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Studying the dynamic evolution of time-varying volumetric data is essential in countless scientific endeavors. The ability to isolate and track features of interest allows domain scientists to better manage large complex datasets both in terms of visual understanding and computational efficiency. This work presents a new trajectory-based feature tracking technique for use in joint particle/volume...
Practical stabilizability of discrete-time (DT) switched systems is studied in this paper. We first prove a sufficient condition for ??-practical asymptotic stabilizability of DT switched systems, then we focus on switched affine systems and present an approach to estimating the minimum bound for practical stabilizability. Based on the approach, we present several new sufficient conditions for global...
This paper studies the linear quadratic regulation problem for linear discrete time-varying systems with one or multiple delays in control input. This type of input-delay system can be used to model delayed actuation, where the system depends on the input after various (could be more than one) time delays. We provide explicit forms of the finite horizon closed-loop optimal control laws. Numerical...
New checkable criteria for persistence of chemical reaction networks are proposed, which extend those obtained by the authors in previous work. The new results allow the consideration of reaction rates which are time-varying, thus incorporating the effects of external signals, and also relax the assumption of existence of global conservation laws, thus allowing for inflows (production) and outflows...
A design scheme of the finite-time tracking controller is given for a general class of nonholonomic systems including extended chained systems, extended power systems, underactuated surface systems, etc. By introducing a time-varying state transformation based on the concept of minimal dilation degree, this class of nonholonomic systems is transformed into a linear time-varying control systems. The...
The approximation of humanoid robot by an inverted pendulum is one of the most used model to generate a stable motion using a planned Zero Moment Point (ZMP) trajectory. In this paper, we aim at proposing to improve the reliability of this model using system identification techniques. To achieve this goal, we propose an identification method which is the result of the comprehensive application of...
We consider control systems of the type x?? = Ax+??(t)ub, where u ?? R, (A; b) is a controllable pair and ?? is an unknown time-varying signal with values in [0; 1] satisfying a permanent excitation condition of the kind ??t+Tt ?? ?? ??for 0 < ?? ?? T independent on t. We prove that such a system is stabilizable with a linear feedback depending only on the pair (T; ??) if the real part of the...
State-feedback model predictive control (MPC) of discrete-time linear periodic systems with possibly time-dependent state and control input dimension is considered. States and inputs are subject to hard, mixed, polytopic constraints. It is described how discrete-time linear systems, both time-invariant and periodic, with multirate or multiplexed control inputs can be modeled as such periodic systems...
This paper deals with stabilization of networked control systems (NCS) affected by uncertain time-varying delays and data packet dropouts. We point out that such network effects are likely to render the classical control Lyapunov function (CLF) method unfeasible, mainly due to the monotonic decreasing condition. To solve this problem we make use of a discrete-time equivalent of a control Lyapunov-Razumikhin...
We study classical families of chemostat models with an arbitrary number of species competing for a single limiting substrate. For families of models, we present some obstructions to the existence of asymptotically stabilizable periodic trajectories. For other families of growth rates, we design a dilution rate and input substrate time-varying feedback controllers so that a positive trajectory of...
In this paper, we propose a new iterative learning control (ILC) scheme, which is devoted to dealing with unknown parameters that are both time varying and iteration varying. In particular, we consider iteration-varying parameters that are generated by a second-order internal model. By incorporating the internal model into the parametric learning law, the ILC scheme can handle more generic nonlinear...
This paper develops semistability analysis results for nonlinear switched systems. Semistability is the property whereby the solutions of a dynamical system converge to Lyapunov stable equilibrium points determined by the system initial conditions. The main results of the paper involve sufficient conditions for semistability using multiple Lyapunov functions and integral-type inequalities.
An ergodic set in the state space of a measure-preserving dynamical system is an invariant set on which the system is ergodic. Moreover, it comprises points on statistically identical trajectories, i.e., time averages of any function along any two trajectories in the set are equal. The collection of such sets partitions the state space and is called the ergodic partition. We present a computational...
Previous inverse optimal adaptive controllers (IOACs) have been developed that can handle structured (i.e., linear in the parameters (LP)) uncertainty for a particular class of nonlinear systems. A full-state feedback IOAC is developed in the companion Part I paper for Euler-Lagrange systems with an uncertain time varying inertia matrix. In this paper, an output feedback IOAC is developed to asymptotically...
We consider a plant switching among a set of dynamic systems each associated with a single stable equilibrium point. We assume that a constraint region for the state is assigned. The main problem is that of finding suitable limitations on the commutation speed in order to avoid constraints violations, even in the absence of state measurements. We introduce the concepts of modal and transition dwell...
In this work, three simple smooth time-varying control laws are derived for global uniform asymptotic stabilization of an underactuated surface vessel. The construction of the control laws relies on the reduced-order model of the surface vessel and the three different Lyapunov-like functions. The convergence of state is proved by Barbalat Lemma, and is verified by computer simulation.
This paper presents a novel, computationally feasible procedure for computing optimal switching surfaces, i.e. optimal feedback controllers for switched autonomous nonlinear systems. Such systems are regulated by appropriately scheduling their operation modes over time. Given a finite mode sequence, the control task is to determine switching surfaces, which implicitly encode locally optimal switching...
A sufficient condition to solve an optimal control problem is to solve the Hamilton-Jacobi-Bellman (HJB) equation. However, finding a value function that satisfies the HJB equation for a nonlinear system is challenging. Inverse optimal control is an alternative method to solve the nonlinear optimal control problem by circumventing the need to solve the HJB equation. Inverse optimal adaptive control...
The stabilizability problem of planar switched systems is investigated. Based on the polar-coordinates interpretation, the intrinsical connections between the conic switching rule and the qualitative features of the subsystems are presented. Therefore, necessary and sufficient stabilizability conditions are established. The stabilizing switching rules are categorized into two types, termed swinging...
In this paper, the design of adaptive controllers is presented for a class of periodically time-varying nonlinear systems. Saturated adaptation mechanisms are suggested for providing bounded estimation, by which the designed controllers can drive the state error to zero, while all the signals in the closed-loop are ensured to be bounded. The flexibility in choice of adaptation laws is illustrated...
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