Periodic Output Feedback Control Research Articles

Event-triggered output feedback control design for polynomial fuzzy systems

This paper presents a novel approach to event-triggered output feedback control of polynomial fuzzy systems that exhibit unmeasurable system states. To stabilize the system state, a fuzzy model-based event-triggered control scheme is proposed based on output measurement information. The transmission frequency is modulated using a periodic event-trigger protocol, which is scheduled by resorting to a set of historically released packets to ensure better dynamic performance. The event-triggering condition uses the current samples to determine the next trigger and also takes into account the triggering time-dependent gain parameter, thereby significantly reducing network burden. The proposed approach ensures the existence of both polynomial controller gain and event-triggered parameters by satisfying sufficient conditions based on the sum-of-squares approach and the polynomial fitting approximation algorithm. The addressed system’s stability conditions are solved using MATLAB SOSTOOLS. Three numerical examples, including an invented pendulum model, illustrate the superiority and applicability of the methodology. The main contributions of this work are the introduction of a triggering instant dependent periodic event-triggered output feedback control design, which reduces network traffic and enhances dynamic performance. The approach is validated through numerical examples, which demonstrate its superiority and applicability.

Periodic event-triggered dynamic output feedback control for networked control systems subject to packet dropouts

This paper proposes a co-design method of dynamic output feedback control law and periodic event-triggered control (PETC) strategy to tolerate a maximum allowable number of successive packet dropouts (MANSDs) in networked control systems (NCSs). For the purpose of striking a balance between saving limited communication resources and reducing complexity of the transmission implementation, we present the periodic event-triggering mechanism (PETM), in which the triggering conditions only needs to be monitored at each event-verifying instant. In NCSs, packets often suffer from some interference in network transmission, such as packet losses. For packet dropouts, we introduce a dropout variable and model the whole closed-loop systems as a hybrid system. Furthermore, some stability conditions for co-design are given by a novel Lyapunov function and stability theorems of hybrid systems, and the explicit designs parameters of controller and triggering conditions are presented to ensure L2 stability. Finally, two illustrated examples are given to show the effectiveness of the proposed design methods.

The Discrete Load Frequency Control System Using a Robust Periodic Output Feedback Controller

The load frequency control (LFC) is a most important tool for the frequency regulation mechanism in the widely spread modern power system. The LFC system consists of a communication structure to transmit the measurement and control signal. Usually the controllers in LFC systems are designed and implemented in continuous mode of operation. This article investigates the discrete mode load frequency control (LFC) mechanism, by employing the concept of the periodic output feedback (POF)-based controller with varying input and output sampling frequencies. Both the optimal sampling frequency and the optimal POF controller gain matrix are found by using the particle swarm optimization (PSO) method. The POF-based controller is intended for usage in two-area multisource LFC systems, with varying input and output sampling frequencies. The performance analysis takes into account a variety of scenarios, including those without a conventional stabilizer, with conventional continuous and corresponding discrete mode PSS, and a proposed discrete mode POF controller. Furthermore, the efficacy of the discrete mode POF controller is evaluated on the MATLAB/Simulink platform.

Recommendations of Optimal Sampling Rates for Periodic Output Feedback Based Discrete Mode PSS

In this paper, an attempt is made to recommend the optimal sampling time period for Periodic Output Feedback (POF) based discrete mode power system stabilizer (DPSS). Various collection of input and output sampling time interval has been used in the designing of POF based DPSS. The Particle Swarm Optimization (PSO) technique is used to obtain the optimal gain matrix of the POF controller as well as the optimal sampling time intervals. The effectiveness of POF based DPSS over continuous mode lead-lag PSS is certified using small-signal stability studies. The parameters of lead-lag type continuous mode PSS is also tuned using the PSO technique. The PSS is designed using POF technique for single machine infinite bus (SMIB) system, considering a variety of sampling time intervals at input-output port. Finally, a trial is made to propose an optimum input and output sampling time period for SMIB test power system, through simulation studies.

