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The problem of determining spacecraft attitude and angular rates from vector measurements is analysed; a number of approaches to the problem are compared and their relative merits discussed with particular reference to the problem of attitude and rate determination from magnetic field vector measurements.
Vibrations in dynamical structures, as those encountered for instance in mechanical, aerospace or civil engineering, are often caused by internal or external excitations. One way to attenuate vibrations that can be undesirable for safety or other reasons is by the use of active control systems. This means to use feedback controllers driving actuators at appropriate locations between the structure...
A nonlinear feedback system is designed and analyzed for a surface micromachined resonant accelerometer. For this, a brief illustration of the plant dynamics is given. In the analysis, the periodic signal in the nonlinear feedback loop is obtained by the limit cycle point, which is best approximated via the describing function method. This approach is reasonable in that the describing function method...
The open loop optimal control (dynamic optimization) of distributed parameter systems is considered here. These problems are usually solved by the Control Vector Parameterization (CVP) approach, which transforms the original dynamic optimization method into an outer nonlinear programming problem, which requires the solution of an inner initial value problem (IVP). The solution of this IVP (set of...
Several subspace algorithms for the identification of bilinear systems have been proposed recently. A key practical problem with all of these is the very large size of the data-based matrices which must be constructed in order to ‘linearise’ the problem and allow parameter estimation essentially by regression. Another shortcoming of currently known subspace algorithms for bilinear systems is that...
This series of two papers deals with the spatial optimization of the heat exchanger temperature profile of an exothermic tubular reactor under the assumption of steady state and plug flow characteristics. The minimum principle of Pontryagin (optimal control theory) is applied in a straightforward, analytical sense. To enable a trade-off between process performance and heat loss a combined cost criterion...
A quantitative model of growth and metabolism of CH0-K1 cell culture in a serum-free medium is presented. The model is validated using five batch experiments with varying glucose and glutamine initial concentrations.
A matrix form representation of discrete analogs of various forms of fractional differentiation and fractional integration is suggested. The suggested approach is new, and it can be used in all fields related to fractional-order dynamical systems and fractional-order control, including development of algorithms and software for real-time control, PIλDμ controllers, and modelling and simulation of...
Volatility of the stock price is the key to the pricing problem of stock related derivatives in finance. Volatility appears in the diffusion term of the usual modeling of stock prices. One popular approach is to take volatility to be stochastic, and assumes that it satisfies a stochastic differential equation. Taking the stock price to be the observation, we may then pose the filtering problem of...
This paper proves the requirement of a time-varying initialization for fractional differential equations. This then requires a new definition for the fractional differintegral that includes the initialization and a new form of the Laplace transform of the fractional differintegral. An initialized fractional system theory is developed.
A brief introduction to the fractional Fourier transform and its properties is given. Its relation to phase-space representations (time- or space-frequency representations) and the concept of fractional Fourier domains are discussed. An overview of applications which have so far received interest are given and some potential application areas remaining to be explored are noted.
In 1996, a new spread spectrum communication system, called Frequency Diversity Spread Spectrum (FDSS), was proposed as a system to mitigate the problems of the common spread spectrum techniques. In this paper, two blind self-reference optimum beamforming methods tailored for the FDSS signalling scheme using the trivial repetition code are derived based on the inherent cross-correlation properties...
Control design methods for the control of the reaction wheel pendulum using a single actuator are presented in this paper. The control algorithms are based on the energy of the system and its passivity properties.
The aim of this paper is to investigate some properties of the solutions of the differential Riccati-type systems arising in control problems for the time-varying linear systems with jumps. A major attention is paid to the stabilising solution of these systems. Necessary and sufficient conditions for the existence of such solution are derived in the time-invariant case.
We describe the effect of physical dissipation on stability of equilibria which have been stabilized, in the absence of damping, using the method of controlled Lagrangians. This method applies to a class of underactuated mechanical systems including "balance" systems such as the pendulum on a cart. Since the method involves modifying a system's kinetic energy metric through feedback, the...
The problem of the global asymptotic stabilization by dynamic output feedback of systems belonging to a particular family of feedforward systems is solved. The equations considered depend nonlinearly on the unmeasured part of the state and are nonminimum phase. Feedback laws arbitrarily small in norm are constructed. The result can be applied repeatedly. It is illustrated by the cart-pendulum system...
In multivariable control the study of loop interactions is of prime importance. The P or V-canonical form structures, where loop interactions are dealt with as feed-forward couplings, are popular transfer function representations used to describe multivariable processes. Another alternative design consists of a bank of several Single Input Single Output (SISO) controllers linked by feed-forward terms...
This article deals with modeling and identification of fractional systems in the time domain. Fractional state-space representation is defined, and a stability condition for fractional systems given. A new identification method for fractional systems is then proposed. The method is based on the generalization to fractional orders of classical methods based on State Variable Filters (SVF). A particular...
The robustness of discrete iterative learning controller a-gainst initial state state error for discrete-time plant is investigated in this paper. When the initial state remains fixed for each iteration but is different from the desired one, it is shown that the output will converge to a trajectory which is the same as the desired one except the initial point for a traditional D-type discrete iterative...
The first purpose of this paper is to present shortly an idea of soft variables and evaluating functions as a tool for the unification and generalisation of decision making problems in control systems with a static plant. The random variables, uncertain variables and fuzzy descriptions are considered here as special cases of the descriptions based on the soft variables. The second purpose of the paper...
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