Controllability

In this paper we propose digital control methods for steering real analytic controllable systems between arbitrary state configurations. The main idea is to achieve a multirate sampled procedure to perform motions in all the directions of controllability under piecewise constant controls. When it is applied to nonholonomic control systems without drift, the procedure simplifies. In particular, it results in exact steering on chained systems recently introduced in the motion planning literature. A classical example is reported.

Most textbooks in linear systems present controllability and observability as being invariant under coordinate transformations. Although this concept is correct from a certain viewpoint, in a more general sense it could be misleading. This latter viewpoint is not usually emphasized in basic courses and the gap left has often proved to be difficult for students to overcome. This paper addresses both viewpoints and special attention is devoted to the one which is often neglected. The controllability/observability of transfer functions is also discussed and important links with the state space representation are pointed out.

Discrete-event systems (DES) are modeled by Biichi automata together with a means of on-line control. In this setting we extend the concept of a controllable language introduced by Ramadge and Wonham to infinite strings and derive conditions for the existence of a supervisor (controller) to implement a prescribed closed-loop behavior. Our main interest is in a class of DES called product systems. These are DES composed of a finite set of asynchronous components. A control problem for such a system typically requires the synthesis of an on-line controller so as to achieve some prescribed coordinated behavior of the component subsystems. One of the principal difficulties in this task is that the size of the state space increases exponentially with the number of components. We show that despite this fact several interesting control synthesis problems for such systems are computationally feasible and we develop algorithms for their solution.

The aim of this study was to investigate whether in stress-prone subjects, carbohydrate-rich, protein-poor food (CR/PP) diminished depressive mood and a cortisol response under controllable as well as uncontrollable laboratory stress. Twenty-two subjects with high stress proneness (HS) and 23 subjects with low stress proneness (LS) participated in a controllable-and uncontrollable-stress experiment during either a CR/PP or protein-rich, carbohydrate-poor (PR/CP) diet. Both controllable and uncontrollable laboratory stress significantly increased pulse rate and skin conductance in HS and LS subjects, whereas uncontrollable stress increased feelings of depression, anger, tension, and fatigue and decreased feelings of vigor. Only in HS subjects, a cortisol response and feelings of depression became lower under the CR/PP diet condition, irrespective of the controllability of the laboratory stressor, suggesting an increased ability to cope with stress. Because the CR/PP diet compared with the PR/CP diet previously has been found to cause a 42% increase in plasma tryptophan/ ⌺ LNAA, seen as an indirect measure of increases in brain serotonin levels, the present results suggest that an enhanced serotonin function in HS subjects may be involved.

work presents a comprehensive classification of the different methods and procedures for integrated synthesis, design and control of chemical processes, based on a wide revision of recent literature. This classification fundamentally differentiates between "projecting methods", where controllability is monitored during the process design to predict the trade-offs between design and control, and the "integrated-optimization methods" which solve the process design and the controlsystems design at once within an optimization framework. The latter are revised categorizing them according to the methods to evaluate controllability and other related properties, the scope of the design problem, the treatment of uncertainties and perturbations, and finally, the type the optimization problem formulation and the methods for its resolution.

This paper investigates the properties of EVA  compensation schemes, which were considered as a major managerial innovation of the 90's. The analysis is carried on in the framework of contract theory and based on a six year longitudinal case study. It is argued that such schemes induce a loss of controllability (the bonus is influenced by factors out of the control of the managers) as compared to more traditional ones. The role of the target setting, based on external standards, and the absence of renegotiation are of particular significance in explaining this loss. This analysis may explain some of the difficulties encountered in the implementation of these schemes and their relative decline.

Objectives: This paper urges revision of the way attributions are conceptualised, investigated, and applied in sport psychology. There has been a recent decline in attribution research in sport psychology, despite the generally accepted relevance of attributions in applied settings. In seeking closer links between attribution theory, research, and practice, we argue that there is a mismatch between research and practice in sport psychology.

L'approche DEA (Data Envelopment Analysis) permet de proposer de nouveaux indicateurs de la performance pour les réseaux de distribution intégrés. Après avoir précisé la méthode de construction d'un indicateur de productivité des points de vente respectant les critères de contrôlabilité et de cohérence transversale, nous modélisons le lien entre un indicateur de performance de la tête de réseau et l'indicateur de productivité pour garantir la cohérence hiérarchique. Enfin, nous insérons ces indicateurs dans un outil d'aide à la décision conforme à l'organisation verticale des réseaux de distribution : un système de tableau de bord prospectif. Mots clés : Data Envelopment Analysis-agences bancaires-tableaux de bord prospectifs-contrôlabilité.

