achievable performance limitations for siso plants with pole location constraints in this paper performance limitations in the linear control of general linear discrete time scalar systems are considered the performance is measured with the 2 norm of an error function which at the same time ensures that the closed loop poles lie in a prescribed region the deleterious effect of this constraint on a classical performance measurement is also quantified in such a way that the interplay between the size of the desired region and structural features of the plant is revealed

a new approach to the perfect regulation and the bounded peaking in linear multivariable control systems this paper presents a new approach to the perfect regulation p r and the bounded peaking b p in linear multivariable control systems based on the pole and the eigenvector assignment technique roughly speaking the p r represents an ideal control action which reduces the settling time to 0 while the b p simply means the bounded overshoot in this ideal situation simple frequency domain characterizations of the p r and the b p are derived they reveal some invariance properties of the p r and the b p that provide a powerful tool for achieving the p r and the b p the existence condition for the p r is derived which turns out to be identical to the result obtained in the optimal regulator theory this result is extended to a more general control objective of attaining the p r for one output while keeping the b p for another output a condition on which the p r is realized by an output feedback is also derived a simple design algorithm is proposed for achieving the p r which is essentially the eigenvector assignment procedure finally an application to a real system is discussed

robust d stability for linear uncertain discrete time delay systems we propose criteria which guarantee robust pole location within a specified circular region for a linear uncertain discrete time delay system the perturbations are treated with structured and unstructured information examples are given to demonstrate the result

output feedback disk pole assignment for systems with positive real uncertainty in this paper the problem of pole assignment in a disk by output feedback for continuous or discrete time uncertain systems is addressed a necessary and sufficient condition for quadratic d stabilizability by output feedback is presented this condition is expressed in terms of two parameter dependent riccati equations whose solutions satisfy two extra conditions an output d stabilization algorithm is derived and a controller formula given some related problems are also discussed

on optimal pole assignment in a specified region in this paper the problem of pole assignment and linear quadratic design have been amalgamated a design method that has the merits of both approaches is presented and the problem of assigning the poles in a specified region is solved the characterizations for quadratic cost functions have been studied and these results used to assign poles in real schur form in a region so that the optimality is maintained designed procedures have been elaborated with examples

pole assignment robustness in a specified disk abstract a sufficient condition is proposed to guarantee robust pole location within a specified circular region for a linear uncertain system the explicit bounds on linear time invariant perturbations with highly structured information are obtained under these allowable highly structured perturbations both stability robustness and certain performance robustness will thus be ensured the merit of the proposed new approach is demonstrated by a given example where the results achieved are much better than the ones reported recently

a successive optimal construction procedure for state feedback gains abstract this paper studies a successive optimal construction procedure of state feedback gains this topic was first studied in the context of the pole assignment problem for lq linear quadratic regulators but the selection of weighting matrices in each successive step was restricted in previous researches in this paper we consider more general selections of weighting matrices and give extended results in both the continuous time and the discrete time cases

robustness of pole assignment in a specified region an analysis of pole assignment is given for systems under linear time invariant perturbations based upon the lyapunov approach new techniques to calculate allowable element bounds for highly structured perturbations are presented under these allowable perturbations both stability robustness and a certain performance robustness are thus ensured examples are given to illustrate the proposed methods

a revisit to inverse optimality of linear systems in this article we revisit the problem of inverse optimality for linear systems by applying certain explicit formulae for coprime matrix fraction descriptions cmfd of linear systems we propose a necessary and sufficient condition for a given stable state feedback law to be optimal for some quadratic performance index compared to existing results in the literature the proposed condition is simpler to check and interpret moreover it reduces the redundancy in the solutions of the associated algebraic riccati equation are as a direct application of the proposed results we consider the problem of inverse optimality of observer based state feedback to be specific for the case where the state is not fully known we consider the inverse optimality problem of an observer based state feedback for the closed loop system augmented by an observer more precisely it is shown that the observer based state feedback is inverse optimal for the closed loop system with some general forms of cost functions on

linear quadratic optimal output feedback control for systems with poles in a specified region the problem of output feedback linear quadratic regulator synthesis with regional pole constraints is studied the synthesis algorithm is presented and its convergence is also proved the effectiveness of the algorithm is illustrated by an example

