System Reference Model Research Articles

ADRC and IFOC Control of a Sensorless Induction Motor Driven by a Multilevel Converter Using SVM Approach and PV Generators

This paper offers a system for an electric vehicle. It consists of digitally controlling an induction motor without using a speed sensor. The machine is powered by a five-level cascading H-bridge inverter. The SVM control principle is used to manage the status of the five-level inverter; this removes harmonics. The H-bridge inverter converter is powered by photovoltaic sources via a serial converter, using the maximum power point tracker control principle. This structure can also reduce shading losses. In the absence of a mechanical sensor, a dynamic model of the asynchronous machine is utilized with the state variables defined in the stator reference frame. The state vector consists of the components of the rotor flux and stator current. The article provides a comparison of two methods widely used on an induction motor drive. The adaptive model-reference system method and Luenberger observer are evaluated using an active control strategy to reject disturbances to minimize the impact of disturbances. The operating principles of each method are described, and the mathematical models of training systems are developed. Both methods provide a promise for high-speed estimate applications in simulation environments. The simulation results obtained show the correct operation of both observers. Perfect decoupling between the velocity and flow control loops is observed, taking into account any disturbances that may affect the system.

Real-Time Implementation of Sensorless DTC-SVM Applied to 4WDEV Using the MRAS Estimator

This article presents the DTC-SVM approach for controlling a sensorless speed induction motor. To implement this approach, a practical prototype is built using a microcontroller, an embedded GPS module, and a memory card to collect real-time data during the driving route, such as road geographical data, speed, and time. These data are then utilized in the laboratory to implement the control law (DTC-SVM) on the electric vehicle. The d-q model of the induction motor is first presented to explain the requirements for calculating the rotor speed. Then, an adaptive model reference system speed estimator is developed based on the rotor flux, along with a controller and DTC-SVM strategy, which are implemented using the dSpace 1104 board to achieve the desired performance. The simulation results demonstrate satisfactory speed regulation with the proposed system. In this study too, an electronic differential system is modeled for the four wheels of an electric vehicle equipped with an integrated motor, all controlled by the DTC-SVM strategy. Vehicle speed and electrical vehicle steering angle variations, as well as wheel speeds estimated by code system, are verified using MATLAB/Simulink simulations.

Construction and application of urban mobility diagnosis model

The scientific diagnosis of urban mobility is beneficial to urban planning to solve urban problems appropriately, especially traffic problems. The existing models for urban accessibility or mobility are confined by data sources and operation conditions. They stay on the level of the static and local analysis but lack of quantitative description of the overall mobility of the city. A standard model of urban mobility covering the node-to-node accessibility relation among all nodes in a city is proposed based on the Internet data and algorithm programs. On this basis, a reference system model is established which is based on the city center, the nearest commercial center, the nearest park and the nodes of the external traffic facilities. In the end, the downtown area of Shanghai is taken as an example and the overall mobility and spatial layout of the city are analyzed and diagnosed by using the reference system model and the network map data. The structural characteristics of the overall accessibility of the downtown area of Shanghai are revealed, such as high inside and low outside, the east–west differences, the finger radiation and other structural features. Besides, the main nodes that require to be improved for the liquidity are indicated.

Common Language for Systems by the ISO/IEC 81346 Reference Model

AbstractThis paper focuses on the practical application of system architecture modeling and reference enabling in systems engineering, introducing the fundamental principles and proof of concept. The fundamental principles are defined by ISO/IEC 81346 standard series, which provides a common language for systems across all engineering disciplines through the Reference Designation System (RDS). RDS is used to create a reference model with unambiguous identifiers representing system breakdowns in different views called aspects, allowing for clear reference designations of system elements and their relationships, complying with the basic rules of ISO 704 – Terminology work. The practical use of this system reference model is demonstrated through a selected use case: the Digital Design, Manufacturing & Services (DDMS) transformation program at AIRBUS S.A.S. (Toulouse, France). This case includes practical experience and a brief introduction to tools that assist with the usage of ontologies and terminology work in daily life.

