simulation. The inner-loop control law is capable of reacting and compensating for off-nominal conditions by employing nonlinear reconfigurable control allocation, dynamic inversion, and model-following/anti-windup prefilters. The results show that the inner loop control can adequately track the desired optimal guidance commands; thus, confirming that applicability of this control architecture for future development involving on-line, optimal trajectory generation and high-fidelity guidance and control for reentry vehicles.
Book Synopsis Flight Test Results of an Adaptive Guidance System for Reusable Launch Vehicles by : John D. Schierman
Download or read book Flight Test Results of an Adaptive Guidance System for Reusable Launch Vehicles written by John D. Schierman and published by . This book was released on 2004 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: To enable autonomous operations in future Reusable Launch Vehicles (RLVs), reconfigurable control and adaptive guidance will often be required to facilitate recovery of the mission following a major anomalous event such as an effector failure. An adaptive guidance system that works in conjunction with a reconfigurable controller and an autonomous trajectory command reshaping algorithm is presented. The guidance law utilizes a backstepping architecture to generate pitch rate commands that drive the inner-loop control system. Under extreme failure conditions the control surfaces can saturate in an attempt to meet commanded moments. In these cases, the guidance feedback gains are reduced to preserve stability margins in the guidance loops. A case study is presented that shows the benefits of the guidance gain adaptation. Without adjusting the gains, the guidance loops go unstable, whereas stability is maintained with gain reduction.
Book Synopsis A Reconfigurable Guidance Approach for Reusable Launch Vehicles by :
Download or read book A Reconfigurable Guidance Approach for Reusable Launch Vehicles written by and published by . This book was released on 2001 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: A guidance system with reconfiguration capabilities has been developed for reusable launch vehicles (RLVs). The focus of the development is on reconfiguration after a catastrophic effector failure during final approach - a failure that would otherwise cause loss of the vehicle. We assume here that the vehicle employs a reconfigurable inner-loop control system that recovers some maneuvering capabilities and maintains attitude stability. However, for RLVs, it is often the case that nominal performance cannot be fully recovered, and the outer-loop guidance system must account for the degraded response characteristics. Two approaches are presented. The first approach augments the existing production guidance system with adaptation capabilities. A case study shows that stability is maintained following a primary pitch effector failure. However, it is shown that the trajectory commands to the guidance loops must also be re-targeted in order to achieve a safe landing. The second approach employs an on-line optimal trajectory re-targeting algorithm. A database of neighboring optimal trajectories is encoded in an efficient manner and interrogated on line at regular intervals. Given the current states and certain vehicle parameters, this procedure generates optimal guidance commands and integrates the optimal trajectory to the next update point. A proof-of-concept study of this approach was performed. Following a primary speed control failure, the study shows that this approach achieves acceptable landing conditions.
Book Synopsis High-Fidelity Real-Time Trajectory Optimization for Reusable Launch Vehicles by : Kevin P. Bollino
Download or read book High-Fidelity Real-Time Trajectory Optimization for Reusable Launch Vehicles written by Kevin P. Bollino and published by . This book was released on 2006 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: Creating simplicity out of complexity, this research abandons the traditional guidance and control architecture for aerospace vehicles and embraces a revolutionary concept based on the principles of nonlinear optimal control theory. Motivated by the emerging needs of the next generation of reusable space vehicles, an autonomous integrated guidance and control system is developed that provides a safe approach to the highly constrained and nonlinear reentry problem. A pseudospectral-based optimal guidance scheme is used to generate high-fidelity, vehicle-tailored solutions to reentry trajectory optimization and guidance problems. To provide an autonomous, onboard capability of satisfying final-approach requirements, a new method is developed that includes an automatic generation of landing constraints given any runway geometry. This unique and simple approach avoids significant complexities arising from previous ideas of trajectory segmentation, trimmed flight, and trajectory tracking schemes. When demonstrating the new ideas, it is shown that the proposed approach can easily compensate for large uncertainties and disturbances consisting of hurricane-force wind gusts. An investigation of these new principles for the complete, nonlinear six degree-of-freedom system dynamics indicates that while the results are quite promising, a substantial amount of new theoretical and computational problems remain open, particularly in the area of over-actuated dynamical systems.
