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A novel flexible fuel thermal management architecture with a switched mode control strategy is proposed that provides a framework for increasing the thermal endurance of aircraft that use fuel as a...

Although all six Apollo lunar landings were successful, the multiple landing site redesignations and landing near hazards suggest crewed planetary landings can be challenging and demand high pilot ...

This article studies the mechanics of reusable retro-propelled flight of slender low lift to-drag bodies via integrated guidance and control simulations. To do this, a simulation benchmark focused on the coupling between flight mechanics, guidance and control must be developed, as opposed to mission-optimisation oriented ones that simplify (or directly ignore) these couplings. The developed simulator covers vertical take-off and landing of a first stage booster for return to launch site and downrange landing missions. In order to steer it towards a controlled entry, followed by descent and precision landing, the vehicle is configured with a deep throttling thrust vector control system, fins and cold gas thrusters. Comparative performance results are derived in terms of aerodynamic loads and heat fluxes for both recovery scenarios, as well as through a detailed closed-loop controllability analysis. The latter demonstrates that the configuration has sufficient authority and resolution to perform stable flight and adequate wind gust rejection. The developed benchmark (because of the coupled flight mechanics, guidance and control) allows to provide a first assessment of operational limits, as well as mission and GNC specifications. This in turn paves the way for the synthesis and assessment of more sophisticated reusable launcher guidance and control algorithms.

The goal of this paper is to introduce an adaptive load frequency control (LFC) technique for power systems. The concept of the proposed adaptive technique is built on the on-line tuning of the gain of an integral controller using Electro-Search optimization (ESO) supported by a modification called the ‘balloon effect’. The main target is to regulate the frequency of isolated and interconnected power systems. The balloon effect is designed to obtain the input/output signals of the power system plant at any moment; then, these signals are utilized to calculate the value of the open loop transfer function of the plant at the same time. This will emphatically affect the specified objective function of the ESO approach and increase its sensitivity to and effect on system difficulties such as system step load changes, parameter uncertainties and the effect of the penetrations resulting from renewable sources. Delayed time resulting from the communication process between the area and control center is considered in the dynamic model of interconnected MGs, and nonlinearities, such as governor dead bands (GDBs) and generation rate constraints (GRCs), are included in the simulation model. The simulation results demonstrate the effectiveness and success of the proposed controller tuned by the ESO approach with a balloon effect and provide better performance of frequency regulation than a fixed controller, as well as other methods such as standard Jaya and ESO methods.

As control precision for Earth-orbiting formations increases, the required ΔV can quickly become infeasible. Missions have demonstrated approximately 5 m/s/yr for 10-m control (TanDEM-X), but that...

An approach for multiple-feedback control of generator power and nacelle fore-aft speed employing blade pitch and generator torque manipulations was developed for a spar-type floating offshore wind turbine-generator system. The development of this approach was carried out through numerical analysis using the aeroelastic simulation model (FAST), measured high wind speed data, and simulated irregular sea waves. The novelty of this multiple-feedback control approach is the increase of the generator torque in response to the platform pitching motion to the leeward side and the control of the generator power instead of the rotational speed. First, theoretical analysis of the open loop transfer function revealed that the multiple-feedback control approach improves the stability of the generator power control in the floating offshore wind turbine-generator system. Then, the optimal parameter settings of the multiple-feedback control were determined and the effectiveness of employing a first-order lag filter for the nacelle fore-aft speed was shown through a sensitivity analysis. A comparison of system performances demonstrated that the multiple-feedback control approach reduces the power output fluctuation, the platform pitching motion, and the damage equivalent fatigue load of the fore-aft bending moment at the tower-base part by 52%, 22%, and 16%, respectively, relative to the gain-scheduled feedback control of the rotational speed.

This paper proposes a systematic analysis and synthesis method for the optimal design of filters for L1 adaptive output feedback controllers. In the L1 adaptive feedback structure, the low-pass fil...

An independent design of adaptive multiloop fractional order internal model control based PID (FOIMC-PID) controller for a two input two output process (TITO) is presented. The multivariable system is decomposed by ideal decoupler to develop effective open loop transfer function (EOTF) and then it is approximated into first order plus dead time (FOPDT) model. The multiloop FOIMC-PID controller is designed for TITO model and controller parameters are optimally tuned using Novel Bat Optimization Algorithm (NBOA). The simulation results are demonstrated to show the effectiveness of proposed controller and also some tuning procedure is suggested to get better FOIMC-PID controller performance.

