bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Adaptive Method For Identification Of Critical Gain Using Saturation Function
Authors: Saeki Masami
Published: September 2010

A new adaptive method for identification of the critical gain is proposed. Instead of using relay feedback, a saturation nonlinearity and an adjusting gain are inserted in the loop, and the gain is tuned by the difference signal between the input and the output of the saturation function. The gain decreases monotonically and converges to a constant, which can be very close to the critical gain. It is shown that the feedback system does not become unstable by this method. This method can be easily extended to the multi‐input multi‐output plants.
Modeling And Robust Pi Control Of A Fluidized Bed Combustor For Sewage Sludge
Authors: Jia Yingmin , Lunze Jan , Wolff Andreas
Published: September 2010

Based on experimental data, a fluidized bed combustor is modeled as an interval system. Severe model uncertainty and large time delays lead to the main difficulties in solving the control problem. The design uses the stability test of closed‐loop systems as the main guideline for developing a robust PI controller. In particular, a new formula to compute the maximal magnitude of an edge rational function at a fixed frequency is derived, which provides a way to deal with time delay by transforming it into multiplicative uncertainty. Both the theoretical and the experimental results show that the designed PI controller can satisfy the desired performance requirements.
P/Pd Types Of Override Control Systems
Authors: Tsai Yaw‐Ying , Cheng Yu‐Chang , Yu Cheng‐Ching
Published: September 2010

The override control provides protective action against abnormal operation and/or incipient process failure. In terms of control theory, it is a logic‐based switching system and, in terms of operation, it is usually activated between the soft constraint and the hard constraint. It is used in all process industries, and most PID control loops are patched with some type of override system. Despite widespread application, little research has been done to analyze override control systems. In this work, the properties of the override control are explored. The stability of the override control is also studied. Counter to intuition, many well‐known override systems may exhibit instability and lead to oscillatory responses as the process approaches constraints. Approaches are proposed for the design of override control systems to ensure inherent safe operation.
Convergence and Robustness of Iterative Learning Control For Strongly Positive Systems
Authors: Andres Daniel , Pandit Madhukar
Published: September 2010

In this paper, we consider the convergence and robustness of a general iterative learning control scheme for a class of systems which we term “strongly positive”. The analysis is made in the framework of Hilbert‐space theory. Thus the results are valid for discrete‐time as well as continuous‐time systems which may be time‐variant or time‐invariant. For the special case of continuous linear time‐invariant systems which are defined over the Hilbert‐space of square integrable functions, we will give a characterization of strongly positive systems in the frequency domain.
Iterative Learning Control With Advanced Output Data
Authors: Jeong Gu‐Min , Choi Chong‐Ho
Published: September 2010

In this paper, iterative learning control using output data, which are more advanced than the relative degree of the system, is being investigated. It is known that the output error can be made zero with the conventional iterative learning control in which the input is updated with the output data advanced by the relative degree. However, the input can become too large for nonminimum phase systems. With the proposed scheme, the input can be prevented from becoming unnecessarily too large, which in turn makes it practical to apply iterative learning control for nonminimum phase systems. Simulations are performed to show the effectiveness of the scheme.
Higher Relative Degree Nonlinear Systems With ilc Using Lower‐order Differentiations
Authors: Sun Mingxuan , Wang Danwei
Published: September 2010

This paper addresses the problem of iterative learning control (ILC) for a class of nonlinear continuous‐time systems with higher relative degree. The proposed ILC solution is a family of updating laws using differentiations of tracking error with the order less than the system relative degree. A unified convergence condition for this family of ILC updating laws is provided and proved to be independent of the highest order of differentiation. The application to path tracking of a robotic manipulator is presented to illustrate the effectiveness of the proposed method.
Analysis Of Linear Iterative Learning Control Schemes Using Repetitive Process Theory
Authors: Owens D.H. , Rogers E. , Moore K. L.
Published: September 2010

The purposes of this paper are (i) to critically review existing results on the use of the systems theory for repetitive processes in the analysis of a wide class of linear iterative control laws, and (ii) to present some new results on controller design using this general approach. This paper first presents results on the stability and convergence properties of a general class of iterative learning control schemes using, in the main, theory first developed for the subclass of so‐called differential and discrete linear repetitive processes. A general learning law that uses information from the current and a finite number of previous trials is considered and the results are interpreted in terms of basic systems theoretic concepts such as the relative degree and minimum phase characteristics. It is also shown that a number of other approaches reported in the literature are, in fact, special cases of the results obtained in the repetitive process setting. In the second part of the paper, new results on controller design are given based on 2D transfer function matrices together with new results on the robustness of norm optimal iterative learning control schemes.
A Practical Iterative Learning Path‐Following Control Of An Omni‐Directional Vehicle
Authors: Chen Yang Quan , Moore Kevin L.
Published: September 2010

