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Mode Control (mode + control)

Distribution by Scientific Domains
Engineering94%
2 Other Domains6%

Kinds of Mode Control

  • sliding mode control
    		•

    Selected Abstracts

    SECOND-ORDER TERMINAL SLIDING MODE CONTROL OF INPUT-DELAY SYSTEMS

    ASIAN JOURNAL OF CONTROL, Issue 1 2006
    Yong Feng
    ABSTRACT This paper proposes a second-order terminal sliding mode control for a class of uncertain input-delay systems. The input-delay systems are firstly converted into the input-delay free systems and further converted into the regular forms. A linear sliding mode manifold is predesigned to represent the ideal dynamics of the system. Another terminal sliding mode manifold surface is presented to drive the linear sliding mode to reach zeros in finite time. In order to eliminate the chattering phenomena, a second-order sliding mode method is utilized to filter the high frequency switching control signal. The uncertainties of the systems are analysed in detail to show the effect to the systems. The simulation results validate the method presented in the paper. [source]

    Experimental performance evaluation of an equipment isolation using MR dampers

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2009
    Yu-Cheng Fan
    Abstract Critical non-structural equipments, including life-saving equipment in hospitals, circuit breakers, computers, high technology instrumentations, etc., are vulnerable to strong earthquakes, and the failure of these equipments may result in a heavy economic loss. In this connection, innovative control systems and strategies are needed for their seismic protections. This paper presents the performance evaluation of passive and semi-active control in the equipment isolation system for earthquake protection. Through shaking table tests of a 3-story steel frame with equipment on the first floor, a magnetorheological (MR)-damper together with a sliding friction pendulum isolation system is placed between the equipment and floor to reduce the vibration of the equipment. Various control algorithms are used for this semi-active control studies, including the decentralized sliding mode control (DSMC) and LQR control. The passive-on and passive-off control of MR damper is used as a reference for the discussion on the control effectiveness. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Improved design of sliding mode control for civil structures with saturation problem

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2004
    Sang-Hyun Lee
    Abstract A systematic and improved design procedure for sliding mode control (SMC) of seismically excited civil structures with saturation problem is provided in this paper. In order to restrict the control force to a certain level, a procedure for determining the upper limits of the control forces for single or multiple control units is proposed based on the design response spectrum of external loads. Further, an efficient procedure using the LQR method for determining sliding surfaces appropriate for different controller types is provided through the parametric evaluation of the dynamic characteristics of sliding surfaces in terms of SMC controller performance. Finally, a systematic design procedure for SMC required to achieve a given performance level is provided and its effectiveness is verified by applying it to multi-degree-of-freedom (MDOF) systems. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Adaptive TS-FNN control for a class of uncertain multi-time-delay systems: The exponentially stable sliding mode-based approach

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 4 2009
    Tung-Sheng Chiang
    Abstract This paper presents an adaptive Takagi,Sugeno fuzzy neural network (TS-FNN) control for a class of multiple time-delay uncertain nonlinear systems. First, we develop a sliding surface guaranteed to achieve exponential stability while considering mismatched uncertainty and unknown delays. This exponential stability result based on a novel Lyapunov,Krasovskii method is an improvement when compared with traditional schemes where only asymptotic stability is achieved. The stability analysis is transformed into a linear matrix inequalities problem independent of time delays. Then, a sliding mode control-based TS-FNN control scheme is proposed to achieve asymptotic stability for the controlled system. Since the TS-FNN combines TS fuzzy rules and a neural network structure, fewer numbers of fuzzy rules and tuning parameters are used compared with the traditional pure TS fuzzy approach. Moreover, all the fuzzy membership functions are tuned on-line even in the presence of input uncertainty. Finally, simulation results show the control performance of the proposed scheme. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    A fractional adaptation law for sliding mode control

