Continuation of theoretical and experimental research on digital adaptive control system, 16 September 1966 - 16 February 1967
Digital adaptive control system
DIGITAL COMPUTER↗
SEARCH · Engineering Papers
Results for “nonlinear systems”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Research in methods of generating Liapunov functions Final report
Liapunov functions for nonlinear systems of differential equations
Drake, R.↗
Research in stability and control theory
Linear and nonlinear systems, and differential equations for control and stability theory
Gunderson, R. W.↗
Parameter plane analysis of forced nonlinear oscillations
Parameter plane analysis of forced oscillations and jump resonance phenomena in nonlinear systems
Moore, J.↗
Asymptotic stability with output constraints.
Initial conditions estimation problem for nonlinear system asymptotic stability and satisfaction of output constraints on state variables
Julich, P. M.↗
A multipurpose frequency-response analyzer
Closed loop frequency response analyzer with steepest descent computing procedure to obtain in-phase and quadrature signal components in linear or nonlinear systems
Kohr, R. H.↗
Admissibility and nonlinear Volterra integral equations
Solutions behavior of nonlinear system of linear Volterra integral equations, discussing applicability of standard fixed point theorems
Miller, R. K.↗
A sequence solution to the Fokker-Planck equation
Sequence solution to multidimensional time varying Fokker-Planck equation for phase locked nonlinear systems
Mayfield, W. W.↗
On the use of piecewise-linear functions in suboptimal feedback control laws
Suboptimal feedback control law for second order nonlinear systems with quadratic performance index, determining power series coefficients
Meyer, R.↗
An all digital phase locked loop for FM demodulation
Digital phase locked loop for FM signals demodulation, considering system nonlinear difference equation
Garodnick, J.↗
Algorithm for Liapunov stability analysis
Development of algorithm provides automatic computation of quadratic estimate of domain of stability for stable equilibrium states of nonlinear systems of ordinary differential equations.
Geiss, G. R.↗
Analytical methods for performance evaluation of nonlinear filters.
In the investigation, the filtering problem is considered in the continuous time domain. The postulated simple suboptimal nonlinear filter structure closely parallels the structure of the Kalman-Bucy optimal linear filter algorithm. Two filter performance evaluation methods are developed based on the Kolmogorov equations for the transition density of Markov processes. The expansions in the approximations for the nonlinear system and observation functions are in effect carried out up to second-order terms in both methods. The description of the filter's performance is sought in terms of second-order statistics in both methods.
Bejczy, A. K.↗
Singular perturbation of absolute stability.
The influence of a small parameter at the higher derivatives in the differential equations describing nonlinear systems of the Lur'e-Postnikov class on absolute stability in the parameter space is investigated. The conditions leading to singular perturbations of absolute stability are examined.
Siljak, D. D.↗
A sequence solution to the Fokker-Planck equation.
In this paper a new approach to nonlinear system analysis based on the Fokker-Planck equation is developed. The development begins as a modification of the parametrix method of partial differential equation theory and provides a sequence solution to the multidimensional time-varying Fokker-Planck equation. This sequence is simplified for the case where only a steady-state solution or a solution for the variance of a particular combination of states is desired. Equations are presented in a form suitable for obtaining numerical results using a digital computer.
Mayfield, W. W.↗
Synthesis of an observation operation and the property of complete observability of nonlinear objects
The observation of nonlinear systems from incomplete information is discussed in terms of the equations for expressing the known dynamic properties. The observation operations synthesized are the integral, differential, and combined.
Galperin, Y. A.↗
Power conversion in electrical networks
Aspects of dc to dc conversion were studied in terms of a class of switching voltage regulators from a stability viewpoint. Background concepts of nonlinear system theory were considered, including the problem of obtaining suitable realizations for a class of positive operators. It is shown that the state evolution equations for a power conversion network are in general of bilinear form, and that the theory of lie groups and lie algebras is useful in analyzing such systems. The feedback stabilization of a class of bilinear systems whose state space is a manifold is also discussed.
Wood, J. R.↗
Prediction of axial-flow instabilities in a turbojet engine by use of a multistage compressor simulation on the digital computer
A method of estimating the undistorted stall line for an axial-flow compressor by using the digital computer is presented. The method involves linearization of nonlinear dynamic equations about an operating point on a speed line, and then application of the first method of Lyapunov to determine the stability of the nonlinear system from the stability of the linear system. The method is applied to a simulation of the J85 compressor, which utilizes stage stacking and lumped volume techniques for the interstage regions to simulate steady-state and dynamic compressor performance. The stability boundary predicted by the digital simulation compares quite well with the stall line predicted by a dynamic simulation of the J85 compressor programmed on the analog computer. Since previous studies have shown that the analog-predicted stall line agrees well with the stall line of the compressor, the digital method presented is also a good means of estimating the stall line.
Daniele, C. J.↗
Modeling the behavior of the helmsman steering a ship
A supertanker is considered as a nonlinear system which responds very slowly to changes in the rudder position. Moreover this type of ship is often unstable in loaded condition. In order to model the helmsman's behavior, a number of tests were performed using a ship maneuvering simulator. The trained subjects had to steer a 200,000 tons tanker along a varying course. The results obtained from these trials are presented.
Veldhuyzen, W.↗