A new practical iterative learning control (ILC) updating law is proposed to improve the path following accuracy for an omni‐directional autonomous mobile robot. The ILC scheme is applied as a feedforward controller to the existing feedback controller. By using the local symmetrical double‐integral of the feedback control signal of the previous iteration, the ILC updating law takes a simple form with only two design parameters: the learning gain and the range of local integration. Convergence analysis is presented together with a design procedure. Simulation results on a difficult maneuver are presented to illustrate the effectiveness of the proposed simple and yet practical scheme. The simulation is based on the model of a novel robotic platform, the Utah State University (USU) Omni‐Directional Vehicle (ODV), which uses multiple “smart wheels,” whose speed and direction can be independently controlled through dedicated processors for each wheel.
Neuro‐Fuzzy Impact Control (NFIC) for Anti‐Personnel (AP) Mines Detection
Authors: Shahri Ali M. , Naghdy Fazel
Published: September 2010

An explicit impact control scheme is modified as the main control scheme, while an intelligent control method is designed to deal with uncertainties and varying environment parameters in a mechatronics approach to anti‐personnel (AP) mine detection. The device imitates the manual hand‐prodding technique for mine detection. It inserts a bayonet into the soil and models the dynamics of the manipulator and environment parameters, such as stiffness variation in the soil, to control the impact caused by making contact with a stiff object.

An adaptive neuro‐fuzzy plus PID controller is employed to switch from a conventional PID controller to neuro‐fuzzy impact control (NFIC) when an impact is detected. The developed control schemes are validated through experimental work.
Right Coprime Factorizations for Single‐Input Descriptor Linear Systems: A Simple Numerically Stable Algorithm
Authors: Duan Guang‐Ren
Published: September 2010

Based on the upper‐triangular Hessenberg forms for descriptor linear systems and a method for right coprime factorization of descriptor linear systems using matrix elementary transformations, a simple, neat and numerically stable iterative formula for right coprime factorization of a regular singleinput descriptor linear system is proposed. This iterative formula gives directly the coefficients of the solutions to the coprime factorization of the system, and involves only multiplication and additions of non‐negative scalar terms. Numerical examples are presented to demonstrate the proposed algorithm.
Robust Analytical Redundancy Relations for Fault Diagnosis In Nonlinear Systems
Authors: Shumsky Alexey
Published: September 2010

The problem of robust analytical redundancy relations design for fault diagnosis in nonlinear systems is investigated. An approach is proposed to solve this problem through an extension of the system state‐space by means of constant (or slow varying) unknown parameters, followed by designing analytical redundancy relations that are insensitive both to state variables and unknown parameters. To make the design practicable, some problems related to nonlinear transformation of the extended system model into observable one are considered. The quasi‐linear computational form for robust analytical redundancy relations is described. Fault detectability and distinguishability conditions are formulated, and a recommendation for choosing the size of the moving time window is made. The results are demonstrated through an example involving an SISO nonlinear model of an underwater vehicle.
Adaptive Control of Partially Known Systems and Application To Active Suspensions
Authors: Fukao Takanori , Yamawaki Akira , Adachi Norihiko
Published: September 2010

In this paper, an adaptive control method is proposed for systems whose structures can be divided into a known part and an unknown part. A non‐adaptive control design, such as H∞ control design can be introduced into the known part of the system, and adaptive control can cope with the unknown part to realize the property designed by non‐adaptive control. This is achieved by means of backstepping. This method is applied to the control design of an active suspension system for a railway vehicle, which is divided into two parts: a main car body part and an actuator part. Some simulation results of the control system designed using H∞ control for the body part and adaptive control for the actuator part are provided.
PID‐Augmented Adaptive Control of a Gyro Mirror Los System
Authors: Tan K.K. , Lee T.H. , Khoh C.J.
Published: September 2010

In this paper, a composite control scheme using a synergy of PID and adaptive control is proposed. The adaptive control component provides an adaptive feedforward control signal, while the PID component provides feedback control for robustness against modeling errors in the feedforward control design. The PID control can be automatically tuned using a relay. The control scheme developed is relevant to a large class of nonlinear servo‐mechanical systems, although in this paper, it is specifically implemented and demonstrated on a gyro mirror line‐of‐sight (LOS) system.
Tracking Control of Multiple Mobile Robots: A Case Study of Inter‐Robot Collision‐Free Problem
Authors: Jongusuk Jurachart , Mita Tsutomu
Published: September 2010

ABSTRACT

Tracking control problem of multiple mobile robots is considered. Our system is composed of a reference and two follower robots of unicycle type, which have their own priority numbers. The purpose is to control the two followers so that the reference is tracked with arbitrary desired clearance and also to avoid an inter‐robot collision, which can occur randomly during the control process subjected to communication range limitation. We introduce two switching controllers and appropriately using their convergence properties leading to the collision‐free movement. Simulation results prove efficiency of our control techniques.
A State‐Space Based New Approach To The Directional Interpolation Problem
Authors: Horiguchi Kazumi
Published: September 2010

