System Performance Specifications Research Articles

Tracking Control of Self-Restructuring Systems: A Low-Complexity Neuroadaptive PID Approach With Guaranteed Performance.

This article investigates the tracking control problem for a class of self-restructuring systems. Different from existing studies on systems with fixed structure, this work focuses on systems with varying structures, arising from, for instance, biological self-developing, unconsciously switching, or unexpected subsystem failure. As the resultant dynamic model is complicated and uncertain, any model-based control is too costly and seldom practical. Here, we explore a nonmodel-based low-complexity proportional-integral-derivative (PID) control. Unlike traditional PID with fixed gains, the proposed one is embedded with neural-network (NN)-based self-tuning adaptive gains, where the tuning strategy is analytically built upon system stability and performance specifications, such that transient behavior and steady-state performance are ensured. Both square and nonsquare systems are addressed by using the matrix decomposition technique. The benefits and feasibility of the proposed control method are also validated and confirmed by the simulations.

Degradation Tolerant Control Learning for Discrete-Time Affine Nonlinear Systems

This paper develops a degradation tolerant optimal control in the framework of Reinforcement Learning (RL). Safety-critical and mission-critical systems require the development of new control designs that maintain system stability and performance specifications but also address incipient degradation. The aim of this work is to decelerate the speed of degradation by minimizing a cost function that includes the rate of evolution of degradation and the performance requirements. The controller is developed for discrete-time nonlinear systems affine in control, where the system's states are affected by a nonlinear degradation. Value iteration (VI) algorithm based approach is developed to find suitable approximations of both optimal control policy and optimal cost, while guaranteeing closed-loop stability and minimization of degradation rate. Offline model-based Adaptive Dynamic Programming (ADP) algorithm is developed and implemented using actor-critic structure which involves training of both actor and critic neural networks (NN). After training the actor NN with the optimal policy, the NN is implemented in real time to generate the input of the system. Simulation example shows the efficiency and feasibility of the algorithm.

New methods for proportional-integral controller design for time-delay systems

The development of structured methods for proportional-integral (PI) controller design for systems with time delay are proposed in this article. Several PI controller design methods for time-delay systems have been reported. However, combining two or more methods to form new ones have not been given serious attention. The system stability region in the controller parameters space was determined by plotting the stability boundaries. In this study, the controller gains were first obtained using genetic algorithm (GA), weighted geometric center (WGC), and centroid of convex stability region (CCSR). Thereafter, these gains were combined by finding the centroids of lines joining any of the two gain locations, and triangle whose vertices are the location of the three gains in the convex stability region, thus yielding four additional methods, M1, M2, M3, and M4. Compared to a particular existing method, some of the proposed methods yield faster response speed at the expense of reference input tracking, while the reverse is the case for others. Any of the proposed methods (M1, M2, M3, and M4) can be selected depending on the system performance specifications.

Improving the Frequency Response of Hybrid Microgrid under Renewable Sources’ Uncertainties Using a Robust LFC-Based African Vulture Optimization Algorithm

Power systems have recently faced significant challenges due to the increased penetration of renewable energy sources (RES) such as frequency deviation due to fluctuations, unpredictable nature, and uncertainty of this RES. In this paper, a cascaded controller called (1+PD)-PID is proposed to reduce the influence of RES uncertainties on the system and to maintain the system’s reliability during fluctuations. The proposed controller is a combination of (1+PD) and PID controllers in order. The output signal of the (1+PD) controller along with the frequency deviation and the power difference between adjacent areas are used as inputs to the PID controller to create the load reference signal. The parameters of the suggested controller are optimally tuned using the African Vulture Optimization Algorithm (AVOA) to ensure the best performance of the controller. A two-area interconnected system with non-reheat thermal power units combined with RES such as solar and wind energy is modeled using MATLAB/Simulink to evaluate the system response. The controller effectiveness is verified by subjecting the studied system to various types of fluctuations such as step load disturbance, variable load perturbation and RES penetration. The obtained simulation results prove that the proposed (1+PD)-PID controller in integration with AVOA offers a significant improvement in the system performance specifications. Moreover, the proposed AVOA-based (1+PD)-PID controller has proven its superiority over other comparable controllers having the least fitness function of 6.01 × 10−5.

