Fighting Risky Population Synchronization: Desynchronization and Stabilization in Spatially Structured Ecological Systems

Population synchronization exists ubiquitously in ecological systems, of which the underlying causes and the roles in species extinction remain a perplexing puzzle. It is generally believed that the coherence of population dynamics is detrimental and regarded as a major cause of global extinction. A central but unsolved question in ecology of great importance for conservation and biological control is how to destroy the pernicious coherent structures. Here, a top-down approach is adopted to tackle the challenge. A feedback strategy accordingly is applied to stabilize the metacommunity, i.e., to reduce excessive metapopulation fluctuations by means of introducing or removing a planned number of individuals. As a result, the feedback desynchronizes correlated population oscillations, giving rise to either complex asynchronous traveling waves or "amplitude death"; cessation of all individual population cycles. Together with the construction of corridors, my method may provide an efficient way to protect those species threatened as a result of, e.g. habitat fragmentation. I anticipate my essay provides a general mechanism against widespread harmful synchronization in physical and biological systems, for example, for developing a "brain anti-pacemaker" for neurological diseases such as Parkinson's disease and epilepsy closely linked to pathologically synchronized neuronal discharges

From Chaos to Order Through Mixing

In this article we consider the possibility of controlling the dynamics of nonlinear discrete systems. A new method of control is by mixing states of the system (or the functions of these states) calculated on previous steps. This approach allows us to locally stabilize a priori unknown cycles of a given length. As a special case, we have a cycle stabilization using nonlinear feedback. Several examples are considered

Reduced-order washout controllers stabilizing uncertain equilibrium points

金沢大学理工研究域電子情報学系We consider a local stabilization problem of an uncertain equilibrium point existed in a nonlinear continuous-time system by a finite-dimensional dynamical state feedback controller. In previous research, it is investigated that steady-state blocking zeros of the stabilizing controller play an important role. Such a controller is called a washout controller. In this paper, we develop a design method for reduced-order washout controllers whose order is less than the plant\u27s order. Additionally, we also consider a local stabilization problem of an uncertain fixed point of a given discrete-time system. © 2007 IEEE

Washout Control for Manual Operations

It is known that limitations of human accuracy in manual manipulation hinder the quality of work performed by human operators of manual control systems. Indeed, movements of operators are apt to cause undesirable vibrations in manual control systems. In this paper, we propose a new operator-support-control scheme for suppressing harmful oscillatory motions in such systems without disturbing human operator\u27s manipulation. The proposed scheme is based on the fact that steady-state blocking zeros of a feedback controller do not affect the steady-state control input. A finite-dimensional feedback controller with steady-state blocking zeros, called a washout controller in this paper, plays the central role in support for operator\u27s manipulation. However, the dynamics of a manual control system may become different significantly from its initial model used for the design of an initial washout controller when it is applied to the manual control system. Such difference can result in poor performance of operator-support-control. In order to improve it, an iterative procedure is presented for re-design of washout controllers based on closed-loop subspace identification. Closed-loop identification is performed to brush up the model for the control design, and then a more sophisticated washout controller is obtained using the identified model. The effectiveness of the proposed scheme is demonstrated by an experiment on manual control of an inverted pendulum. © 2007 EUCA

Washout control for manual operations

金沢大学理工研究域電子情報学系It is known that limitations of human accuracy in manual manipulation hinder the quality of work performed by human operators of manual control systems. Indeed, movements of operators are apt to cause undesirable vibrations in manual control systems. In this paper, we propose a new operator-support control scheme for suppressing harmful oscillatory motions in such systems without disturbing human operator\u27s manipulation. The proposed scheme is based on the fact that steady-state blocking zeros of a feedback controller do not affect the steady-state control input. A finite-dimensional feedback controller with steady-state blocking zeros, called a washout controller in this paper, plays the central role in support for operator\u27s manipulation. However, the dynamics of a manual control system may become different significantly from its initial model used for the design of an initial washout controller when it is applied to the manual control system. Such difference can result in poor performance of operator-support control. In order to improve it, an iterative procedure is presented for redesign of washout controllers based on closed-loop subspace identification. Closed-loop identification is performed to refine the model for the control design, and then a more sophisticated washout controller is obtained using the identified model. The effectiveness of the proposed scheme is demonstrated by an experiment on manual control of an inverted pendulum. © 2008 IEEE