Controller Gain Parameters Research Articles

Robust adaptive neural network-based trajectory tracking control approach for nonholonomic electrically driven mobile robots

This paper presents a robust intelligent controller to be applied to a class of nonholonomic electrically driven mobile robots. This class of robotic systems has an inherent sensitivity to high degree time-varying parametric uncertainties, unmodeled dynamics, and external disturbances. Furthermore, the effects of coupling terms between the mechanical subsystem and the electrical subsystem may cause severe degradations due to the time-varying variations of DC motors and mechanical structure components around their nominal values. To overcome the effects of all these quantities, the robust adaptive neural network tracking controller developed here introduces adaptive laws to estimate a local upper bound of each subsystem of the nonholonomic mobile robot, then, these laws are used on-line as controller gain parameters in order to robustly improve the transient response of the closed-loop system and reduce conservative, in the sense that the local upper bounds to characterize the corresponding uncertainties dynamics for each subsystem, initially computed based on the worse-case scenario, are not updated during the effective control of the mobile robot. In fact, even if more data become available, then they are avoided when estimating local upper bounds, and hence, the level of uncertainty is considerably decreased. According to the universal approximation theorem and the Lyapunov stability theory, the proposed intelligent controller guarantees global stability in the sense that all the states and signals of the closed-loop system, and the trajectory tracking errors are all bounded. Simulation results on two typical examples of nonholonomic electrically driven mobile robots show the effectiveness and robustness of the proposed controller.

Stability improvement of PV‐BESS diesel generator‐based microgrid with a new modified harmony search‐based hybrid firefly algorithm

Using a new improved harmony search-based hybrid firefly algorithm (IHBFA), a comprehensive controller gain parameter estimation of all distributed resources-based microgrid is proposed. To ensure a fast convergence and to endeavour less randomisation to conventional firefly algorithm (FA), diversity of population is increased by an improved harmony search (HS) algorithm. To decrease local optima searching delay, a linear incremental pitch adjustment rate and exponential decaying bandwidth is considered for proposed HS-based hybrid FA. Photovoltaic (PV), an auxiliary battery energy storage system (BESS) with the second-order phase-locked loop control, is considered as a primary DG ( DG 1) for the proposed microgrid. Pade approximation delay-based governor control is used for the diesel generator unit, considered as a secondary DG ( DG 2). The overall gain optimisation improves the dynamic stability limits by minimising low-frequency network behaviour. The effectiveness of proposed IHBFA in terms of power oscillation damping and improved stability limits is clearly demonstrated for microgrid applications.

外乱抑制FRIT法を用いたPI制御ゲインチューニングの浮体式洋上風車への応用

Floating offshore wind turbines (FOWTs) have attracted interest in recent years. FOWTs operate under irregular wind and waves, and these disturbances cause generator output fluctuation and platform motions. In this paper, a PI controller in collective blade pitch control is used to mitigate these fluctuation and motions. The PI controller gain parameters are tuned by the FRIT (Fictitious Reference Iterative Tuning) method, and we design a gain-scheduled PI controller based on tuned gains at multiple operating points. We show that the gain-scheduled PI controller improves the disturbance suppression performance.

COORDINATION CONTROLLER POWER SYSTEM IN JAVA-BALI 500 KV INTERCONECTED BASED ON BACTERIA FORAGING - PARTICLE SWARM OPTIMIZATION FOR STABILITY IMPROVEMENT

Power system stabilizer (PSS) and flexible AC transmission system (FACTS) damping controller to improve the stability of the power system has been widely used. A coordinated control method based on the combined computational evolutionary theory is proposed to overcome some of damping controllers simultaneously so as to keep the allowable level of power system damping. It works by making full use of favorable interaction between the controlling and minimizing adverse interactions so that the power system oscillations can be suppressed effectively. Proportional integral derivative (PID) controller tuning based power system stabilizer types PSS3B (PIDPSS3B), static var compensator (SVC) and automatic voltage regulator (AVR) presented in this paper. PID controller gain parameters such as proportional, integral factor, differential coefficient and get AVR selected and optimized by BF-PSOTVAC. The integral time absolut error (ITAE) standards of optimization design as objective function. The results of simulations show that performance index of system the proposed method is 42.7890. The BF-PSOTVAC method has the capability to damping optimally and suppresses error to minimum.

