An efficient composite control strategy is proposed in this paper permitting simultaneous multi-axis reorientation of a spacecraft with flexible structures. The proposed control, separating large and small motions of ...
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An efficient composite control strategy is proposed in this paper permitting simultaneous multi-axis reorientation of a spacecraft with flexible structures. The proposed control, separating large and small motions of the dynamic system, includes three parts that can be independently designed and tuned. For each maneuver, an open-loop referencing attitude control trajectory is derived by considering the spacecraft as rigid and executed by part 1. Flexural deformations of the structures are stabilized by part 2. Part 3, encompassing part 1 and part 2 control results and external disturbances, is an optimal guidance that tracks part 1 reference trajectory and achieves the specified final attitude in finite time. Three simulation cases are included in which a flexible model spacecraft is used. Collocated actuators and sensors are placed on the hub and on the flexible structures of the spacecraft.
In this paper we consider two mathematical models for a multiple beam system (MBS) which is composed of two rigidly and angularly connected Euler-Bernoulli beams. The cantilevered structure is clamped at one end, and ...
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In this paper we consider two mathematical models for a multiple beam system (MBS) which is composed of two rigidly and angularly connected Euler-Bernoulli beams. The cantilevered structure is clamped at one end, and has point controls for forces and bending moments imposed at the other end and at the connection between the two beams. The first model incorporates not only transverse deformations of both beams, but also axial compression/extension of the beams. The second model involves only transverse deformations of the beam. By imposing point controls, an unbounded input operator is obtained. A variational formulation of the models is used to show well-posedness. Uniform exponential stabilizability of the second model through boundary feedback is established via energy arguments.
This study shows how the optimal control theory for distributed parameter systems can be implemented for a problem of tubular reactor with axial dispersion described by partial differential equations. Two methods are ...
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This study shows how the optimal control theory for distributed parameter systems can be implemented for a problem of tubular reactor with axial dispersion described by partial differential equations. Two methods are implemented. One is based on differential equation approach and the other is based on integral equation approach. It was found that the approach with partial differential equations is preferable to the one with integral equations for the type of problems treated in this study. Computation algorithms and programs for both cases are developed.
This paper deals with the dynamical properties (observability, reachability, stabilizability, detectability) of fixed bed reactors. The class of processes considered here are plug flow reactors in which sequential rea...
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ISBN:
(纸本)0780326857
This paper deals with the dynamical properties (observability, reachability, stabilizability, detectability) of fixed bed reactors. The class of processes considered here are plug flow reactors in which sequential reactions take place (at the exclusion of reversible reactions, and 'loop' reactions). The analysis is based on a linear distributedparameter model of the process. It is shown that the system is stable, whence detectable and stabilizable when the control inputs are the influent reactant concentrations. But it is not approximately reachable. Besides observability is studied when either the concentrations of the process components or the products of the sequential reactions' endpoints are measured at the reactor output.
The variable structure control problems of distributed parameter system are in vestrigated in this *** the conditions more general than in[1],[2],the equivalent, control theorem is ***,as an application to system of ...
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The variable structure control problems of distributed parameter system are in vestrigated in this *** the conditions more general than in[1],[2],the equivalent, control theorem is ***,as an application to system of heat process,we give some conditons for sliding model such that the solution of system of heat process is exonentially stable unde the variable structure control.
The industrial process of vulcanization is modelized by a system of two nonlinear equations depending on the temperature and on the reticulation rate. A control problem is proposed and written as a optimization one. D...
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The industrial process of vulcanization is modelized by a system of two nonlinear equations depending on the temperature and on the reticulation rate. A control problem is proposed and written as a optimization one. Deterministic methods are presented to minimize a cost function. A stochastic approach is introduced in order to improve the numerical resolution. The numerical effect of the coupling between stochastic methods and a deterministic one is investigated. The interest of the introduction of random perturbations is shown. Le processus industriel de vulcanisation des élastomères est modélisé par un système de deux équations non-linéaires dépendant de la température et du degré de réticulation. Un problème de contrôle est décrit sous forme d'un problème de optimisation. Des methodes déterministes sont présentées afin de minimiser le critére. Une approche stochastique est proposée afin d'améliorer la résolution numérique. Les effets numériques du couplage entre les méthodes stochastiques et les méthodes purement déterministes sont étudiés. L'intérêt de l'adjonction de perturbations aléatoires est mis en évidence.
An Augmented Kalman Filter is applied to a non-linear model of a gas phase copolymer reactor where 90 state variables and 7 parameters are estimated. The distributed process is represented by a series of volume elemen...
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An Augmented Kalman Filter is applied to a non-linear model of a gas phase copolymer reactor where 90 state variables and 7 parameters are estimated. The distributed process is represented by a series of volume elements and the model equations are based on the conservation of mass, energy and momentum for the volume elements. The filter estimates the state variables very well. The estimates of the parameters are reasonable even though heat transfer coefficients are affected by mismatches in the energy balance of the model.
A search method of optimal allocation of sensors is proposed for state estimation of a linear distributed parameter system. It was applied to a one-dimensional heat conduction process in order to test the state estima...
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A search method of optimal allocation of sensors is proposed for state estimation of a linear distributed parameter system. It was applied to a one-dimensional heat conduction process in order to test the state estimation performance. The results show that this method gives an accurate optimal allocation of sensors. It was also found that optimal-sensor location depends not only on the system dynamics but also on both the initial and steady states of the state variable. It was also suggested that increase in number of sensors would not always lead to improvement of estimator performance.
Recently, chemical process operations are becoming more precise, making process control more difficult by conventional dynamics and control theories alone. The zone melting process considered in this work is a typical...
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Recently, chemical process operations are becoming more precise, making process control more difficult by conventional dynamics and control theories alone. The zone melting process considered in this work is a typical example of advanced chemical processes and requires highly precise operations. A precise temperature profile must be achieved and maintained against strong disturbances due to the movement of a sample tube or heaters and to interactions between heaters. To overcome this difficult problem, a new zone melting process is proposed in this paper. Without movement of either sample tube or heaters, realization of, the desired time-varying temperature profile is attempted by manipulation of fixed heaters. The process dynamics are treated as a distributed-parametersystem. Applying distributedparameter control to the zone melting process in a simulation, stimulation verified that the process could be realized. Moreover, experimental results using an anthracene zone melting apparatus also showed good control performance.
The paper presents an overview and assessment of the technology leading to the development of intelligent structures. Intelligent structures are those which incorporate actuators and sensors that are highly integrated...
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The paper presents an overview and assessment of the technology leading to the development of intelligent structures. Intelligent structures are those which incorporate actuators and sensors that are highly integrated into the structure and have structural functionality, integrated control, signal conditioning and power amplification electronics. Intelligent structures are subsets of active structures that have highly distributed actuators and sensor systems with structural functionality, distributed control and computing architecture.
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