The iterative learning control (ILC) technique is extended to distributed parameter systems governed by parabolic partial differential equations (PDEs). ILC arises as an effective method to approach constrained optimi...
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The iterative learning control (ILC) technique is extended to distributed parameter systems governed by parabolic partial differential equations (PDEs). ILC arises as an effective method to approach constrained optimization problems in PDE systems. We discuss both P-type and D-type ILC schemes for a distributedparameter system formulated as a general linear system Sigma(A,B,C,D) on a Hilbert space, in which the system operator A generates a strongly continuous semigroup. Under the assumption of identical initialization condition (IIC), conditions on the learning parameters are obtained to guarantee convergence of the P-type and D-type ILC schemes. Numerical simulations are presented for a 1D heat conduction control problem solved using ILC based on semigroup analysis. The numerical results show the effectiveness of the proposed ILC schemes.
Effortless control of the human hand is mediated by the physical and neural couplings inherent in the structure of the hand. This concept was explored for environmental interaction tasks with the human hand, and a nov...
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Effortless control of the human hand is mediated by the physical and neural couplings inherent in the structure of the hand. This concept was explored for environmental interaction tasks with the human hand, and a novel human-inspired feedback synergy (HFS) controller was developed for a robotic hand which synchronized position and force feedback signals to mimic observed human hand motions. This was achieved by first recording the finger joint motion profiles of human test subjects, where it was observed that the subjects would extend their fingers to maintain a natural hand posture when interacting with different surfaces. The resulting human joint angle data were used as inspiration to develop the HFS controller for the anthropomorphic robotic hand, which incorporated finger abduction and force feedback in the control laws for finger extension. Experimental results showed that by projecting a broader view of the tasks at hand to each specific joint, the HFS controller produced hand motion profiles that closely mimic the observed human responses and allowed the robotic manipulator to interact with the surfaces while maintaining a natural hand posture. Additionally, the HFS controller enabled the robotic hand to autonomously traverse vertical step discontinuities without prior knowledge of the environment, visual feedback, or traditional trajectory planning techniques.
The aim of this work is to propose a method for the simultaneous state and parameter estimation of the individual columns in the Simulated Moving Bed chromatographic process based on concentration measurements only in...
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The aim of this work is to propose a method for the simultaneous state and parameter estimation of the individual columns in the Simulated Moving Bed chromatographic process based on concentration measurements only in the switched product outlets. The method exploits the fact that the measurements switch from the inlets of the columns to their outlets sequentially. The estimation problem is cast as a dynamic optimization problem where the prediction error of the output profile is minimized. The initial concentrations in the individual columns and the parameters of the columns are treated as degrees of freedom of the optimization problem. As at each outlet the concentrations of one component are very small and therefore are subject to large relative measurement errors for given expected absolute errors of the concentration measurements, measurements for two different points in time, when the extract port and when the raffinate port is at the outlet of the column under consideration are taken into account simultaneously. The effectiveness of the method is demonstrated for the separation of an isopropanolol racemic mixture.
This work focuses on the design of a fault detection and fault-tolerant control framework for spatially distributed processes modeled by highly-dissipative partial differential equations (PDEs) subject to external dis...
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This work focuses on the design of a fault detection and fault-tolerant control framework for spatially distributed processes modeled by highly-dissipative partial differential equations (PDEs) subject to external disturbances and sensor faults. The main objective is to devise a suitable sensor reconfiguration strategy to reduce the performance degradation due to the errors resulting from the sensor faults. Initially, a finite-dimensional system that captures the slow dynamics of the PDE is derived and used to design a obverse-based output feedback controller. Using Lyapunov techniques, the fault-free and faulty behavior of the closed-loop system are characterized in terms of the sensor spatial placement, the size of the disturbances, the magnitude of the sensor faults as well as the controller and observer design parameters. Based on the fault-free closed-loop dynamics, the Lyapunov stability bound is used as an alarm threshold to declare the presence of sensor faults. To suppress the performance deterioration, a performance-based sensor reconfiguration policy is developed whereby the supervisor determines either to continue using the current faulty sensors or to switch to suitable backup sensors based on a comparison between the sizes of the achievable terminal sets. A singular perturbation formulation is used to analyze the implementation of the sensor fault-tolerant control structure on the infinite-dimensional system. Finally, the results are illustrated through an application to a representative diffusion-reaction process example.