An automatic aircraft loss-of-control prevention system by bandwidth adaptation is presented in this paper. The adaptation law employs the time-varying parallel differential eigenvalues for a tradeoff between tracking performance and severe wind tolerance capability in real time. It is implemented as an augmentation to a 6-DOF trajectory tracking controller designed with constant gains by the singular perturbation (timescale separation) principle in a multiple-timescale nested-loop architecture. Theoretical analysis is presented to justify the design rationale. It relates the ratio of timescale separation between the inner and outer loop (singular perturbation) to the phase margin of the outer-loop (perturbed) system, which is important in its own right. Simulation studies on tailwind, headwind, crosswind, downdraft, and updraft are presented to demonstrate the effectiveness of the proposed loss-of-control prevention strategy.

Due to high efficiency and high power density LLC resonant converters are getting very popular and are gaining more and more interest in DC to DC power conversion applications. Usually, these converters are used in low power applications, however they are very popular in high power and renewable energy applications as well as in many more applications which are affected by line or load variation. In this paper, in order to keep the output voltage regulated step by step methodology to design analog compensator is presented. This analog compensator controls the frequency of the pulses generated by voltage control oscillator (VCO) for driving the MOSFETs. For obtaining the open loop transfer function of the plant, extended describing function (EDF) method is used. The proposed compensator design is developed in MATLAB/Simulink environment and simulation results showed that the proposed compensator can adjust the output voltage level effectively for both the line and load variations.

In this paper, the control law design for flexible aircraft is discussed. First, the traditional procedure of decoupling rigid-body and aeroelastic dynamics with low-pass and notch filters is addressed, with focus on controller performance as well as the resulting stability margin issues. A procedure based on a unified formulation of the flexible aircraft dynamics for flight control law design is proposed. In this procedure, the aeroservoelastic dynamics is assessed in the loop, and the offline filtering process is avoided. The formulation is applied to the virtual aircraft generic narrow-body airliner, with improvements in closed-loop performance and stability margins.

The design of algorithms for impact time control seeks to enforce the desired final time without violating the primary requirement of the guidance process, which is achieving an acceptable miss distance. Being able to control the impact time may provide survivability against close-in weapon systems that are mounted shipboard to thwart threats such as missiles and aircraft. Usually, multi-to-one engagements are preferred to saturate such defense mechanisms. A typical solution for this requirement is a preprogrammed guidance strategy, where the launch conditions are likely to need adjusting according to the desired impact conditions. However, such a possibly manual routine might not be a straightforward task to accomplish. Thus, automatic guidance schemes to satisfy the mission criteria could be preferred by the designer. In the following two paragraphs, an overview of the guidance algorithms in the literature that focus on control of impact time will be provided. Most of these methods are effective against stationary targets; those that can be used against moving targets will be indicated.

In this study, the problem of controlling integrating and unstable systems with long time delay is analysed in the discrete-time domain for digital implementation. Based on a generalised predictor-based control structure, where the plant time delay can be taken out of the control loop for the nominal plant, an analytical controller design is proposed in terms of the delay-free part of the nominal plant model. Correspondingly, further improved control performance is obtained compared with recently developed predictor-based control methods relying on numerical computation for controller parameterisation. The load disturbance rejection controller is derived by proposing the desired closed-loop transfer function, and another one for set-point tracking is designed in terms of the H-2 optimal control performance specification. Both controllers can be tuned relatively independently in a monotonic manner, with a single adjustable parameter in each controller. By establishing the sufficient and necessary condition for holding robust stability of the closed-loop control system, tuning constraints are derived together with numerical tuning guidelines for the disturbance rejection controller. Illustrative examples taken from the literature along with temperature control tests for a crystallisation reactor are used to demonstrate the effectiveness and merit of the proposed method., This work was supported in part by the National Thousand Talents Program of China, NSF China Grants 61473054, the Fundamental Research Funds for the Central Universities of China, and the Grants TIN2014-56158-C4-4-P and PROMETEOII/2013/004 from the Spanish and Valencian Governments.