pole assignment for uncertain systems in a specified disk by state feedback this paper presents a method for assigning the poles in a specified disk by state feedback for a linear discrete or continuous time uncertain system the uncertainty being norm bounded for this the quadratic d stabilizability concept which is the counterpart of quadratic stabilizability in the context of pole placement is defined and a necessary and sufficient condition for quadratic d stabilizability derived this condition expressed as a parameter dependent discrete riccati equation enables one to design the control gain matrix by solving iteratively a discrete riccati equation

generalized robustness of optimally of linear quadratic regulators robustness of the optimality of linear quadratic lq optimal regulators is studied it is shown that under a mild assumption optimality of lq regulators is preserved under small perturbations on both f and g matrices this is made possible by allowing modifications on both weighting parameters q and r and it also extends the existing results where perturbations on f only are allowed it is also observed that this modification leads to a possible change in gain margin a numerical example is discussed in detail to illustrate the results

controller design with regional pole constraints a design procedure is developed that combines linear quadratic optimal control with regional pole placement specifically a static and dynamic output feedback control problem is addressed in which the poles of the closed loop system are constrained to lie in specified regions of the complex plane these regional pole constraints are embedded within the optimization process by replacing the covariance lyapunov equation by a modified lyapunov equation whose solution in certain cases leads to an upper bound on the quadratic cost functional the results include necessary and sufficient conditions for characterizing static output feedback controllers with bounded performance and regional pole constraints sufficient conditions are also presented for the fixed order i e full and reduced order dynamic output feedback problem with regional pole constraints circular elliptical vertical strip parabolic and section regions are considered

cross standard form a solution to improve a given controller with h 2 or h specifications this paper introduces in cross standard form csf as a solution to the inverse optimal control problem that is the csf is a canonical standard problem whose unique h or h 2 optimal controller is a given controller from the control design point of view the general idea is to apply the csf to a given controller in order to set up a standard problem which can be completed to handle frequency domain h 2 or h specification the analytical formulation of the csf proposed in this paper can be applied to reduced full or augmented order compensators or two degree of freedom compensations numerical and academic examples are given

linear quadratic control with stability degree constraint abstract the problem of static state feedback linear quadratic lq optimal control subject to a prescribed degree of stability for the closed loop system is considered in this paper a necessary optimality condition is given via the lagrange multiplier method a globally convergent algorithm is provided to solve the optimization problem it is shown that the algorithm recovers the standard lq feedback gain provided the desired stability degree is small enough to be within the range by the standard lq design as for other cases the optimum occurs on the boundary of the region a numerical example shows that the proposed algorithm provides a better design compared to the existing methods

model predictive control tuning by controller matching the effectiveness of model predictive control mpc in dealing with input and state constraints during transient operations is well known however in contrast with several linear control techniques closed loop frequency domain properties such as sensitivities and robustness to small perturbations are usually not taken into account in the mpc design this technical note considers the problem of tuning an mpc controller that behaves as a given linear controller when the constraints are not active e g for perturbations around the equilibrium that remain within the given input and state bounds therefore inheriting the small signal properties of the linear control design and that still optimally deals with constraints during transients we provide two methods for selecting the mpc weight matrices so that the resulting mpc controller behaves as the given linear controller therefore solving the posed inverse problem of controller matching and is globally asymptotically stable

lyapunov approach to robust pole assignment analysis abstract the robust pole assignment of systems with linear time invariant perturbations is considered based upon the lyapunov approach new techniques for calculating the robustness bounds for pole assignment in any chosen region are presented these take account not only of stability robustness but also of certain types of performance robustness examples are presented to illustrate the merit of the proposed analysis methods

new solution to the inverse regulator problem by the polynomial matrix method abstract this paper gives a new criterion for the inverse regulator problem in terms of polynomial matrix fractions the generalized kalman equation in polynomial matrix form leads to a necessary and sufficient condition for a stable feedback law to be optimal for some unknown quadratic performance index this criterion consists of i a symmetric factorizability of a polynomial matrix and ii a polynomial type criterion that guarantees detectability the relationship between the riccati and kalman equations is also established finally an example is given to illustrate the new result in contrast with the existing result

input independent chaos synchronization of switched systems input independent chaos synchronization of switched systems is addressed the synchronization is carried out by designing an observer which involves a switched matrix gain a special structure of this gain enables both an input independence of the state reconstruction error equation and a global convergence of this equation input independence is ensured by a suitable partial pole placement while the global convergence is based on the poly quadratic stability concept those theoretical results would be interesting for possible applications in communications