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 10 2008
    Mehmet Önder Efe
    Abstract This paper presents a novel parameter tuning law that forces the emergence of a sliding motion in the behavior of a multi-input multi-output nonlinear dynamic system. Adaptive linear elements are used as controllers. Standard approach to parameter adjustment employs integer order derivative or integration operators. In this paper, the use of fractional differentiation or integration operators for the performance improvement of adaptive sliding mode control systems is presented. Hitting in finite time is proved and the associated conditions with numerical justifications are given. The proposed technique has been assessed through a set of simulations considering the dynamic model of a two degrees of freedom direct drive robot. It is seen that the control system with the proposed adaptation scheme provides (i) better tracking performance, (ii) suppression of undesired drifts in parameter evolution, (iii) a very high degree of robustness and improved insensitivity to disturbances and (iv) removal of the controller initialization problem. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Passivity-based sliding mode control for nonlinear systems

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 9 2008
    Ali J. Koshkouei
    Abstract Passivity with sliding mode control for a class of nonlinear systems with and without unknown parameters is considered in this paper. In fact, a method for deriving a nonlinear system with external disturbances to a passive system is considered. Then a passive sliding mode control is designed corresponding to a given storage function. The passivity property guarantees the system stability while sliding mode control techniques assures the robustness of the proposed controller. When the system includes unknown parameters, an appropriate updated law is obtained so that the new transformed system is passive. The passivation property of linear systems with sliding mode is also analysed. The linear and nonlinear theories are applied to a simple pendulum model and the gravity-flow/pipeline system, respectively. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Design of the fuzzy multiobjective controller based on the eligibility method

    INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 5 2003
    Hwan-Chun Myung
    A multiobjective control problem has been handled in many different ways such as fuzzy, neural network and reinforcement learning, etc. Among them, a reinforcement learning method solves a multiobjective control problem without any prior knowledge. In this article, a new reinforcement learning method for a multiobjective control problem is proposed in consideration of its convergence. The proposed method, in which objective eligibility is considered for handling multirewards, reformulates a multiobjective control problem in a form of a reinforcement learning problem under non-Markov environment. Using a similar relation to eligibility, the proposed method dealt with the previous research results of eligibility and was implemented with the concept of a decoupled fuzzy sliding mode control (DFSMC). © 2003 Wiley Periodicals, Inc. [source]

    Static output feedback sliding mode control for time-varying delay systems with time-delayed nonlinear disturbances

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 7 2010
    X. G. Yan
    Abstract In this paper, a robust stabilization problem for a class of linear time-varying delay systems with disturbances is studied using sliding mode techniques. Both matched and mismatched disturbances, involving time-varying delay, are considered. The disturbances are nonlinear and have nonlinear bounds which are employed for the control design. A sliding surface is designed and the stability of the corresponding sliding motion is analysed based on the Razumikhin Theorem. Then a static output feedback sliding mode control with time delay is synthesized to drive the system to the sliding surface in finite time. Conservatism is reduced by using features of sliding mode control and systems structure. Simulation results show the effectiveness of the proposed approach. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Robust delay-dependent sliding mode control for uncertain time-delay systems

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 11 2008
    Yuanqing Xia
    Abstract In this paper, the problem of robust sliding mode control for a class of linear continuous time-delay systems is studied. The parametric uncertainty considered is a modelling error type of mismatch appearing in the state. A delay-dependent sufficient condition for the existence of linear sliding surfaces is developed in terms of linear matrix inequality, based on which the corresponding reaching motion controller is designed. A numerical example is given to show the potential of the proposed techniques. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Robust tracking control for a class of MIMO nonlinear systems with measurable output feedback