This paper deals with the speed controller design in DFIG based wind turbines, and investigates stability and performance of the drive train dynamics against different control strategies. It is shown that speed controller design based on the single mass drive train model may result in unstable mechanical modes, because it ignores the dynamics of the flexible shaft. Then, another control approach, known as feedforward compensation of the shaft torsional torque, is examined. It is shown that this control method results in poorly damped oscillations of torsional torque and turbine speed during the transient conditions. The open loop transfer function from the electromagnetic torque to the generator speed contains a dual quadratic function representing the dynamics of flexible shaft. The dual quadratic function comprises resonant and anti-resonant frequencies that greatly affect the stability of the drive train dynamics. Next, a step-by-step procedure for designing the speed controller based on the two-mass drive train model is proposed. The proposed speed controller provides stable closed loop system, zero tracking error, low-frequency disturbance rejection, and open-loop gain attenuation at the resonant frequency. At the end, performance of the proposed controller is investigated by the time domain simulations.

IMC based PID controller with lead-lag filter is designed for multivariable unstable processes. The design is based on H2 optimal closed loop transfer function for set point changes and step input disturbances. The individual controllers are designed based on the corresponding equivalent transfer function (ETF) model. Simplified decouplers are designed based on the ETF model. Two examples are considered to show the closed loop responses. The proposed method provides significantly improved closed loop performances when compared to the methods in the literature.

Nowadays, the majority of wind turbine blades are produced from composite materials which are subject to severe operational loadings. Thus, the composite material's behavior against in-service loadings is a great concern for wind turbine blade designers. This dictates the need for an experimental set-up for conducting real part experiments as similar as possible to in-service loadings. This research proposes a cost effective blade testing machine which is capable of conducting ultimate static and fatigue tests according to wind turbine blade standards. A new control unit is designed and implemented to track fatigue block loading in the frequency range of 1–3 Hz. The main focus is on designing a controller to perform desired block loading fatigue tests. The open loop transfer function is identified and the system uncertainty is calculated. PI, robust feedback and Two-Degree-of-Freedom robust controllers are designed and analyzed. Due to the poor robust performance, an adaptive feed forward controller is proposed based on the gain scheduling algorithm. Experimental results of the newly developed controller indicate a performance robustness. The proposed controller could be implemented for systems with large low frequency uncertainty at its operational frequency range, for example applications that the stiffness is variable during operation.

This paper develops a novel approach for pole placement method of discrete proportional-integral-derivative (PID) control with industrial application of Bitumen system. The approach utilizes first order discrete-time transfer function (TF) with samples time delay more than unity for tuning the PID compensators, in order to achieve a priori set point of Bitumen mixing temperature. The work also introduces the well established Ziegler Nichols (ZN) and Chien-Hrones-Reswick (CHR) tuning techniques of discrete PID control, when applied to the same TF of Bitumen system, as benchmark. Bitumen system, sited at INSUMAT Company, is considered as a demonstrator for which the discrete PID control with the novel discrete pole placement approach is applied. Here, it is required to achieve a certain temperature for the Bitumen prior to the mixing process with the additives (polymers and fillers) in order to achieve a certain properties for insulation purposes. The key factor for the mixing process is the temperature of Bitumen which should not exceed $$\pm 5\,\%$$ of the specified temperature, which ranges from 90 to $$180\,^{\circ }\hbox {C}$$ , to avoid reaching self-ignition state for the vapor inside the tank ( $$\sim $$ 220 $$\,^{\circ }\hbox {C}$$ ). This explains the avoidance of using conventional online tuning for PID compensators. Simulation results verify the applicability of the new approach and show satisfactory steady state response with very good control action when compared to the noisy control action of the ZN and CHR techniques. Finally, the paper shows successful implementation ‘onsite’ for the discrete PID control using the new approach for pole placement technique, for which all the control design criteria are verified.

Lean Premixed Pre-vaporized technology aiming at reducing nitrogen oxide emission has an inherent drawback of causing combustion instability. Model-based active controller design to suppress the unstable combustion needs the open-loop transfer function of the object which is difficult to acquire and often with inaccuracies in many ways. Desired dynamic equation based PID (DDE-PID) is a model free control strategy which requires little knowledge of the object process, and also has the advantage of limited number of parameter variables to be tuned and simplicity of tuning method. A certain DDE-PID controller is designed and a set of parameter tuning method is given and tested on a open loop transfer function obtained from real experimental data fitting. With nonlinear features like input amplitude limiting and output limiting to resemble the actual system, the simulation results are compared with two model based control strategies which has been tested in actual system and proved to be feasible. The result shows DDE-PID could achieve similar control effect with structural simplicity and tuning easiness.