Design, construction, and commissioning of a deployable liquid hydrogen production and fueling system for unmanned aerial systems

Liquid hydrogen has historically been limited in proximity to baseload liquefiers and research laboratories. This accessibility barrier is a primary limitation to the development of advanced aircraft and is exacerbated by recent trends in unmanned aerial systems to convert to electric propulsion systems. This article describes the design, construction, and commissioning of a self-contained, automated, and deployable liquid hydrogen production and fueling system. Housed within a mil-spec shipping container, the system utilizes a water purifier, proton exchange membrane electrolyzer, cryogenic refrigerator, and custom liquid hydrogen dewar. The system requires only water, electricity, and periodic helium purge gas input for continuous operation. Overall system performance specifications are provided. The system demonstrates the capability of field deployable hydrogen liquefiers and fueling systems.

Implementing nonuniversal features with a random matrix theory approach: Application to space-to-configuration multiplexing.

We consider the efficiency of multiplexing spatially encoded information across random configurations of a metasurface-programmable chaotic cavity in the microwave domain. The distribution of the effective rank of the channel matrix is studied to quantify the channel diversity and to assess a specific system's performance. System-specific features such as unstirred field components give rise to nontrivial interchannel correlations and need to be properly accounted for in modeling based on random matrix theory. To address this challenge, we propose a two-step hybrid approach. Based on an ensemble of experimentally measured scattering matrices for different random metasurface configurations, we first learn a system-specific pair of coupling matrix and unstirred contribution to the Hamiltonian, and then add an appropriately weighted stirred contribution. We verify that our method is capable of reproducing the experimentally found distribution of the effective rank with good accuracy. The approach can also be applied to other wave phenomena in complex media.

A simple colorimeter based on microcontrollers to detect food dyes

A simple colorimeter has been successfully designed using a microcontroller to detect food dyes. This article describes the performance specifications and design specifications of the colorimeter that was designed as a detector for food dyes using a photodiode sensor and a light emitting diode lamp as a source. System performance specifications consist of mechanical systems that are supported by electronic systems. Data collection techniques were carried out directly and indirectly. Color absorption data were measured directly using an ultraviolet-visible spectrophotometer and indirect absorption data is determined by the voltage that was processed by the microcontroller. The test was carried out by measuring 10 variations in the concentration of food dye liquid, in the range of 0.1% - 1.0%. Measurements were made with 10 repetitions. The data were analyzed in two ways, statistically and graphically. The accuracy of the colorimeter design was done by comparing it with the measurement results from the ultraviolet-visible spectrophotometer. The average percentage of errors are 1.7% and the average relative accuracy of the system is 93.3%. These results indicate that a simple colorimeter can be used to measure the concentration of food dyes quickly and with good accuracy.

Rancang Bangun Sistem Pengukuran Tekanan Udara Menggunakan DT-Sense Barometric Pressure Berbasis Internet of Things dengan Display Smartphone

Weather be a very important thing to observe. One of the weather paramaters is air pressure. The air pressure on a surface is the force given to a surface or area by the air column above the surface. This research designed an air pressure gauge using DT-Sense Barometric Pressure which used to measure the value of the air pressure based of Internet Of Things with measurement result displayed on a smartphone. For data retrieval techniques were done by directly and indirectly. The amount that carried out directly is air pressure, while the indirect amount is the precision and the accuracy of air pressure measurements. The result of this research was the system performance specifications consist of mechanical systems that were supported by electronic systems. The precision measurements were done by comparing the results from Digital Barometer with the air pressure gauge that has been made. The percentage of average erros that obtained was 0.02965%, the relative precision average on the system was 0.99955, and the precision percentage of the tool was very good at 99.995%. The accuracy measurements were done by measuring the air pressure under the same conditions. The measurements were done by 10 times with reading on a constant standard measuring tools. The average accuracy of the system was 0.99 with an average standard deviation of 0.7 and relative errors average 0.0098%.

A Randomized Algorithm for Optimal PID Controllers

A randomized algorithm is suggested for the syntheses of optimal PID controllers for MIMO coupled systems, where the optimality is with respect to the H ∞ -norm, the H 2 -norm and the LQR functional, with possible system-performance specifications defined by regional pole-placement. Other notions of optimality (e.g., mixed H 2 / H ∞ design, controller norm or controller sparsity) can be handled similarly with the suggested algorithm. The suggested method is direct and thus can be applied to continuous-time systems as well as to discrete-time systems with the obvious minor changes. The presented algorithm is a randomized algorithm, which has a proof of convergence (in probability) to a global optimum.