The Recovering Stability of a Towing Taxi-Out System from a Lateral Instability with Differential Braking Perspective: Modeling and Simulation

The traditional method of taxiing for civil aircraft, which relies on their engines, may be surpassed by the new method of towing taxi-out due to its superior advantages such as reduced energy consumption, lower emissions, and higher efficiency. However, the towing taxi-out system poses a challenge to lateral stability due to the concentration of mass at the rear, leading to severe instability when turning at high speeds. To address this issue, a nonlinear civil aircraft towing and taxiing system model and a linear four-degree-of-freedom civil aircraft towing and taxiing system reference model were established using TruckSim and Matlab/Simulink software. The fuzzy proportional–integral–derivative controller was utilized, with the braking torque of each wheel serving as the control variable and the real-time yaw rate difference and its rate of change as the fuzzy control input. The controller was compared and validated with a traditional PID controller. The results of the simulation showed that the fuzzy PID control has better nonlinear characteristics and stronger adaptability to operating conditions compared to traditional PID control, providing timely, effective, adaptive, and robust control effects for the vehicle dynamics model. Under the fuzzy PID control, the peak yaw speed of the civil aircraft decreased to 10 degrees per second under double-shift conditions, representing an increase of 23.1%. Furthermore, the lateral stability and safety of the towing taxi-out system were improved, as evidenced by the reduction in the yaw rate of the tractor and civil aircraft under the hook condition. The use of this controller provides valuable technical guidance and support for the practical development and safe application of the towed glide mode.

An interaction design model for virtual reality mindfulness meditation using imagery‐based transformation and positive feedback

AbstractIn recent years, mindfulness meditation has become increasingly popular as a way to relieve negative emotions. Although many studies have shown the advantages of the most immersive virtual reality (VR) technologies to support mindfulness meditation, few have summarized a standardized process for developing a VR tool to aid mindfulness meditation. We propose an interaction design model for VR mindfulness meditation using imagery‐based transformation and positive feedback to help users quickly soothe their negative emotions. Based on the traditional mindfulness meditation model, we propose the three detailed transformational steps to build (1) an interaction guidance process, (2) an interaction experience context, and (3) an interaction feedback mechanism. We build two scenarios based on them. Our experimental results suggest that our design can effectively alleviate a user's anxiety and provide emotional relief. Our insights on the transformation model of VR mindfulness meditation can be applied in related research, providing an effective reference model for VR mindfulness meditation systems, while providing new ideas for non‐pharmacological interventions in psychotherapy.

Adaptive Control of Second-Order Safety-Critical Multiagent Systems With Nonlinear Dynamics

In this article, we propose a distributed adaptive control architecture for leader-following consensus of uncertain multiagent systems with second-order nonlinear dynamics. A nonlinear reference model system captures an ideal behavior of the agents for the leader-following consensus problem. We design a modified nonlinear reference model system and propose a distributed model reference adaptive control architecture to suppress the effects of system uncertainties without a strict knowledge of their magnitude and rate upper bounds. Consequently, each agent evolves within a (possibly different) prescribed distance from the corresponding modified reference system trajectories. Based on an input-to-state stability analysis, it is shown that the trajectories of the modified reference model system can get arbitrarily close to the trajectories of the ideal reference model system. As a result, the trajectories of the agents evolve within a user-specified prescribed distance from their ideal system trajectories, satisfying the safety constraints. The key feature of the presented control architecture in this article is the elimination of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ad hoc</i> tuning process for the adaptation rate that is conventionally required in model reference adaptive control systems to ensure safety. An illustrative numerical example finally demonstrates the efficacy of the proposed distributed adaptive control architecture.

Explainable software systems: from requirements analysis to system evaluation

The growing complexity of software systems and the influence of software-supported decisions in our society sparked the need for software that is transparent, accountable, and trustworthy. Explainability has been identified as a means to achieve these qualities. It is recognized as an emerging non-functional requirement (NFR) that has a significant impact on system quality. Accordingly, software engineers need means to assist them in incorporating this NFR into systems. This requires an early analysis of the benefits and possible design issues that arise from interrelationships between different quality aspects. However, explainability is currently under-researched in the domain of requirements engineering, and there is a lack of artifacts that support the requirements engineering process and system design. In this work, we remedy this deficit by proposing four artifacts: a definition of explainability, a conceptual model, a knowledge catalogue, and a reference model for explainable systems. These artifacts should support software and requirements engineers in understanding the definition of explainability and how it interacts with other quality aspects. Besides that, they may be considered a starting point to provide practical value in the refinement of explainability from high-level requirements to concrete design choices, as well as on the identification of methods and metrics for the evaluation of the implemented requirements.