This paper presents the implementation of Smith predictor structure for the control of a first order plus delay time process. Water heater for vacuum distillation apparatus is studied, the open loop transfer function shows a first order plus delay time. The control system is analyzed using open loop Bode plot and root locus method through “sisotool” in MATLAB control tool box. The Smith predictor control design carried out using MATLAB (7.11.0) command windows. The controller gain is found to be 96.3 and the integral time 256.4

Virtual absorbed energy of the piezoelectric patch actuator is a cost function for the optimal feedback gain which has been proved theoretically. Previously, simulations have shown that maximizing the virtual absorbed energy and minimizing the kinetic energy of the plate can obtain almost the same feedback gain. In this work, the performance of virtual absorbed energy is validated by experiments on the reduction of the vibration of a smart panel with decentralized control loops. Each control unit consists of a collocated piezoelectric patch actuator and accelerometer sensor with a single channel digital controller. The open loop sensor/actuator frequency response function with different physical parameters (such as dimensions of plate and actuator), has been analyzed numerically and experimentally, to enhance the stability of the control system. Since the system is not unconditionally stable, a digital phase lag compensator is designed to guarantee the stability for larger feedback gains. The stability of the multi-channel decentralized feedback control system has been assessed by the eigenvalue locus of the open loop transfer function matrix. The control effectiveness of the reduction of the panel kinetic energy has been assessed by error sensors.

A key feature of future active implants will include wireless transcutaneous energy transfer (TET). A novel closed-loop control scheme is presented here for coupled resonant tank circuits that is capable of providing stable and maximally efficient power transfer under various load and disturbance conditions as well as for varying implants. The control algorithm consists of four cascaded control loops using capacitance, frequency, and voltage as the primary control variables. The innermost, D, control loop uses the primary side voltage to control the secondary side current. The C-loop uses the excitation frequency to set the optimal working point for the TET system and the secondary side tank behavior. The secondary side tank may either act as voltage or current source dependent upon the frequency setting of the primary side. The TETs transfer function is shaped by setting the primary capacitance in the B-control loop, determining the performance and transmission efficiency. The exact positioning of primary and secondary coils is determined by an online measurement of the mutual inductance M. In this paper, the D-control loop has been both simulated and realized, for the A–C loops a proof of concept is shown.

Embedded power regulators, such as low dropout regulators (LDOs), are generally tested for DC behavior and are rarely characterized dynamically. However, LDO loop dynamics play an important role in the overall behavior of the system. Dynamic characterization of LDOs based directly on LDO specifications requires measurement of output transient response with a step input at various points in the circuit. Such characterization is both difficult and costly. Alternatively, LDOs can be characterized by measuring loop dynamics in the form of a transfer function. Since the system is highly non-linear, transfer function can be characterized around a given operating point in terms of poles and zeros. The stability of the system can be inferred from the loop transfer function. This indirect characterization is more feasible but may result in test escapes. In this paper, we investigate the dynamic LDO characterization by closed loop transfer function and evaluate the test coverage with respect to modeled faults in the circuit. We show that faults that are not detectable with DC tests only become detectable with dynamic testing. We also show that the majority of undetectable faults are redundant with regards to the overall operation in terms of step response.

Output characteristics of phase module combined three-phase single-stage PFC converter based on full-bridge structure are analyzed in detail. The module combined three-phase single-stage PFC converter is the combination of three single phase full-bridge PFC converters, whose topology and operation principle are presented. Two times line frequency output voltage ripple under balanced and unbalanced three- phase grid condition is analyzed. A comprehensive analysis of the six times line frequency output voltage ripple is done by considering the high frequency component in current. By analyzing the bandwidth of the open loop transfer function in different situations, the phase module combined PFC converter is proved to have a faster dynamic response than a single phase module. Finally, a 1.8kW prototype is built to verify the theoretical analysis.