Book Synopsis Closed-loop Endo-atmospheric Ascent Guidance for Reusable Launch Vehicle by : Hongsheng Sun
Download or read book Closed-loop Endo-atmospheric Ascent Guidance for Reusable Launch Vehicle written by Hongsheng Sun and published by . This book was released on 2005 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation focuses on the development of a closed-loop endo-atmospheric ascent guidance algorithm for the 2nd generation reusable launch vehicle. Special attention has been given to the issues that impact on viability, complexity and reliability in on-board implementation. The algorithm is called once every guidance update cycle to recalculate the optimal solution based on the current flight condition, taking into account atmospheric effects and path constraints. This is different from traditional ascent guidance algorithms which operate in a simple open-loop mode inside atmosphere, and later switch to a closed-loop vacuum ascent guidance scheme. The classical finite difference method is shown to be well suited for fast solution of the constrained optimal three-dimensional ascent problem. The initial guesses for the solutions are generated using an analytical vacuum optimal ascent guidance algorithm. Homotopy method is employed to gradually introduce the aerodynamic forces to generate the optimal solution from the optimal vacuum solution. The vehicle chosen for this study is the Lockheed Martin X-33 lifting-body reusable launch vehicle. To verify the algorithm presented in this dissertation, a series of open-loop and closed-loop tests are performed for three different missions. Wind effects are also studied in the closed-loop simulations. For comparison, the solutions for the same missions are also obtained by two independent optimization softwares. The results clearly establish the feasibility of closed-loop endo-atmospheric ascent guidance of rocket-powered launch vehicles. ATO cases are also tested to assess the adaptability of the algorithm to autonomously incorporate the abort modes.
Book Synopsis Minimum-fuel Optimal Trajectory for Reusable First-stage Rocket Landing Using Particle Swarm Optimization by : Kevin Spencer G. Anglim
Download or read book Minimum-fuel Optimal Trajectory for Reusable First-stage Rocket Landing Using Particle Swarm Optimization written by Kevin Spencer G. Anglim and published by . This book was released on 2016 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Reusable Launch Vehicles (RLVs) present a more environmentally-friendly and cost-effective approach to accessing space when compared to traditional launch vehicles that are discarded after each flight. This paper studies the recyclable nature of RLVs by presenting a solution method for determining minimal-fuel optimal trajectories using principles from optimal control theory and Particle Swarm Optimization (PSO). The problem is formulated as a minimum-fuel, minimum-landing error powered descent problem where it is desired to move the RLV from a fixed set of initial conditions to three different sets of terminal conditions: an unspecified downrange landing, a specified downrange landing, and a return-to-launch-site landing. However, unlike other powered descent studies, this paper considers the highly nonlinear effects caused by atmospheric drag, which are often ignored for similar powered descent studies on the Moon or Mars. Rather than optimize the controls directly, the throttle control is assumed to be bang-off-bang with a predetermined thrust direction for each phase of flight. An overview of optimal control theory and particle swarm optimization is first presented. The PSO method is presented and verified in a one-dimensional comparison study, and is then applied to the two-dimensional cases, the results of which are illustrated.
Book Synopsis Taming Liquid Hydrogen by : Virginia Parker Dawson
Download or read book Taming Liquid Hydrogen written by Virginia Parker Dawson and published by . This book was released on 2004 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hypersonic and Planetary Entry Flight Mechanics by : Nguyen X. Vinh
Download or read book Hypersonic and Planetary Entry Flight Mechanics written by Nguyen X. Vinh and published by . This book was released on 1980-01-01 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seize the High Ground by : James A. Walker
Download or read book Seize the High Ground written by James A. Walker and published by Government Printing Office. This book was released on 2003 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: "[Seize the high ground is a] narrative history of the Army's aerospace experience from the 1950s to the present. The focus is on ballistic missile defense, from the early NIKE-HERCULES missile program through the SAFEGUARD acquisition site allowed by the 1972 ABM Treaty to the more advanced 'Star Wars' concepts studies toward the end of the century. [What is] covered is not only the technological response to the threat but the organizational and tactical development of the commands and units responsible for the defense mission"--CMH website.
Download or read book After LM written by John F. Connolly and published by . This book was released on 2020 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Department of Defense Dictionary of Military and Associated Terms by : United States. Joint Chiefs of Staff
Download or read book Department of Defense Dictionary of Military and Associated Terms written by United States. Joint Chiefs of Staff and published by . This book was released on 1979 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Beyond Horizons by : David N. Spires
Download or read book Beyond Horizons written by David N. Spires and published by . This book was released on 1997 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Digital Integrated Circuit Design by : Hubert Kaeslin
Download or read book Digital Integrated Circuit Design written by Hubert Kaeslin and published by Cambridge University Press. This book was released on 2008-04-28 with total page 878 pages. Available in PDF, EPUB and Kindle. Book excerpt: This practical, tool-independent guide to designing digital circuits takes a unique, top-down approach, reflecting the nature of the design process in industry. Starting with architecture design, the book comprehensively explains the why and how of digital circuit design, using the physics designers need to know, and no more.