Directional interpolation plays an important role in robust control, system realization and model reduction. Several solutions to various directional interpolation problems have been proposed. In this paper, we consider the directional interpolation problem in a general setting and present a statespace based new approach to solving the problem. The solution is simple, and its exposition is as self‐contained as possible. We describe all the (strictly) bounded real rational matrix functions that satisfy the directional interpolation requirements by means of linear fractional transformation. Moreover, we give a necessary and sufficient condition for the interpolating function to be unique and show that the unique interpolating function is an inner (a co‐inner). The main procedures used to generate the interpolating function consist of standard matrix operations consisting of easy numerical computations, so the present solution is significant from the numerical viewpoint as well as the analytical viewpoint.
Synthesis Of μ Controllers Using Statistical Iterations
Authors: Yang Ciann‐Dong , Tai Hung‐Chung
Published: September 2010

This paper introduces the integration of robust control and quality control, based on which a statistical iteration scheme of μ synthesis is proposed. In this statistical solution, μ controller structures are fully flexible, and controller orders do not increase during iterations. In addition, it can reveal the directions of parameter changes, which may lead to improvements in the performance of the resulting controllers. Statistical interpretations and systematical procedures for this quality‐oriented control design are also addressed.
Two‐Stage Tracking Control Via Output Feedback
Authors: Wu Shang‐Teh
Published: September 2010

An algorithm is proposed combining a high‐gain control and an internal‐model control for asymptotic output tracking in the presence of non‐decaying external disturbances. The plant output is the only signal used in the feedback loops. The algorithm is divided into two stages: high‐gain control is activated in the transient phase, forcing the output to quickly approach the reference trajectory, and is then taken over by an internal‐model controller in the steady phase so that perfect output tracking can be achieved with moderate gains and smooth control efforts. Smooth transition between the two control laws is ensured through an internal‐model observer, which serves as a relaying mechanism between the high‐gain control and the internal‐model control.
Exponential Stabilization of Bilinear Systems With Open‐Loop Unstable Dynamics
Authors: Hwang Yean‐Ren
Published: September 2010

The quadratic control (or its modification) can stabilize a homogeneous bilinear system asymptotically (or exponentially) if its open‐loop dynamics are neutrally stable. When the open‐loop dynamics are unstable, the quadratic control can only bring the system state to a bounded region around the origin. In this paper, we propose a new nonlinear control which can drive the state of an open‐loop unstable system to the origin exponentially. This control algorithm can be easily extended to time varying systems with slight modification.
Stability Analysis of Linear Shift‐Invariant Dynamics in Honeycomb Structure
Authors: Ooba Tatsushi , Funahashi Yasuyuki
Published: September 2010

This paper deals with the stability of linear shift‐invariant multidimensional dynamical systems defined on honeycomb structure. Two different honeycomb structures are discussed. The local dynamical states are assumed to be distributed to honeycomb cells in the first consideration, and they are assumed to be distributed to the nodes of honeycomb mesh in the second consideration. In each honeycomb structure, the fundamental linear shift‐invariant dynamics is introduced and then the stability criterion is presented.
Observability of Depth Estimation for a Hand‐Eye Robot System
Authors: Fang Chang‐Jia , Lin Shir‐Kuan
Published: September 2010

This paper deals with the depth observability problem of a hand‐eye robot system. In contrast to earlier works, this paper presents a complete study of this observability problem. The velocity of the active camera in the hand‐eye robot system is considered as the input. The observability of depth estimation is then related to the velocity of the camera. A necessary and sufficient condition for the types of camera velocities necessary to ensure observability is found. This compensates for the results of earlier works, in which the velocity of camera was estimated. The theory is also verified by both simulations and experiments in this paper. Furthermore, a modified LQ visual servo control law is proposed to vary the weighting matrices so that depth estimation is improved while the level of control performance is still retained.
Robust Isolation Of Sensor Failures
Authors: Xu R. , Kwan C.
Published: September 2010

Sensor self‐validity check is a critical step in system control and fault diagnostics. In this paper, a robust approach to isolate sensor failures is proposed. First, a residual model for a given system is built off‐line and directly based on input‐output measurement data. The residual model outputs are called “primary residuals” and are zero when there is no fault. Most conventional approaches to residual model generation are indirect, as they first require the determination of state‐space or other models using standard system identification algorithms. Second, a new max‐min design of structured residuals, which can maximize the sensitivity of structured residuals with respect to sensor failures, is proposed. Based on the structured residuals, one can then isolate the sensor failures. This design can also be done in an off‐line manner. It is an optimization procedure that avoids local optimal solutions. Simulation and experimental results demonstrated the effectiveness of the proposed method.
Torque Maximisation Of The Pmac Motor For High Performance, Low Inertia Operation
Authors: Stewart Paul
Published: September 2010

