Fast Output Sampling Research Articles

Advanced discrete-time sliding mode control with fast output sampling and its application to buck converter

In this paper, a relative degree two (RD2) sliding variable based discrete time sliding mode control (DTSMC) is designed for a linear time invariant system when output sampling is done faster than control input computation. The RD2 framework has been established for better performance and improved robustness of the discrete time sliding mode control system. The paradigm of fast output sampling (FOS) is utilized since it allows control computation using only the sampled output information, which is important from the implementation perspective making the design practical. A formal analysis is presented to establish the range of the controller parameters for this novel combination of DTSMC with RD2 sliding variable in the FOS framework. Also, a quantitative analysis of robustness in terms of ultimate band for the RD2 approach is done and compared with that of the RD1 approach. The theory is validated in a test bench application of a buck converter for tracking voltage references utilizing the FOS paradigm. The FOS paradigm had previously not been tested in any practical system with DTSMC, and this is the first time it is presented for the dc–dc buck converter system.

Advanced Nonswitching Discrete Time Sliding Mode Control for Speed Tracking of a DC Motor

In this article, a detailed analysis of fast output sampling (FOS)-based multirate output feedback (MROF) technique is done in the context of discrete time sliding mode control (DTSMC) based on nonswitching reaching law. In addition, for better performance and improved robustness, the relative degree of the sliding variable is chosen as two instead of one. Quantitative analysis of robustness in terms of ultimate band for the relative degree two (RD2) approach is done and compared with that of relative degree one (RD1) approach. First, only RD1 and RD2 approaches are proposed for speed tracking of a dc motor under parametric uncertainty. Then the same task is done using MROF-based RD1 and RD2 approaches. The proposed work is validated experimentally and is used for tracking a reference speed of a dc motor.

Design of hybrid sliding mode controller based on fireworks algorithm for nonlinear inverted pendulum systems

The objective of this article is to optimize parameters of a hybrid sliding mode controller based on fireworks algorithm for a nonlinear inverted pendulum system. The proposed controller is a combination of two modified types of the classical sliding mode controller, namely, baseline sliding mode controller and fast output sampling discrete sliding mode controller. The simulation process is carried out with MATLAB/Simulink. The results are compared with a published hybrid method using proportional–integral–derivative and linear quadratic regulator controllers. The simulation results show a better performance of the proposed controller.

A hybrid control design of FOPID and FWA for inverted pendulum systems

Nowadays, along with the dramatic development of industrial automatic, optimization problem has been playing an important role in designing controllers for nonlinear systems. This paper proposes a hybrid control design of Fast Output Sampling Discrete Sliding Mode Control (FOSDSMC) and fractional order PID controller (FOPID) based on I ireworks algorithm (FWA) to optimize controller parameters. The hybrid controller is veriI ied on a nonlinear inverted pendulum system. The simulation of controller optimization process is carried out using MATLAB/Simulink. The results are compared with two published controllers such as a hybrid control design of PID controller and fast output sampling discrete sliding mode control, and a hybrid control conI iguration of PID and state feedback controller based on linear quadratic regulator method. The comparison results show the better performance of the proposed method.

Discrete-Time Nonlinear Control of VSC-HVDC System

Because VSC-HVDC is a kind of strong nonlinear, coupling, and multi-input multioutput (MIMO) system, its control problem is always attracting much attention from scholars. And a lot of papers have done research on its control strategy in the continuous-time domain. But the control system is implemented through the computer discrete sampling in practical engineering. It is necessary to study the mathematical model and control algorithm in the discrete-time domain. The discrete mathematical model based on output feedback linearization and discrete sliding mode control algorithm is proposed in this paper. And to ensure the effectiveness of the control system in the quasi sliding mode state, the fast output sampling method is used in the output feedback. The results from simulation experiment in MATLAB/SIMULINK prove that the proposed discrete control algorithm can make the VSC-HVDC system have good static, dynamic, and robust characteristics in discrete-time domain.