a quadratic weight selection algorithm a new algorithm is presented which determines a positive semi definite state weighting matrix in the linear quadratic optimal control design problem the algorithm chooses the weighting matrix by attempting to place dosed loop eigenvalues and eigenvectors near desired locations using optimal feedback gains a simplified flight control design example is used to illustrate the algorithm s capabilities

optimal pole shifting for continuous multivariable linear systems a method for shifting the real parts of the open loop poles to any desired positions while preserving the imaginary parts is presented the method is based on the mirror image property which has been reported by molinari in other words molinari s results are extended and then a recursive approach is developed in each step of this approach it is required to solve a first order or a second order linear matrix lyapunov equation for shifting one real pole or two complex conjugate poles respectively the presented method yields a solution which is optimal with respect to a quadratic performance index the attractive feature of this method is that it enables solutions to complex problems to be easily found without solving any non linear algebraic riccati equation

robustness of regional pole placement for uncertain continuous time implicit systems in this note under assumptions that the nominal linear implicit system is regular impulse free with all its generalized eigenvalues lying inside some specified regions sufficient conditions are proposed to preserve the assumed properties when structured perturbations are added into the nominal system explicit bounds on perturbations with different structures are given in terms of the spectral radii of some nonnegative matrices

compositional semantics and behavioural equivalences for reaction systems with restriction abstract reaction systems are an abstract model of interactions among biochemical reactions developed around two opposite mechanisms facilitation and inhibition the evolution of a reaction system is driven by the external objects which are sent into the system by the environment at each step in order to increase the modelling expressiveness of the calculus we consider an extension of reaction systems with restriction which allows the hiding of entities such as those occurring inside membranes to this purpose we recently developed the reaction algebra a calculus resembling reaction systems extended with a restriction operator in the present paper three equivalent semantics for the reaction algebra are presented a reduction semantics and two state abstract compositional semantics the reduction semantics is meant to capture the behaviour of reaction algebra models at a high level while the two compositional semantics make the interactive nature of reaction systems explicit the difference between the two compositional semantics lies in how the behaviour with respect to the contextual entities is described one uses an extensional description while the other uses an intensional one we also define in the settings of both compositional semantics a behavioural equivalence subsuming the functional equivalence of reaction systems which is also shown to be congruence thus providing a formal ground to the modular description of models finally as an example of application of the techniques developed in the paper we compare the semantics of two different reaction algebra models of the functioning of the lac operon in the e coli bacterium

a simple solution to the optimal eigenvalue assignment problem the problem of the optimal eigenvalue assignment for multi input linear systems is considered it is proven that for an n order system with m independent inputs the problem is split into the following two sequential stages initially the n m eigenvalues are assigned using an n m order system this assignment is not constrained to satisfy optimality criteria next an m order system is used to assign the remaining m eigenvalues in such a way that linear quadratic optimal criteria are simultaneously satisfied therefore the original n order optimal eigenvalue assignment problem is reduced to an m order optimal assignment problem moreover the structure of the equivalent m order system permits further simplifications which lead to solutions obtained by inspection

constrained pole placement using transformation and lq design a new procedure for constrained pole placement is presented the poles of the closed loop system are placed within a circle in the left half plane the design procedure is noniterative and the solution is obtained via linear quadratic lq design for a transformed system the circle can be chosen in order to obtain good transient properties of the closed loop system the method combines the properties of pole placement and lq design

perturbation bounds for root clustering of linear systems in a specified second order subregion sufficient bounds for structured and unstructured uncertainties for root clustering in a specified second order subregion of the complex plane for both continuous time and discrete time systems are given using the generalized lyapunov theory furthermore for unstructured uncertainties a still less conservative result is obtained by shifting the center or focus of the subregion along the real axis to the origin and by applying root clustering to the shifted eigenvalue system matrix which is obtained by shifting the eigenvalues of the system matrix correspondingly

the inverse problem of linear optimal control for constant disturbance this paper presents the solution to the inverse problem of linear optimal control systems to achieve pole placement and at the same time minimize the cost function and accommodate a constant but unknown disturbance the sufficient conditions for an optimal feedback law to have a positive r and positive semi definite q are found the relationships between the open loop poles and the closed loop poles that guarantee a positive r and q 0 are also obtained these relations offer a rule for selection of the appropriate closed loop poles which will guarantee the required feedback properties