This paper describes the techniques applied to maximise the torque envelope of the permanent magnet AC (PMAC) motor operating under current and voltage constraints. Standard steady‐state descriptions of the system are often suitable for control purposes when the rotor velocity is varying relatively slowly. In low inertia applications such as clutchless gearchange operations, where in the pursuit of driveability, the motor is required to accelerate and decelerate its own rotor inertia as quickly as possible. In this case, the voltage drop due to the current dynamics start to become significant. This paper presents a method to reserve voltage headroom dynamically in the field‐weakening region in order to maximise the torque envelope when the effective inertia is low. Experimental results show the effectiveness of this approach.
Discretization Of A Non‐Linear, Continuous‐Time Control Law With Small Control Delays
Authors: Herrmann Guido , Spurgeon Sarah K. , Edward Christopher
Published: September 2010

This paper considers time‐discretized, non‐linear, continuous‐time control laws with small computational time‐delays. The discretized control is not initiated immediately after the sampling instant ti. Small variable computational delays ∞ are assumed to be present. Provided the sampling time ∞ is small and the maximum ratio ∞ is known, then the main theorem provides a stability result. In contrast to a former result, the theoretical framework considers robust control problems allowing a class of uncertainty and disturbances to be investigated. The different techniques are compared numerically for a discretized continuous‐time sliding‐mode based state‐feedback control.
A Parallel Block Scaled Gradient Method With Decentralized Step‐Size For Block Additive Unconstrained Optimization Problems Of Large Distributed Systems
Authors: Lin Shin‐Yeu , Lin Shieh‐Shing
Published: September 2010

In this paper, we propose a modified parallel block scaled gradient method for solving block additive unconstrained optimization problems of large distributed systems. Our method makes two major modifications to the typical parallel block scaled gradient method: First, we include a pre‐processing step which reduces the computational time; second, we propose a decentralized Armijo‐type step‐size rule. This rule circumvents the difficulty of determining a step‐size in a distributed computing environment and enables the proposed parallel algorithm to execute in a distributed computer network with a limited amount of data transfer.

We have applied our method to the weighted‐least‐square problems of power system state estimation and demonstrated the convergence of our method by testing numerous examples on a PC network. The speedup ratio of the distributed version of our method tends to increase proportionally with the number of subsystems (or computers).
Robust Stabilization Of Interval Plants With Constant Disturbance
Authors: Fernández‐Anaya G. , Alvarez‐Ramírez J.
Published: September 2010

The aim of this brief paper is to study the output feedback, robust stabilization problem for a class of SISO interval plants with unknown constant disturbance. For interval plants of minimum phase and known high‐frequency gain, it shows that a simple controller with integral action is able to reject the disturbance. A procedure to compute the parameters of the controller is discussed.
Reliable Robust Preview Tracking Control Against Actuator Faults
Authors: Liao Fang , Wang Jianliang , Yang Guang‐Hong
Published: September 2010

In this paper we provide a solution to the reliable robust preview tracking problem against actuator faults for discrete LTI systems with polytopic uncertainties. This solution is in terms of the solvability of linear matrix inequalities (LMIs). The method is based on multi‐objective optimization and LQ tracking performance indices. To avoid the conservativeness problem associated with using a common LMI solution for the normal case and the fault cases, different LMI solutions are used in the proposed method. Two iterative algorithms are proposed and compared. Numerical examples are used to show the effectiveness of the algorithms.
Control Routh Array And Its Applications
Authors: Cheng Daizhan , Tarn T.J.
Published: September 2010

In this paper the Routh stability criterion [16] has been developed into control Routh array. Some formulas for calculating the array are provided. Certain properties are investigated. Using it, the problem of stabilization of bilinear systems via constant controls is solved. Then by converting the problems, the method of control Routh array is also used to solve some other stability related problems, such as the stabilization of control systems, the stability of uncertain Hurwitz matrix and the stability of interval matrices. Several algorithms have been developed to provide numerical solutions.
Reliable Decentralized Supervisory Control For Marked Language Specifications
Authors: Takai Shigemasa , Ushio Toshimitsu
Published: September 2010

We consider a discrete event system controlled by a decentralized supervisor consisting of n local supervisors. In our previous work, we have studied reliable decentralized supervisory control for closed language specifications. In this paper, we extend this work to the specifications given by marked languages. A decentralized supervisor is said to be k‐reliable (1 ∞ k ∞ n) if it exactly achieves a specification language without blocking under possible failures of any less than or equal to n ‐ k local supervisors. We present necessary and sufficient conditions for the existence of a k‐reliable decentralized supervisor. Then we define a weaker version of k‐reliability, called weak k‐reliability, by relaxing the nonblocking requirement. We obtain necessary and sufficient conditions for the existence of a weakly k‐reliable decentralized supervisor. Moreover, we propose an iterative scheme for computing a sublanguage of a specification for which the existence conditions of a weakly k‐reliable decentralized supervisor are satisfied.
RobustH∞Control Problem For General Nonlinear Systems With Uncertainty
Authors: Wu Jenq‐Lang , Lee Tsu‐Tian
Published: September 2010

