Design Of Control Algorithms Research Articles

Recent Advances on Anti-interference Control Strategies for Better Operation

Background: Under the influence of complex external environment and the internal parameter perturbation of the system itself, many interference problems hinder the development of the controlled object according to the predetermined trajectory. Objective: The objective of this study is to provide the corresponding anti-interference control methods for different degrees of interference and introduce their respective characteristics. Methods: This paper mainly summarizes the application examples of anti-interference control algorithms in the face of different interference problems, which are mainly divided into three categories. Especially two new concepts, whose names are composite anti-interference control and innovative anti-interference control algorithm design, are presented. At the same time, this paper not only summarizes the outstanding contribution of anti-interference control in the mechanical field, but also expounds on the application examples of coupling of anti-interference control in electrical aspect and describes the application of anti-interference control in other planets. Results: From the interference problem on the earth to the anti-interference control of outer space, the control algorithm shows the unique charm step by step. In the future, to cope with the complex and changeable environment, the anti-interference algorithm will continue to be optimized in depth, letting the control system run steadily in direction of fast, accurate and stable on the expected track. Conclusion: Anti-interference control plays an important practical role in the control of systems. Whether in the mechanical field or coupling in other aspects such as electrical, it can help the system run better according to the needs of the controller. It is effective and reasonable to combine different strategies for the systems, so that the systems are more accurate and stable.

Competent and uncomplicated PID control algorithm design expressions for controlling second order systems

Proportional-integral-derivative (PID) control algorithm with its various forms, namely P (proportional), PI (proportional-integral), PD (proportional-derivative), PID, and compensators, is considered the most applied and widely used control algorithms in industry; this is because of its simple construction, robustness and capabilities to achieve desired control over plant performance. Designing PID algorithm is accomplished with a compromise to result in an overall system responds with acceptable levels of stability, response fastness, smoothness and costs. Various PID design methodologies and expressions have been introduced in text and literature,each has its advantages, disadvantages and limitations. In the present work, a new, efficient, simple, easy to apply and linear expressions for PID algorithmP-. PI, PD, and PID modes design are derived and presented. Expressions are derived based on relating parameters of both controller and plant. The expressions are intended to control the behavior of second order systems and approximated as such systems, such that it responds with acceptable stability level, minimum possible overshoot, oscillations and steady state error. To further improve the resulted response, only one tuning parameter α, is introduced To test, analyze, and evaluate the design expressions, MATLAB/Simulink software was used. A simulation model was built by integrating the next sub-models; PID control algorithm modes, drive with limitation and saturation blocks, sensor, desired output signal generator and finally various forms of second order systems. The simulation model was developed and refined to be as close as possible to real life conditions and processing. Studying the recorded testing, graphical and numerical results show that the suggested expressions are being simple and easy to apply, and also efficient in providing better control over controlled system’s behavior in terms of response measures and performance indices.Moreover, expressions are efficient to speed up response and eliminate or reduce overshoot, rise time and settling time. Studying results show that, the overall system responds with acceptable fast response, in most cases without overshoot, oscillation and with minimum steady state error and better ISE and IAE indices values.

Lyapunov-Bregman functions for speed-gradient adaptive control of nonlinear time-varying systems

The paper is devoted to application of Bregman divergence to nonlinear adaptive control. Using Bregman divergence instead of quadratic function leads to a new class of Lyapunov functions in adaptive control that can be called Lyapunov-Bregman functions. An extended control algorithms design scheme is proposed and the properties of the designed control systems in presence of disturbances and time-varying parameters are studied. A special case of model reference adaptive control for nonlinear time-varying systems is studied based on the speed-gradient methodology.

Droop Control Algorithm Design for Power Balancing in Island Inverter Based Microgrid

Droop Control Algorithm Design for Power Balancing in Island Inverter Based Microgrid

Reduction of the CO emission from wood pellet small-scale boiler using model-based control

The paper presents new approach in reducing of the CO emission in exhaust gases from small-scale wood pellet boilers. The results are obtained by control of the airflow to the boiler using a model-based nonlinear predictive controller. The complex-structure nonlinear model designed, and simplified to the nonlinear block-oriented Hammerstein system. Finally, the Hammerstein system is used to design the nonlinear predictive controller of the combustion process. The effectiveness analysis of the designed control algorithm under operating conditions at nominal heat power shows that 1) the airflow changes to the boiler is crucial for the CO concentration in the flue gasses and 2) accurate control of the airflow may lead to a significant reduction of the CO emission without any changes of the boiler design. The paper shows that reducing CO emissions from small-scale wood pellet boilers decreased by 35–50% of the original value with low implementation cost to fit industrial scale.