robustness of disk stability for perturbed large scale systems in this paper a sufficient condition of robust disk stability for perturbed large scale systems is presented if all the eigenvalues of each nominal subsystem are assigned within the disk d r then the proposed sufficient condition guarantees that all the eigenvalues of the overall uncertain large scale system remain inside the same disk the proposed technique for robust pole assignment in a specified circular region is available both for continuous and discrete time systems the application of the proposed method is illustrated by two examples

robustness analysis of interval matrices based on kharitonov s theorem this paper deals with the robustness analysis problem of interval matrices expansion of det a b is used to get characteristic polynomials of two corresponding systems kharitonov s theorem is applied to test hurwitz properties of the two polynomials a new sufficient condition for all eigenvalues of the interval matrix to lie in a damping cone on complex plan is derived illustrative examples are given

h control with pole assignment in a specified disc in this paper a method of pole assignment in h control theory is proposed by this method all the poles can be placed in a left half plane or inside a disc on the complex plane and at the same time an h norm constraint is satisfied this result can be derived by a bilinear transformation of the complex variable of a transfer function in h control theory

investigating dynamic causalities in reaction systems reaction systems are a qualitative formalism for modeling systems of biochemical reactions characterized by the non permanency of the elements molecules disappear if not produced by any enabled reaction moreover reaction systems execute in an environment that provides new molecules at each step brijder ehrenfeucht and rozenberg investigated dynamic causalities in reaction systems by introducing the idea of predictors a predictor of a molecule s for a given n is the set of molecules to be observed in the environment in order to determine whether s is produced or not by the system at step n in this paper we continue the investigation on dynamic causalities by defining an abstract interpretation framework containing three different notions of predictor formula based predictors that is a propositional logic formula that precisely characterizes environments that lead to the production of s after n steps multi step based predictors that consist of n sets of molecules to be observed in the environment one for each step and set based predictors that are those proposed by brijder ehrenfeucht and rozenberg and consist of a unique set of molecules to be observed in all steps for each kind of predictor we define an effective operator that allows predictors to be computed for any molecule s and number of steps n the abstract interpretation framework allows us to compare the three notions of predictor in terms of precision to relate the three defined operators and to compute minimal predictors we also discuss a generalization of this approach that allows predictors to be defined independently of the value of n and a tabling approach for the practical use of predictors on reaction systems models as an application we use predictors generalization and tabling to give theoretical grounds to previously obtained results on a model of gene regulation

d stability of continuous time delay systems subjected to a class of highly structured perturbations the d stability testing problem for continuous time delay systems subjected to a class of highly structured parametric perturbations is addressed in this note by means of the lyapunov stability theorem razumikhin type theorem gersgorin theorem concept of spectral radius and norm and matrix measure techniques the author has developed several new sufficient conditions for guaranteeing that all characteristic roots of the above systems are located inside a specified disk d spl alpha r with center at spl alpha j0 and radius r in the left half complex plane for the present results it is not necessary to solve any lyapunov equation which may be unsolvable though the lyapunov stability theorem is utilized

robust control with pole shifting via performance index modification robust controllers that ensure closed loop eigenvalue placement are designed for linear systems with parametric uncertainties by using an appropriate state weighting matrix choice and a relative stability degree an lmi based algorithm is proposed to provide guaranteed cost controllers that ensure i the closed loop nominal eigenvalues shifting by a pre specified amount ii a prescribed degree of stability for all system uncertainties of a given class a certain level of closed loop performance is also ensured by minimizing the associated guaranteed cost

orthonormal basis functions applied to optimal control design with closed loop pole location constraints this article proposes an optimal control design technique to ensure that the closed loop poles are assigned to prescribed locations in the complex plane a key element in this approach is the usage of orthonormal basis functions to parametrise the main design parameter this goal is achieved by using a quadratic cost based optimisation approach considering control effort penalisation as well as cheap control youla parametrisation is used subject to a set of constraints which guarantee stability zero steady error to constant references and disturbances and yielding the prescribed set of closed loop poles

inverse optimal control for discrete time finite horizon linear quadratic regulators abstract in this paper we consider the inverse optimal control problem for discrete time linear quadratic regulators lqr over finite time horizons given observations of the optimal trajectories or optimal control inputs to a linear time invariant system the goal is to infer the parameters that define the quadratic cost function the well posedness of the inverse optimal control problem is first justified in the noiseless case when these observations are exact we analyze the identifiability of the problem and provide sufficient conditions for uniqueness of the solution in the noisy case when the observations are corrupted by additive zero mean noise we formulate the problem as an optimization problem and prove that the solution to this problem is statistically consistent the performance of the proposed method is illustrated through numerical examples