In this paper, both state and output feedback robustH∞control problems for general nonlinear systems with norm‐bound uncertainty are considered. Sufficient conditions for the existence of robust output feedbackH∞controller are provided. State space formulas for robustH∞output controller are provided.
Fuzzy Sliding Mode Control For Ship Roll Stabilization
Authors: Chen Shyh‐Leh , Hsu Wei‐Chih
Published: September 2010

A fuzzy sliding mode controller is proposed in this study for ship roll stabilization. Ship dynamic models usually contain large uncertainty. Sliding mode control is well known for its good robustness to large uncertainty. However, the required uncertainty bound is usually difficult to estimate. A fuzzy logic is designed here for the upper bound estimation of the uncertainty coming mostly from the wave excitation. As a result, the uncertainty‐related parameters in the sliding mode controller are automatically tuned by fuzzy logic according to the encountered wave amplitude. The present controller has the advantage that smaller control efforts are required for the anti‐capsizing purpose under the same sea states. A numerical example is investigated to confirm the analysis.
Design Of Robust Pole Assignment Based On Pareto‐Optimal Solutions
Authors: Tagami Takanori , Ikeda Kenji
Published: September 2010

In this paper, a new design method for robust pole assignment based on Pareto‐optimal solutions for an uncertain plant is proposed. The proposed design method is defined as a two‐objective optimization problem in which optimization of the settling time and damping ratio is translated into a pole assignment problem. The uncertainties of the plant are represented as a polytope of polynomials, and the design cost is reduced by using the edge theorem. The genetic algorithm is applied to optimize this problem because of its multiple search property. In order to demonstrate the effectiveness of the proposed design method, we applied the proposed design method to a magnetic levitation system.
A Stable Output Feedback Position Control With Integral Action For Robot Manipulators
Authors: Alvarez‐Ramirez Jose , Kelly Rafael , Cervantes Ilse
Published: September 2010

In this paper, the problem of robust regulation of robot manipulators using only position measurements is addressed. The main idea of the control design methodology is to use an observer to estimate simultaneously the velocity and the modeling error signal induced by model/system mismatches. The controller is obtained by replacing the velocity and the modeling error in an inverse dynamics feedback by their estimates, which leads to a certainty equivalence controller. The resulting controller has a PID‐type structure which, under least prior knowledge, reduces to the PI2D regulator studied in [20]. Moreover, the controller is endowed with a natural antireset windup (ARW) scheme to cope with control torque saturations. Regarding the closed‐loop behavior, it is proven that the region of attraction can be arbitrarily enlarged with high observer gains only, thus we prove semiglobal asymptotic stability. Our result supersedes previous works in the direction of performance estimates; specifically, it is also proven that the performance induced by a saturated inverse dynamics controller can be recovered by our PID‐type controller. In this sense, our work reveals some connections between PID‐type and inverse dynamics controllers.
Dynamical Output Feedback Stabilization Of Mimo Bilinear Systems With Undamped Natural Response
Authors: Lu Guoping , Zheng Yufan , Zhang Cishen
Published: September 2010

This paper considers the globally asymptotic stabilization problem of multi‐input multi‐output bilinear systems with undamped natural response. Under the conditions for asymptotic stabilization by static state feedback control and system detectability, two output dynamic feedback controllers with saturation bounded control are constructed. The global asymptotic stability of the closed‐loop system is verified by Lyapunov stability theory and LaSalle's Lemma. An example is given to demonstrate the obtained results.
Indexing Valve Plate Pump: Modeling And Control
Authors: Zhang X. , Cho J. , Nair S. S.
Published: September 2010

A reduced order dynamic modeling method, and a pressure control strategy are proposed for a novel axial variable‐displacement pump design. The reduced order model provides insights into the dynamics, and is useful for control design. Theoretical as well as implementation insights for the control problem are also developed, including proportional control limitations which provides guidance for effective control designs.
Characterisation Of Receding Horizon Control For Constrained Linear Systems
Authors: Seron María M. , Goodwin Graham C. , De Doná José A.
Published: September 2010

This paper characterises the geometric structure of receding horizon control (RHC) of linear, discrete‐time systems, subject to a quadratic performance index and linear constraints. The geometric insights so obtained are exploited to derive a closed‐form solution for the case where the total number of constraints is less than or equal to the number of degrees of freedom, represented by the number of control moves. The solution is shown to be a partition of the state space into regions for which an analytic expression is given for the corresponding control law. Both the regions and the control law are characterised in terms of the parameters of the open‐loop optimal control problem that underlies RHC and can be computed off line. The solution for the case where the total number of constraints is greater than the number of degrees of freedom is addressed via an algorithm that iteratively uses the off‐line solution and avoids on‐line optimisation.
Determination Of The Phase Current Waveform For A Disc‐Type Axial‐Flux Wheel Motor
Authors: Yang Yee‐Pien , Luh Yih‐Ping , Pan Yann‐Guang
Published: September 2010