Approximation-free control based on the bioinspired reference model for suspension systems with uncertainty and unknown nonlinearity

Uncertainty and unknown nonlinearity are often inevitable in the suspension systems, which were often solved using fuzzy logic system or neural networks. However, these methods are restricted by the structural complexity of the controller and the huge computing cost. Meanwhile, the estimation error of such approximators is affected by adopted adaptive laws and learning gains. Thus, in view of the above problem, this paper proposes the approximation-free control based on the bioinspired reference model for a class of uncertain suspension systems with unknown nonlinearity. The proposed method integrates the superior vibration suppression of the bioinspired reference model and the structural advantage of the prescribed performance function in approximation-free control. Then, the vibration suppression performance is improved, the calculation burden is relieved, and the transient performance is improved, which is analyzed theoretically in this paper to provide guidelines for the parameter setting. Finally, the simulation results validate the approach, and the comparisons show the advantages of the proposed control method in terms of good vibration suppression, fast convergence, and less calculation burden.

An experimental determination of the liquidus and a thermodynamic melt model in the CaCO3-MgCO3 binary, and modelling of carbonated mantle melting

The binary CaCO3-MgCO3 constitutes the reference model system to reconstruct the petrogenesis of carbonated rocks, and of carbonatite magmas possibly generated in the Earth's mantle. We experimentally determined the melting of aragonite and magnesite to pressures of 12 GPa, and of calcite-magnesite mixtures at 3 and 4.5 GPa, at variable Ca/(Mg + Ca) (XCa). The melting curves of aragonite, and magnesite have similar slopes, the latter melting ≈ 30 °C higher than aragonite. In the Ca-Mg binary, the minimum of the liquidus surface situates at an XCa of 0.65–0.60, at 1200 °C − 3 GPa, and 1275 °C − 4.5 GPa. Together with available data at 1 and 6 GPa, the minimum liquid composition remains approximately constant with pressure. All available experimental data are then fit by the first thermodynamic model for CaCO3-MgCO3 liquids. Surprisingly, although carbonate liquids should behave as relatively simple molten salts, the liquids display large non-ideality and a three-component, pressure dependent, asymmetric liquid solution model is required to model the liquidus surface. Attempts to use only the two end-member components fail, invariably generating a very wide magnesite-liquid loop in disagreement with the experimental evidence.The liquid model is then used to evaluate results of experimentally determined phase relationships for carbonated peridotites in CaO-MgO-SiO2-CO2 (CMS-CO2), and CaO-MgO-Al2O3-SiO2-CO2 (CMAS-CO2). Computations highlight that the liquid composition formed in a model carbonated mantle do not represent “minimum melts” but are more magnesian at high pressure. The pressure–temperature position of the solidus, as well as its dP/dT slope, including the appearance or absence of the “carbonatite ledge”, depend on bulk composition, unless truly invariant assemblages occur.

A subject-oriented reference model for Digital Twins

The term “Digital Twin” is used in context of a wide range of applications but neither research nor industry have agreed upon one singular definition. Presented here is a novel and formal, subject-oriented reference model for Digital Twin systems that does not focus on technical architectural concepts or particular implementation specific details, but rather on the general possibilities and functionalities that can be expected or missed from Digital Twins. The model depicts the interactions of a Digital Twin system with other entities (i.e. humans, IT-systems and other Digital Twin systems). The purpose of the model is to help practitioners understand and especially communicate about Digital Twins and improve their ability to assess and express their own needs and role in context of designing specific Industry 4.0 use cases accordingly.

Symbiotic Evolution of Digital Twin Systems and Dataspaces

This paper proposes to combine the concept of digital twins with the concept of dataspaces to fulfill the original expectation that a digital twin is a comprehensive virtual representation of physical assets. Based upon a terminological and conceptual discussion of digital twins and dataspaces, this paper claims that a systemic approach towards digital twin Systems is required. The key conceptual approach consists of a Reference Model for Digital Twin Systems (DTS-RM) and a hypothesis regarding a symbiotic evolution. The DTS-RM distinguishes between a digital twin back-end platform comprising the access and management of comprehensive digital twin instances and digital twin-related services, and digital twin front-end services that are tailored to the demands of applications and users. The main purpose of the back-end platform is to decouple the digital twin’s generation and management from the usage of the digital twin for applications.