This paper aims to add a controller to the exiting milling machining transfer function according to some design requirements, while establishing a control system based on Simulink simulation, the system corrected through Mat lab simulation. This experiment uses advanced correction methods to improve the system performance, observe its step and ramp response to determine the parameters needs be used to describe the corrector. The basic idea of this correction is use using the bodes diagrams and root locus method to check the system is stable or not through the static gain, root locus gain will be used to improve the system through the phase lead and phase lag methods, simulation analysis of the steady state error of the closed loop transfer function ramp input and the analyses of the step response of the open loop transfer function of the system overshoot will be used as good indicator to obtain the design requirements.

In this paper, small signal modeling, analysis and closed-loop control of Г-Z-Source Inverter (Г-ZSI) as a member of the magnetically coupled impedance-source converters family are investigated. The Г-ZSI is modeled using the state-space averaging method. By applying perturbations to state variables, system control and disturbance inputs, the small signal model is obtained. Using the derived small signal model and calculation of open loop transfer functions, the closed loop control strategy is designed for DC side (shoot-through duty cycle control) as well as the AC side (inverter output voltage control). The small signal model of the converter is validated through comparison of the dynamic responses analysis of the derived model and detailed electrical model simulations. Besides, closed loop simulation results are presented to evaluate the effectiveness of the control strategy. Finally, frequency response analysis is carried out to verify the dynamic performance characteristics and design limitations of the Г-ZSI. All provided simulation results and analysis approves the proposed model accuracy and control system performance.

According to the mathematical models of voltage-type PWM rectifiers under the synchronous rotating coordinate system, the power mathematical models are established based on voltage orientation. By analyzing the characteristics of the direct power control system, the double-closed loop structure with power voltage-square outer loop and power internal loop is derived in the paper. To solve the accuracy of coordinate change, the design of a single-phase voltage signal phase-locked loop is designed to obtain the accurate voltage phase. The theory is validated by MATLAB simulation experiment. The results show that the designed control system has good dynamic and static performance and can satisfy the requirements of voltage-type rectifiers.

Multivariable model predictive control is a widely used advanced process control methodology, where handling delays and constraints are its key features. However, successful implementation of model predictive control requires an appropriate tuning of the controller parameters. This paper proposes an analytical tuning approach to multivariable model predictive controllers. The considered multivariable plants are square and consist of first-order plus dead time transfer functions. Most of the existing model predictive control tuning methods are based on trial and error or numerical approaches. In the case of no active constraints, closed loop transfer function matrices are derived and decoupling conditions are addressed. For control horizon of one, analytical tuning equations and achievable performances are obtained. Finally, simulation results are used to verify the effectiveness of the proposed tuning strategy.

In this study, a new serial cascade controller design methodology is proposed. The inner-loop process is taken as a stable first-order process with time delay and the outer-loop process as an integrating or non-integrating nth-order stable process with time delay. Classical Smith predictors are used to compensate for the time delay in each loop. In the outer loop when the process order is greater than 1, the process model transfer function is decomposed into first-order transfer functions of the required quantity. Next, for each first-order transfer function, a control loop is established and then for each loop an appropriate controller is built up. The controllers are designed to provide a simplified closed-loop transfer function for the existing loop using zero pole cancellation. The decomposed first-order transfer functions results in either an integrator form or a transfer function with one real pole. The resulting controller evolves to be a proportional-type controller for the loops involving the integrator and they appear as a PI-type of controller for the loops involving the real stable pole. To illustrate the effectiveness of the proposed methodology, it is compared with another method given in the literature via simulations.

This paper presents an approach to design a measurement-based controller for induction machines. The proposed control approach is motivated by the fact that developing an appropriate mechanical model of such induction machines is a challenging task. Since our proposed control methodology is only on the basis of measured data, the controller design does not require any information about the model of the mechanical part. The control of motor drive is often based on sensorless field-oriented control techniques because of their advantages such as noise and cost reductions and high reliability. Hence, we assume here that measurements used for the controller design are collected using an estimator based on the electrical equations of the induction machine. A practical application to control the speed of an induction machine is presented to validate and demonstrate the efficiency of the proposed method.