An optimal design of the driving current pattern for a disc‐type axial‐flux brushless DC wheel motor of an electric vehicle is proposed in this paper. The electro‐magnetic dynamic model of the motor is established with magnetic circuits, describing the relationship between the output torque and excitation current. The optimal current pattern, in terms of magnitude and phase angle, is then obtained by maximizing the output torque with respect to the rotor shift. Compared with the traditional three‐phase‐on current pattern of fixed 120–degree phase shift, both the average torque and efficiency with the driving current of an optimal advanced switching angle are seen to be improved under various loading conditions. The motor performance with the optimal driving waveform is simulated and verified by experiments.
Time Varying Deadbeat Control Of High Order Chained Systems
Authors: Mita Tsutomu , Nam Taek Kun
Published: September 2010

A new digital control method for a time varying sampled data system called a time varying deadbeat control is proposed for the control of high order nonholonomic chained systems with drift terms. This control law has the potential to avoid excessive overshoot and prevent trajectories from getting close to the singular manifolds of the transformation needed to obtain the chained forms.
Modified Weak‐Pseudo‐Sliding Mode Controller With One Sampling Period Computation Delay
Authors: Changy Kuo‐Ming , Chen Chieh‐Li , Zhu Zhi‐Hong
Published: September 2010

In this paper, a so‐called discrete‐time modified weak‐pseudo‐sliding mode controller with one sampling period computation delay is proposed for the system with system parameter uncertainty. In the meantime, the upper bound of the sampling period is also determined to guarantee the existence of the modified weak‐pseudo‐sliding mode along the prescribed sliding surface in the proposed discrete‐time sliding mode control system.
Robust Mrac Of A Nonautonomous Parabolic System With Spatiotemporally Varying Coefficients And Bounded Disturbance
Authors: Yang Kyung‐Jinn , Hong Keum‐Shik
Published: September 2010

In this paper, a robust model reference adaptive control of a parabolic system with unknown spatiotemporally varying coefficients and disturbance is investigated. In the adaptive control of time‐varying plants, the derivative of a Lyapunov function candidate, which allows the derivation of adaptation laws, is not negative semi‐definite in general. Under the assumption that the disturbance is uniformly bounded, the proposed robust adaptive scheme guarantees the boundedness of all signals in the closed loop system and the asymptotic convergence of the state error near to zero. With an additional persistence of excitation condition, the parameter estimation errors are shown to converge near to zero as well. Simulation results are provided.
Pid Controller Design With Guaranteed Gain And Phase Margins
Authors: Ho Ming‐Tzu , Wang Hsing‐Sen
Published: September 2010

This paper considers the problem of designing PID controllers that achieve the guaranteed gain and phase margin specifications for a given but arbitrary single‐input single‐output plant. Using definitions of gain and phase margins, the given specifications are translated into simultaneous stabilization of two families of polynomials. Thereafter, an extension of the results of PID stabilization to the case of complex polynomials is shown to be useful in providing a solution to this simultaneous stabilization problem. A computational characterization of all admissible PID controllers is given. This characterization for all admissible PID controllers involves the solution of a linear programming problem. An example is presented to illustrate use of the design procedure in detail.
Quaternion Feedback Attitude Control Design: A NonlinearH∞Approach
Authors: Show Long‐Life , Juang Jyh‐Ching , Jan Ying‐Wen , Lin Chen‐Tzung
Published: September 2010

The paper presents a quaternion feedback attitude control law for spacecraft attitude maneuver. A nonlinear feedback controller is designed to achieveL2gain performance,i.e., the resulting closed‐loop system is designed such that theL2gain from the exogenous disturbance to the performance measure is less than a scalar. The solution of the nonlinearH∞control problem is known to be related to the existence of a solution to the Hamilton‐Jacobi inequality. In the paper, a solution for spacecraft attitude control is conjectured and shown to satisfy theH∞criterion. The result generalizes existing methods in two regards: the proposed Hamilton‐Jacobi function is more general than existing ones and the resulting controller contains a nonlinear term that can be used to address the nonlinear couplings between quaternion terms. The method is applied to the ROCSAT‐3 orbit raising control problem to verify its effectiveness.
Mixed Constrained Infinite Horizon Linear Quadratic Optimal Control
Authors: Choi Jinhoon , Lee Kwang Soon
Published: September 2010