Flow control has recently become an attractive technique to manipulate the behavior of fluid flow to achieve either mixing enhancement or the stabilization of turbulent flow. While it is understood that the location w...
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Flow control has recently become an attractive technique to manipulate the behavior of fluid flow to achieve either mixing enhancement or the stabilization of turbulent flow. While it is understood that the location where mixing occurs is important, existing studies on mixing enhancement are limited to the hydrodynamics without considering the direct effect on mass/heat transfer improvement. This paper presents a reduced-order model for mass transfer equation which allows the analysis of the effect of an external actuation on mass transfer enhancement in a channel flow. When Reynolds number and temporal frequency of the external force are low, the effect of a forced wall slip velocity on the overall flow profile in a channel can be approximated by its instantaneous component. The estimated concentration profiles from the reduced-order model are in good agreement with CFD simulations. The key feature of the reduced-order model proposed in this paper is that it allows system analysis and control design to be performed by considering both spatial and temporal variables simultaneously.
In this paper we employ a new controller structure in solving the robust output regulation problem for a linear distributedparameter system with finite or infinite-dimensional exosystems. In the case of an infinite-d...
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ISBN:
(纸本)9781467360890
In this paper we employ a new controller structure in solving the robust output regulation problem for a linear distributedparameter system with finite or infinite-dimensional exosystems. In the case of an infinite-dimensional exosystem we also present additional conditions for achieving polynomial or logarithmic nonuniform decay rates for the closed-loop semigroup.
This article deals with a new approach to stabilizing boundary control for nonlinear parabolic PDEs. The system under investigation is the quadratic heat equation. In order to stabilize this system in this contributio...
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ISBN:
(纸本)9781479932757
This article deals with a new approach to stabilizing boundary control for nonlinear parabolic PDEs. The system under investigation is the quadratic heat equation. In order to stabilize this system in this contribution the use of a generalized distance measure, the discrepancy, is proposed. Applying, the associated stability theory, i.e. stability theory with respect to two discrepancies, a stabilizing control law can be derived.
Adaptive sliding mode and integral sliding mode grasped object slip prevention controllers are implemented for a prosthetic hand and compared to a proportional derivative shear force feedback slip prevention controlle...
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Adaptive sliding mode and integral sliding mode grasped object slip prevention controllers are implemented for a prosthetic hand and compared to a proportional derivative shear force feedback slip prevention controller as well as a sliding mode controller without slip prevention capabilities. Slip of grasped objects is detected by band-pass filtering the shear force derivative to amplify high frequency vibrations that occur as the grasped object slides relative to the fingers. The integral sliding mode slip prevention controller provides a robust design framework for slip prevention while addressing the issue of reducing the amount of deformation that the grasped object experiences to prevent slip. Averaged results from bench top experiments show that the integral sliding mode slip prevention controller produces the least amount of deformation to the grasped object while simultaneously preventing the object from being dropped.
This paper presents a boundary control formulation for distributed parameter systems described by partial differential equations (PDEs) and whose output is given by a spatial integral of weighted functions of the stat...
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This paper presents a boundary control formulation for distributed parameter systems described by partial differential equations (PDEs) and whose output is given by a spatial integral of weighted functions of the state. This formulation is directly applicable to the control of small robotic aircraft with articulated flexible wings, where the output of interest is the net aerodynamic force or moment. The deformation of flexible wings can be controlled by actuators that are located at the root or the tip of the wing. The problem of designing a tracking controller for wing twist is addressed using a combination of PDE backstepping for feedback stabilization and feed-forward trajectory planning. We also design an adaptive tracking controller for wing tip actuators. For wing bending, we present a novel control scheme that is based on a two-stage perturbation observer. A trajectory planning-based feed-forward tracker is designed using only one component of the observer whose dynamics are homogeneous and amenable to trajectory planning. The two components, put together, estimate the external forces and unmodeled system dynamics. The effectiveness of the proposed controllers for twist and bending is demonstrated by simulations. This paper also reports experimental validation of the perturbation-observer-based controller for beam bending.
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