Design of feedback controller for TCP/AQM networks

In this paper, we propose a novel proportional-differential-type feedback controller called Novel-PD as new active queue management (AQM) to regulate the queue length with small oscillation. It measures the current queue length and uses the current queue length and differential error signals to adjust packet drop probability dynamically. We provide control theoretic analysis of system stability and develop guidelines to select control gain parameters of Novel-PD. The design of Novel-PD for TCP/AQM system is given in details. NS2 is used for conducting extensive simulation. The proposed controller is compared with random early detection (RED), random exponential marking (REM), proportional integrator (PI) and proportional derivative (PD) controller. Result shows that, Novel-PD is stable and achieves faster response in dynamic environments where number of TCP connections, bottleneck capacity, round trip time (RTT) keeps changing. The proposed controller outperforms other AQM schemes.

Active sloshing control in a smart flexible cylindrical floating roof tank

An exact three dimensional fully-coupled hydro-elastic analysis for transient liquid sloshing in a partially-filled vertically-standing flexible circular cylindrical shell container fitted with a freely floating smart piezo-sandwich thin elastic circular plate is presented. The problem formulation is based on the linear water wave theory, the classical (Kirchhoff/Sanders) thin plate and shell models, Maxwell's equations of electrodynamics, Stokes’ transformation, and eigen-function expansions in cylindrical coordinates. The control action is achieved by combined volume displacement and volume velocity feedbacks (VDF, VVF) implemented in a second order active damping (AD) compensator via two competent evolutionary heuristic optimization techniques that systematically tune the controller gain parameters while constraining the floating panel displacement and control voltage. The uncontrolled and controlled transient responses of the coupled hydro-elastic system under various external disturbances (i.e., a harmonic base excitation, a real seismic event, a severe launch vehicle liftoff event, and a distributed impulsive transverse load on the floating panel) are calculated by means of Durbin's numerical inverse Laplace transform scheme. Moreover, the free vibration characteristics of the coupled fluid/structure interaction (FSI) system are briefly studied. The superior performance of the proposed active floating roof control configuration in effective suppression of the key hydro-elastic parameters (panel displacement, and shell displacements/stresses) is demonstrated. It is also found that, in the current FSI control problem, the Multi-objective Particle Swarm Optimization (MOPSO)-based ADC outperforms the Non-dominated Sorting Genetic Algorithm (NSGA-II)-based method, in terms of convergence rate and computational effort. Limiting cases are examined and the precision of results is verified by comparisons with the existing data as well as with the results produced by a commercial finite element package.

Pattern search algorithm based automatic online parameter estimation for AGC with effects of wind power

The increasing portion of wind energy in the power system puts forward stability challenges to the power grid. With introduction of wind generating systems, maintaining constant frequency became one of the important problems taking stability into account. The system could be maintained with constant frequency with the help of controllers. The controller gains are usually designed with fixed values for various scenarios of power system which considerably vague due to existing system complexity. Also, the usage of conventional techniques consumes a lot of computational time and does not possesses accurate control gain parameters. To address the aforementioned challenges, an automatic online gain estimation algorithm by using pattern search optimization technique has been proposed in this article. This method computes the parameters on its own based on variable wind power output and controller gains will adjust automatically to achieve the best desired performance. The proposed method was tested in a modified IEEE 39 bus system for scenarios like system with 3% and 10% GRC (Generator Rate Constraint) with 10% and 20% SLP (Step Load Perturbation). Following that the system with proposed method was investigated with variable wind power and results demonstrate significant better results which comply with IEEE standards.

An integrated control and structural design approach for mesh reflector deployable space antennas

An integrated control and structural design approach for mesh reflector deployable space antennas is presented in this paper. The coupled relationship of the antenna structure, deployment trajectory, and control system is discussed, and then the integrated design model is proposed. A multi-objective function is set to simultaneously minimize the antenna mass, the impact on antenna, and the energy dissipation of control system. The cross section areas of links, Bezier control points, and controller gain parameters are selected as the design variables. With the eigenfrequency, rigidity, stability, rapidity and accuracy constraints, the optimal integrated design is achieved. The highly nonlinear characteristic of this problem is discussed and corresponding solving strategy and methodology are described. Experiments are carried out to verify the rationality and validity of the structural analysis models and the control algorithm. Numerical simulations demonstrate the feasibility of the proposed design method.

Torsional wave propagation in a circular plate of piezoelectric radial phononic crystals

Piezoelectric rings are periodically introduced and inserted in a base plate along the radial direction, forming a one-dimensional circular plate of piezoelectric radial phononic crystals (CPPRPC). The transfer matrix of the torsional wave between adjacent units is derived in cylindrical coordinates. Then, by introducing Lyapunov exponents, the phenomenon of the torsional wave band gap is analyzed with consideration of outer control. Furthermore, the effects of some factors, namely, radial span ratio, inner radius of the plate, open-circuit, and short-circuit statuses of the piezoelectric ceramics, on the torsional wave band gap are also discussed in detail. The results show that the distinct band gaps are obtained for torsional waves propagating in CPPRPC. Together with the outer control gain, structural and piezoelectric parameters have significant effects on the band gaps. In particular, middle-low frequency band gaps can be effectively obtained by rationally varying the outer active control gain.