A Hybrid H∞-MRAS Observer of Wind Turbines Conversion Systems based on DFIG

This study proposes the robust sensor-less advanced frequency control (robust H∞ control) of the system of wind turbine based on a doubly fed induction generator (DFIG), the power exchange between the machine stator and the network is achieved by applying the rotor of DFIG via a bidirectional converter. The purpose of the control is to regulate the stator active and reactive power produced by the DFIG using a robust H∞ controller. The Model reference and adaptive system (MRAS-Observer) uses the error between the actual and estimated values ​​(voltage/current) to construct the observed mechanical parameters (speed and position) value, this technique uses two separate models: the first is the reference model, the second is the adjustable mode. The error between these models is used by the adaptive mechanism. The adjustment mechanism is mostly a PI controller, to improve the performance and robustness of the classical MRAS observer, we replace the classical PI controller with a robust H∞ controller. The results simulations confirm the robustness of the sensorless robust H∞ control using the H∞-MRAS observer compared to conventional MRAS, which improves the quality and quantity of generated power.

Robust Iterative Learning Control for 2-D Linear Nonrepetitive Discrete Systems With Iteration-Dependent Trajectory

In the existing robust iterative learning control (ILC) for 2-D discrete systems, they typicallly require to satisfy a core hypothesis that the strict repetitiveness of tracking reference trajectory and system model should be satisfied. This paper first investigates the robustness and convergence of a P-type ILC law and a high-order ILC law for 2-D linear nonrepetitive discrete systems (LNDS) with arbitrarily bounded reference trajectory and iteration-dependent reference trajectory described by a high order internal model (HOIM) operator in iteration domain, respectively. It is theoretically proved by using the 2-D linear nonrepetitive inequalities that the ILC tracking error and the control input robustly converge to a bounded range, the bound of which depends continuously on the bounds of all the nonrepetitive uncertainties. If these uncertainties are progressively convergent along the iteration domain, a precise tracking on the 2-D reference trajectory can be achieved. Two illustrative examples are provided to demonstrate the validity of the presented ILC law. Additionally, some comparative result on the practical dynamical processes is given.

Analysis and Performance Improvement of Induction Motor drive for Traction Application

Induction motor is widely used in many fields due to its simple structure, well-grounded operation, and small capacity of precise power. The conventional traction motor drives have been observed experimentally that there is a presence of speed deviation and torque ripples. Therefore, it becomes much essential to verify the control performance of the system by including its non- linear characteristics. To overcome the disadvantages mentioned above, the parameters of an induction motor which is most efficient will be estimated. The induction motor is dynamically modelled using this estimated parameter. So the proposed system focuses on improving the performance of traction motor drive by implementing the multilevel inverter fed sensor less induction motor using modified model reference adaptive system and compared with conventional model reference system based voltage source inverter. The simulation and hardware results will be realized for proposed system and compared with conventional system.

Generic Design Methodology for Smart Manufacturing Systems from a Practical Perspective, Part I—Digital Triad Concept and Its Application as a System Reference Model

Rapidly developed information technologies (IT) have continuously empowered manufacturing systems and accelerated the evolution of manufacturing system paradigms, and smart manufacturing (SM) has become one of the most promising paradigms. The study of SM has attracted a great deal of attention for researchers in academia and practitioners in industry. However, an obvious fact is that people with different backgrounds have different expectations for SM, and this has led to high diversity, ambiguity, and inconsistency in terms of definitions, reference models, performance matrices, and system design methodologies. It has been found that the state of the art SM research is limited in two aspects: (1) the highly diversified understandings of SM may lead to overlapped, missed, and non-systematic research efforts in advancing the theory and methodologies in the field of SM; (2) few works have been found that focus on the development of generic design methodologies for smart manufacturing systems from the practice perspective. The novelty of this paper consists of two main aspects which are reported in two parts respectively. In the first part, a simplified definition of SM is proposed to unify the existing diversified expectations, and a newly developed concept named digital triad (DT-II) is adopted to define a reference model for SM. The common features of smart manufacturing systems in various applications are identified as functional requirements (FRs) in systems design. To model a system that is capable of reconfiguring itself to adapt to changes, the concept of IoDTT is proposed as a reference model for smart manufacturing systems. In the second part, these two concepts are used to formulate a system design problem, and a generic methodology, based on axiomatic design theory (ADT), is proposed for the design of smart manufacturing systems.