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 1 2008
    Ya-Jun Pan
    Abstract This paper proposes a robust output feedback controller for a class of nonlinear systems to track a desired trajectory. Our main goal is to ensure the global input-to-state stability (ISS) property of the tracking error nonlinear dynamics with respect to the unknown structural system uncertainties and external disturbances. Our approach consists of constructing a nonlinear observer to reconstruct the unavailable states, and then designing a discontinuous controller using a back-stepping like design procedure to ensure the ISS property. The observer design is realized through state transformation and there is only one parameter to be determined. Through solving a Hamilton,Jacoby inequality, the nonlinear control law for the first subsystem specifies a nonlinear switching surface. By virtue of nonlinear control for the first subsystem, the resulting sliding manifold in the sliding phase possesses the desired ISS property and to certain extent the optimality. Associated with the new switching surface, the sliding mode control is applied to the second subsystem to accomplish the tracking task. As a result, the tracking error is bounded and the ISS property of the whole system can be ensured while the internal stability is also achieved. Finally, an example is presented to show the effectiveness of the proposed scheme. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    A sliding mode control approach for systems subjected to a norm-bounded uncertainty

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 4 2007
    Anis Sellami
    Abstract This paper proposes a design approach of continuous sliding mode control of uncertain systems, the uncertainty being norm bounded. The two steps of the design methodology are investigated. The existence step, in which we choose the sliding surface that gives good behaviour during the sliding mode, is formulated as a pole assignment of linear uncertain system in a sector through convex optimization. The solution to this problem is therefore numerically tractable via linear matrix inequalities (LMI) optimization. In the reaching step, we propose a continuous nonlinear control strategy ensuring a bounded motion about the ideal sliding mode, thus approximating the ideal dynamic behaviour in the presence of uncertainty. Finally, the validity and the applicability of this approach are illustrated by a flight stabilization benchmark example. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Robust output regulation of minimum phase nonlinear systems using conditional servocompensators

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 2 2005
    Sridhar Seshagiri
    Abstract We consider the design of a robust continuous sliding mode controller for the output regulation of a class of minimum-phase nonlinear systems. Previous work has shown how to do this by incorporating a linear servocompensator in the sliding mode design, but the transient performance is degraded when compared to ideal sliding mode control. Extending previous ideas from the design of ,conditional integrators' for the case of asymptotically constant references and disturbances, we design the servocompensator as a conditional one that provides servocompensation only inside the boundary layer; achieving asymptotic output regulation, but with improved transient performance. We give both regional as well as semi-global results for error convergence, and show that the controller can be tuned to recover the performance of an ideal sliding mode control. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Adaptive sliding mode control of air,fuel ratio in internal combustion engines

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2004
    Jason S. Souder
    Abstract A simplified model of an internal combustion engine is used to derive a sliding mode control law. Adaptive update laws are derived for two fueling parameters that describe fuel flow into the cylinders, and a third parameter that describes air flow into the cylinders. The update laws allow the sliding mode control gain, which is usually increased to overcome model uncertainty, to be reduced. This improves the tracking performance of the sliding mode controller in the presence of the feedback time delays. The parameter update laws are modified to bound the parameter values and allow all three parameter update laws to run simultaneously. The effect of the sampling rate on the adaptive sliding mode controller performance and air,fuel ratio biasing via gain selection are also addressed. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Sliding mode control of boost and buck-boost power converters using the dynamic sliding manifold

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 14 2003
    Yuri B. Shtessel
    Abstract Non-minimum phase tracking control is studied for boost and buck-boost power converters. A sliding mode control algorithm is developed to track directly a causal voltage tracking profile given by an exogenous system. The approximate causal output non-minimum phase asymptotic tracking in non-linear boost and buck-boost power converters is addressed via sliding mode control using a dynamic sliding manifold (DSM). Use of DSM allows the stabilization of the internal dynamics when the output tracking error tends asymptotically to zero in the sliding mode. The sliding mode controller with DSM links features of conventional sliding mode control (insensitivity to matched non-linearities and disturbances) and a conventional dynamic compensator (accommodation to unmatched disturbances). Numerical examples demonstrate the effectiveness of the sliding mode controller even for a known time-varying load. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Sliding mode control design for uncertain time-delay systems subjected to a class of nonlinear inputs