Multivariable modelling of intelligent flexible mechanical structures using smart materials with FEM, Euler-Bernoulli beam theory, state space & multi-sensor data fusion techniques

In this research paper, the multivariable modelling of intelligent flexible mechanical structures using smart materials with Euler-Bernoulli beam theory & state space techniques is being presented with multi-sensor data fusion concept. To start with from the fundamental principles of E-B theory, a Lagrange equation of motion is obtained both for the regular beam element as well as for the PZT & PVDF sensor actuator pair. Following which, a dynamic equation of motion of the smart intelligent structure developed using the smart materials consisting of PZT& PVDF is obtained. Smart materials have got some special properties that react to the changes in their environmental conditions. This means that some of their special properties can be changed by using an external condition, such as temperature, light, pressure, electricity, voltage, pH, or chemical compounds, which could be considered as the special characteristics and this change is reversible, which can be repeated many times. The dynamic equation is transformed into a state space model with 2 inputs and 2 outputs using the concepts of state space theory in the advanced control engineering. The model is developed considering the first 2 modes of vibration, which are the most dominant modes in the vibration theory. The developed state space model is used for active vibration control. An external force of 1 N is applied at the end of the smart flexible multivariable multimodel cantilever beam after which the beam is subjected to vibrations. A Periodic Output Feedback controller can be designed and put in loop with the plant, after which the plant vibrations decays to zero in no time. The work done can also compared with others to show the authenticity or the profoundness of the methodology that is being developed by us.

Periodic event-triggered dynamic output feedback control of switched systems

This paper considers the problem of co-design of a dynamic output feedback controller and a periodic event-triggering mechanism for control of switched systems under limited communication resources. The dynamic output feedback controller is designed to utilize quantized output measurements which can reduce the load on communication; a logarithmic quantizer model is assumed. The event-triggering mechanism is designed to detect events periodically which can significantly reduce sampling frequency and preclude the occurrence of Zeno behavior due to continuous-time sampling. The governing equations of the physical system combined with the equations of the dynamic output feedback controller and the event-triggering mechanism are formulated as a switched delay system. For the closed-loop switched delay system, sufficient conditions in terms of Linear Matrix Inequalities (LMIs) are obtained to achieve exponential stability with a prescribed L2−L∞ attenuation performance with respect to an exogenous disturbance; both weighted and non-weighted performance can be achieved with the proposed approach. Tools and techniques from delay-dependent Lyapunov theory, free-weighting matrices, Singular Value Decomposition (SVD), and average dwell time for switched systems are used to obtain the main results. A synthesis procedure is provided for obtaining the dynamic output feedback controller gains, event-triggering condition parameters, and a lower bound on the average dwell time of the switching signal. Numerical simulation results on a switched boost converter circuit system are provided to evaluate the proposed design and results.

Periodic event-triggered robust output feedback control for nonlinear uncertain systems with time-varying disturbance

This paper investigates the periodic event-triggered robust output feedback control problem for a class of nonlinear uncertain systems subject to time-varying disturbance. By means of the feedback domination approach and disturbance compensation technique, a new framework of periodic event-triggered robust control strategy is developed in the form of output feedback, which encompasses a discrete-time event-triggering transmission scheme that is only intermittently monitored at sampling instants and a discrete-time output feedback controller consisting of a set of linear difference equations. The proposed robust method may reduce the communication resource utilization as compared to the non-event triggering schemes while maintaining a desirable closed-loop system performance even in the presence of a general class of time-varying disturbance and nonlinear uncertainties. The closed-loop system under the proposed control scheme is actually modeled as a hybrid system, and it is shown that the global practical stability of the closed-loop hybrid system is guaranteed by selecting a sufficiently large scaling gain and a sufficiently small sampling period. Finally, the experimental results on a DC–DC buck power converter are presented to illustrate the effectiveness of the proposed control approaches.

Discrete Wide-area Power System Damping Controller using Periodic Output Feedback

In this article, the concept of periodic output feedback is used to design a discrete mode wide-area damping controller using different sets of input and output sampling time intervals. The optimal periodic output feedback controller gain matrix along with the optimal sampling time intervals are obtained using the particle swarm optimization technique. The periodic output feedback based controller is designed for two typical test power systems—a two-area four-machine and the IEEE 39-bus 10-machine systems—with various sets of input and output sampling time intervals. The effectiveness of the periodic output feedback based wide area damping controller has been validated through non-linear simulation studies and eigenvalue analysis in the presence of signal latency. Finally, the recommended optimum input and output sampling period is also provided at the end of the article.

