Jinhoon Choi

On Stability of Constrained Receding Horizon Control with Finite Terminal Weighting Matrix

In this paper, a new stabilizing receding horizon control, based on a finite input and state horizon cost with a finite terminal weighting matrix, is proposed for time-varying discrete linear systems with constraints. We propose matrix inequality conditions on the terminal weighting matrix under which closed loop stability is guaranteed for both cases of unconstrained and constrained systems with input and state constraints. We show that such a terminal weighting matrix can be obtained by solving an LMI (Linear Matrix Inequality). In the case of constrained time-invariant systems, an artificial invariant ellipsoid constraint is introduced in order to relax the conventional terminal equality constraint and to handle constraints. Using the invariant ellipsoid constraints, a feasibility condition of the optimization problem, is presented and a region of attraction is characterized for constrained systems with the proposed receding horizon control.

On the stabilization of linear discrete time systems subject to input saturation

Abstract In this paper, an exponentially unstable linear discrete time system subject to input saturation is shown to be exponentially stabilizable on any compact subset of the constrained asymptotically stabilizable set by a linear periodic variable structure controller. We also point out that any marginally stable system 2 subject to input saturation can be globally asymptotically stabilized via linear feedback.

Analysis and reduced-order design of quadratic criterion-based iterative learning control using singular value decomposition

Abstract Employing the singular value decomposition (SVD), quadratic criterion-based iterative learning control (Q-ILC) is analyzed and useful design guidelines for tuning factors are obtained. A reduced-order design technique, which not only reduces computational demand and input energy but also enhances robustness, is also proposed. An example highlights the key features of the proposed reduced-order Q-ILC algorithm.

Constrained digital regulation of hyperbolic PDE systems: A learning control approach

In this paper, exploiting repetitive properties, a constrained digital regulation technique for first order hyperbolic PDE systems is proposed that guarantees the stability and performance of the closed loop system.

A control-relevant model reduction technique for nonlinear systems

Abstract A novel control-relevant model reduction technique for nonlinear systems is proposed utilizing the idea of the balanced truncation. Unlike the widely-accepted Karhunen — Loeve method where the state basis for the reduced system is found from the state snapshots, the proposed technique takes into account the input, state, and output information together and provides a near-balanced reduced-order model that approximates the system map instead of the state snapshots. Performance of the technique is demonstrated for a linear system and a non-adiabatic fixed-bed reactor model.

On the constrained asymptotic stabilizability of unstable linear discrete time systems via linear feedback

In this paper, the author show that some 2- or higher-dimensional systems cannot be asymptotically stabilized on the constrained asymptotically stabilizable set via linear feedback.

Receding Horizon Control of Cocurrent First Order Hyperbolic Partial Differential Equation Systems

Cocurrent first order hyperbolic partial differential equations (PDE’s) have finite impulse response (FIR) characteristics. A finite difference scheme that preserve these nice dynamic characteristics is recently developed [Choi, submitted]. Employing the resulting genuine FIR model, the design of receding horizon control is easier. In this paper, a receding horizon control scheme for cocurrent first order hyperbolic PDE systems is proposed using the FIR model and is elucidated with a tubular reactor example.

CONTINUITY AND EXPONENTIAL STABILITY OF MIXED CONSTRAINED MODEL PREDICTIVE CONTROL

For the infinite horizon cost function mixed constrained model predictive control, the largest possible stabilizable region for stable plants is the entire state space for both state and output feedback cases. However, for marginal or unstable cases, the largest possible stabilizable region is the constrained m-step stabilizable set for the state feedback case, and it is the region where the estimated state is in the constrained m-step stabilizable set throughout the trajectory for the output feedback case. Only attractivity over the largest stabilizable region is established for the state feedback case with stable or marginal plants and the output feedback case with stable plants [A. Zheng and M. Morari, IEEE Trans. Automat. Control, 40 (1995), pp. 1818--1823]. In this paper we show, for both state and output feedback cases, that the closed loop system with the mixed constrained model predictive controller possesses the exponential stability property, much stronger than the attractivity, on the largest p...

Constrained linear quadratic optimal control of chemical processes

Abstract In this paper, we address the constrained infinite horizon linear quadratic optimal control (CIHLQOC) of chemical processes. Employing the exponential bound of the closed loop system trajectory that can be computer off-line from the exponential stability properties, it was shown that a finite dimensional quadratic program equivalent to the CIHLQOC problem without any on-line optimization. This technique is illustrated with a chemical reactor example.

Investigation of charge transport in the molecular photodiode consisting of ferrocene/flavin/viologen/TCNQ molecular heterojunction

Abstract A molecular photodiode with the hetero-Langmuir–Blodgett (LB) film consisting of an electron donor (D), sensitizer (S), relay (R), and acceptor (A) was fabricated. Ferrocene octadecyl amine (Ferrocene), 7,8-dimethyl-10-dodecyl isoalloxazine (flavin), N-Allyl-N′-[3-propylamido-N″,N″-di(n-octadecyl)]-4,4′-bipyridium dibromide (viologen) and N-docosilquinolinium tetracyanodimethan (TCNQ) were used as the D, S, R, and A units, respectively. By aligning the hetero-LB film of the D/S/R/A units on indium tin oxide (ITO) coated glass with an aluminum thin film, a molecular photodiode with a Metal/Insulator/Metal (MIM) structure was constructed. The decay of the transient photocurrent of MIM device was measured using a 355 nm Nd:YAG pulse laser as the light source and the charge transfer rate was obtained. The charge transfer rate was faster in the D/S/R/A heterojunction than in S/R and S/R/A heterojunction devices due to less recombination from the A to S and less back electron transport due to the existence of D molecules. Various effects such as the LB film thickness, interface structure, and Schottky barrier on the charge transfer rate were investigated. The results showed that the charge transport efficiency of the molecular photodiode became higher when the LB film thickness increased and the head/head interfaced structure of the S/R hetero LB films was adopted. Furthermore, improvement of the molecular device efficiency occurred when spacer molecules were adopted between the electrode and the LB film.