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2003
    Jun-Juh Yan
    Abstract A sliding mode controller is developed for uncertain time-delay systems with a class of nonlinear inputs. Two main results are derived in this paper. The first result is the presentation of a new delay-dependent stability condition of uncertain time-delay systems. In a comparison example, this stability condition is shown to be less conservative than the ones reported recently. The second result is to present a new sliding mode control for uncertain time-delay systems subjected to a class of nonlinear inputs. The stability of time-delay systems with unmatching condition in the sliding mode is also discussed. Two illustrative examples are included to demonstrate the superiority of the obtained results. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Robust stabilization of a class of uncertain system via block decomposition and VSC

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 15 2002
    Alexander G. Loukianov
    Abstract In this paper, a block decomposition procedure for sliding mode control of a class of nonlinear systems with matched and unmatched uncertainties, is proposed. Based on the nonlinear block control principle, a sliding manifold design problem is divided into a number of sub-problems of lower dimension which can be solved independently. As a result, the nominal parts of the sliding mode dynamics is linearized. A discontinuous feedback is then used to compensate the matched uncertainty. Finally, a step-by-step Lyapunov technique and a high gain approach is applied to obtain hierarchical fast motions on the sliding manifolds and to achieve the robustness property of the closed-loop system motion with respect to unmatched uncertainty. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Sliding mode control of DC-to-DC power converters using integral reconstructors

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 13 2002
    H. Sira-Ramirez
    Abstract A sliding mode feedback controller, based on integral reconstructors is developed for the regulation of the ,boost' DC-to-DC power converter circuit conduction in continuous conduction mode. The feedback control scheme uses only output capacitor voltage measurements, as well as knowledge of the available input signal, represented by the switch positions. The robustness of the feedback scheme is tested with abusively large, unmodelled, sudden load resistance variations. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Chattering-free sliding mode control for a class of nonlinear mechanical systems

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 12 2001
    Vicente Parra-Vega
    Abstract Second-order sliding mode control (2-smc) and dynamic sliding mode control (dsmc) eliminate the disturbing characteristic of chattering in static sliding mode control under the assumption that the derivative of the sliding surface is available or complex inequalities at the acceleration level can be constructed. In this paper, passivity-based adaptive and non-adaptive chattering-free sliding mode controllers are proposed assuming that the upper bound of the norm of the derivative of the sliding surface is available, a weaker and easy to implement assumption in comparison to those of 2-smc and dsmc. The closed-loop system accounts explicitly for the invariance condition without reaching phase, and therefore for a desired transient response with global exponential convergence of tracking errors. Preliminary experiments are presented. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    DC-to-AC power conversion on a ,boost' converter

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2001
    Hebertt Sira-Ramírez
    Abstract In this article, we provide an approximate sliding mode control-based solution to the DC,AC power conversion problem on a ,boost' converter. The approach uses the flatness property of the system as a pivot for generating a sequence of minimum phase output reference trajectory candidates. The generated candidates are obtained as differential parameterizations of the minimum phase inductor current variable in terms of the non-minimum phase desired output capacitor voltage. The associated residual dynamics of the ideal sliding motions is shown to reasonably approximate the desired biased sinusoidal output capacitor voltage signal. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Experimental testing of a discrete-time sliding mode controller for trajectory tracking of a wheeled mobile robot in the presence of skidding effects

    JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 4 2002
    M. Letizia Corradini
    This article addresses the trajectory tracking problem for a wheeled mobile base, considering the presence of disturbances that violate the nonholonomic constraint, and using an approximated discrete-time model for the vehicle. The proposed solution is based on discrete-time sliding mode control, in order to ensure that the controller is both robust and implementable. The asymptotic boundedness of the discrete-time tracking errors is theoretically proved, and experimental results are reported, showing the effectiveness of the proposed control law. © 2002 Wiley Periodicals, Inc. [source]

    Perfect position/force tracking of robots with dynamical terminal sliding mode control

    JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 9 2001
    V. Parra-Vega
    According to a given performance criteria, perfect tracking is defined as the performance of zero tracking error in finite time. It is evident that robotic systems, in particular those that carry out compliant task, can benefit from this performance since perfect tracking of contact forces endows one or many constrained robot manipulators to interact dexterously with the environment. In this article, a dynamical terminal sliding mode controller that guarantees tracking in finite-time of position and force errors is proposed. The controller renders a dynamic sliding mode for all time and since the equilibrium of the dynamic sliding surface is driven by terminal attractors in the position and force controlled subspaces, robust finite-time convergence for both tracking errors arises. The controller is continuous; thus chattering is not an issue and the sliding mode condition as well the invariance property are explicitly verified. Surprisingly, the structure of the controller is similar with respect to the infinite-time tracking case, i.e., the asymptotic stability case, and the advantage becomes more evident because terminal stability properties are obtained with the same Lyapunov function of the asymptotic stability case by using more elaborate error manifolds instead of a more complicated control structure. A simulation study shows the expected perfect tracking and a discussion is presented. © 2001 John Wiley & Sons, Inc. [source]

    Adaptive robust stabilization of dynamic nonholonomic chained systems

    JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 3 2001
    S. S. Ge
    In this article, the stabilization problem is investigated for dynamic nonholonomic systems with unknown inertia parameters and disturbances. First, to facilitate control system design, the nonholonomic kinematic subsystem is transformed into a skew-symmetric form and the properties of the overall systems are discussed. Then, a robust adaptive controller is presented in which adaptive control techniques are used to compensate for the parametric uncertainties and sliding mode control is used to suppress the bounded disturbances. The controller guarantees the outputs of the dynamic subsystem (the inputs to the kinematic subsystem) to track some bounded auxiliary signals which subsequently drive the kinematic subsystem to the origin. In addition, it can also be shown all the signals in the closed loop are bounded. Simulation studies on the control of a unicycle wheeled mobile robot are used to show the effectiveness of the proposed scheme. © 2001 John Wiley & Sons, Inc. [source]

    Robust sliding mode design for uncertain stochastic systems based on H, control method

    OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 2 2010
    Yugang Niu
    Abstract In this paper, the design problem of sliding mode control (SMC) is addressed for uncertain stochastic systems modeled by Itô differential equations. There exist the parameter uncertainties in both the state and input matrices, as well as the unmatched external disturbance. The key feature of this work is the integration of SMC method with H, technique such that the robust stochastic stability with a prescribed disturbance attenuation level , can be achieved. A sufficient condition for the existence of the desired sliding mode controller is obtained via linear matrix inequalities. The reachability of the specified sliding surface is proven. Finally, a numerical simulation example is presented to illustrate the proposed method. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Chattering reduction of sliding mode control by low-pass filtering the control signal

    ASIAN JOURNAL OF CONTROL, Issue 3 2010
    Ming-Lei Tseng
    Abstract The conventional approach to reducing control signal chattering in sliding mode control is to use the boundary layer design. However, when there is high-level measurement noise, the boundary layer design becomes ineffective in chattering reduction. This paper, therefore, proposes a new design for chattering reduction by low-pass filtering the control signal. The new design is non-trivial since it requires estimation of the sliding variable via a disturbance estimator. The new sliding mode control has the same performance as the boundary layer design in noise-free environments, and outperforms the boundary layer design in noisy environments. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

    Design of nonlinear terminal guidance/autopilot controller for missiles with pulse type input devices,

    ASIAN JOURNAL OF CONTROL, Issue 3 2010
    Fu-Kuang Yeh
    Abstract This investigation addresses a nonlinear terminal guidance/autopilot controller with pulse-type control inputs for intercepting a theater ballistic missile in the exoatmospheric region. Appropriate initial conditions on the terminal phase are assumed to apply after the end of the midcourse operation. Accordingly, the terminal controller seeks to minimize the distance between the commanded missile and the target missile to ensure a hit-to-kill interception. In particular, a 3D terminal guidance law is initially developed to eliminate the so-called "sliding velocity, " thus, constraining the relative motion between the missile and the target along the line of sight. Sliding mode control is adopted to design stable pulse-type control systems. Then, a quaternion-based attitude controller is used to orient appropriately the commanded missile, taking into account the fact that the missile is a rigid body, to realize interceptability. The stability of the overall integrated terminal guidance/autopilot system is then analyzed thoroughly, based on Lyapunov stability theory. Finally, extensive simulations are conducted to verify the validity and effectiveness of the integrated controller with the pulse type inputs developed herein. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