The  Code  of  Practice  (CoP)  comprises  a  suitable ADAS  (Advanced  Driver  Assistance  System) description  concept  including ADAS  specific requirements  for  system  development. It  summarises best  practices  and  proposes  methods  for  risk assessment and controllability evaluation. The Code of Practice has been pro-duced  by  a  group  of  experts within  the  RESPONSE  3  project,  a subproject  of  the integrated  project  PReVENT,  a  European  automotive industry  activity,  co-funded  by  the  European Commission, to contribute to road safety by developing and demonstrating pre-ventive safety applications and technologies.

theory of planned behavior (TPB) to explain and predict the process of e-commerce adoption by consumers. The process is captured through two online consumer behaviors: (1) getting information and (2) purchasing a product from a Web vendor. First, we simultaneously model the association between these two contingent online behaviors and their respective intentions by appealing to consumer behavior theories and the theory of implementation intentions, respectively. Second, following TPB, we derive for each behavior its intention, attitude, subjective norm, and perceived behavioral control (PBC). Third, we 1 Ritu Agarwal was the accepting senior editor for this paper. Elena Karahanna was the associate editor. D. Harrison McKnight, Jonathan Palmer, and David Gefen served as reviewers.

More than 70% of the IT projects in the UK fail every year and over 80% of them fail in the requirements analysis phase. Poor project management, bad organisational politics, false business priorities, lack of commitment and other issues can also cause a project to fail. Patterns of software systems failures and their study have resulted in the development of numerous models, methodologies and frameworks, yet project and system failures persist. Requirements understanding, analysis and specification have emerged as critical areas in software and systems engineering. More recent developments have indicated the shift from the technical view to the human factor embodied strongly in the agile movement. The papers were presented at the International Workshop for Requirements Analysis (IWRA2010) which focussed on concepts, ontologies, models, methods and techniques such as methods for eliciting, analysing and measuring requirements. The papers in this issue come from both academia and industry where theory is applied to case studies such as Service Provisioning for the Greek Banking Sector, home care systems and Aeronautics.

We consider the two and three-dimensional system of linear thermoelasticity in a bounded smooth domain with Dirichlet boundary conditions. We analyze whether the energy of solutions decays exponentially uniformly to zero as t->∞ . First of all, by a decoupling method, we reduce the problem to an observability inequality for the Lamé system in linear elasticity and more precisely to whether the total energy of the solutions can be estimated in terms of the energy concentrated on its longitudinal component. We show that when the domain is convex, the decay rate is never uniform. In fact, the lack of uniform decay holds in a more general class of domains in which there exist rays of geometric optics of arbitrarily large length that are always reflected perpendicularly or almost tangentially on the boundary. We also show that, in three space dimensions, the lack of uniform decay may also be due to a critical polarization of the energy on the transversal component of the displacement. In two space dimensions we prove a sufficient (and almost necessary) condition for the uniform decay to hold in terms of the propagation of the transversal characteristic rays, under the further assumption that the boundary of the domain does not have contacts of infinite order with its tangents. We also give an example, due to D. Hulin, in which these geometric properties hold. In three space dimensions we indicate (without proof) how a careful analysis of the polarization of singularities may lead to sharp sufficient conditions for the uniform decay to hold. In two space dimensions we prove that smooth solutions decay polynomially in the energy space to a finite-dimensional subspace of solutions except when the domain is a ball or an annulus. Finally we discuss some closely related controllability and spectral issues.

Local and global Carleman estimates play a central role in the study of some partial differential equations regarding questions such as unique continuation and controllability. We survey and prove such estimates in the case of elliptic and parabolic operators by means of semi-classical microlocal techniques. Optimality results for these estimates and some of their consequences are presented. We point out the connexion of these optimality results to the local phase-space geometry after conjugation with the weight function. Firstly, we introduce local Carleman estimates for elliptic operators and deduce unique continuation properties as well as interpolation inequalities. These latter inequalities yield a remarkable spectral inequality and the null controllability of the heat equation. Secondly, we prove Carleman estimates for parabolic operators. We state them locally in space at first, and patch them together to obtain a global estimate. This second approach also yields the null controllability of the heat equation.