Adaptive sliding mode synchronization for a class of fractional-order chaotic systems with disturbance

This paper studies the fractional-order disturbance observer (FODO)-based adaptive sliding mode synchronization control for a class of fractional-order chaotic systems with unknown bounded disturbances. To handle unknown disturbances, the nonlinear FODO is explored for the fractional-order chaotic system. By choosing the appropriate control gain parameter, the disturbance observer can approximate the disturbance well. On the basis of the sliding mode control technique, a simple sliding mode surface is defined. A synchronization control scheme incorporating the introduced sliding mode surface and the designed disturbance observer is then developed. Under the control of the synchronization scheme, a good synchronization performance is realized between two identical fractional-order chaotic systems with different initial conditions. Finally, the numerical simulation results illustrate the effectiveness of the developed synchronization control scheme for fractional-order chaotic systems in the presence of external disturbances.

Active Transient Sound Radiation Control from a Smart Piezocomposite Hollow Cylinder

Abstract The linear 3D piezoelasticity theory along with active damping control (ADC) strategy are applied for non-stationary vibroacoustic response suppression of a doubly fluid-loaded functionally graded piezolaminated (FGPM) composite hollow cylinder of infinite length under general time-varying excitations. The control gain parameters are identified and tuned using Genetic Algorithm (GA) with a multi-objective performance index that constrains the key elasto-acoustic system parameters and control voltage. The uncontrolled and controlled time response histories due to a pair of equal and opposite impulsive external point loads are calculated by means of Durbin’s numerical inverse Laplace transform algorithm. Numerical simulations demonstrate the superior (good) performance of the GA-optimized distributed active damping control system in effective attenuation of sound pressure transients radiated into the internal (external) acoustic space for two basic control configurations. Also, some interesting features of the transient fluid-structure interaction control problem are illustrated via proper 2D time domain images and animations of the 3D sound field. Limiting cases are considered and accuracy of the formulation is established with the aid of a commercial finite element package as well as comparisons with the current literature.

Multimode Modified Positive Position Feedback to Control a Collocated Structure

Multimode modified positive position feedback (MMPPF) is proposed to suppress vibrations at multi-resonance frequencies in flexible collocated structures. Typically, flexible structures have large numbers of active modes in low frequency bandwidths, which make them susceptible to multi-frequency resonant vibrations. Hence, it is essential for the controller to have effective suppression on all participating modes. The MMPPF controller consists of a first- and a second-order compensator for each mode, as they are all set parallel for all active modes. Because of suppression performance sensitivity to controller gain parameters, proper gain selection is essential. Here, the linear quadratic regulator (LQR) approach and a proposed method called M-norm are used for gain optimization of the MMPPF controller. The optimized controller is then evaluated experimentally using a cantilever beam, enhanced by a piezoelectric actuator. According to the obtained results, the MMPPF controller reduces vibration amplitudes to the expected lower level, under both LQR and M-norm optimization methods. In some cases, vibration amplitude at the place of piezo-actuator is reduced to even less than the vibration amplitude level of the disturbance input at clamped end.

Synchronization enhancement via an oscillatory bath in a network of self-excited cells

The possibility of using a dynamic environment to achieve and optimize phase synchronization in a network of self-excited cells with free-end boundary conditions is addressed in this paper. The dynamic environment is an oscillatory bath coupled linearly to a network of four cells. The boundaries of the stable solutions of the dynamical states as well as the ranges of coupling parameters leading to stability and instability of synchronization are determined. Numerical simulations are used to check the accuracy and to complement the result obtained from analytical treatment. The robustness of synchronization strategy is tested using a local and global injection of Gaussian white noise in the network. The control gain parameter of the bath coupling can modulate the occurrence of synchronization in the network without prior requirement of direct coupling among all the cells. The process of synchronization obtained through local injection is independent of the node at which noise is injected into the system. As compared to local injection, the global injection scheme increases the range of noise amplitude for which synchronization occurs in the network.