In this paper, the proposed hardware logic type digital controller for on-board SMPS which has a very small time-delay in control loop has been described. Some experimental has been done including evaluation of load current change and frequency characteristic of open loop transfer function. These results have been revealed that the proposed circuit could be suppressed the time delay to sub - micro second order., 29th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2014; Fort Worth, TX; United States; 16 March 2014 through 20 March 2014, Applied Power Electronics Conference and Exposition (APEC), 2014 Twenty-Ninth Annual IEEE, 6803346; 2014

The scan speed of the Atomic Force Microscope (AFM) is limited by the highly resonant nature of the nanopositioner which scans the sample relative to the probe tip. Feedback control may be used to dampen the resonance; however this requires external displacement sensors which may introduce high frequency noise into the feedback loop. In this work an active piezoelectric shunt control system, which requires no external feedback sensors, is designed to damp the resonance of a high speed flexure guided nanopositioner. The shunt impedance is designed in such a way that the closed loop transfer function from applied voltage to actuator displacement is equivalent to that of a displacement feedback system using a Positive Position Feedback (PPF) controller. This impedance design is an improvement over a passive impedance in that higher damping of the resonance is achievable. AFM images of a test sample were obtained to demonstrate the reduction of image artifacts when this control technique is applied.

This paper will discuss about the proposed hard-ware logic type digital controller for on-board SMPS which has a very small time-delay in control loop. Some experimental has been done including estimation of the load current change experiment and the frequency characteristic of open loop transfer function. These result reveal the proposed circuit could be suppressed the time delay to sub-microsecond order. To use the multi-phase system reduces the output ripple., 7th International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014; Hiroshima; Japan; 18 May 2014 through 21 May 2014, 2014 International Power Electronics Conference (IPEC-Hiroshima 2014 - ECCE-ASIA), pp.2737-2744; 2014

Design of next generation aircraft/sensorcraft for improved performance, such as gust load alleviation towards aircraft stability and flutter suppression during its flight operation, may necessitate wing technology that can be controlled and manipulated by active means. Moreover, in recent years the efforts are underway to realize “Fly by Feel” concepts, which are aimed in utilizing on-board sensors (embedded) and actuators (control surfaces) of the aircraft towards the design of active control system for desired performance. This paper presents active control strategies for wings having multiple control surfaces, which are purely based upon in-flight receptance (measured) data. The proposed receptance based control approach has several advantages over the traditional state-space based control because it circumvents approximation errors in reduced order modeling; it captures the true interaction between structure and aerodynamic loads; and it requires modest size of matrices (depending upon the available number of sensors and actuators) for control gain computations. In this study, multi-input state and output feedback control strategies for active aeroelastic control using the method of receptances is developed. The control gains are computed for the extension of flutter boundaries via pole placement. At first, by using numerical receptances obtained from the aeroelastic model of a flexible wing having multiple control surfaces, the proposed methodology is demonstrated. In order to test and demonstrate the receptance method for more complex aircraft geometries, configurations and aerodynamic loading conditions, numerical receptances from Finite Element models of aircraft wings with multiple control surfaces were extracted for the proposed control design. Presented studies and control approach may become the basis for optimal placement and sizing of control surfaces in a given wing section for active aeroelactic control and enhanced flight performance.

The interconnected power systems are complex and stabilizing control design still remains challenging task. The use of wide area monitoring system (WAMS) offers an integrated measurement-based and model-based control, which suits to the operation of large electric power system (EPS), along with online analysis. This paper presents a study on fixed-order controller design for equivalent network of coherent generator in order to stabilize inter-area electromechanical oscillations in the system. Firstly, the coherent generators in each area of large EPS are determined by mutual information theory, which represents the dynamic equivalence. Then network of each area with input–output variables of the selected generator that participates dominantly is reduced to lower size by square-root variant of balanced truncation algorithm. The dynamics and important oscillation modes are verified in equivalent representation of each area. Finally a local controller (decentralized) in each coherent area and a centralized controller between two coherent areas for selected generator are designed by reducing the H ∞ norm of its closed loop transfer function as much as possible. These controllers feed supplementary control signal in addition to one fed by local conventionally tuned PSS. The decentralized controller for selected generator is fed by local bus power or generator’s speed signal. On other hand, the centralized controller uses difference of power flow/speed of generators as input signal to dampen the oscillations between equivalent networks of two areas. The simulation results reveal effective damping of power/speed oscillations achieved by designed controller with respect to conventional PSS implemented. The robustness of controller is verified for heavy and light load operating conditions.

