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Feedback Controllers (feedback + controllers)
Kinds of Feedback Controllers Selected AbstractsNon-smooth structured control design with application to PID loop-shaping of a processINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 14 2007Pierre Apkarian Abstract Feedback controllers with specific structure arise frequently in applications because they are easily apprehended by design engineers and facilitate on-board implementations and re-tuning. This work is dedicated to H, synthesis with structured controllers. In this context, straightforward application of traditional synthesis techniques fails, which explains why only a few ad hoc methods have been developed over the years. In response, we propose a more systematic way to design H, optimal controllers with fixed structure using local optimization techniques. Our approach addresses in principle all those controller structures which can be built into mathematical programming constraints. We apply non-smooth optimization techniques to compute locally optimal solutions, and provide practical tests for descent and optimality. In the experimental part we apply our technique to H, loop-shaping proportional integral derivative (PID) controllers for MIMO systems and demonstrate its use for PID control of a chemical process. Copyright © 2007 John Wiley & Sons, Ltd. [source] Pose Controlled Physically Based MotionCOMPUTER GRAPHICS FORUM, Issue 4 2006Raanan Fattal Abstract In this paper we describe a new method for generating and controlling physically-based motion of complex articulated characters. Our goal is to create motion from scratch, where the animator provides a small amount of input and gets in return a highly detailed and physically plausible motion. Our method relieves the animator from the burden of enforcing physical plausibility, but at the same time provides full control over the internal DOFs of the articulated character via a familiar interface. Control over the global DOFs is also provided by supporting kinematic constraints. Unconstrained portions of the motion are generated in real time, since the character is driven by joint torques generated by simple feedback controllers. Although kinematic constraints are satisfied using an iterative search (shooting), this process is typically inexpensive, since it only adjusts a few DOFs at a few time instances. The low expense of the optimization, combined with the ability to generate unconstrained motions in real time yields an efficient and practical tool, which is particularly attractive for high inertia motions with a relatively small number of kinematic constraints. [source] Virtual reference feedback tuning for two degree of freedom controllersINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 5 2002A. Lecchini The virtual reference feedback tuning (VRFT) is a data-based method for the design of feedback controllers. In the original formulation, the VRFT method gives a solution to the degree of freedom model-reference control problem in which the objective is to shape the input,output transfer function of the control system. In this paper, the extension of the method to the design of 2 d.o.f. controllers is presented and discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] A feedforward,feedback controller for infinite-dimensional systems and regulation of bounded uniformly continuous signalsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 5 2006Eero Immonen Abstract We design a controller for infinite-dimensional linear systems (with bounded control, observation and feedthrough operators) which, under certain assumptions, achieves asymptotic tracking of arbitrary bounded uniformly continuous reference signals in the presence of disturbances. The proposed controller is of feedforward,feedback type: The dynamic feedback part is used to stabilize the closed-loop system consisting of the plant and the controller, whereas the feedforward part is tuned using the regulator equations to achieve the regulation of desired signals. We also completely solve the regulator equations for SISO systems, and we discuss robustness properties of the proposed controller. A useful feature in our design is that the feedforward part of the controller can be designed independently of the feedback part. This automatically leads to a degree of robustness in the stabilizing part of the controller, which is not present in the existing state feedback controllers solving the same output regulation problem. Copyright © 2006 John Wiley & Sons, Ltd. [source] Optimal fixed-structure control for linear non-negative dynamical systemsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 5 2004Sergey G. Nersesov Abstract In this paper, we develop optimal output feedback controllers for set-point regulation of linear non-negative dynamical systems. Specifically, using a constrained fixed-structure control framework we develop optimal output feedback control laws that guarantee that the trajectories of the closed-loop system remain in the non-negative orthant of the state space for non-negative initial conditions. In addition, we characterize domains of attraction predicated on closed and open Lyapunov level surfaces contained in the non-negative orthant for unconstrained optimal linear-quadratic output feedback controllers. Output feedback controllers for compartmental systems with non-negative inputs are also given. Copyright © 2004 John Wiley & Sons, Ltd. [source] Design of full state feedback finite-precision controllersINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2002Raffaello D'Andrea Abstract In this paper, the Generalized L2 Synthesis framework is brought to bear on the problem of control design of full state feedback finite-precision controllers. In particular, we