Voltage Tracking of a Single-phase Inverter in an Islanded Microgrid

Voltage source inverters (VSI's) are generally used to interface with the distributed generators (DG) in microgrid. The voltage quality of the network is controlled on the basis of reference voltage tracking strategy of the VSI. In this paper, mathematical formula is derived for voltage tracking strategy, and its validity and robustness are demonstrated for both steady-state and transient conditions. Furthermore, the eectiveness of various controller has been analysed on the system response, and the eects of control gain parameters on the system characteristics are studied using root locus analysis. The performance of the system is found to be eective to track the reference grid voltage (Vg*)

Distributed tracking control of second-order multi-agent systems with sampled data

This paper studies the leader–follower consensus problem of second-order multi-agent dynamical systems with fixed and stochastic switching topologies in a sampled-data setting. A distributed linear consensus protocol is designed to track an active leader, where the current position information of neighbor agents and self-velocity data are utilized. A necessary and sufficient condition is established under fixed and directed topology for reaching consensus, which depends on the sampling period and control gain parameters. A sufficient condition is obtained under the Markov switching topology case. Finally, some numerical simulations are provided to verify the effectiveness of the theoretical results.

Bounded stabilisation of stochastic port-Hamiltonian systems

This paper proposes a stochastic bounded stabilisation method for a class of stochastic port-Hamiltonian systems. Both full-actuated and underactuated mechanical systems in the presence of noise are considered in this class. The proposed method gives conditions for the controller gain and design parameters under which the state remains bounded in probability. The bounded region and achieving probability are both assignable, and a stochastic Lyapunov function is explicitly provided based on a Hamiltonian structure. Although many conventional stabilisation methods assume that the noise vanishes at the origin, the proposed method is applicable to systems under persistent disturbances.

Parametrically Excited Oscillations of Second-Order Functional Differential Equations and Application to Duffing Equations with Time Delay Feedback

We study oscillatory behaviour of a large class of second-order functional differential equations with three freedom real nonnegative parameters. According to a new oscillation criterion, we show that if at least one of these three parameters is large enough, then the main equation must be oscillatory. As an application, we study a class of Duffing type quasilinear equations with nonlinear time delayed feedback and their oscillations excited by the control gain parameter or amplitude of forcing term. Finally, some open questions and comments are given for the purpose of further study on this topic.

Line spectrum chaotification of a double-layer vibration isolation floating raft system under multi-source excitation

The line spectrum characteristics of the radiated waterborne noises of an underwater vehicle can be reconstructed using the technique of chaotification, which can improve the acoustic stealth of the underwater vehicle. According to the particular application background, in this paper we study the chaotification issue with nonlinear time-delay feedback control for a double-layer vibration isolation floating raft system under multi-source excitation. From a simplified two-dimensional floating raft system model, a chaotification method with nonlinear time-delay feedback control is presented completely. It provides a standard procedure for line spectrum chaotification design. Numerical simulation results show the feasibility of this method. Under multi-source excitation, the effects of the control gain, time-delay and feedback frequency parameters on chaotification are investigated, and discussion is also extended to the case of the single-source excitation.

Average consensus of continuous‐time multi‐agent systems with quantized communication

SUMMARYThis paper focuses on the average consensus problem of first‐order and second‐order continuous‐time multi‐agent systems with logarithmic quantized information transmission. The balanced and strongly connected digraphs are utilized to characterize the interaction topologies between agents. Based on the state estimation, distributed state updating mechanisms are introduced for every agent such that all agents’ states achieve average consensus asymptotically. By means of differential inclusion theory, we discuss the existence and convergence property of the Krasovskii solutions to the closed‐loop system models. By designing the proper control gain parameters and quantizer accuracy, two sufficient conditions are established to guarantee the achievement of average consensus. Finally, two numerical simulations are provided to illustrate the effectiveness of theoretical results. Copyright © 2013 John Wiley & Sons, Ltd.

Intentional GNSS Interference Detection and Characterization Algorithm Using AGC and Adaptive IIR Notch Filter

A Ground Based Augmentation System (GBAS) is an enabling technology for an aircraft’s precision approach based on a Global Navigation Satellite System (GNSS). However, GBAS is vulnerable to interference, so effective GNSS interference detection and mitigation methods need to be employed. In this paper, an intentional GNSS interference detection and characterization algorithm is proposed. The algorithm uses Automatic Gain Control (AGC) gain and adaptive notch filter parameters to classify types of incoming interference and to characterize them. The AGC gain and adaptive lattice IIR notch filter parameter values in GNSS receivers are examined according to interference types and power levels. Based on those data, the interference detection and characterization algorithm is developed and Monte Carlo simulations are carried out for performance analysis of the proposed method. Here, the proposed algorithm is used to detect and characterize single-tone continuous wave interference, swept continuous wave interference, and band-limited white Gaussian noise. The algorithm can be used for GNSS interference monitoring in an excessive Radio Frequency Interference environment which causes loss of receiver tracking. This interference detection and characterization algorithm will be used to enhance the interference mitigation algorithm.