Modeling and Control of a Micro Flapping Wing Rotor

The system of Micro Flapping-wing Rotor to achieve the flapping and rotation motions is first introduced briefly. Then the system dynamic model which includes the flapping rotary flight aerodynamics at a low Reynolds number regime, the body dynamics, the electromagnetic actuator and the control surface is described. This model and system simulation in the preliminary design phase may provide the opportunity for designers to make fundamental design decisions early to improve the flight performance. Also, the simulator is used to study open loop flight dynamics and test a periodic proportional output feedback control law. Simulation testing shows that the control system has a good flight performance for this flapping wing rotor.

A novel adaptive force control method for IPMC manipulation

IPMC is a type of electro-active polymer material, also called artificial muscle, which can generate a relatively large deformation under a relatively low input voltage (generally speaking, less than 5 V), and can be implemented in a water environment. Due to these advantages, IPMC can be used in many fields such as biomimetics, service robots, bio-manipulation, etc. Until now, most existing methods for IPMC manipulation are displacement control not directly force control, however, under most conditions, the success rate of manipulations for tiny fragile objects is limited by the contact force, such as using an IPMC gripper to fix cells. Like most EAPs, a creep phenomenon exists in IPMC, of which the generated force will change with time and the creep model will be influenced by the change of the water content or other environmental factors, so a proper force control method is urgently needed. This paper presents a novel adaptive force control method (AIPOF control—adaptive integral periodic output feedback control), based on employing a creep model of which parameters are obtained by using the FRLS on-line identification method. The AIPOF control method can achieve an arbitrary pole configuration as long as the plant is controllable and observable. This paper also designs the POF and IPOF controller to compare their test results. Simulation and experiments of micro-force-tracking tests are carried out, with results confirming that the proposed control method is viable.

Vibration attenuation and shape control of surface mounted, embedded smart beam

Active Vibration Control (AVC) using smart structure is used to reduce the vibration of a system by automatic modification of the system structural response. AVC is widely used, because of its wide and broad frequency response range, low additional mass, high adaptability and good efficiency. A lot of research has been done on Finite Element (FE) models for AVC based on Euler Bernoulli Beam Theory (EBT). In the present work Timoshenko Beam Theory (TBT) is used to model a smart cantilever beam with surface mounted sensors / actuators. A Periodic Output Feedback (POF) Controller has been designed and applied to control the first three modes of vibration of a flexible smart cantilever beam. The difficulties encountered in the usage of surface mounted piezoelectric patches in practical situations can be overcome by the use of embedded shear sensors / actuators. A mathematical model of a smart cantilever beam with embedded shear sensors and actuators is developed. A POF Controller has been designed and applied to control of vibration of a flexible smart cantilever beam and effect of actuator location on the performance of the controller is investigated. The mathematical modeling and control of a Multiple Input multiple Output (MIMO) systems with two sensors and two actuators have also been considered.

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.

Robust dynamical compensator design for discrete-time linear periodic systems

This paper considers dynamical compensators design for purpose of pole assignment for discrete-time linear periodic systems. Similar to linear time-invariant systems, it is pointed out that the design of a periodic dynamical compensator can be converted into the design of a periodic output feedback controller for an augmented system. Utilizing the recent result on output feedback pole assignment, parametric solutions for this problem are obtained. The design approach can be used as a basis for the robust dynamical compensator design for this type of systems. Combined with a robustness index presented in this paper, robust dynamical compensator design problem is converted into a constrainted optimization problem. A numerical example is employed to illustrate the validity and feasibility of the methods.

Optimal Discrete-Time Design of Three-Axis Magnetic Attitude Control Laws

The problem of designing discrete-time attitude controllers for three-axis stabilization of magnetically actuated spacecraft is considered. Several methods are discussed and an approach to the tuning of various classes of projection-based controllers is proposed relying on periodic optimal output feedback control techniques. The main advantages of the proposed methods are discussed and illustrated in a simulation study.