For a given initial state, a constrained infinite horizon linear quadratic optimal control problem can be reduced to a finite dimensional problem [12]. To find a conservative estimate of the size of the reduced problem, the existing algorithms require the on‐line solutions of quadratic programs [10] or a linear program [2]. In this paper, we first show based on the Lyapunov theorem that the closed‐loop system with a mixed constrained infinite horizon linear quadratic optimal control is exponentially stable on proper sets. Then the exponentially converging envelop of the closed‐loop trajectory that can be computed off‐line is employed to obtain a finite dimensional quadratic program equivalent to the mixed constrained infinite horizon linear quadratic optimal control problem without any on‐line optimization. The example considered in [2] showed that the proposed algorithm identifies less conservative size estimate of the reduced problem with much less computation.
A New Delay‐Dependent Stability Criterion For Neutral Delay‐Differential Systems
Authors: Yang Bin , Wang Jincheng , Zhong Chongquan
Published: September 2010

This paper investigates the problem of asymptotic stability for neutral delay‐differential systems. Using the Lyapunov method, we derive a new delay‐dependent sufficient condition for the stability of systems in terms of the linear matrix inequality (LMI). Numerical examples show that the results obtained in this paper significantly improve the estimate of stability limit over some existing results reported previously in the literature.
Visual Tracking For References Generated By A Stochastic Model
Authors: Kamiya T. , Doi M. , Mochiyama H. , Mori Y.
Published: September 2010

This paper describes a visual tracking system for an unknown reference signal. A time‐varying reference signal is realized as a random process generated by an auto‐regressive (AR) model, which is identifed by a recursive algorithm. Based on the obtained AR model, the future value of reference signal is predicted. We propose a new visual tracking system using generalized minimum variance control (GMVC) and illustrate its properties through experiments.
DYNAMIC SLIDING MANIFOLDS FOR REALIZATION OF HIGH INDEX DIFFERENTIAL‐ALGEBRAIC SYSTEMS
Authors: Gordon Brandon W.
Published: September 2010

Differential‐algebraic equation (DAE) systems present a number of difficult problems in nonlinear simulation and control. One of the key difficulties is that DAEs are not expressed in an explicit state space form required by many simulation and control design methods. In this paper, the problem is addressed using a new approach that constructs an explicit state space approximation of the DAEs using a sliding controller. The state space model can in turn be used with existing nonlinear control and simulation methods. This procedure, known as realization, is achieved by developing a boundary layer sliding controller with a dynamic sliding manifold. The approach builds on previous realization methods proposed by the author that employ a static sliding control surface. The approach is generalized by employing a dynamic sliding manifold which allows much greater freedom in determining optimality, robustness, and convergence of the realization than previous methods allow. The necessary criteria for key properties such as convergence, stability, and controllability of this new method are proven using a special type of sliding normal form. Furthermore, the important property of observability for sliding realizations is established for the first time by analyzing the convergence of local eigenvectors of the approximation. Together these results establish a new general framework for realization of a large class of nonlinear high index DAE systems.
STABILIZATION OF SWITCHED LINEAR SYSTEMS
Authors: Zhang Lijun , Cheng Daizhan , Liu Jiang B.
Published: September 2010

This paper addresses stabilization of switched linear control systems with unstabilizable individual switching models. First we consider the stabilization of switched systems via a controllable switching strategy. Then stabilization by both controls and switching laws is investigated. Certain sufficent conditions are obtained.
UNIVERSAL OUTPUT‐FEEDBACK SISO CONTROLLERS
Authors: Levant Arie
Published: September 2010

It is proved in the paper that practically all known higher‐order sliding controllers can be combined with recently developed 2‐sliding‐mode‐based differentiators yielding universal output‐feedback Single‐Input‐Single‐Output (SISO) controllers. These controllers can be applied at least locally, whenever the system relative degree is known. The convergence is global, provided the system relative degree is permanent and few boundedness restrictions hold. No detailed mathematical model of the system is needed. The proposed output‐feedback controller provides for the exact finite‐time‐convergent output tracking of real‐time‐given smooth signals if the output measurements are exact. Otherwise the tracking accuracy is proportional to the magnitude of the sampling noise. The control may be made arbitrarily smooth, thereby removing the chattering effect. The theoretical results are illustrated by computer simulation.
ROBUST VIBRATION CONTROL FOR FLEXIBLE ARMS USING THE SLIDING MODE METHOD
Authors: Chen Xinkai , Su Chun‐Yi , Fukuda Toshio
Published: September 2010

The vibration control of flexible arms is accomplished here using the sliding mode method, where the traditional discontinuous approach is modified by a differentiable one. The higher order modes of the flexible arm are treated as disturbances and are compensated by introducing a disturbance observer. Simplified expressions of the motor angular and the strain moment for the flexible arm with a disturbance observer are obtained, where the remaining disturbance and the model uncertainties are considered as system uncertainties. The robustness of the sliding mode control is effectively employed to cope with the system uncertainties, where the bounds of the uncertainties are adaptively updated. The proposed control law simultaneously causes the motor angular to track a desired signal and the strain moment to approach zero. The stability of the controlled flexible arm is analyzed based on the obtained important fact that a part of the control input is the approximate estimate of a special signal generated by the uncertainty. The motor angular tracking error and the converging speed of the controlled signals are determined by means of design parameters. Experimental results demonstrate the robustness of the proposed method.
CONTROL OF INTERCONNECTED JUMPING SYSTEMS: AN H∞ APPROACH
Authors: Mahmoud Magdi S. , Shi Peng , Ismail Abdulla
Published: September 2010

