Abstract: The dynamic behavior of friction-induced vibration problems is governed by second-order differential equations having asymmetric matrices, due to the coupling of structures and external loads, which are functions of some parameters. Asymmetric systems are prone to unstable vibration (flutter) as a parameter reaches a critical value. Placement of these unstable poles to the left-hand half of the complex pole plane for stabilization can be achieved by active (feedback control) and passive means (structural modification). Moreover, placement of poles is also done to achieve the desirable dynamic response and system performance. However, such active pole assignment control introduces inherent time delays in the feedback control loop. This paper presents a method for assigning complex poles to second-order damped asymmetric systems by using state-feedback control while considering a constant time-delay in the feedback control loop. The control strategy is based on receptances of the symmetric part of the asymmetric open-loop system (without time delay), which can be easily obtained from transfer function measurements. This method does not require the knowledge of mass, damping and stiffness matrices, and hence circumvents the modeling errors (finite element or reduced order). In this research, with numerical examples, it is shown that by means of active state feedback control and by using a relatively small number of available receptances, open-loop poles of the asymmetric system can be assigned precisely. The stability of the closed-loop system is analyzed by computing primary closed-loop poles and the associated critical time delay.

Abstract: A standard result of linear-system theory states that a single-input-single-output (SISO) rational n th-order transfer function always has a state-space realization of the same order. In some applications, one is interested in having a realization with nonnegative entries (i.e., a positive system) and it is known that such constraints may lead to a minimal order positive realization of order much greater than the transfer function order n. In this technical note, necessary and sufficient conditions for a third-order transfer function with distinct real poles to have a third-order positive realization are given: these conditions are expressed in terms of lower bounds for the first three samples of the impulse response and therefore are very easy to check. This result is an extension of a previous result for transfer functions with distinct real positive poles.

Abstract: This article presents a novel optimal control design technique based on a quadratic performance index, and using orthonormal basis functions to achieve prescribed closed loop poles. These functions are introduced through a Youla parametrization for the stable and unstable plant case, thus forcing a structural constraint into the controller.

Abstract: An amplifier is characterized by its transfer function T, which expresses the dependence of the output signal on the input signal. This signal may be related to power, intensity, energy of a pulse, or its fluence, or any similar physical quantity. The internal structure of the amplified signal (e.g., its spectral content, polarization, temporal behavior, and spatial distribution) is not taken into account. The amplifier is considered to be spatially homogeneous and uniformly pumped. The transfer function is supposed to be known (measured in an experiment). The problem of reconstruction of the behavior of the signal inside the amplifier is formulated. For a given transfer function T, the evolution of the signal inside is interpreted as the superfunction F, satisfying the transfer equation F(z + 1) T(F(z)), where z is of coordinate along the propagation direction, while the length of the amplifier is used as a unit of measurement. (For simplicity, distances are measured in units of the length of the amplifier.) Two examples of realistic transfer function T are considered; they correspond to amplification of continuous wave and to amplification of pulses. In these examples, the transfer function and the distribution of the signal along the amplifier can be expressed in terms of special functions. The iterative procedure is suggested as a general method of reconstructing the signal along the amplifier, if neither the transfer function T, nor the superfunction F can be expressed with a simple combination of special functions. The examples show that the iterations converge to a physically meaningful solution. This method is expected to be useful for the characterization of laser materials from the measurement of the transfer function of a bulk sample.

Abstract: This paper presents a new control technique for vibration reduction based on modal approach and named Dependent Modal Space Control (DMSC). It is an active control logic that allows to assign the closed loop poles and the corresponding mode shapes of a system in a discrete number of degree of freedom depending on the amount of the sensors and actuators available. In order to perform the eigenstructure assignment, modal sensors and actuators are necessary unless both control and observation spillover are minimized.

Abstract: This article presents the application of a state feedback, Pole-Placement temperature-tracking control formulation leading to a comprehensive Single-input, multiple-output (SIMO) structure for cooling of a steel plate by an impinging air jet. . Following a semi-discrete control volume formulation of the 1-D transient heat conduction; the state space model of nodal variation of metal temperature with time has been arrived. Stable temperature track with respect to the reference temperature track was obtained by using the state feedback control algorithm. To solve this prescribed state feedback problem, an efficient pole placement technique was implemented in two ways i.e., initially, the fixed poles and then variable poles in the complex plane. The control models were simulated in the MATLAB and SIMULINK environments. The state feedback pole placement technique was found efficient in controlling the parameters in the given application. It was observed that the response of the non-linear system is sensitive to linearization time interval. Better control is implemented by increasing the frequency of adjustment of the closed-loop poles.