Optimal periodic output feedback control: a continuous-time approach and a case study

This article deals with the problem of optimal static output feedback control of linear periodic systems in continuous time, for which a continuous-time approach, which allows to deal with both stable and unstable open loop systems, is presented. The proposed approach is tested on the problem of designing attitude control laws for a Low-Earth Orbit (LEO) satellite on the basis of feedback from a triaxial magnetometer and a set of high-precision gyros. Simulation results are used to demonstrate the feasibility of the proposed strategy and to evaluate its performance.

Experimental evaluation of periodic output feedback control for SMA actuated structures

This paper presents the design and experimental evaluation of periodic output feedback controller to minimise structural vibration of a cantilever beam using shape memory alloy (SMA) wires as control actuators and piezoceramics as sensor and disturbance actuator. Online recursive least square parameter estimation is used to obtain linear dynamic models of the smart cantilever beam. Simulink™ modelling software and dSPACE DS1104 controller board are used for identification and control. The performance of the controller is evaluated experimentally at resonance.

Design and experimental evaluation of simultaneous periodic output feedback control for piezoelectric actuated beam structure

This paper presents the design and experimental implementation of a simultaneous periodic output feedback controller to minimize 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 a cantilever beam structure of three different lengths and mass. The effectiveness of the controller is demonstrated experimentally by exciting the structures at resonance. The advantage of the simultaneous periodic output feedback controller implemented in this paper is unique in the sense that the common controller gain reduces the first two vibration modes of three plants, which is not commonly shown in the literature with other feedback controllers. From the experimental results it is observed that with the simultaneous output feedback controller the vibration reduction is approximately 75% for the first mode and 60% for the second mode for all the three plants. Copyright © 2008 John Wiley & Sons, Ltd.

Design and implementation of precise position controller of active probe of atomic force microscopy for nanomanipulation

Efficiency and accuracy of AFM-based nanomanipulation are still major problems to be solved, due to the nonlinearities and uncertainties, such as drift, creep, hysteresis, etc. The deformation of cantilevers caused by manipulation force is also one of the most major factors of nonlinearities and uncertainties. It causes difficulties in precise control of the tip position and causes the tip to miss the position of the object. In order to solve this problem, the traditional approach is to use a rigid cantilever. However, this will significantly reduce the sensitivity of force sensing during manipulation, which is essential for achieving an efficient and reliable nanomanipulation. In this paper, a kind of active AFM probe has been used to solve this problem by directly controlling the cantilever’s flexibility or rigidity during manipulation. Based on Euller-Bernoulli Model, a kind of controller of the active probe employing Periodic-Output-Feedback (POF) law is implemented. The results of simulation and experiments have demonstrated that this theoretical model and POF controller are suitable for precise position control of nanomanipulation.

Vibration Suppression of Timoshenko Beams with Embedded Piezoelectrics Using POF

Abstract —This paper deals with the design of a periodic output feedback controller for a flexible beam structure modeled with Timoshenko beam theory, Finite Element Method, State space methods and embedded piezoelectrics concept. The first 3 modes are considered in modeling the beam. The main objective of this work is to control the vibrations of the beam when subjected to an external force. Shear piezoelectric sensors and actuators are embedded into the top and bottom layers of a flexible aluminum beam structure, thus making it intelligent and self-adaptive. The composite 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. 4 state space SISO models are thus developed. Periodic Output Feedback (POF) Controllers are designed for the 4 SISO models of the same plant to control the flexural vibrations. 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. Conclusions are finally drawn.

Design of Simultaneous Periodic Output Feedback Control for Smart Structures

This paper presents the problem of modelling simultaneous periodic output feedback control design to control the first two vibration modes of a flexible smart cantilever beam. The entire structure is modeled by finite element method using a piezoelectric beam element which includes a piezoelectric sensor and actuator dynamics. Simulation results demonstrate that a single controller can be employed to control the first two vibration modes for six different sensor/actuator locations along the beam. Application of simultaneous control introduces a redundancy in smart structure control.