    Force/motion sliding mode control of three typical mechanisms

    ASIAN JOURNAL OF CONTROL, Issue 2 2009
    Rong-Fong Fung
    Abstract This paper proposes a sliding mode control (SMC) algorithm for trajectory tracking of the slider-crank mechanism, quick-return mechanism, and toggle mechanism. First, the dynamic models suitable for the controls of both the motion and constrained force are derived using Hamilton's principle, the Lagrange multiplier, and implicit function theory. Second, the SMC is designed to ensure the input torques can achieve trajectory tracking on the constrained surfaces with specific constraint forces. Finally, the developed method is successfully verified for effectiveness of the force/motion controls for these three typical mechanisms from the results of simulation. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

    SECOND-ORDER TERMINAL SLIDING MODE CONTROL OF INPUT-DELAY SYSTEMS

    ASIAN JOURNAL OF CONTROL, Issue 1 2006
    Yong Feng
    ABSTRACT This paper proposes a second-order terminal sliding mode control for a class of uncertain input-delay systems. The input-delay systems are firstly converted into the input-delay free systems and further converted into the regular forms. A linear sliding mode manifold is predesigned to represent the ideal dynamics of the system. Another terminal sliding mode manifold surface is presented to drive the linear sliding mode to reach zeros in finite time. In order to eliminate the chattering phenomena, a second-order sliding mode method is utilized to filter the high frequency switching control signal. The uncertainties of the systems are analysed in detail to show the effect to the systems. The simulation results validate the method presented in the paper. [source]

    ADAPTIVE SLIDING MODE BACKSTEPPING CONTROL OF NONLINEAR SYSTEMS WITH UNMATCHED UNCERTAINTY

    ASIAN JOURNAL OF CONTROL, Issue 4 2004
    Ali J. Koshkouei
    ABSTRACT This paper considers an adaptive backstepping algorithm for designing the control for a class of nonlinear continuous uncertain processes with disturbances that can be converted to a parametric semi-strict feedback form. Sliding mode control using a combined adaptive backstepping sliding mode control (SMC) algorithm, is also studied. The algorithm follows a systematic procedure for the design of adaptive control laws for the output tracking of nonlinear systems with matched and unmatched uncertainty. [source]

    Feed development for fed-batch CHO production process by semisteady state analysis

    BIOTECHNOLOGY PROGRESS, Issue 3 2010
    Sarwat F. Khattak
    Abstract Semisteady state cultures are useful for studying cell physiology and facilitating media development. Two semisteady states with a viable cell density of 5.5 million cells/mL were obtained in CHO cell cultures and compared with a fed-batch mode control. In the first semisteady state, the culture was maintained at 5 mM glucose and 0.5 mM glutamine. The second condition had threefold higher concentrations of both nutrients, which led to a 10% increase in lactate production, a 78% increase in ammonia production, and a 30% reduction in cell growth rate. The differences between the two semisteady states indicate that maintaining relatively low levels of glucose and glutamine can reduce the production of lactate and ammonia. Specific amino acid production and consumption indicated further metabolic differences between the two semisteady states and fed-batch mode. The results from this experiment shed light in the feeding strategy for a fed-batch process and feed medium enhancement. The fed-batch process utilizes a feeding strategy whereby the feed added was based on glucose levels in the bioreactor. To evaluate if a fixed feed strategy would improve robustness and process consistency, two alternative feeding strategies were implemented. A constant volume feed of 30% or 40% of the initial culture volume fed over the course of cell culture was evaluated. The results indicate that a constant volumetric-based feed can be more beneficial than a glucose-based feeding strategy. This study demonstrated the applicability of analyzing CHO cultures in semisteady state for feed enhancement and continuous process improvement. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source]