eigenvalue placement in a specified sector for variable structure control systems the design of the sliding hyperplanes of a variable structure control system is an important part of the controller design process and will be considered in this paper the method outlined here results in the eigenvalues of the closed loop system during sliding lying in a specified sector in the left hand half plane numerical examples are given and the effect of an arbitrary positive definite matrix in a complex riccati equation on the positioning of the eigenvalues within the sector is investigated

optimal controller synthesis with d stability abstract in this paper we consider the problem of finding controllers which place the eigenvalues of the closed loop system matrix in a prespecified circular region in the left half plane and minimize an associated quadratic cost function we give solutions to both state feedback and output feedback synthesis problems

robust controller design for uncertain linear systems with circular pole constraints in this paper the problem of robust controller design for uncertain linear continuous and discrete time systems with circular pole constraints is considered the problem we address is the design of robust state feedback controllers such that all poles of the closed loop systems are placed within a prescribed circular region sufficient conditions for the existence of the desired controllers are given based on the generalized inverse theory the analytical expression of the set of desired controllers is also presented it is emphasized that when the uncertainties are absent the results include the characterization of all state feedback controllers achieving the specified circular pole constraints an illustrative example is given to show the applicability of the proposed design procedure accepted in final revised form 7 february 1996 communicated by professor h kimura

an lmi approach to d stability and d stabilization of linear discrete singular systems with state delay abstract the problems of d stability and d stabilization for linear discrete singular systems with state delay are addressed in this paper by using the state augmentation technique a necessary and sufficient d stability condition and a sufficient d stabilization condition for linear discrete singular time delay systems are firstly proposed then based on these conditions quadratic d stability and d stabilization conditions for linear discrete singular time delay systems with norm bounded uncertainties and interval uncertainties are obtained respectively both the d stability and d stabilization conditions are proposed in terms of linear matrix inequalities finally illustrative examples show that the proposed conditions are effective to check the d stability and to design the d stabilizing controller for linear discrete singular time delay systems

compositional semantics and behavioral equivalences for p systems the aim of the paper is to give a compositional semantics in the style of the structural operational semantics sos and to study behavioral equivalence notions for p systems firstly we consider p systems with maximal parallelism and without priorities we define a process algebra called p algebra whose terms model membranes we equip the algebra with a labeled transition system lts obtained through sos transition rules and we study how some equivalence notions defined over the lts model apply in our case then we consider p systems with priorities and extend the introduced framework to deal with them we prove that our compositional semantics reflects correctly maximal parallelism and priorities

dual polarized spatial modulation over correlated fading channels we address multiple input multiple output mimo communication employing spatial modulation sm with dual polarized dp antennas the proposed architecture adds the polarization dimension to the conventional sm mappings and offers performances which are comparable to or under certain conditions even better than those of the uni polarized systems while occupying half as much space we consider the generalized spatially correlated rayleigh and rician fading channel models and present an average bit error probability upper bounding framework for the proposed dp sm mimo system the theoretical error analysis is also extended to the case where the channel coefficients are estimated with gaussian estimation errors this upper bounding method is also used to determine the conditions in which the dual polarized sm is better than equivalent systems with uni polarized antennas theoretical derivations are also validated by extensive simulations both corroborating that sm combined with dual polarization forms an attractive alternative not only for its improved multiplexing gains and space efficiency but also for performance gains over correlated channels

optimal linear regulator pole placement by weight selection a recursive algorithm for selecting the state weighting matrix of a linear quadratic regulator lqr problem to result in a set of desired closed loop eigenvalues is presented aggregation is used so that at each step of the recursive process where either a real pole or a complex conjugate pair is being placed one has to deal with two or four dimensional matrix equations regardless of the system s dimensionality in addition the algorithm is capable of placing a complex conjugate pair at a new complex conjugate location or at two distinct real locations

simultaneous control of linear systems by state feedback in this paper a new method for finding a state feedback matrix in order to control simultaneously a collection of linear systems of the same size by using similarity operations is presented for stabilization of all the systems it is necessary that the eigenvalues of the closed loop systems lie inside a specified region in the left hand side of the complex plane this aim is achieved by solving linear and nonlinear parametric systems of equations using nonlinear programming the presented method is implemented in two examples and the results are verified in view of the norm of the state feedback matrix and stabilizability