An alternative adaptive-optic controller, using both flow control and a phase-lock-loop control strategy, has been designed to overcome bandwidth limitations inhibiting current adaptive-optic controllers. A discrete-vortex code and weakly compressible model were used to simulate high-speed shear layer adaptive-optic corrections based upon the proposed phase-lock-loop controller given a range of upper and lower Mach numbers. The shear layer was forced at its origin, creating a region of regularized large-scale structures through which a simulated optical beam was projected. The controller applied a predicted conjugate correction to the shear layer’s emerging wavefront in a feedforward approach. The phase-lock-loop controller produces a sinusoidal signal for which the amplitude and phase are adjusted in real time to synchronize with the reference input. The controller is designed to track abrupt changes in phase or frequency. An overview of the design process is provided along with the alternative adaptive-...

Two types of guidance and control design concepts are explored: a traditional separated approach and an integrated one. Using the integrated approach, two different guidance systems are presented: a single-loop guidance law and a two-loop autopilot-guidance law. In the two-loop case, the autopilot loop is designed separately from the guidance one, but all the states are fed back into the guidance loop. It is proven that the integrated guidance laws achieve the same performance for single-input single-output systems. The performance of the three guidance laws is evaluated and compared via a thrust vector control missile. It is shown that the performance of the separated guidance law is inferior to that of the integrated laws.

The problem of designing PID type-III control loops is investigated. On a theoretical basis and if frequency domain modeling of the control loop is followed, type-III control loops are characterized by the presence of three pure integrators in the open-loop transfer function. Therefore, such a control scheme has the advantage of tracking fast reference signals since it exhibits zero steady-state position, velocity, and acceleration error. This advantage is considered critical in many industry applications, i.e., control of electrical motor drives and control of power converters, since it allows the output variable, i.e., current or speed, to track perfectly step, ramp, and parabolic reference signals. The proposed PID control law has the following characteristics: 1) it consists of analytical expressions that involve all modeled process parameters; 2) it can be straightforwardly applied to any process regardless of its complexity since, for its development, a generalized transfer function process model is employed consisting of n poles and m zeros plus unknown time delay d; and 3) it allows for accurate investigation of the performance of the control action to exogenous and internal disturbances in the control loop and investigation of different operating points. For justifying the potential of the proposed control law, several examples of process models met in many industry applications are investigated.

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.

The paper presents a PWM control system of a sinusoidal voltage as output of a single-phase inverter with resistive load and LC low-pass filter. First the PWM control for a sinusoidal voltage and the control loop optimization via modulus criterion for step input signal are discussed, further analyzing the stationary error for a sinusoidal signal. This error can be reduced to zero by introducing a resonant element in the control loop. A new method of introducing a resonant element is proposed, such that the open loop transfer function of the system equals the transfer function derived from the modulus criterion multiplied by a resonant element and added by one or two compensating zeros. The presented method is confirmed by simulation results.

An attempt is made to design the centralized controller based on the inverted decoupling structure (CCID) for non-square (nxm) processes with multiple time delays. To avoid the Moore-Penrose pseudo-inverse of the nominal plant with multiple time delays and Maclaurin series approximation, a centralized controller is decomposed into two components using inverted decoupling structure. The two components of the centralized controller (Gd, Go) is found through analytical method without taking pseudo-inverse of the nominal plant transfer function with multiple time delay. Here centralized controller is designed based on the desired closed loop transfer function matrix. Simulation studies demonstrate the effectiveness and simplicity of this method.

This paper will discuss about the proposed hardware logic type digital controller for on-board SMPS which has a very small time-delay in control loop. Experimental results of the load current change experiment and the frequency characteristic of open loop transfer function has been described respectively. These results reveal the validity of the proposed technique., 2013 15th European Conference on Power Electronics and Applications, EPE 2013; Lille; France; 2 September 2013 through 6 September 2013, Power Electronics and Applications (EPE), 2013 15th European Conference on, pp.1-10; 2013

Flexible control is widely used in the field of robot and it is a very important platform for human-robot interaction. In this paper, a new approach is proposed for flexible control of the robot end-effector using pneumatic system. The pneumatic system model consists of proportional valves and pneumatic actuators. The friction model based on the actual system was built. The open loop transfer function of the system was built based on linear system and selected parameters were used to analyze the system preliminarily. A speed control without force feedback was used to control the pneumatic system to contact the target object and an adaptive control system was designed to compensate the friction and the uncertainty of the effective load. A cylinder with a proportional valve was used as the control objects and the control method and model are verified through simulation and experiment.

