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  • 1
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    Piloted simulation of an onboard trajectory optimization algorithm (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Previously cited in issue 07, p. 975, Accession no. A82-20296
    Keywords: AIRCRAFT COMMUNICATIONS AND NAVIGATION
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 355-360
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  • 2
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    Near-optimal, asymptotic tracking in control problems involving state-variable inequality constraints (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The class of all piecewise time-continuous controllers tracking a given hypersurface in the state space of a dynamical system can be split by the present transformation technique into two disjoint classes; while the first of these contains all controllers which track the hypersurface in finite time, the second contains all controllers that track the hypersurface asymptotically. On this basis, a reformulation is presented for optimal control problems involving state-variable inequality constraints. If the state constraint is regarded as 'soft', there may exist controllers which are asymptotic, two-sided, and able to yield the optimal value of the performance index.
    Keywords: CYBERNETICS
    Type: AIAA PAPER 93-3748 , In: AIAA Guidance, Navigation and Control Conference, Monterey, CA, Aug. 9-11, 1993, Technical Papers. Pt. 1 (A93-51301 22-63); p. 417-426.
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  • 3
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    Fixed order dynamic compensation for multivariable linear systems (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: This paper considers the design of fixed order dynamic compensators for multivariable time invariant linear systems, minimizing a linear quadratic performance cost functional. Attention is given to robustness issues in terms of multivariable frequency domain specifications. An output feedback formulation is adopted by suitably augmenting the system description to include the compensator states. Either a controller or observer canonical form is imposed on the compensator description to reduce the number of free parameters to its minimal number. The internal structure of the compensator is prespecified by assigning a set of ascending feedback invariant indices, thus forming a Brunovsky structure for the nominal compensator.
    Keywords: CYBERNETICS
    Type: AIAA PAPER 86-2200
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  • 4
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    Development of homotopy algorithms for fixed-order mixed H2/H(infinity) controller synthesis (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A major difficulty associated with H-infinity and mu-synthesis methods is the order of the resulting compensator. Whereas model and/or controller reduction techniques are sometimes applied, performance and robustness properties are not preserved. By directly constraining compensator order during the optimization process, these properties are better preserved, albeit at the expense of computational complexity. This paper presents a novel homotopy algorithm to synthesize fixed-order mixed H2/H-infinity compensators. Numerical results are presented for a four-disk flexible structure to evaluate the efficiency of the algorithm.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-TP-3507 , M-759 , NAS 1.60:3507
    Format: application/pdf
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  • 5
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    Piloted simulation of an algorithm for onboard control of time-optimal intercept (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A piloted simulation of algorithms for onboard computation of trajectories for time-optimal intercept of a moving target by an F-8 aircraft is described. The algorithms, use singular perturbation techniques, generate commands in the cockpit. By centering the horizontal and vertical needles, the pilot flies an approximation to a time-optimal intercept trajectory. Example simulations are shown and statistical data on the pilot's performance when presented with different display and computation modes are described.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: NASA-TP-2445 , L-15896 , NAS 1.60:2445
    Format: application/pdf
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  • 6
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    Optimization of aircraft altitude and flight-path angle dynamics (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Previously cited in issue 03, p. 331, Accession no. A82-13107
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 123-125
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  • 7
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    Optimal guidance and propulsion control for transatmospheric vehicles (1989)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Problems associated with on-board trajectory optimization and with the synthesis of guidance laws are addressed for ascent to LEO of an air-breathing, single-stage-to-orbit vehicle. A multimode propulsion system is assumed which incorporates turbojet, ramjet, scramjet, and rocket engines. An energy-state approximation is applied to a four-state dynamic model for flight of a point mass over a spherical nonrotating earth. An algorithm for generating fuel-optimal climb profiles is derived via singular perturbation theory. This algorithm results from application of the minimum principle to a low-order dynamic model that includes general functional dependence on angle of attack and a normal component of thrust. Switching conditions are derived which, under appropriate assumptions, govern optimal transition from one propulsion mode to another. The use of bank angle to modulate the magnitude of the vertical component of lift is shown to improve the index performance. Numerical results illustrate the nature of the resulting fuel-optimal climb paths.
    Keywords: LAUNCH VEHICLES AND SPACE VEHICLES
    Type: AIAA PAPER 89-3617
    Format: text
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  • 8
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    Application of variable structure system theory to aircraft flight control (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The current status of research on the application of variable structure system (VSS) theory to design aircraft flight control systems is summarized. Two aircraft types are currently being investigated: the Augmentor Wing Jet STOL Research Aircraft (AWJSRA), and AV-8A Harrier. The AWJSRA design considers automatic control of longitudinal dynamics during the landing phase. The main task for the AWJSRA is to design an automatic landing system that captures and tracks a localizer beam. The control task for the AV-8A is to track velocity commands in a hovering flight configuration. Much effort was devoted to developing computer programs that are needed to carry out VSS design in a multivariable frame work, and in becoming familiar with the dynamics and control problems associated with the aircraft types under investigation. Numerous VSS design schemes were explored, particularly for the AWJSRA. The approaches that appear best suited for these aircraft types are presented. Examples are given of the numerical results currently being generated.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: NASA-CR-164321
    Format: application/pdf
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  • 9
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    Optimal output feedback design of systems with ill-conditioned dynamics (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Singular perturbation concepts are exploited to develop a procedure for designing a constant gain, output feedback control system. It is assumed that the original system is ill-conditioned in the sense that the plant contains widely separated dynamics, and that an accurate description for the high frequency behavior may not be available. The design procedure attempts to stabilize the system by minimizing a quadratic cost function made up of the control and states associated with a reduced order (low frequency) model for the plant, and a measure of stability for the neglected fast dynamics. The resulting design procedure does not require knowledge of the fast dynamics.
    Keywords: CYBERNETICS
    Type: Automatica (ISSN 0005-1098); 21; 271-276
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  • 10
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    Piezoceramic devices and artificial intelligence time varying concepts in smart structures (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: The problem of development of smart structures and their vibration control by the use of piezoceramic sensors and actuators have been discussed. In particular, these structures are assumed to have time varying model form and parameters. The model form may change significantly and suddenly. Combined identification of the model from parameters of these structures and model adaptive control of these structures are discussed in this paper.
    Keywords: CYBERNETICS
    Type: Fiber Optic Smart Structures and Skins II; Sept. 5-8, 1989; Boston, MA; United States
    Format: text
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