Optimal structure control for earthquake resistance

This work developed the optimal and active control algorithms applicable to structural control for earthquake resistance. [Lewis, F. L., Vrabie, D. and Syrmos, V. L. [2012] Optimal Control (John Wiley & Sons)] developed a rigorous and comprehensive procedure for the derivation of an optimal control strategy based on the calculus of variation. This work is an application of Lewis’ formulation to the control of a structure for earthquake resistance. We developed a computer software which can be used to generate a dynamic model to simulate a planar structure and to construct the control law. This model also includes the tendon driven actuators, sensors and true history of earthquake excitation. The control law has two parts: (I) the feedback control which depends on the estimate state variables (Kalman filter) and (II) the record of the realistic earthquake excitation. The optimal control problem eventually leads to a two-point boundary value problem whose solution hinges on the knowledge of the entire history of the earthquake excitation. We employ true records of earthquake excitation as input. This approach enables one to solve the Riccati equations rigorously. Then, from the simulation results, one may study the relations between the control algorithm design and the characteristics (frequency, amplitude and duration) of earthquake excitation.

Interactive and Visualized Online Experimentation System for Engineering Education and Research.

Experimentation is crucial in engineering education. This work explores visualized experiments in online laboratories for teaching and learning and also research. Interactive and visualizing features, including theory-guided algorithm implementation, web-based algorithm design, customizable monitoring interface, and three-dimensional (3-D) virtual test rigs are discussed. To illustrate the features and functionalities of the proposed laboratories, three examples, including the first-order system exploration using a circuit-based system with electrical elements, web-based control algorithm design for virtual and remote experimentation, are provided. Using user-designed control algorithms, not only can simulations be conducted, but real-time experiments can also be conducted once the designed control algorithms have been compiled into executable control algorithms. The proposed online laboratory also provides a customizable monitoring interface, with which users can customize their user interface using provided widgets such as the textbox, chart, 3-D, and camera widget. Teachers can use the system for online demonstration in the classroom, students for after-class experimentation, and researchers to verify control strategies.

An Approach for Modeling and Performance Analysis of Three-Leg Landing Gear Mechanisms Based on the Virtual Equivalent Parallel Mechanism

In order to realize the safe taking-off and landing of aircrafts on unstructured terrains, the landing gear on the aircraft is required to have a terrain-adaptive function. As a kind of aircraft onboard equipment, adaptive landing gear puts forward higher requirements for its design. This article proposes a virtual equivalent parallel mechanism (VEPM) modeling and performance analysis approach for the landing gear mechanism with three kinematic branch chains. In this approach, the unstructured terrain data were mapped to a moving platform. The moving platform, virtual restrained chains and the original mechanism of the landing gear mechanism combines the VEPM. In this way, the performance analysis object of the landing gear can be converted from a single kinematic branch to the entire system. The new approach can more effectively evaluate the overall motion performance and stability performance of the landing gear, and can help improve the structural design and control algorithm design of the spacecraft landing gear.

Research on algorithms for control design of human–machine interface system using ML

Research on algorithms for control design of human–machine interface system using ML

Distributed Control of DC Microgrids for Optimal Coordination of Conventional and Renewable Generators

DC microgrids are increasing in popularity due to their simplicity and high energy efficiency, and becoming an appealing solution for the coordination of multiple conventional generators (CGs) and renewable generators (RGs). This article presents a distributed discrete-time control scheme to achieve the optimal coordination of CGs and RGs, where the generation cost of the CGs is minimized and the energy utilization of RGs is maximized. A certain degree of proportional load sharing among the RGs is also achieved to improve the stability margin and dynamic performance of dc microgrids. The designed control algorithm can maintain the bus voltages in their safe operating ranges. Besides, since the proposed control algorithm is developed in the discrete-time domain directly, it can avoid the possible instability impact of the digital implementation of control algorithms. Based on the Lyapunov analysis, the stability and convergence of the closed-loop system are analyzed rigorously. Finally, simulation results based on a detailed switch-level dc microgrid model illustrate the advantages of the proposed optimal control algorithm.

Design and implementation of active frequency control algorithm for virtual power plant based on flexible resource rapid response

At present, the power generation resources in the power system show a clean and decentralized development trend. These distributed generation resources are small in scale and lack of special regulation system. Aiming at the uncertain and intermittent output characteristics of photovoltaic distributed generation virtual power plant(VPP), this paper puts forward the scheme of active frequency response intelligent control, completes the hardware and communication design, algorithm design and software implementation. Finally, the actual engineering practice is carried out in three photovoltaic VPP in Zhongshan City, Guangdong Province, which verifies the feasibility of relevant schemes and algorithms, and provides a certain basis for the next research.