Je voudrais en premier montrer ma gratitude envers tous les membres du Departement de Mathematiques de l'Université de Versailles Saint-Quentin, notamment envers ceux appartenant au Laboratoire de Mathématiques Appliquées, pour leur gentil et chaleureux accueil. Ils ont toujoursété très aimables et disponibles pour résoudre tout type de problème.

This paper presents a concept of improving the transient stability of power system by simultaneous AC–DC power transmission through a transmission line. A double circuit long transmission line is converted to simultaneous AC–DC line for feasibility study. Loss of synchronism is prevented by quickly producing sufficient decelerating energy to counteract accelerating energy gained during fault and subsequently due to loss of line after clearing the fault. Fast controllability and modulation of DC component is utilized to achieve this feature. The system under consideration is found to remain stable under transient condition up to transmission angle of 80°. Simulation study on PSCAD/EMTDC is carried out to validate the concept.

The current legislation imposes tighter restrictions in order to reduce the impact of chemical process industry on the environment. In this context, this study presents the dynamic model, simulation and optimization results for an industrial sulfuric acid plant. The dynamic model, implemented in PSE gPROMS includes a catalytic reactor (five pass converter), heat exchangers such as economizers and feed-effluent heat exchangers, mixers, splitters and reactive absorption columns. The kinetic parameters were fitted to the real plant data, while the remaining model parameters were estimated using classical correlations. The modeling results agree very well with the real plant data.The model implemented in gPROMS is useful for evaluating the dynamic behavior of the plant and for minimization of the total amount of SOx emissions. The SOx emissions could be significantly reduced by over 40% by optimizing operating parameters such as air feed flow rates or split fractions. However, only minor increases in energy production can be achieved due to the plant already operating near full capacity. The simulations also show that operational problems may occur when the process is disturbed due to production rate changes or catalyst deactivation, the non-linear response of the plant leading to sustained oscillations. Besides controllability, operability and optimization studies the gPROMS plant model is also useful for operator training and various scenario assessments.

This paper presents a framework called Music via Motion (MvM) designed for the transdomain mapping between physical movements of the performer(s) and multimedia events, translating activities from one creative domain to another-for example, from physical gesture to audio output. With a brief background of this domain and prototype designs, the paper describes a number of inter-and multidisciplinary collaborative works for interactive multimedia performances. These include a virtual musical instrument interface, exploring video-based tracking technology to provide an intuitive and nonintrusive musical interface, and sensor-based augmented instrument designs. The paper also describes a distributed multimedia-mapping server which allows multiplatform and multisensory integrations and presents a sample application which integrates a real-time face tracking system. Ongoing developments and plausible future explorations on stage augmentation with virtual and augmented realities as well as gesture analysis on the correlations of musical gesture and physical gesture are also discussed.

In this paper, the dynamic model of a wheeled inverted pendulum (e.g., Segway, Quasimoro, and Joe) is analyzed from a controllability and feedback linearizability point of view. First, a dynamic model of this underactuated system is derived with respect to the wheel motor torques as inputs while taking the nonholonomic no-slip constraints into considerations. This model is compared with the previous models derived for similar systems. The strong accessibility condition is checked and the maximum relative degree of the system is found. Based on this result, a partial feedback linearization of the system is obtained and the internal dynamics equations are isolated. The resulting equations are then used to design two novel controllers. The first one is a two-level velocity controller for tracking vehicle orientation and heading speed set-points, while controlling the vehicle pitch (pendulum angle from the vertical) within a specified range. The second controller is also a two-level controller which stabilizes the vehicle's position to the desired point, while again keeping the pitch bounded between specified limits. Simulation results are provided to show the efficacy of the controllers using realistic data.

Constructions with depictive attributes representing a special kind of secondary predication have been the object of recent discussions within the formal and constructional frameworks. One of the key issues in understanding this phenomenon and the variants of its realization in various languages is the identification of its prototypical model. The present paper shows that in Bulgarian, the core construction with the subject-oriented depictive secondary predicate contains the verb of controlled action as the main predicate and a non-finite form of the verb of uncontrolled action. In this way, the search of the prototypical model is related to the feature " controllability/uncontrollability of action " discerned in the semantics of both main and secondary predication. Based on the suggested parameter, the other variety of the construction in question, the one with the object-oriented depictive secondary predicate, has a different organization not only in the syntactic but also in the semantic aspect. It is demonstrated that different semantic varieties of constructions with the depictive secondary predicate have different translations in Russian.