Analysis and Design of Improved Weighted Average Current Control Strategy for LCL-Type Grid-Connected Inverters

The LCL grid-connected inverter has the ability to attenuate the high-frequency current harmonics. However, the inherent resonance of the LCL filter affects the system stability significantly. To damp the resonance effect, the dual-loop current control can be used to stabilize the system. The grid current plus capacitor current feedback system is widely used for its better transient response and high robustness against the grid impedance variations. The weighted average current (WAC) feedback scheme is capable to provide a wider bandwidth at higher frequencies but show poor stability characteristics under weak grid scenarios. To overcome this shortcoming, the improved WAC damping method is proposed with an additional capacitor current feedback loop. In this paper, a systematic parameter design guideline for the optimal selection of the current loop proportional resonant controller and the additional capacitor current feedback coefficient are presented for the improved WAC feedback control strategy. The satisfactory range of the system control parameters can be obtained under different delay conditions to meet the system performance specifications. The improved WAC method enhances system robustness under weak grid scenarios, and the stability and robustness have been enhanced under control delay. Finally, the experimental results are presented to validate the effectiveness of the proposed improved WAC control strategy and the parameter design method.

Fourth-Generation Fan Assessment Numeration System (FANS) Design and Performance Specifications

Fourth-Generation Fan Assessment Numeration System (FANS) Design and Performance Specifications

Modeling and Control of the CSCEC Multi-Function Testing System

In order to promote the research and development on evaluating the seismic performance of structures, China State Construction Engineering Corporation (CSCEC) planned to construct a large-scale loading testing facility, the Multi-Function Testing System (MFTS). This facility can perform full-scale, real-time, 6-degree-of-freedom static and dynamic testing of rubber bearings and many types of structural components including long columns, shear walls and cross shape joints. The basic performances of the MFTS are a clearance of 9.1 m × 6.6 m × 10 m for specimen installation, maximum x-directional displacement 1500 mm, maximum y-directional velocity 1570 mm/s and maximum z-directional compressive load 108 MN. The system configuration and performance specifications of the MFTS are presented in this paper. The inverse kinematics model and the nonlinear model of the hydraulic servosystem of the MFTS are built. A modified feedback forward kinematics algorithm is developed for real-time control of the MFTS. Internal force characteristics of the loading system are analyzed. The internal force control method based on real-time solution of basis of internal force space is proposed for the system with large motion ranges. The motion controller combining position control loop and internal force control loop is developed. To meet the requirement of simultaneously imposing vertical compressive load and horizontal displacement, a mixed load and displacement controller is designed, where a direct force control loop is used to improve the response speed of the force control and reduce spatial dynamic coupling effects. Finally, a dynamic bearing testing is performed. The test results demonstrate that the system using the proposed controller has good abilities on position tracking, force balance, and load following.

A Study of H infinity and H2 synthesis for Active Vibration Control

Abstract Minimization of car vibrations has been a topic of research over the years and many control strategies have been developed. Therefore, there needs to be a method for active vibration control in cars. This paper presents two methods for designing the controller for a quarter car model which would help in minimizing car vibrations and increasing passenger comfort subjected to road disturbances. The methodologies used are H-infinity and H-2 optimal control. The main aim of this article is to design a controller to control the response of a quarter car model to various road inputs. This is a non-linear model with 2 degrees of freedom. It is linearized and modelled as a disturbance rejection (regulatory) problem wherein the effect of disturbances are minimised. Different weighing functions have been considered to take the impact of road disturbances into account. The results are compared with the Proportional Integral Derivative (PID) controller designed using the same system parameters and performance specifications. The behaviour of the open loop and closed loop system is observed by examining the impulse and frequency responses in MATLAB. A detailed discussion is done with the choice of weighing functions. It is found that the disturbance rejection techniques suggested in this paper help in improving the system response

Progress toward a DoD Ground Vehicle Tradespace and Affordability Analysis Framework

