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Multiple nonlinear systems have been studied, particularly in multiple-input and multiple-output cases., by modifying the small loop-gain theorem and circle criterion. For these kinds of multiple nonlinear systems., the conventional stability analyses techniques are not employed because of the complexity and non-linearity. The input-output stability analysis technique, therefore, has been applied...
An algorithm is reported for the sequential detection and estimation of parametric failures (deviations) which affect the system matrices of a linear, discrete time system. This represents the generalization of a technique, previously reported by the authors [1, 2], for the detection and estimation of soft failures in the statistical parameters of System inputs and measurement errors. In general,...
Adaptive control techniques are presented here to minimize the settling time of second-order systems (with a fixed natural frequency) by periodic or continuous resetting of the damping factor. Adaptive continuous control is shown to be faster and more general than adaptive periodic switching. The illustrated parametric curves present guidelines for selecting control system configurations for minimizing...
An autonomous navigation concept is introduced when a space lasercom (laser communications) system is used for crosslink between two or several orbiting satellites. An on-board tracking estimator is developed based upon the measurement, quantities of ranging data from the communication laser beacon, the line-of-sight vector of the returned signal the optical receiver, together with the satellite attitude...
An algorithm has been developed for the analysis and design of controls for nonlinear systems. The technical approach is to use statistical linearization to model the nonlinear dynamics of a system. A covariance analysis is performed to determine the behavior of the dynamical system and a quadratic cost function. Expressions for the cost function and its derivatives are determined so that numerical...
A simple buat powerful method to detect failures or changes in an attitude determination system employing a Kalman Filter is to monitor the filter residuals. By construction, the residuals should be a white sequence with zero mean and known variances. Departure of the residual statistics from the predicted values can be indicative of unknown parameter changes (gyro biases, star sensor alignment, etc...
A theorem is developed, based on the circle criterion, which gives sufficient conditions for the stability of a saturating linear control for a linear system with bounded states. This theorem can be applied to determine a range of gains for the linear control which insures stability. It is shown by example that this approach results in an increased speed of response over that obtained by previous...
Controller design criteria are given for a special class of uncertain nonlinear systems. These criteria are formulated to be explicit, quantitative, and computer oriented, yielding controllers realizable as nonlinear observers and guaranteeing servo tracking consistent with specified error bounds.
The tracking domain problem is imposed for control systems incorporating multiple nonlinearities that violate Lurie sector condition. Domains of different tracking properties are defined. General result reduces analysis of tracking domains to analysis of stability domains of the corresponding free control systems, which is shown fundamental for application of the Popov method for solving tracking...
The applicability of the describing function method of analysis to a plant/controller system containing a nonlinear relay with feedback is investigated. A second order plant model is employed, with system parameters based on a ship steering system application. Analytical predictions of limit-cycle behavior are made and are found to be in disagreement with time-domain results. It is hypothesized that...
For parameter-adaptive control of nonlinear single input/single output processes a nonlinear parameter-adaptive state space controller is presented, which can be designed with small computational expense from identified nonlinear parametric process models based on Volterra-series. The resulting nonlinear state space controller will be applied to an analog simulated process (liquid level control in...
The linear-quadratic-Gaussian regulator problem is considered for multivariable linear stochastic systems with uncertain second-order statistical properties. Uncertainty is modeled by allowing process and observation noise spectral density matrices to vary arbitrarily within given classes, and a minimax control formulation is applied to the quadratic objective functional. General theorems proving...
The realization problem is approached by assuming that the observed process is generated by a time invariant, possibly nonstationary linear system with noisy measurements. The proposed approach suggests a simple method for reduced order representation.
In (1-2), global convergence for a stochastic adaptic control based on (modified) least squares algorithms has been established. The proofe of lemma 3.4 of (1) and δ(t-d)-0 of (2) both made use of (3, A6). However, the conclusion of (3,A6) is questionable. Without using these conclusion, this paper attemps to establish global convergence for a discrete-time stochastic adaptive control and prediction...
For a class of multivariable nonlinear systems a sufficient condition for the existence of control to generate output which asymptotically tends to a given real analytic vector function is derived. A prefilter (right inverse) is constructed to generate the required control. Based on this result, a control to steer the alert state of an interconnected power system to a secure state is derived. The...
An electropneumatic converter is described which converts a voltage of ?? 7v into a blocked pressure difference of ?? 1.72 kPa (0.25 psi). It uses a piezoelectric blender., squeeze-film damping and laminar proportional amplifiers to provide a 90?? phase log frequency of 130 Hz with no resonances below that frequency.
We consider the problem of using an exponential detection function to search for a target whose motion is a Markov process satisfying a stochastic differential equation of the diffusion type. The overall objective is to minimize the probability of nondetection. The approach is to reformulate the problem as one of seeking an optimal control (search strategy) with an optimal stopping time. The decision...
When obtaining measurements of a system state is costly, it is important to determine when the benefits of having a measurement will out weigh its cost. Here discrete LQG sequential differential games are considered, and the optimal observation strategies are seen to depend in a fundamental way on the game information structure. Three structures are treated, and the observation decision at each stage...
The development of a low cost, reliable, linear pressure amplifier to interface Laminar Proportional Amplifiers (LPA) to pneumatic controllers is presented. The amplifier consists of an LPA input stage and an output stage consisting of a venturi in series with a bellows nozzle valve. The LPA output drives the bellows nozzle valve thereby altering the flowrate through the venturi. The pressure within...
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