Abstract: A method including: setting a weighting function based on an amount of change in impedance of a control target; and determining, for a power controller, a transfer function composed of a transfer function of an internal model obtainable by performing Laplace transform on the voltage reference value and a transfer function of a partial controller, the transfer function of the partial controller being for outputting the control output after receiving, as an input, an output of the transfer function of the internal model, wherein the determining includes determining the transfer function of the partial controller using an H∞control theory so as to reduce (i) a first amount of control obtainable by multiplying the control output and the weighting function and (ii) a second amount of control that is an output of the transfer function of the internal model.

Abstract: We examine relations between denominator assigning proper compensators in the feedback path of linear, time invariant (LTI) multivariable systems, described by square strictly proper transfer function matrices, and pole assignment by state variable feedback. Through these results we establish conditions for the existence and computation of such compensators.

Abstract: This paper proposes an approach to a robust PI controller design for real uncertain Coupled-Tank process in time domain. Only the first independent tank is considered (single-input single-output system). Polytopic model of uncertain system is considered as a plant model to be controlled. Stability and performance of the closed loop system is determined through the LMI region, where the closed loop poles of whole uncertainty domain are placed. A robust stability condition based on the parameter-dependent Lyapunov function (PDLF) is used.

Abstract: The performances of position controllers for a throttle valve used with internal combustion engines of heavy goods vehicles is investigated using different control techniques. The throttle valve is modelled including the hard stops and static friction (stick-slip friction), which are nonlinear components. This includes a new simple approach to the modelling of static friction. This nonlinear model was validated in the time domain using experimental results, parameterised by experimental data using a Matlab based parameter estimation tool. The resulting state space model was linearised for the purpose of designing various linear model based controllers. This linearised model was validated using experimental data in the frequency domain. The correct design of each model based controller is first confirmed by simulation using the linear throttle valve model, the specified step response being expected. Then the robustness is assessed in the frequency domain using the Matlab® Control System Design Toolbox and in the time domain by simulation using Monte Carlo based plant parameter mismatching between the simulated real plant and its model used for the control system design. Once satisfactory performance of a specific controller is predicted by simulation using the linear model, this is replaced by the nonlinear model to ascertain any deterioration in performance. Controllers exhibiting satisfactory performance in simulation with the nonlinear plant model are then investigated experimentally. The set of controllers investigated in this work includes types that are not currently employed commercially, as well as traditional ones, consisting of the IPD, PID, DPI controllers and the linear state feedback controller with and without an integrated observer. The other controllers are the sliding mode iii controller, observer based robust controller (OBRC) and the polynomial controller. The traditional controllers are designed using partial pole placement with the derived linear plant model. The other controllers have structures permitting full pole placement, of which robust pole placement is an important option. In the pole placement design, the locations of the closed loop poles are determined using the settling time formula. Despite the use of robust pole placement, the static friction caused a limit cycle, which led to the use of an anti-friction measure known as dither. The 14 different controllers were investigated for their ability to control the throttle valve position with nonlinear friction, parameter variations and external disturbances. This information was gathered, together with qualitative information regarding ease of design and practicability to form a performance comparison table. The original contributions emanating from the research programme are as follows:  The successful application of new control techniques for throttle valves subject to significant static friction  The first time investigation of partial and robust pole placement for throttle valve servo systems.  A simplified static friction model which can be used for other applications.

Abstract: At least one example embodiment discloses a method of controlling steering of a vehicle. The method includes identifying a reduced-order vehicle model, the reduced-order vehicle model representing a vehicle transfer function in which a least one high-frequency pole is removed. The method further includes generating target closed loop pole locations based on at least one user preference parameter. The method further includes determining calibration parameters that place closed loop poles of a composite system at the target closed loop poles. The composite system in this context includes the reduced-order vehicle model and a steering control system. Finally, the method includes controlling the steering using the steering control system configured using the calibration parameters.