During ground system conceptual design and engineering development many tradeoff decisions are made to balance functional performance, cost, risk, robustness, reliability, interoperability, growth margin, and other life-cycle characteristics. Tradespace analysis reveals and quantifies the compound and ripple effects and interactions among performance requirements and system design options. An analytic tradespace framework is an executable model that represents the logical and causal relationships among vehicle subsystems and system performance characteristics. Logical relationships define compatibility requirements between interacting subsystems. Causal relationships quantify higher level system attributes as functions of lower level subsystem attributes. Research at the US Army, TARDEC, has been developing a generic ground system performance specification framework, and a ground system standard product classification hierarchy. The current research seeks to integrate these two frameworks with a unifying framework of the logical and causal relationships. The tradespace framework identifies the relevant subsystem attributes and how they interact to govern product performance and life-cycle characteristics, and identifies the subsystem interfaces and compatibility characteristics that constrain and enable practical ground vehicles. The objective is a qualitative and quantitative framework integrating system architecture and technology options with functional and life cycle performance to support design and performance requirement decisions. The goal is to integrate the ground system architecture and performance specification frameworks for interactive tradespace analysis and exploration. The research is motivated by, and grounded in, an understanding of the performance and affordability tradespace decisions and supporting analysis in ground vehicle development programs.

Kriging Based Surrogate Modeling for Fractional Order Control of Microgrids

This paper investigates the use of fractional order (FO) controllers for a microgrid. The microgrid employs various autonomous generation systems like wind turbine generator, solar photovoltaic, diesel energy generator, and fuel-cells. Other storage devices like the battery energy storage system and the flywheel energy storage system are also present in the power network. An FO control strategy is employed and the FO-proportional integral derivative (PID) controller parameters are tuned with a global optimization algorithm to meet system performance specifications. A kriging based surrogate modeling technique is employed to alleviate the issue of expensive objective function evaluation for the optimization based controller tuning. Numerical simulations are reported to prove the validity of the proposed methods. The results for both the FO and the integer order controllers are compared with standard evolutionary optimization techniques, and the relative merits and demerits of the kriging based surrogate modeling are discussed. This kind of optimization technique is not only limited to this specific case of microgrid control, but also can be ported to other computationally expensive power system optimization problems.

Optimum Power Transmission-Based Droop Control Design for Multi-Terminal HVDC of Offshore Wind Farms

Power generation through wind is expected to play a major role in the world's future energy portfolio. Nevertheless, wind power integration remains a challenging research area due to the special characteristics of wind power generation. Specifically, offshore wind has received significant attention worldwide due to the vast generation potential available. The electrical infrastructure of offshore wind farms is thus of significant importance. The multi-terminal HVDC solution represents a preferable solution and has shown promise in solving wind farm interconnection problems. Droop control techniques have been proposed as a means to regulate the DC voltage and facilitate the automatic coordination between different converters without the need for fast communication between units. Different methodologies have been developed to select the droop gains to satisfy the system performance specifications. In this work, a control design methodology is proposed for power sharing among the multi-terminal HVDC feeders providing that the power transmission efficiency is optimized. A simulation study on a 400-kV/1000-MW four-terminal HVDC transmission topology is conducted to ensure the validity of the proposed methodology.

Designing An Optimal Pid Controller For Control The Plans Height, Based On Control Of Autopilot By Using Evolutionary Algorithms

The dangers of poor pilot performance as well as time and place conditions, and such as low altitude and climate, damage critical aircraft control system. Mentioned factors, caused damage in control of sensitive military and research aircraft. So researchers had to find a solution for this problem. Therefore, the use of Unmanned Aircraft Vehicle or (UAV) in sensitive and important Operation is required. Furthermore, designing the controller system is one of the main discussed Dynamic issues in Flying Objects. Here, has been attempted to determine the optimal coefficients of PID1 controller in Autopilot based on Optimization Algorithm such as Evolutionary Algorithms in order to regulate and desired control on height of an Unmanned Aircraft Vehicle (UAV). The proposed Cost Function simultaneously optimized the system performance specifications. Optimization done by using Evolutionary Algorithms such as \(GA^2\), \(PSO^3\) and Social Policy Optimization Algorithm or \(ICA^4\). Finally, the system response based on Evolutionary Algorithms compared with the advantages of Classic method Optimization based on Constraints design, then you can easily decide on the superiority and being optimized of the proposed system.