h sub spl infin design with pole placement constraints an lmi approach this paper addresses the design of state or output feedback h sub spl infin controllers that satisfy additional constraints on the closed loop pole location sufficient conditions for feasibility are derived for a general class of convex regions of the complex plane these conditions are expressed in terms of linear matrix inequalities lmis and the authors formulation is therefore numerically tractable via lmi optimization in the state feedback case mixed h sub 2 h sub spl infin synthesis with regional pole placement is also discussed finally the validity and applicability of this approach are illustrated by a benchmark example

design of linear quadratic regulators with assigned eigenstructure a recursive design procedure is presented which assigns the closed loop eigenstructure in linear quadratic regulators at each stage the required solution for the steady state riccati matrix which shifts a pole or pole pair to specified values is obtained for pole pair placement a free parameter in the solution permits selection of closed loop eigenvectors the interactive design procedure is summarized and illustrated by an example

some properties of optimal regulators and their applications some properties of linear optimal regulators are discussed first some fundamental relations on the bound of the overshoot of the output are derived then an explicit description of a solution set of linear optimal regulator problems for a linear system and all possible quadratic cost functions is derived as an application of these properties a new design method for a feedback law is proposed which takes into account the requirement on the output overshoot

a general formula for eigenvalue assignment by static output feedback with application to robust design in this note generalizing an idea of a previous paper we derive a new expression of the characteristic polynomial of a linear system subject to static output feedback from this expression an explicit form of the assignment equations in the unknown elements of the feedback matrix is obtained the equations are completely general and seem much simpler than many others proposed until now in special cases a closed or almost a closed form solution is obtained the assignment equations are then used within an algorithm for global optimization to solve the problem of exactly assigning the eigenvalues of the nominal plant while maximizing the norm of perturbation matrices for which the perturbed eigenvalues remain in specified regions of the complex plane

on successive pole assignment by linear quadratic optimal feedbacks abstract this paper studies a method of shifting poles of linear constant systems via lq optimal feedback by making use of a solution to the so called inverse regulator problem this method enables us to shift poles successively by pairs while maintaining the well known advantages of lq regulators polynomial fractional representation is effectively used both to characterize the maximal pole assignable area which clarifies the theoretical bound of the lq optimal pole shifting and to derive an algorithm a numerical example is given to illustrate the results

d stability analysis for discrete systems with a time delay this paper first discusses the d pole placement problem of discrete time delay systems some criteria are proposed to ensure that all the closed loop eigenvalues of discrete systems with a time delay are located inside a specific disk d r centered at 0 with radius r then several sufficient conditions for guaranteeing the d stability of discrete time delay systems subjected to parametric perturbations are presented both unstructured and highly structured parametric perturbations are considered by these sufficient conditions the tolerable parametric perturbation bounds that ensure all the closed loop poles of discrete time delay perturbed systems to remain inside the desired disk d r can be estimated finally illustrative examples are given for demonstration

performance bounds in linear control of unstable mimo systems with pole location constraint this paper proposes a methodology to compute quadratic performance bounds when the closed loop poles of a discrete time multivariable control loop are confined to a disk centred at the origin and with radius less than one the underlying philosophy in this constraint is to avoid certain undesirable dynamic features which arise in quadratic optimal designs an expression for the performance loss due to the pole location constraint is also provided using numerical examples we show that the performance loss is compensated by an improved transient performance specially visible in the control signals

continuous time inverse quadratic optimal control problem in this paper the problem of finite horizon inverse optimal control ioc is investigated where the quadratic cost function of a dynamic process is required to be recovered based on the observati

enhanced spatial modulation with multiple signal constellations in this paper we introduce a new spatial modulation sm technique using one or two active antennas and multiple signal constellations the proposed technique which we refer to as enhanced sm or esm conveys information bits not only by the index es of the active antenna s but also by the constellations transmitted from each of them the main feature of esm is that it uses a primary signal constellation during the single active antenna periods and some other secondary constellations during the periods with two active transmit antennas the secondary signal constellations are derived from the primary constellation by means of geometric interpolation in the signal space we give design examples using two and four transmit antennas and qpsk 16qam and 64qam as primary modulations the proposed technique is compared to conventional sm as well as to spatial multiplexing smx and the results indicate that in most cases esm provides a substantial performance gain over conventional sm and smx while reducing the maximum likelihood ml decoder complexity