Abstract: This paper considers the problem of controlling rotating machinery with actuators and sensors fixed in inertial space. Such a problem arises in control of charging and fusing stages in the xerographic process, drilling and milling machines, and turbo machinery. If a rotating device is represented as a set of discrete wedges, the resulting system can be conceptualized as a set of plants (wedges) with a single actuator and sensor. In such architecture, each plant can be controlled only intermittently, in a stroboscopic manner. This leads to the problem of Cyclic Control (CC) considered in this paper. Specifically, the problem of stabilizability in CC architecture is considered, and the resulting stabilizability conditions are compared with those in the usual, permanently acting control (PAC). In this regard, it is shown that the domain of asymptotic stability under CC is an open disc in the open left half plane (OLHP), rather than the OLHP itself, and the controller gains that place the closed loop poles at the desired locations under CC are N times larger than those under PAC, where N is the number of wedges. The results are applied to temperature stabilization of the fusing stage of a xerographic process.

Abstract: The problem of minimizing the number of state measurements (and hence the number of sensors) required for placing the poles of a linear time invariant single input system with state feedback, is considered. It is assumed that only a subset of the closed loop poles are required to be placed in pre-specified locations in the complex plane. The remaining poles can assume any locations inside a pre-defined region in the complex plane. The resulting binary program with polynomial constraints is convexified using the theory of moments. Numerical examples illustrate the theory developed.

Abstract: An iterative linear matrix inequalities (ILMIs) algorithm is presented for centralized and decentralized state feedback controller designs The controller is designed in such a way that places the closed loop poles under desired area and bounds near the boundary region with low gain controller The application of algorithm is demonstrated through simulation studies of two-area power system model and formation control of unmanned aerial vehicles

Abstract: The invention discloses a method for designing a controller for an aircraft time lagging and varying model and aims to solve the technical problems that an aircraft controller cannot be directly designed due to the shortage of design steps in the conventional robust control theory. According to the technical scheme, the subsection robust stability solvability condition of a time varying and lagging system is given, expected closed loop points of state feedback of a linear system are directly used for selection, and according to the characteristic that all real parts of the expected closed loop poles are negative numbers, limited conditional inequality is given, and a feedback matrix is designed directly. Engineering technicians in the research field can directly design the aircraft controller for the aircraft model which is obtained through the wind tunnel experiment or flight test and has time lagging and varying uncertainty, and the technical problems that the aircraft controller cannot be directly designed because only the robust stability inequality is given in the current research can be solved.

Abstract: It is important for the control system analyst to understand the complete relationship of the complex-frequency representation of a linear system, the poles and zeros of its transfer function, and its time-domain response to step and other inputs. In such areas as signal processing and control, many of the analysis and designed collations are done in the complex-frequency plane, where a system model is represented in terms of the poles and zeros of its transfer functions.

Abstract: The distribution of poles affects the property of the automatic control system. The paper studies how the poles in the left half of s-plane affect the transient performance of the system by Matlab tools and analyzes the reasons for these effects. Discuss the different effects of the closed-loop poles and the open-loop poles to the same automatic control system.

Abstract: In this paper the author proposed a model that depicts not only the basic features of liquid catheter sensor but also improvement of those features. The optimum performance of the 2nd order liquid catheter sensor system depends on parameters namely natural frequency of oscillation and damping ratio and two basic features namely high frequency response and flat frequency response. As the system dynamics of the liquid catheter sensor is evolved as closed loop transfer function therefore it is very difficult to design this system with help the of root locus method where the open loop gain is varied to estimate the behavior of the closed loop poles of the system. In this paper the author has used a novel approach of basic vector field method for two dimensional linearized systems. The model clearly indicates the optimum performance criterion of the liquid catheter sensor based on the model proposed by the author. The proposed model not only gives the various dynamic features of liquid catheter sensor but also highlights both inertia controlled and thermally controlled vapor bubble dynamics. Copyright © 2013 IFSA.

Abstract: In some control problems, it is convenient to use a precompensator to alter the transfer function of the system so as the transfer function of the compensated system has a specified property. Then, if possible, the action of the compensator on the system is realized by a static state feedback law applied to the system. Non-square compensators result in non-regular state feedback. In this paper, necessary and sufficient conditions are presented for the compensated system to be stabilizable by such a non-regular static state feedback law.