In this paper, the dynamic model of a wheeled inverted pendulum (e.g. Segway [9], Quasimoro [8], Joe [6]) is analyzed from a controllability and feedback linearizability point of view. First, a dynamic model of this underactuated system is derived with respect to the wheel motor torques as inputs while taking the nonholonomic noslip constraints into considerations. This model is compared with the previous models derived for similar systems. The strong accessibility condition is checked and the maximum relative degree of the system is found. Based on this result, a partial feedback linearization of the system is obtained and the internal dynamics equations are isolated. The resulting equations are then used to design a two-level controller for tracking vehicle orientation and heading speed set-points, while controlling the vehicle pitch within a specified range. Simulation results are provided to show the efficacy of the controller.

This paper deals with the problem of stabilizing a system in the presence of small measurement errors. It is known that, for general stabilizable systems, there may be no possible memoryless state feedback which is robust with respect to such errors. In contrast, a precise result is given here, showing that, if a (continuous-time, finite-dimensional) system is stabilizable in any way whatsoever (even by means of a dynamic, time varying, discontinuous, feedback) then it can also be semiglobally and practically stabilized in a way which is insensitive to small measurement errors, by means of a hybrid strategy based on the idea of sampling at a "slow enough" rate.

Power systems security in the case of contingencies is ensured by maintaining adequate ''short-term generation reserve''. This reserve must be appropriately activated by means of the primary frequency control (PFC). Because the generation is an electro-mechanical process, the primary control reserve controllability is not as fast as required, especially by modern power systems. Since the new improvements achieved on the conventional control methods have not been enough to satisfy the high requirements established, the necessity of enhancing the performance of the PFC has arisen.

ATPG) algorithms for analog circuits have been under intense investigation for the last several years. As system design aggressively moves to system-on-a-chip (SoC) and core-based integration, hierarchical analog ATPG emerges as an even more difficult challenge. Attempts to develop an effective algorithm have had varying degrees of success. This article reviews some fundamental issues and recent work in hierarchical analog ATPG and presents an algorithm based on controllability and observability computation. This algorithm has been implemented in a prototype tool, and results based on several case studies show the application of the technique.

OUR STORY STARTS nearly two million years ago. A caveman named Og realized that he could choose the best stones for making tools by banging two rocks together really hard. The one that didn't break was the best one to use for his tool. And so, the age of testing was born.

System structure is a key determinant of system
behavior. There is a particularly strong link between a system’s
structure and its flexibility – it’s capacity to respond to changes.
Often, adding flexibility entails adding complexity. In this paper,
we propose measures for a system’s complexity that are
complementary to existing flexibility measures. Furthermore,
flexibility often comes at the cost of some measure of control over
the system’s behavior. We therefore propose a metric for system
controllability that is complementary to our flexibility metric.

Presently, decentralized feedback control is the only control strategy used in wet limestone flue gas desulfurization (WLFGD) plants. Proper tuning of this control strategy is becoming an important issue in WLFGD plants because more stringent SO 2 regulations have come into force recently. 3 Controllability analysis is a highly valuable tool for proper design of control systems, but it has not been applied to WLFGD plants so far. In this paper a decentralized control strategy is designed and applied to a WLFGD pilot plant taking into account the conclusions of a controllability analysis. The results reveal that good SO 2 control in WLFGD plants can be achieved mainly because the main disturbance of the process is well-aligned with the plant and interactions between control loops are beneficial to SO 2 control.

Analysis and simulations are performed for a simplified model of a commercially available variant on the skateboard, known as the Snakeboard 1 . Although the model exhibits basic gait patterns seen in a large number of locomotion problems, the analysis tools currently available do not apply to this problem. The difficulty is seen to lie primarily in the way in which the nonholonomic constraints enter into the system. As a first step towards understanding systems represented by our model we present the equations of motion and perform some controllability analysis for the snakeboard. We also perform some numerical simulations of the gait patterns.

This paper presents a method to determine stable pushing motions for a planar stack of polygonal parts. The approach consists of solving a series of subproblems where each part in the stack is pushing the parts ahead of it. The solutions to these subproblems are sets of stable motions, and their intersection is the set of stable motions for the entire stack. The motion of multiple parts depends on the exact locations of the centers of mass and the relative masses of the parts. If either or both of these is unknown, it is still possible to calculate a conservative set of motions guaranteed to be stable by using a center of mass uncertainty region.