investigate the problem of designing full state feedback controllers that achieve guaranteed H-infinity performance objectives, subject to finite precision constraints on the controller. It is shown that by adopting the Generalized L2 Synthesis framework, the errors in the controller implementation can be captured as full structured uncertainty, and computationally tractable linear matrix inequality techniques used for analysis and synthesis. Copyright © 2002 John Wiley & Sons, Ltd. [source] Optimal operation of CVT-based powertrainsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 11 2001Rolf Pfiffner Abstract Continuously Variable Transmissions (CVTs) are considered by many as a promising contribution to the improvement of the fuel economy of passenger cars. This paper discusses the fuel-optimal operation of a CVT-equipped powertrain in stationary and in transient conditions. The well-known optimal solution in the stationary case will be given only a short review discussing the importance of a correct CVT efficiency model. For transient vehicle operation so far only heuristic control strategies are known. This work aims to fill this gap. After detailed modelling of the complete powertrain and the introduction of a meaningful cost function, the resulting nonlinear optimal control problem is solved. The optimization is carried out for two different engines: a conventional SI engine and a downsized supercharged (DSC) SI engine. Each can be considered as a typical representative of the corresponding engine class. In both cases the optimal solutions are shown to be superior to standard CVT control algorithms, yielding larger gains in fuel economy for DSC engines. The optimal feedforward controls are then approximated by suboptimal feedback controllers that realize almost the same benefits in fuel economy at a substantially reduced computational effort. Finally, it is shown how the well-known ,single track modified' control approach can be changed such that it produces the same results as the suboptimal controller. Copyright © 2001 John Wiley & Sons, Ltd. [source] H, control for nonlinear affine systems: a chain-scattering matrix description approachINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 4 2001Jang-Lee Hong Abstract This paper combines an alternative chain-scattering matrix description with (J, J,)-lossless and a class of conjugate (,J, ,J,)-lossless systems to design a family of nonlinear H, output feedback controllers. The present systems introduce a new chain-scattering setting, which not only offers a clearer expression for the solving process of the nonlinear H, control problem but also removes the fictitious signals introduced by the traditional chain-scattering approach. The intricate nonlinear affine control problem thus can be transformed into a simple lossless network and is easy to deal with in a network-theory context. The relationship among these (J, J,) systems, L2 -gain, and Hamilton,Jacobi equations is also given. Block diagrams are used to illustrate the central theme. Copyright © 2001 John Wiley & Sons, Ltd. [source] Feedback control design for an anaerobic digestion processJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2002Jose Alvarez-Ramirez Abstract An approach for the design of linear feedback controllers for anaerobic digestion systems is presented. The effluent chemical oxigen demand (COD) concentration and the dilution rate are taken respectively as the regulated and the manipulated variables. The control design is based on simple step-response models of the process endowed with an input delay to account for dead-times induced by measurement devices. The resulting feedback controller has a traditional proportional-integral (PI) control structure, so it can be easily implemented with conventional control technologies. Since the concentration of volatile fatty acids can be easily and quickly measured as compared with COD concentration, it is used as a secondary measurement that is incorporated into the feedback loop scheme to enhance the robustness of the control scheme with respect of influent disturbances. The performance of the proposed control scheme is illustrated via numerical simulations and experimental work. © 2002 Society of Chemical Industry [source] Adaptive tracking control of flexible-joint manipulators without overparametrizationJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 7 2004Min S. Kim In this paper, an adaptive controller is designed for rigid-link flexible-joint robot manipulators based on link and actuator position measurements only. It is based on the adaptive integrator backstepping method and the link and actuator velocity filters are used to estimate the unknown velocity terms. Moreover, the proposed controller exploits the estimate of the joint stiffness matrix inverse to overcome the overparametrization problem, which has been a significant drawback in adaptive partial state feedback controllers. It achieves asymptotic tracking of link positions while keeping all states and signals bounded. The tracking capability of the presented method is shown through simulation results of one- and two-link flexible joint manipulators. © 2004 Wiley Periodicals, Inc. [source] Gain Scheduled LPV H, Control Based on LMI Approach for a Robotic ManipulatorJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 12 2002Zhongwei Yu A new approach to the design of a gain scheduled linear parameter-varying (LPV) H, controller, which places the closed-loop poles in the region that satisfies the specified dynamic response, for an n -joint rigid robotic manipulator, is presented. The nonlinear time-varying robotic manipulator is modeled to be a LPV system with a convex polytopic structure with the use of the LPV convex decomposition technique in a filter introduced. State