Robust consensus tracking based on hABC algorithm with parameters identification for uncertain nonlinear FOMASs with external disturbances

Distributed coordination of multi-agent systems (MASs) has been investigated for many years, and fractional-order calculus has been proved that it can model the dynamics more accurately in certain circumstances. Hence, in this paper, combining the above two aspects, the distributed coordination of fractional-order MASs (FOMASs) is researched, which is a promising topic. Besides, in this paper, the uncertainty, inherent nonlinearity and external disturbances are taken into consideration, aiming at achieving the robust consensus tracking. In particular, the uncertain parameters will be identified from an optimization perspective using artificial bee colony algorithm (ABC). Firstly, to ameliorate the performance of the standard ABC, a hybrid ABC (hABC) incorporating two groups of searching mechanisms is designed, it facilitates the identification of unknown parameters. After obtaining the identified parameters, an efficient distributed nonlinear controller is raised to fulfill the robust consensus tracking. Finally, experiments prove that the designed parameters identification approach can successfully estimate the uncertain parameters with high accuracy, besides the designed control algorithm can robustly control the FOMASs.

Optimal control of multi-task Boolean control networks via temporal logic

Boolean control networks (BCNs) with temporal logic specifications have great potential to deal with multiple tasks or complex environments. We first express the tasks of BCNs with temporal logic specifications, and transform these specifications into finite time sets dwell problems. By using the semi-tensor product (STP), some results that satisfying the specifications of temporal logic through time-varying control are obtained. Our method provides a unified framework for studying the stabilizability, synchronizability, path planning and other issues of BCNs. The controller design algorithms are then proposed to generate state sequences that fulfill the given tasks as much as possible while minimizing the cost function. Finally, two examples are given to verify the effectiveness of the theoretical results.

Mechanisms of dynamic near-wake modulation of a utility-scale wind turbine

The current study uses large eddy simulations to investigate the transient response of a utility-scale wind turbine wake to dynamic changes in atmospheric and operational conditions, as observed in previous field-scale measurements. Most wind turbine wake investigations assume quasi-steady conditions, but real wind turbines operate in a highly stochastic atmosphere, and their operation (e.g. blade pitch, yaw angle) changes constantly in response. Furthermore, dynamic control strategies have been recently proposed to optimize wind farm power generation and longevity. Therefore, improved understanding of dynamic wake behaviours is essential. First, changes in blade pitch are investigated and the wake expansion response is found to display hysteresis as a result of flow inertia. The time scales of the wake response to different pitch rates are quantified. Next, changes in wind direction with different time scales are explored. Under short time scales, the wake deflection is in the opposite direction of that observed under quasi-steady conditions. Finally, yaw changes are implemented at different rates, and the maximum inverse wake deflection and time scale are quantified, showing a clear dependence on yaw rate. To gain further physical understanding of the mechanism behind the inverse wake deflection, the streamwise vorticity in different parts of the wake is quantified. The results of this study provide guidance for the design of advanced wake flow control algorithms. The lag in wake response observed for both blade pitch and yaw changes shows that proposed dynamic control strategies must implement turbine operational changes with a time scale of the order of the rotor time scale or slower.

Novel Robust Control of Stochastic Nonlinear Switched Fuzzy Systems

This paper addresses the problem of designing novel switching control for a class of stochastic nonlinear switched fuzzy systems with time delay. Firstly, a stochastic nonlinear switched fuzzy system can precisely describe continuous and discrete dynamics as well as their interactions in the complex real-world systems. Next, novel control algorithm and switching law design of the state-dependent form are developed such that the stability is guaranteed. Since convex combination techniques are used to derive the delay independent criteria, some subsystems are allowed to be unstable. Finally, various comparisons of the elaborated examples are conducted to demonstrate the effectiveness of the proposed control design approach. All results illustrate good control performances as desired.

An Optimized Circulating Current Control Method Based on PR and PI Controller for MMC Applications

Modular multilevel converter (MMC) is an excellent topology for medium- and high-voltage applications due to its advantages over other multilevel converters. However, the control algorithm design needs meticulous attention as each submodule (SM) capacitor voltage is balanced around their reference. Any voltage inequality between the SM voltage causes the second harmonic-dominated circulating current inside the MMC. The circulating current increases the rms value of the arm currents, component ratings, and the ripple in the capacitor voltages unless it is appropriately controlled. This article proposes an optimized closed-loop circulating current control method based on PR and PI controllers in abc reference frame to prevent high circulating current inside an MMC. The proposed method suppresses the magnitude of circulating current while reducing the ripple in capacitor voltages. The ripple in the dc link voltage is also reduced without any supplementary controller under balanced and unbalanced ac grid conditions. Thus, the proposed circulating current control method reduces the conduction losses and component ratings, while the converter's efficiency and reliability increase. The method's verification is tested on a point-to-point connected MMC-based high voltage direct current system in a real-time simulator with Xilinx FPGA-based MMC emulator and arm controller.