This paper investigates, by using an approach, the problems of stochastic stability and control for a class of interconnected systems with Markovian jumping parameters. Both cases of finite‐ and infinite‐horizon are studied. It is shown that the problems under consideration can be solved if a set of coupled differential or algebraic Riccati equations are solvable.
PERFORMANCE ANALYSIS OF CONTROL SYSTEMS WITH INPUT CONSTRAINTS VIA PIECEWISE QUADRATIC STORAGE FUNCTIONS
Authors: Morinaga Eiji , Hirata Kenji , Ohta Yoshito
Published: September 2010

Input constraints exist in almost all real‐world systems and frequently cause unexpected undesirable phenomena, such as performance degradation or instability. Although many studies have focused on this problem, precise performance analysis of whole control systems with constraints is still difficult. In this paper, such control systems are represented as piecewise affine systems, and global and local L2 incremental gain analysis methods via piecewise quadratic storage functions are presented.
DECENTRALIZED CONTROL OF GENERALIZED SYSTEMS VIA A FREQUENCY DOMAIN APPROACH
Authors: Gao Zhiwei , Liu Wanquan , So Albert T. P.
Published: September 2010

In this paper, the decentralized control of generalized systems is considered via a frequency domain approach. Firstly, based on the design of generalized decentralized observer‐based controllers, a state‐space representation of the decentralized Bezout identity is developed for generalized decentralized control systems with two control channels. Secondly, all the stabilizing decentralized controllers are parameterized. Thirdly, a design procedure is proposed, and an example is given to illustrate the design procedure.
VIBRATION CONTROL OF A SMART STRUCTURE USING PERIODIC OUTPUT FEEDBACK TECHNIQUE
Authors: Manjunath T. C. , Bandyopadhyay B.
Published: September 2010

Active vibration control is an important problem in structures. One of the ways to tackle this problem is to make the structure smart, adaptive and self‐controlling. The objective of active vibration control is to reduce the vibration of a system by automatic modification of the system's structural response. This work features the modeling and design of a Periodic Output Feedback (POF) control technique for the vibration control of a smart flexible cantilever beam system for a Single Input Single Output case. A POF controller is designed for the beam by bonding patches of piezoelectric layer as sensor/actuator to the master structure at different locations along the length of the beam. The entire structure is modeled in state space form using the Finite Element Method by dividing the structure into 3, 4, 5 elements, thus giving rise to three types of systems, viz., system 1 (beam divided into 3 finite elements), system 2 (4 finite elements), system 3 (5 finite elements).

POF controllers are designed for the above three types of systems for different sensor/actuator locations along the length of the beam by retaining the first two vibratory modes. The smart cantilever beam model is developed using the concept of piezoelectric bonding and Euler‐Bernouli theory principles. The effect of placing the sensor/actuator at various locations along the length of the beam for all the three types of systems considered is observed and the conclusions are drawn for the best performance and for the smallest magnitude of the control input required to control the vibrations of the beam. The tip displacements with the controller is obtained. Performance of the system is also observed by retaining the first 3 vibratory modes and the conclusions are drawn.
H2 CONTROLLER DESIGN FOR NETWORKED CONTROL SYSTEMS
Authors: Lu Lilei , Xie Lihua , Cai Wenjian
Published: September 2010

This paper deals with the problem of designing an H2 controller for a networked control system (NCS) with communication delays from the sensor to the controller and/or from the controller to the plant. Our objective is to design a robust controller that will not only stabilize the system but also achieve a sub‐opti‐ mal H2 performance in the face of possible communication delays. Both the state feedback control and output feedback control are considered. The feedback control problem for the original system is first converted to a static output feedback control problem. A recursive linear matrix inequality (LMI) algorithm is then presented to compute a state or output feedback H2 controller for the system. Our approach allows a fixed order controller. Numerical examples are given to demonstrate the effectiveness of the proposed approach.
FEEDBACK STABILIZATION OF NONHOLONOMIC CONTROL SYSTEMS WITH DRIFT
Authors: Rehman Fazalur
Published: September 2010

This paper presents a differential geometric approach for feedback stabilization of nonholonomic control systems with drift and its applicability is tested on two different systems possessing different algebraic structures: a system with six state variables and three controls, and a knife edge example. The approach is universal in the sense that it is independent of the vector fields determining the motion of the system, or of the choice of a Lyapunov function. The proposed feedback law is as a composition of a standard stabilizing feedback control for a Lie bracket extension of the original system and a periodic continuation of a specific solution to an open loop control problem stated for an abstract equation on a Lie group, an equation which describes the evolution of flows of both the original and extended systems. The open loop problem is solved as a trajectory interception problem in logarithmic coordinates of flows.