feedback controllers, which satisfy the H, performance and the closed-loop pole-placement requirements, for each vertex of the convex polyhedron parameter space, are designed with the use of the linear matrix inequality (LMI) approach. Based on these designed feedback controllers for each vertex, a LPV controller with a smaller on-line computation load and a convex polytopic structure is synthesized. Simulation and experiment results verify that the robotic manipulator with the LPV controller always has a good dynamic performance along with the variations of the joint positions. © 2002 Wiley Periodicals, Inc. [source] Optimal stabilizing controllers for linear discrete-time stochastic systemsOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 3 2008Jun-E Feng Abstract The relationship between the spectral radius and the decay rate for discrete stochastic systems is investigated. Several equivalent conditions are obtained, which guarantee a specified decay rate of the closed-loop systems. Based on the relationship, this paper provides a design method for state feedback controllers, which ensure that the closed-loop systems converge as fast as possible. Finally, a numerical example is used to illustrate the developed method. Copyright © 2007 John Wiley & Sons, Ltd. [source] A note on the robust control of Markov jump linear uncertain systemsOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 2 2002D. P. de Farias Abstract This note addresses a robust control problem of continuous-time jump linear Markovian systems subject to norm-bounded parametric uncertainties. The problem is expressed in terms of a H, control problem as in the purely deterministic case. The present formulation is simpler and it contains previous results in the literature as particular cases. Robust state feedback controllers are parameterized by means of a set of linear matrix inequalities. The result is illustrated by solving some examples numerically. Copyright © 2002 John Wiley & Sons, Ltd. [source] Minimum effort dead-beat control of linear servomechanisms with ripple-free responseOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 3 2001Abstract A new and systematic approach to the problem of minimum effort ripple-free dead-beat (EFRFDB) control of the step response of a linear servomechanism is presented. There is specified a set of admissible discrete error feedback controllers, complying with general conditions for the design of ripple-free dead-beat (RFDB) controllers, regardless of the introduced degree of freedom, defined as the number of steps exceeding their minimum number. The solution is unique for the minimum number of steps, while their increase enables one to make an optimal choice from a competitive set of controllers via their parametrization in a finite-dimensional space. As an objective function, Chebyshev's norm of an arbitrarily chosen linear projection of the control variable was chosen. There has been elaborated a new, efficient algorithm for all stable systems of the given class with an arbitrary degree of freedom. A parametrized solution in a finite space of polynomials is obtained through the solution of a standard problem of mathematical programming which simultaneously yields the solution of a total position change maximization of servomechanism provided that a required number of steps and control effort limitation are given. A problem formulated in this way is consecutively used in solving the time-optimal (minimum-step) control of a servomechanism to a given steady-state position with a specified limitation on control effort. The effect of EFRFDB control on the example of a linear servomechanism with torsion spring shaft, with the criterions of control effort and control difference effort, is illustrated and analysed. Copyright © 2001 John Wiley & Sons, Ltd. [source] Simulation of a deformable multibody system with hydraulics and controlPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2006Markus Dibold Numerous contributions have been made concerning multibody systems, hydraulic actuators or the design of feedback controllers. A system that combines these fields has been studied rarely. In the present work the systematic simulation of an entire machine, which consists of structural mechanical elements where single masses are transported, hydraulic actuation systems and a closed loop controller is studied. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Stabilization of uncertain chained nonholonomic systems using adaptive output feedback,ASIAN JOURNAL OF CONTROL, Issue 6 2009Z. P. Yuan Abstract In this paper, adaptive output feedback control is presented to solve the stabilization problem of nonholonomic systems in chained form with strong nonlinear drifts and uncertain parameters using output signals only. The objective is to design adaptive nonlinear output feedback laws which can steer the closed-loop systems to globally converge to the origin, while the estimated parameters remain bounded. The proposed systematic strategy combines input-state scaling with backstepping technique. Motivated from a special case, adaptive output feedback controllers are proposed for a class of uncertain chained systems. The simulation results demonstrate the effectiveness of the proposed controllers. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Identification, control and hysteresis compensation of a 3 DOF metrological AFMASIAN JOURNAL OF CONTROL, Issue 2 2009Roel Merry Abstract Atomic Force Microscopes (AFMs) are widely used for the investigation of samples at the nanometer scale. The metrological AFM used in this work uses a 3 degrees-of-freedom (DOFs) stage, driven by piezo-stack actuators, for sample manipulation in combination with a fixed cantilever. The piezo-stack actuators suffer from hysteresis, which acts as a nonlinear disturbance on the system and/or can change the system dynamics. The contributions of this paper are the application of feedback control to all 3 DOFs of the metrological AFM and the design and application of a hysteresis feedforward for the asymmetric hysteresis present in the system. The amount of coupling between the DOFs is assessed by a non-parametric multiple-input-multiple-output (MIMO) identification. Since the dynamics appear to be decoupled in the frequency range of interest, feedback controllers are designed for each DOF separately. For the modeling of the asymmetric hysteresis an extended Coleman-Hodgdon model is proposed. This model is used for feedforward compensation of the hysteresis. The combination of feedback control for all DOFs and the asymmetric hysteresis feedforward enables the AFM to track scanning profiles within the sensor bound of 5,nm. Real-time imaging of the sample is possible with an accuracy of 2,nm. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] A comparison of control architectures for atomic force microscopes,ASIAN JOURNAL OF CONTROL, Issue 2 2009J. A. Butterworth Abstract We evaluate the performance of two control architectures applied to atomic force microscopes (AFM). Feedback-only control is a natural solution and has been applied widely. Expanding on that, combining feedback controllers with plant-injection feedforward filters has been shown to greatly improve tracking performance in AFMs. Alternatively, performance can also be improved by the use of a closed-loop-injection feedforward filter applied to the reference input before it enters the feedback loop. In this paper, we compare the plant-injection architecture with the closed-loop-injection architecture when used in controlling AFMs. In particular, we provide experimental results demonstrating the closed-loop-injection architecture yields better tracking performance of a raster scan. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Network-based robust control of stochastic systems with nonlinear perturbations,ASIAN JOURNAL OF CONTROL, Issue 1 2009Xiaomei Zhang Abstract Network-based robust control of stochastic systems with nonlinear perturbations is investigated in this paper. State and static output feedback controllers are designed, respectively, for stochastic networked control systems subject to the presence of network-induced delay, transmitted data dropout and nonlinear perturbations. Using the Lyapunov-Krasovskii functional and descriptor system approach, a state feedback controller and a static output feedback controller are constructed in terms of linear matrix inequalities, respectively. With the controllers, the corresponding closed-loop systems are stochastically ultimately bounded in the mean square. Two examples are provided to demonstrate the effectiveness of the proposed methods. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] SYSTEMS WITH NONEQUIDISTANT SAMPLING: CONTROLLABLE?ASIAN JOURNAL OF CONTROL, Issue 4 2005OBSERVABLE? ABSTRACT Some qualitative properties of systems with nonequidistant sampling are investigated. First, it is proved that the nonequidistant sampling pattern mentioned in [1] does not affect the controllability and observability of time-varying linear systems during discretization. The result is claimed to be true for linear systems with periodic behavior and time-varying sampling. Second, closed-loop stability conditions are established, respectively, for linear and nonlinear sampled-data systems consisting of continuous plants and linear digital feedback controllers. The stability results are extended to general systems consisting of nonlinear continuous plants and nonlinear digital controllers with time-varying sampling periods. [source] GENERALIZED QUADRATIC STABILIZATION FOR DISCRETE-TIME SINGULAR SYSTEMS WITH TIME-DELAY AND NONLINEAR PERTURBATIONASIAN JOURNAL OF CONTROL, Issue 3 2005Guoping Lu ABSTRACT This paper discusses a generalized quadratic stabilization problem for a class of discrete-time singular systems with time-delay and nonlinear perturbation (DSSDP), which the satisfies Lipschitz condition. By means of the S-procedure approach, necessary and sufficient conditions are presented via a matrix inequality such that the control system is generalized quadratically stabilizable. An explicit expression of the static state feedback controllers is obtained via some free choices of parameters. It is shown in this paper that generalized quadratic stability also implies exponential stability for linear discrete-time singular systems or more generally, DSSDP. In addition, this new approach for discrete singular systems (DSS) is developed in order to cast the problem as a convex optimization involving linear matrix inequalities (LMIs), such that the controller can stabilize the overall system. This approach provides generalized quadratic stabilization for uncertain DSS and also extends the existing robust stabilization results for non-singular discrete systems with perturbation. The approach is illustrated here by means of numerical examples. [source] Regularizability Of Linear Descriptor Systems Via Output Plus Partial State Derivative FeedbackASIAN JOURNAL OF CONTROL, Issue 3 2003Guang-Ren Duan ABSTRACT Regularizability of a linear descriptor system via output plus partial state derivative feedback is studied. Necessary and sufficient conditions are obtained, which are only dependent upon the open-loop coefficient matrices. It is also shown that under these necessary and sufficient conditions, "almost all" output plus partial state derivative feedback controllers can regularize a regularizable linear descriptor system. The proposed conditions generalize many existing results. The presented example demonstrates the proposed results. [source] | |||||||||||||