We propose a method to derive the loop gain from the open-loop and closed-loop output impedances in dc-dc buck converter. This enables to measure the loop gain without injecting a signal into feedback loop, i.e. without breaking the feedback loop; hence the proposed method can be applied for the control circuits implemented on an IC. Our simulation and experiment results show that the loop gain obtained from the proposed method matches very well with the one from the conventional method.

Discrete time robust linear quadratic Gaussian controller with loop transfer recovery (LQG/LTR) considering the augmented system with the addition of backward Euler integrator at controller output is applied to a practical quadruple tank system. The plant developed in this work is a benchmark of a multivariable two-input-two-output (TITO) system with coupled channels, frequently used in academic works, mainly due to its versatility for generating minimum phase or non-minimum phase systems and to the coupled channels characteristic. For the LQG/LTR controller, the singular values of the open loop transfer function are matched in the frequency range from zero up to the Nyquist rate using the same approach considered for continuous time system design. Simulation and practical experiments are performed in order to validate the controller design considering set-point tracking and disturbance rejection. It is possible to observe that the resulting controller performs very well tracking step and sinusoidal inputs and rejecting sinusoidal disturbances. Practical and simulated results are very similar to each other.

H∞ based sliding mode control has several advantage viz. fast response, robustness to parameter variation and disturbance rejection ability. Inverted pendulum qualifies as a benchmark system to test the suitability of controller design for under-actuated, nonlinear unstable system. In this context, H∞ based integral sliding mode controller is designed for inverted pendulum for stabilizing the system. The H∞ state feedback gains are obtained by formulating the Riccati equation. These gains stabilize not only the closed loop transfer function, which maps the performance output to the disturbance input but also the system around its unstable equilibrium point. However this will not account for parameter variation and disturbance effect. Hence, a robust integral sliding surface is constructed such that during sliding motion the closed loop system will lead to disturbance rejection. Next, the switching control law is synthesized to maintain the states on the sliding surface from the initial time. The effectiveness of the controller design is verified by considering various uncertainties.

Robust feedback control with large parameter uncertainties in a high precision stage with large sample mass variation is presented. Instead of expressing the nominal plant and its uncertainty by parametric models, they are expressed using the identified frequency response data. The open loop transfer function is mapped onto a Nyquist plot, to assess robust stability. Next, the complementary sensitivity function is derived from this data to describe tracking performance, which is verified by experiments. The advantage is that the parameter estimation step is omitted, without compromising robust stability and performance.

Buck-derived topologies are a popular alternative for the inverter stage of distributed generation systems. The lack of a grid connection places high reliability demands on the inverter controller. Dual-loop linear schemes are traditionally employed for the control of single-phase full-bridge inverters because of their simple implementation. However, the voltage loop dynamics are usually sluggish due to the requirement of making the outer loop's bandwidth much lower than the inner loop one. On the other hand, state-plane-based controllers offer fast and stable response against large signal disturbances, but constant switching frequency can only be achieved at the expense of a high computational cost. This work introduces a hybrid dual-loop control technique for inverters that combines the advantages of linear and state-plane-based controllers. The proposed dual loop scheme features a geometric-based voltage outer loop that provides fast and robust performance. The outer loop controller is complemented with a linear inner loop that ensures constant switching frequency and simple implementation. The derivation of the geometric controller is performed in the normalized state plane. Simulation and experimental results are provided in order to validate the proposed control scheme.

A new method for PI-PD controller tuning based on direct synthesis for integrating and unstable processes with time delay. Guidelines are provided for selection of the desired closed loop transfer function in the direct synthesis method and adjustable parameter ω. Design for some typical unstable processes with time delay shows that the PI-PD controller can reduce the overshoot effectively and achieve good tradeoff between dynamic performance and robustness.

The aim of the paper is to present the simple method of determining a fractional order controller to control the pump in Festo MPS® PA Compact Workstation. Transfer function of the controller follows directly from using of Bode's ideal transfer function as a reference one for the open loop system. Such systems generally are unsensitive to gain changes in the open loop. In Festo MPS® PA Compact Workstation by using a corresponding controllers a level and a flow rate can be set up as a cascade control system. The design process allows to use conventional continuous P, I, PI, PID controllers and discontinuous controllers (two-point controllers). In the presented study the fractional order controller is tested to obtain parameters controller of this system.