Design and Control of A Novel Dual Function Grid-Connected Solar Inverter

In this paper, a novel dual-function grid-connected solar inverter is developed for better utility interaction applications. The proposed topology is able to inject active power, reactive power, and mitigate harmonic problems caused by non-linear loads. The proposed configuration consists of switched LC-connected inverter (SLC-CI) in parallel with static VAR compensator (SVC) to achieve the design requirements. The system description, mathematical model, control algorithm, and parameter design of the proposed system is systematically developed to ensure acceptable performance. The system performance is evaluated with both linear and non-linear loads and compared to two conventional topologies; inductive and capacitive grid connected inverters. The results demonstrate that the proposed topology have better performance, comparing to other topologies, in terms of using lower DC-bus voltage (25% less) and using around half the power rating of inverter. Moreover, the proposed double switched LC filter-connected inverter (DSLC-CI) shows its ability to work as active power filter and mitigate harmonics to acceptable level.

Real-Time Implementation of Robust Loop-Shaping Controller for a VSC HVDC System

Voltage source converter (VSC) based HVDC systems are one of the most promising technologies for high voltage bulk power transmission. The reliability and stability of a VSC-based HVDC system greatly depends on the design of a proper controller for the inner decoupled d-q current loop. One of the major causes of instability in a properly tuned controller is due to system parameter variation. This paper presents the design of a fixed parameter robust controller for the inner decoupled d-q current loop for a VSC-based HVDC system to deal with the uncertainties due to system parameter variations. The method of multiplicative uncertainty is employed in the robust design to model the variations in the system parameters. The robust control design was realized through a graphical procedure known as the loop-shaping technique. The graphical loop shaping technique is a much simpler and more straightforward method compared to the traditional H∞-based algorithms for robust controller design. The designed robust controller was experimentally verified using a real-time hardware in loop (HIL) system and was tested on a VSC HVDC system. The performance of the designed robust controller is compared to that of a traditional PI controller. It has been observed that a classical PI controller is effective for a given operating point, and its performance deteriorates when the operating point changes or when the system parameters change. The studies conducted using real-time hardware in the loop (HIL) system prove that the designed loop-shaping-based robust controller provides very good performance and stability for a wide range of system parameter variations, such as changes in resistance and the inductance of the VSC HVDC system compared to the PI controller tuned using conventional methods.

Hybrid spiral-bacterial foraging algorithm for a fuzzy control design of a flexible manipulator

A novel hybrid strategy combining a spiral dynamic algorithm (SDA) and a bacterial foraging algorithm (BFA) is presented in this article. A spiral model is incorporated into the chemotaxis of the BFA algorithm to enhance the capability of exploration and exploitation phases of both SDA and BFA with the aim to improve the fitness accuracy for the SDA and the convergence speed as well as the fitness accuracy for BFA. The proposed algorithm is tested with the Congress on Evolutionary Computation 2013 (CEC2013) benchmark functions, and its performance in terms of accuracy is compared with its predecessor algorithms. Consequently, for solving a complex engineering problem, the proposed algorithm is employed to obtain and optimise the fuzzy logic control parameters for the hub angle tracking of a flexible manipulator system. Analysis of the performance test with the benchmark functions shows that the proposed algorithm outperforms its predecessor algorithms with significant improvements and has a competitive performance compared to other well-known algorithms. In the context of solving a real-world problem, it is shown that the proposed algorithm achieves a faster convergence speed and a more accurate solution. Moreover, the time-domain response of the hub angle shows that the controller optimised by the proposed algorithm tracks the desired system response very well.

Design of the Active Control Algorithm to Reduction of the Vibrations due to Interaction High-Speed Railway Vehicle Bogie and Structure

This study analyzes excessive vibrations that occurred on the railway vehicle bogie with the computer simulation of a 4-DOF half car railway bogie dynamic physical model and Euler-Bernoulli flexible bridge beam with the simply supported boundary conditions has been introduced considering some limitations which affect problem formulation. To reduce these excessive vibrations other than conventional suspension systems such as passive one, an active suspension system has been designed and attached to the primary suspension system of the railway bogie car. Then, to control these active suspension systems, a control algorithm based on PID and SMC is considered. The coupled equation of motion of the railway bogie car and flexible Euler-Bernoulli bridge beam is obtained by Hamilton’s principle in the time domain with the active suspension system. Finally, to demonstrate the effect of the active suspension system with the PID and SMC algorithm upon these excessive vibrations, a computer simulation has been implemented, and the results are presented comparatively. Consequently, the maximum railway vehicle bogie vertical displacement and vertical acceleration have been significantly reduced.