State Variables Estimation of Fuel Cell—Boost Converter System Using Fast Output Sampling Method

Estimation of state variables of a peak current mode (PCM) controlled DC-DC boost converter supplied by a PEM fuel cell is described in this paper. Since this system is highly nonlinear and non-minimum phase, its state variables are estimated by using fast output sampling method. Estimated state variables are the converter output voltage and its first derivative, and they are suitable for model reference adaptive control or sliding mode based control techniques. The estimator has been designed in a way that it gives a good estimate of the state variables in the continuous and in the discontinuous conduction mode of the converter, and in the presence of measurement and process noise caused by converter switching-mode operation. Experimental results of estimating the state variables on a 450 W boost converter supplied by the emulator of the PEM fuel cell BCS 64–32 show good results of the estimation, regardless of the conduction mode of the converter, i.e. the operating point determined by its output current.

Design of Fast Output Sampling Controller for Three-Time-Scale Systems: Application to Spatial Control of Advanced Heavy Water Reactor

This paper introduces a formulation for design of Fast Output Sampling (FOS) controllers for three-time-scale systems. It is shown that the FOS control gain for a three-time-scale system can be obtained by combining the solutions of the three subsystem problems, obtained separately. Since three smaller order subsystem problems are to be solved in lieu of one high order problem, numerical ill-conditioning is completely avoided. Techniques for block-diagonalization and composite control of a three-time-scale system are also discussed. The proposed method is applied to the problem of spatial control of advanced heavy water reactor (AHWR). The model of AHWR is decomposed into three subsystems respectively named “slow,” “fast 1,” and “fast 2,” and separate subsystem control problems are cast from which an FOS controller for the original system is derived. Efficacy of the controller thus obtained is demonstrated through dynamic simulations. The controller thus designed employs only the output information to achieve arbitrary pole placement.

State Based Functional Observer Design for Linear Uncertain Systems Using Multirate Output Sampling

In this paper a design of controller has been proposed for linear uncertain systems based on multirate output sampling for the purpose of state feedback and nullification of disturbance effect on system response. If certain conditions are satisfied, construction of proposed functional type controller require less number of output samples than any other method based on fast output sampling. The advantage of proposed method is that it can be extended to unobservable systems and avoids the boundedness constraint on disturbance. A numerical exam- ple demonstrates the procedure, superiority in terms number of required output samplings and application to unobservable systems.

Design and implementation of fast output sampling feedback control for shape memory alloy actuated structures

This paper presents the design and experimental evaluation of fast output sampling feedback controller to minimize structural vibration of a cantilever beam using Shape Memory Alloy (SMA) wires as control actuators and piezoceramics as sensor and disturbance actuator. Linear dynamic models of the smart cantilever beam are obtained using online recursive least square parameter estimation. A digital control system that consists of <TEX>$Simulink^{TM}$</TEX> modeling software and dSPACE DS1104 controller board is used for identification and control. The effectiveness of the controller is shown through simulation and experimentation by exciting the structure at resonance.

Multirate feedback control of piezoactuated structures with multisensor data fusion

This article aims in bringing out the benefits of multiSensor data fusion in controlling vibrating modes of a piezoactuated beam, using multirate output feedback control namely, periodic output feedback control and fast output sampling control. The vibrating modes are measured by two homogeneous piezoelectric sensors. The states estimated from sensor outputs using information filters are fused using information fusion. The system output is computed from the fused states and it is used to generate the controller output. The performance of the controllers for the suppression of first two modes of vibration is evaluated through simulation and in real time. Improved closed-loop performance is obtained with data fusion.

Solid Launcher Dynamical Analysis and Autopilot Design

The dynamics of a small solid launch vehicle has been investigated. This launcher consists of a liquid upper stage and three fundamental solid rocket boosters aligned in series. During the ascent flight phase, lateral jets and grid fins are adopted by the flight control system to stable the attitude of the launcher. The launcher is a slender and aerodynamically unstable vehicle with sloshing tanks. A complete set of six-degrees-of-freedom dynamic models of the launcher, incorporation its rigid body, aerodynamics, gravity, sloshing, mass change, actuator, and elastic body, is developed. Dynamic analysis results of the structural modes and the bifurcation locus are calculated on the basis of the presented models. This complete set of dynamic models is used in flight control system design. A methodology for employing numerical optimization to develop the attitude filters is presented. The design objectives include attitude tracking accuracy and robust stability with respect to rigid body dynamics, propellant slosh, and flex. Later a control approach is presented for flight control system of the launcher using both State Dependent Riccati Equation (SDRE) method and Fast Output Sampling (FOS) technique. The dynamics and kinematics for attitude stable problem are of typical nonlinear character. SDRE technique has been well applied to this kind of highly nonlinear control problems. But in practice the system states needed in the SDRE method are sometimes difficult to obtain. FOS method, which makes use of only the output samples, is combined with SDRE to accommodate the incomplete system state information. Thus, the control approach is more practical and easy to implement. The resulting autopilot can provide stable control systems for the vehicle.

