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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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Modified perturbation method for solving optimal control boundary value problems with state variable inequality constraints, noting application to reentry trajectories
Absolute stability of dynamic control systems with single nonlinear element function of two feedback state variables, giving sufficient conditions
Sufficient conditions derived for absolute stability of dynamic systems containing nonlinear functions of several state variables
Popov type nonlinear control systems from synthesis viewpoint, using state variable feedback results to insure absolute stability
Slack variable to transform optimal control problem with scalar inequality constraint on state variables into unconstrained problem of higher dimension
Slack variable to transform optimal control problem with scalar inequality constraint on state variables into unconstrained problem
Digital computer program based on matrix formulation for analysis and design of linear state variable feedback systems
Thermodynamic properties effects on transverse acceleration wave propagation in inhomogeneous isotropic elastic bodies with internal state variables
The paper describes methods for extracting unknown state variables and parameters from dynamic rotor model tests given transient cyclic pitch stirring inputs, blade root flap-bending measurements, and the form of the dynamic rotor equations, including a rotor dynamic inflow description, when none of the physical parameters are known. A simplified version of the maximum likelihood method seems best suited for this purpose. The measurement equation error covariance matrix is assumed constant during each iteration, but updated for the subsequent iteration. A detailed analysis of the suitability of the derived techniques for studying various rotor dynamic inflow effects is provided.
This paper derives three discrete state variable representations for a continuous-time plant driven by a zero-order hold with a combination of instantaneous measurements and measurements prefiltered by a multiinput/multioutput moving average (MA) process. These representations allow the control system engineer to model plants of this type accurately in a form which permits him to use standard techniques to design digital feedback controllers for them. An example is presented which illustrates how to obtain the coefficient matrices in each representation. Guidelines are presented for choosing the best representation to use for any given plant of this type.
Optimum state variable selection to determine constraints for nonlinear system stability, using Liapunov second method
Markov parametric algorithm for effective construction of minimal realizations of linear state-variable finite-dimensional dynamical systems from input-output data
Discontinuous integrands in calculus of variations formulations of trajectory optimization and maximum payload problems with discontinuous state variables
The numerical value for the sensitivity coefficient of each scalar state variable with respect to each parameter of a five body model of the rotational dynamics of a flexible spacecraft with modular attitude control is generated. The maximum magnitudes of these sensitivity coefficients are arranged in descending order in one table while the final time (steady state) values of these sensitivity coefficients are arranged in order of descending magnitude in a second table.
A mathematical model utilizing the internal state variable concept is proposed for predicting the upper bound of the reduced axial stiffnesses in cross-ply laminates with matrix cracks. The axial crack opening displacement is explicitly expressed in terms of the observable axial strain and the undamaged material properties. A crack parameter representing the effect of matrix cracks on the observable axial Young's modulus is calculated for glass/epoxy and graphite/epoxy material systems. The results show that the matrix crack opening displacement and the effective Young's modulus depend not on the crack length, but on its ratio to the crack spacing.
Feasibility of optimal control theory in synthesis of manual control system - human compensatory tracking performance with quickened display, state variable display, and display gains
Four design problems are considered: two on the optimal minimum order observer-based compensator design and two on the optimal limited state variable feedback controller. The problem of designing an optimal discrete time linear time-invariant observer-based compensator for the regulation of an n dimensional linear discrete time time-invariant plant with m independent outputs is considered. This is a stochastic design problem to the extent that the initial plant state is assumed to be a random vector with known first and second order statistics. The compensator parameters are obtained by minimizing the expectation, with respect to the initial conditions, of the standard cost, quadratic in the state and control vectors with the inclusion of cross terms.
State vector determination for digital optimal control of system characterized by matrix equation