consensus rate regulation for general linear multi agent systems under directed topology recently optimization in distributed multi agent coordination has been studied concerning convergence speed the optimal convergence speed of consensus for multi agent systems consisting of general linear node dynamics is still an open problem this paper aims to design optimal distributed consensus protocols for general identical linear continuous time cooperative systems which not only minimize some local quadric performances but also regulate the consensus rate including convergence rate and damping rate for the multi agent systems the graph topology is assumed to be fixed and directed the inverse optimal design method is utilized and the resulting optimal distributed protocols place part of close loop poles of the global disagreement systems at specified locations asymptotically while the remains far from the imaginary axis enough it turns out that for the identical linear continuous time multi agent systems the convergence speed has no upper bound the main advantages of the developed method over the lqr design method are that the resulting multi agent systems can achieve specified consensus rate asymptotically and the resulting protocols have the whole right half complex plane as its asymptotical consensus region numerical examples are given to illustrate the effectiveness of the proposed design procedures

spatial calculus of looping sequences this paper presents spatial cls an extension of the calculus of looping sequences cls with spatial features spatial cls allows keeping track of the position of biological elements in a continuous space 2d or 3d as time passes the movement of elements in the space can be precisely described and elements can interact when constraints on their positions are satisfied such as for example if two elements are close enough as for cls membranes and elements inside them can be directly modeled in the syntax spatial cls allows describing the space occupied by elements and membranes the space occupied by different objects is always kept disjoint the validity of this constraint is ensured at all times by the semantics of the calculus in order to model specific behaviors the modeler can provide an algorithm to rearrange the position of objects in case of a space conflict being an extension of cls spatial cls provides a simple and powerful syntax based on rewrite rules for describing the possible reactions among elements of a system moreover rewrite rules are endowed with a stochastic reaction rate parameter the aim of spatial cls is to enable a more accurate description of those biological processes whose behavior depends on the exact position of the elements as example applications of the calculus we present a model of cell proliferation and a model of the quorum sensing process in pseudomonas aeruginosa

pole assignment in a specified disk the problem of assigning all poles of a closed loop system in a specified disk by state feedback is considered for both continuous and discrete systems a state feedback control law is determined by using a discrete riccati equation this kind of pole assignment problem is named d pole assignment and its relation to the optimal control problem and its robustness properties are discussed the gain and phase margins for all closed loop poles to stay inside the specified disk d are determined for the proposed control

a new approach to optimal regional pole placement abstract the multi constraints optimal regional pole placement problem is studied the constrained region is represented by several algebraic inequalities necessary conditions for which the optimal solution must be satisfied are derived furthermore a solution algorithm is provided finally an analysis of robustness with rsepest to structured uncertainty for continuous system is discussed 1997 elsevier science ltd

robust state derivative pole placement lmi based designs for linear systems in some practical problems for instance in the control systems for the suppression of vibration in mechanical systems the state derivative signals are easier to obtain than the state signals necessary and sufficient lmi based conditions for pole placement of linear systems using state derivative feedback are proposed sufficient conditions for pole placement for a class of uncertain systems or systems subject to structural failures are also presented the simulation of practical applications illustrates the efficiency of the proposed methods

a complete optimality condition in the inverse problem of optimal control a complete optimality condition in the standard inverse problem of optimal control for the multi input case is established the optimality of a feedback control law is characterized completely in terms of a new geometric condition as well as the well known return difference condition the new condition not only provides a better insight into the well known sensitivity reduction property of optimal control for the multi input case but also indicates an essential difference between the solutions of the single and multi input inverse problem

robust h control for uncertain discrete time systems with circular pole constraints this paper investigates the problem of robust h control for uncertain discrete time systems with circular pole constraints the system under consideration is subject to norm bounded time invariant uncertainties in both the state and input matrices the problem we address is to design state feedback controllers such that the closed poles are located within a prespecified circular region and the h norm of the closed loop transfer function is strictly less than a given positive scalar for all admissible uncertainties by introducing the notion of quadratic d stabilizability with an h norm bound the problem is solved necessary and sufficient conditions for quadratic d stabilizability with an h norm bound are derived our results can be regarded as extensions of existing results on robust h control and robust pole assignment of uncertain systems

partial pole placement by lq regulators an inverse problem approach this paper gives a necessary and sufficient condition under which a state feedback control law places part of the closed loop poles exactly at specified points and at the same time is linear quadratic optimal for some quadratic weightings this is made possible by means of a solution to the inverse problem of optimal control a design example is given to illustrate the result