Design of periodic output feedback and fast output sampling based controllers for systems with slow and fast modes

AbstractIt is well known that the straight forward application of controller design methods to two‐time‐scale systems is susceptible to numerical ill‐conditioning and stiffness problems. However, it has been demonstrated in this paper that the presence of time‐scales can be exploited for achieving better computational efficiency in case of the design of controllers based on periodic output feedback and fast output sampling principles. In particular, an approach for design of periodic output feedback and fast output sampling controllers for a two‐time‐scale system by decomposition into a slow and a fast subsystem problems, has been presented. These smaller order problems are then separately solved and the results thus obtained for the slow and fast subsystems are combined to obtain the solution of the original design problems. The procedure has been illustrated with the help of a very simplified nuclear reactor model.Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

Design of fast output sampling feedback controller for hyperthermia system via reduced order model

This paper describes the design, control and modelling of a fast output sampling feedback control technique for the hyperthermia system via reduced order model. A tumour layer surrounded by muscle layer is modelled in higher-order state space by solving bio heat transfer equation using finite difference method. The reduced model of the higher-order system is obtained using dominant eigenvalue retention and the Davison technique. A stabilising state feedback gain is obtained using aggregation technique from the reduced model. An output feedback gain which realises this state feedback gain is obtained using linear matrix inequality approach. The performance of the controller is evaluated by framing a desired trajectory which meets the goals of the control system. The closed loop and the open loop error norm are validated to prove the efficiency of the controller. This method does not need the states for feedback, and the designed controller placed in closed loop with the original system guarantees the closed loop stability. The closed-loop response of the system with tissue property variation is simulated. The simulated response shows good closed-loop stability.

Applying Optimal Sliding Mode Based Load-Frequency Control in Power Systems with Controllable Hydro Power Plants

In this paper an optimal load-frequency controller for a nonlinear power system is proposed. The mathematical model of the power system consists of one area with several power plants, a few concentrated loads and a transmission network, along with simplified models of the neighbouring areas. Firstly, a substitute linear model is derived, with its parameters being identified from the responses of the nonlinear model. That model is used for load-frequency control (LFC) algorithm synthesis, which is based on discrete-time sliding mode control. Due to a non-minimum phase behaviour of hydro power plants, full-state feedback sliding mode controller must be used. Therefore, an estimation method based on fast output sampling is proposed for estimating the unmeasured system states and disturbances. Finally, the controller parameters are optimized using a genetic algorithm. Simulation results show that the proposed control algorithm with the proposed estimation technique can be used for LFC in a nonlinear power system.

Design and experimental evaluation of simultaneous fast output sampling feedback control for smart structures

This paper presents the design and experimental implementation of simultaneous fast output sampling feedback controller to minimise structural vibration using collocated piezoelectric actuator and sensor. The linear dynamic model of piezoelectric bonded cantilever beams is obtained using online recursive least square parameter estimation. A digital control system that consists of simulink modelling software and dSPACE 1104 controller board is used for identification and control. The performance of simultaneous controller is evaluated by considering three structure models. These models are obtained by introducing parameter variation in length and mass of a single cantilever beam structure. The effectiveness of the controller is demonstrated experimentally by exciting the structures at resonance.

Static Synchronous Compensator Damping Controller Design Using Fast Output Sampling Feedback Technique

In this article, the design of a damping controller for a static synchronous compensator using a fast output sampling feedback technique is presented. The proposed technique needs only the information of locally available signals, and moreover, by this technique, a very simple controller in the form of a simple gain matrix is obtained, which is effective over a range of operating conditions. Because of these two reasons, the control system designed by the proposed technique is very easy to implement. The effectiveness of the proposed technique has been validated through detailed non-linear simulation studies on the 10-machine 39-bus New England system.