Robust Fuzzy Adaptive Control with MRAC Configuration for a Class of Fractional Order Uncertain Linear Systems

This paper investigates a novel robust fractional adaptive control design for a class of fractional-order uncertain linear systems. Based on the Model Reference Adaptive Control (MRAC) configuration, the objective of the proposed controller is to ensure the output of the controlled plant to track the output of a given reference model system, while maintaining the overall closed-loop stability despite external disturbances and model uncertainties. An adaptive fuzzy logic controller is employed to eliminate unknown dynamics and disturbance. Lyapunov stability analysis demonstrates and verifies the desired fractional adaptive control system stability and tracking performance. Numerical simulation results illustrate the efficiency of the proposed adaptive fuzzy control strategy to deal with uncertain and disturbed fractional-order linear systems.

A cytofluorimetric analysis of a Saccharomyces cerevisiae population cultured in a fed-batch bioreactor.

The yeast Saccharomyces cerevisiae is a reference model system and one of the widely used microorganisms in many biotechnological processes. In industrial yeast applications, combined strategies aim to maximize biomass/product yield, with the fed-batch culture being one of the most frequently used. Flow cytometry (FCM) is widely applied in biotechnological processes and represents a key methodology to monitor cell population dynamics. We propose here an application of FCM in the analysis of yeast cell cycle along the time course of a typical S. cerevisiae fed-batch culture. We used two different dyes, SYTOX Green and SYBR Green, with the aim to better define each stage of cell cycle during S. cerevisiae fed-batch culture. The results provide novel insights in the use of FCM cell cycle analysis for the real-time monitoring of S. cerevisiae bioprocesses.

On the electrochemical hydrogenation of Nb: An insight into the effect of hydrogen absorption on the kinetics of the hydrogen evolution reaction

The electrochemical hydrogenation (galvanostatic charging) and desorption (potentiostatic discharging) of Nb in an alkaline solution was investigated, using Pd as a reference model system. The phases formed during hydrogenation and those present after desorption were investigated by X-ray diffraction (XRD). The cathodic charging induced the formation of NbH0.89 and NbH2 for Nb and PdH0.6 for Pd. Nb hydrides appeared to be irreversibly formed, unlikely to the PdH0.6 that spontaneously decomposed back into Pd. The irreversible character of absorption process in Nb is likely to be related to oxide/hydroxides formation on the electrode surface in the alkaline media, which might hinder the dehydrogenation reaction. The electrochemical behavior was evaluated through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Results were analyzed according to both thermodynamic and kinetic approaches. EIS results indicated that Pd and Nb have very similar hydrogen evolution reaction (HER) kinetic parameters. A theoretical development based on the different kinetic contributions to the overall charge-transfer resistance, including the absorption step's indirect contribution, is presented.

Вдосконалення методу моделювання потоку повітряних суден за рахунок імплементації моделі генерації його випадкових елементів

The article presents the approach to improve the aircraft flow modelling method for the intelligent training system «ATC of Tower», developed by the Department of Information Technologies of the Flight Academy of the National Aviation University. The improvement concerns the aspect of automatic random data generation for the «Aircraft» class, which is the important and integral part of this system. The presence of the mechanism for generating random data in relation to aircraft with different flight performance characteristics in the stream makes it possible to supplement the system with dynamic and stochastic components. This approach ensures the variability of the air situation in the area of responsibility of the air traffic controller of the aerodrome control tower (Tower ATCO), as close as possible to real conditions, and also makes it possible to work out a qualitatively larger number of technological operations when servicing the air traffic. The approach is based on the algorithmic generator of pseudo-random numbers and logical functions. This generator randomly identifies an airline company, a type of aircraft with specific performance characteristics, which performs flight on a random route. The listed parameters are input data for the class forming the aircraft queue in the developed training system. They make it possible to recreate the situation in the area of responsibility of the air traffic controller of the aerodrome control tower and check the adequacy of the trainee reference model. The proposed improvement makes it possible to implement a mechanism for the automatic formation of the exercises with various levels of complexity, bring an intellectual component into the system, thereby providing an individual training trajectory for the training subject as a result of the interaction between the system reference and current models