This paper is concerned with the control properties of the Korteweg-de Vries (KdV) equation posed on a bounded interval with a distributed control. When the control region is an arbitrary open subdomain, we prove the null controllability of the KdV equation by means of a new Carleman inequality. As a consequence, we obtain a regional controllability result, the state function being controlled on the left part of the complement of the control region. Finally, when the control region is a neighborhood of the right endpoint, an exact controllability result in a weighted L 2 -space is also established.

The aim of this memory is to study the averaged controllability for parameter-dependent systems. We discuss the notion of averaged control which has been introduced recently by E.Zauzua [12]. We apply the method HUM where it is based on uniqueness criteria (the direct and inverse inequalities) to some hyperbolic equations with an unknown parameter. First, we consider the problem of controllability for linear finite and infinite dimensional systems and we give the averaged rank condition for averaged controllability. Secondly, we study the averaged controllability of wave equation depending on a parameter when the control is applied on the boundary, by using the Hilbert Uniqueness Method (the method HUM) which has been introduced by J.L. Lions [8], where this method allows us to design the avraged control of our parameter-dependent wave equation.
Finally, we study with the same argument of the HUM method the problem of vibrating plate equation depending on a parameter when the control is applied on the boundary also.

We consider the two and three-dimensional system of linear thermoelasticity in a bounded smooth domain with Dirichlet boundary conditions. We analyze whether the energy of solutions decays exponentially uniformly to zero as t → ∞. First of all, by a decoupling method, we reduce the problem to an observability inequality for the Lamé system in linear elasticity and more precisely to whether the total energy of the solutions can be estimated in terms of the energy concentrated on its longitudinal component. We show that when the domain is convex, the decay rate is never uniform. In fact, the lack of uniform decay holds in a more general class of domains in which there exist rays of geometric optics of arbitrarily large length that are always reflected perpendicularly or almost tangentially on the boundary. We also show that, in three space dimensions, the lack of uniform decay may also be due to a critical polarization of the energy on the transversal component of the displacement. In two space dimensions we prove a sufficient (and almost necessary) condition for the uniform decay to hold in terms of the propagation of the transversal characteristic rays, under the further assumption that the boundary of the domain does not have contacts of infinite order with its tangents. We also give an example, due to D. Hulin, in which these geometric properties hold. In three space dimensions we indicate (without proof) how a careful analysis of the polarization of singularities may lead to sharp sufficient conditions for the uniform decay to hold. In two space dimensions we prove that smooth solutions decay polynomially in the energy space to a finite-dimensional subspace of solutions except when the domain is a ball or an annulus. Finally we discuss some closely related controllability and spectral issues.

This paper addresses several questions related to the control of timed continuous Petri Nets under infinite server semantics. First, some results regarding equilibrium states and control actions are given. In particular, it is shown that the considered systems are piecewise linear, and for every linear subsystem the possible steady-states are characterized. Second, optimal steady-state control is studied, a problem that surprisingly can be computed in polynomial time, when all transitions are controllable and the objective function is linear. Third, an interpretation of some controllability aspects in the framework of linear dynamic systems is presented. An interesting finding is that non controllable poles are zero valued.

Through use of the local state isomorphism theorem instead of the algebraic equivalence theorem of linear systems theory, the similarity transformation approach is extended to nonlinear models, resulting in finitely verifiable sufficient and necessary conditions for global and local identifiability.

We study the controllability for a class of semilinear control problems in Hilbert spaces, for which the uniqueness is unavailable. Using the fixed point theory for multivalued maps with nonconvex values, we show that the nonlinear problem is approximately controllable provided that the corresponding linear problem is. We also obtain some results on the continuity of solution map and the topological structure of the solution set of the mentioned problem.

A macroscopic traffic flow model, called the switchingmode model (SMM), has been derived from the cell transmission model (CTM) and then applied to the estimation of traffic densities at unmonitored locations along a highway. The SMM is a hybrid system that switches among different sets of linear difference equations, or modes, depending on the mainline boundary data and the congestion status of the cells in a highway section. Using standard linear systems techniques, the observability and controllability properties of the SMM modes have been determined. Both the SMM and a density-based version of the CTM have been simulated over a section of I-210 West in Southern California, using several days of loop detector data collected during the morning rush-hour period. The simulation results show that the SMM and CTM produce density estimates that are both similar to one another and in good agreement with measured densities on I-210. The mean percentage error averaged over all the test days was approximately 13% for both models.