Vibration control of Timoshenko smart structures using multirate output feedback based discrete sliding mode control for SISO systems

In this paper, the modeling and design of a multirate output feedback based discrete sliding mode control scheme application for the vibration control of a smart flexible Timoshenko cantilever beam for a single input single output (SISO) case by retaining the first two dominant vibratory modes is presented. In our work, the effect of shear and axial displacement has been considered. The algorithm uses a fast output sampling based sliding mode control strategy that would avoid the use of switching in the control input and hence avoids chattering. This method does not need the measurement of the system states for feedback as it makes use of only the output samples for designing the controller. Thus, this methodology is more practical and easy to implement. Piezoelectric patches are bonded as sensor/actuator to the master structure at different locations along the length of the beam. The beam structure is modeled in the state space form using the concept of piezoelectric theory, the Timoshenko beam theory and the FEM technique and by dividing the beam into four finite elements and placing the piezoelectric sensor/actuator at one location as a collocated pair at a time, i.e., as surface mounted sensor/actuator, say, at finite element position 1 or 2 or 3 or 4, thus giving rise to four SISO models of the same smart structure plant. Controllers are designed for the above four models of the same plant by retaining the first two dominant vibratory modes. The performance of the smart system for higher modes (say three vibratory modes) is also investigated. The piezo sensor/actuator pair is moved from the free end to the fixed end of the beam. The effect of placing the sensor/actuator at various locations along the length of the beam is observed and the conclusions are drawn for the best performance (best model) and for the smallest magnitude of the control input required to control the vibrations of the smart flexible beam.

Sliding Mode Control of Gas Turbines Using Multirate-Output Feedback

The advent of electronic controllers in the field of gas turbine control has allowed the implementation of sophisticated control algorithms. The design of a control system requires accurate models of the plant to be controlled. A real-time program for the dynamic simulation of a gas turbine engine has been developed. Most of the control design techniques need the linear representation of a plant at various operating points. In this regard, the linear analysis tool box of MATLAB-SIMULINK (Anon., 2004, SIMULINK: User’s Guide, The Math Works, Inc.) has been used to obtain linear models at various operating points. The linear models are discretized at various sampling times. The algorithm for discrete sliding mode control using the output samples has been reviewed and the same has been used to develop a controller for the gas turbine engine. A fast output sampling sliding mode controller is synthesized using a linear model of the engine. The controller developed is implemented in the nonlinear model and simulation with external disturbance is carried out. The responses with and without the controller are compared. It is shown that discrete sliding mode control law can be directly obtained in terms of the output samples and immediate past control function. The control law thus obtained is of practical importance. The algorithm needs the states of the system neither for feedback purpose nor for switching function evaluation. Thus, it is easily implemented in practice. The algorithm is computationally simple and easy to implement on a gas turbine.

Modeling and FOS Feedback Based Control of SISO Intelligent Structures with Embedded Shear Sensors and Actuators

Active vibration control is an important problem in structures. The objective of active vibration control is to reduce the vibrations of a system by automatic modification of the system's structural response. In this paper, the modeling and design of a fast output sampling feedback controller for a smart flexible beam system embedded with shear sensors and actuators for SISO system using Timoshenko beam theory is proposed. FEM theory, Timoshenko beam theory and the state space techniques are used to model the aluminum cantilever beam. For the SISO case, the beam is divided into 5 finite elements and the control actuator is placed at finite element position 1, whereas the sensor is varied from position 2 to 5, i.e., from the nearby fixed end to the free end. Controllers are designed using FOS method and the performance of the designed FOS controller is evaluated for vibration control for 4 SISO models of the same plant. The effect of placing the sensor at different locations on the beam is observed and the performance of the controller is evaluated for vibration control. Some of the limitations of the Euler-Bernoulli theory such as the neglection of shear and axial displacement are being considered here, thus giving rise to an accurate beam model. Embedded shear sensors and actuators have been considered in this paper instead of the surface mounted sensors and actuators for vibration suppression because of lot of advantages. In controlling the vibration modes, the first three dominant modes of vibration of the system are considered.

Active Vibration Control of SMA Actuated Structures using Fast Output Sampling Based Sliding Mode Control

Fast Output Sampling (FOS) based discrete sliding mode control is designed for Shape Memory Alloy (SMA) actuated structures to suppress the structural vibration. For the design of discrete sliding mode control the reaching law, method proposed by W. Gao is used. The simulation results demonstrate the performance of the controller. The proposed control technique achieves good vibration suppression. This methodology is more practical and easier to implement, since the measurement or estimation of the system states is not needed for designing the controller.