Oil whip instability control using μ-synthesis technique on a magnetic actuator

Rotating machines have a wide application range and since those machines have high trust levels, several rotor vibrations control methods are investigated in order to avoid sudden cracks, improve rotor performance or even to reach higher operation speeds by controlling some instabilities, critical speeds resonances or oil whip effect. Rotor instabilities are associated to the operation speed and can have structural or dynamic sources from the shaft, bearings and foundation or even from an actuator external force. This work focuses on a strategy that uses the μ-synthesis control technique to attenuate the oil whip instability effect of flexible hydrodynamically supported rotors and allows the rotor to operate in higher speeds. For the identified rotor model and the synthesized controller applied on a magnetic actuator, the control system stability and performance specifications are analyzed with regard to the model uncertainties and μ-synthesis controlled vibration levels are compared to PID controller in vertical and horizontal directions. The performance specifications within the μ-synthesis are optimized to suppress unbalance vibration and, in order to contribute to industrial acceptance, the controller design is presented as a strategy which focuses on a design at reduced effort.

Control-oriented modelization of a satellite with large flexible appendages and use of worst-case analysis to verify robustness to model uncertainties of attitude control

The design of large space structures (LSS) requires the use of design and analysis tools that include different disciplines. For such a kind of spacecrafts it is in fact mandatory that mechanical design and guidance navigation and control (GNC) design are developed within a common framework. One of the key-points in the development of LSS is related to the dynamic phenomena. These phenomena usually lead to two different interpretations. The former one is related to the overall motion of the spacecraft, i.e., the motion of the centre of gravity and motion around the centre of gravity. The latter one is related to the local motion of the elastic elements that leads to oscillations. These oscillations have in turn a disturbing effect on the motion of the spacecraft. From an engineering perspective, the structural model of flexible spacecrafts is generally obtained via FEM involving thousands of degrees of freedom (DOFs). Many of them are not significant from the attitude control point of view. One of the procedures to reduce the structural DOFs is tied to the modal decomposition technique. In the present paper a technique to develop a control-oriented structural model will be proposed. Starting from a detailed FE model of the spacecraft and using a special modal condensation approach, a continuous model is defined. With this transformation the number of DOFs necessary to study the coupled elastic/rigid dynamic is reduced. The final dynamic model will be suitable for the control design implementation. In order to properly design a satellite controller, it is important to recall that the characteristic parameters of the satellite are uncertain. The effect that uncertainties have on control performance must be investigated. A possible solution is that, after the attitude controller is designed on the nominal model, a Verification and Validation (V&V) process is performed to guarantee a correct functionality under a large number of scenarios. The V&V process can be very lengthy and expensive: difficulty and cost do increase because of the overall system dimension that depends on the number of uncertainties. Uncertain parameters have to be parametrically investigated to determine robust performance of the control laws via gridding approaches. In particular in this paper we propose to consider two methods: (i) a conventional Monte Carlo analysis, and (ii) a worst-case analysis, i.e., an optimization process to find an estimation of the true worst-case behaviour. Both techniques allow to verify that the design is robust enough to meet the system performance specification in case of uncertainties.

The Evolution of LED Packaging: New Approaches for Solid State Lighting

The rapid evolution of solid state lighting is driving rapid and innovative approaches to LED packaging. While the bulk of LEDs are still packaged using decades old technology, the cost and performance needs of solid state lighting are forcing the development of new light emitter packaging technology, some of it being imported from more conventional electronic packaging. Concepts like wafer level packaging, chip on flex technology and SIP technology are infiltrating the LED packaging landscape, but with innovations developing from the need to simultaneously manage input power, thermal dissipation and light extraction for energy efficient lighting. Lighting cost constraints are also driving new requirements for higher packaging speeds and LED integration directly into lighting fixtures rather than through the conventional die-to-package-to-board-to-system sequence. Finally, lighting system performance specifications like intensity, color quality, glare, and beam pattern, all dependent on how light moves from inside the die to the user, are forcing new system level requirements into the LED packaging arena. This talk will discuss how the development and evolution of solid state lighting systems are working to drive innovation and evolution in the development of LED packaging materials, structures and methods. With the need for energy efficient lighting driving a rapid transition from bulbs and tubes to solid state devices, LED packaging is poised for a revolution where the conventional roles of semiconductor packaging are redefined in new and exciting ways that are needed to make solid state lighting a practical reality.