optimization and pole placement for a single input controllable system given the system xdot ax bu and the cost function j dt relations are to be determined among the open loop characteristic polynomial the closed loop characteristic polynomial and the matrices a and q those relations take a simple form if the system is in the standard controllable form in this case the optimal control law can be found easily without solving the matrix riccati equation while the minimum value of the cost function if it is required can be determined by solving a matrix equation of the form c t x xc d

space time block coded spatial modulation a novel multiple input multiple output mimo transmission scheme called space time block coded spatial modulation stbc sm is proposed it combines spatial modulation sm and space time block coding stbc to take advantage of the benefits of both while avoiding their drawbacks in the stbc sm scheme the transmitted information symbols are expanded not only to the space and time domains but also to the spatial antenna domain which corresponds to the on off status of the transmit antennas available at the space domain and therefore both core stbc and antenna indices carry information a general technique is presented for the design of the stbc sm scheme for any number of transmit antennas besides the high spectral efficiency advantage provided by the antenna domain the proposed scheme is also optimized by deriving its diversity and coding gains to exploit the diversity advantage of stbc a low complexity maximum likelihood ml decoder is given for the new scheme which profits from the orthogonality of the core stbc the performance advantages of the stbc sm over simple sm and over v blast are shown by simulation results for various spectral efficiencies and are supported by the derivation of a closed form expression for the union bound on the bit error probability

linear quadratic regulators with eigenvalue placement in a vertical strip a computational method is presented for finding the linear quadratic regulator such that the optimal closed loop system has eigenvalues lying within a vertical strip in the complex plane the proposed method is suitable for the two stage optimal design of two time scale systems

generalized guaranteed cost control with d stability and multiple output constraints abstract this paper is concerned with the problem of robust generalized guaranteed cost control with d stability and multiple output constraints for a class of linear uncertain systems being a combination of output performance indices a generalized cost function is considered to the linear polytopic uncertain systems described in a unified framework the aim is to design a state feedback controller such that the closed loop system is robust d stable and the upper bound of the generalized cost function is as small as possible subject to multiple output constraints based on parameter dependent lyapunov functions convex conditions for the existence of such controllers are presented in terms of linear matrix inequality the proposed approach shows a unified treatment of the linear systems in the differential shift and delta domains numerical examples are provided to illustrate the effectiveness of the design method

technical communique d stability and d stabilization of linear discrete time delay systems with polytopic uncertainties sufficient conditions for d stability and d stabilization of linear discrete time delay systems with polytopic uncertainties are proposed in this paper the results are based on parameter dependent lyapunov functions obtained from the feasibility of a set of linear matrix inequalities defined at the vertices of polytopic systems these conditions guarantee all the poles of a corresponding system in a specified circular region finally an illustrative example shows that the proposed conditions are effective to check the d stability and to design the d stabilizing controller for linear discrete time delay systems

a new approach to the lq design from the viewpoint of the inverse regulator problem a new design method of lq regulators is developed by reverse application of pertinent results on the inverse regulator problem the lq regulator of interest here is unlike the usual one designed without specifying a quadratic cost but it proves to minimize some quadratic cost hence it possesses those well known robustness properties shared by all lq regulators a basic design procedure is developed first and followed by practical ones in which the design parameters are chosen based on asymptotic modal properties of the regulator this new method requires no riccati solutions thereby leading to simplification of the lq design as compared to the usual one

space shift keying ssk mimo with practical channel estimates in this paper we study the performance of space modulation for multiple input multiple output mimo wireless systems with imperfect channel knowledge at the receiver we focus our attention on two transmission technologies which are the building blocks of space modulation i space shift keying ssk modulation and ii time orthogonal signal design tosd ssk modulation which is an improved version of ssk modulation providing transmit diversity we develop a single integral closed form analytical framework to compute the average bit error probability abep of a mismatched detector for both ssk and tosd ssk modulations the framework exploits the theory of quadratic forms in conditional complex gaussian random variables rvs along with the gil pelaez inversion theorem the analytical model is very general and can be used for arbitrary transmit and receive antennas fading distributions fading spatial correlations and training pilots the analytical derivation is substantiated through monte carlo simulations and it is shown over independent and identically distributed i i d rayleigh fading channels that ssk modulation is as robust as single antenna systems to imperfect channel knowledge and that tosd ssk modulation is more robust to channel estimation errors than the alamouti scheme furthermore it is pointed out that only few training pilots are needed to get reliable enough channel estimates for data detection and that transmit and receive diversity of ssk and tosd ssk modulations are preserved even with imperfect channel knowledge