A new educational software tool for robust control design using the QFT method

We present a new educational software tool for robust control design based on the Quantitative Feedback Design (QFT) method. This is a graphical design methodology for systems with large parametric uncertainty, which has been successfully applied to many complex practical problems. The software tool is implemented in Matlab and may be used to introduce students to robust control methods via small and medium-size design applications. The software is a library of programmable M-files with open access to users and is intended as a test-bed for developing new techniques in this area and for automating parts of the design procedure, such as loop-shaping. A simple design problem is used to illustrate the main features of the software

H∞ voltage control of a direct high-frequency converter

Providing a secure power network is a demanding task but as network complexity is expected to grow with the connection of large amounts of distributed generation so the problem of integration, not just connection, of each additional generator becomes more protracted. A fundamental change to contemporary network architectures may eventually become necessary and this will provide new opportunities for power electronic converters to deliver advanced management and new power flow control features. Direct resonant converters (Dang 2005), could be used in novel devices such as the Active Transformers (Garlick 2008). The key to the successful exploitation of these devices will be their versatility, controllability and cost efficiency

AI-based actuator/sensor fault detection with low computational cost for industrial applications

A low computational cost method is proposed for detecting actuator/sensor faults. Typical model-based fault detection units for multiple sensor faults, require a bank of estimators (i.e., conventional Kalman estimators or artificial intelligence based ones). The proposed fault detection scheme uses an artificial intelligence approach for developing of a low computational power fault detection unit abbreviated as ‘iFD’. In contrast to the bank-of-estimators approach, the proposed iFD unit employs a single estimator for multiple actuator/sensor fault detection. The efficacy of the proposed fault detection scheme is illustrated through a rigorous analysis of the results for a number of sensor fault scenarios on an electromagnetic suspension system

The architecture and control of large power networks with distributed generation

This paper briefly summarises the evolution of transmission and distribution networks since the late 19th century, and explains that the introduction of significant amounts of distributed generation may bring about a future fundamental change to the network architecture. Providing a secure power network is a demanding task, but as network complexity is expected to grow with the connection of large amounts of distributed generation, so the problem of integration, not just connection, of each successive generator becomes more protracted. A fundamental change to the network architecture may eventually become necessary and a new architecture, perhaps based on power cells, containing generation, energy storage and loads has been proposed by some researchers. This paper describes a novel power cell interface. It makes the case for the conventional power transformer to be replaced by an Active Transformer, the objective being to provide a more controllable, flexible and robust connection that will facilitate greater network management and business opportunities, and new power flow control features. The Active Transformer design is based on an a.c. link system described by Thomas Lipo in 1986 and an a.c.-a.c. high-frequency direct converter design demonstrated by Dang in 2006. It consists of a resonant, supply-side converter, a high frequency transformer and a resonant, load-side converter. This paper describes a model of the Active Transformer, built in Simulink®, and presents the results of simulations that demonstrate its action to control current in a resistive load

A new educational software tool for robust control design using the QFT method

ABSTRACT We present a new educational software tool for robust control design based on the Quantitative Feedback Design (QFT) method. This is a graphical design methodology for systems with large parametric uncertainty, which has been successfully applied to many complex practical problems. The software tool is implemented in Matlab and may be used to introduce students to robust control methods via small and medium-size design applications. The software is a library of programmable M-files with open access to users and is intended as a test-bed for developing new techniques in this area and for automating parts of the design procedure, such as loop-shaping. A simple design problem is used to illustrate the main features of the software

A modular UAV hardware platform for aerial indoor navigation research and development

This study introduces a specialised hardware plat-form designed for indoor navigation, featuring a quadrotor equipped with either a NVIDIA Jetson Nano or a Z-turn Zynq onboard computer. The onboard computer communicates via ROS2 with the flight controller, the Inertial Measurement Unit (IMU), Ultra-WideBand (UWB) localisation system, stereo camera, Light Detection and Ranging (LiDAR), and ultrasonic sensors. The focus is on creating a low-cost modular Unmanned Aerial Vehicle (UAV) system adaptable to various indoor navigation applications. The modular design encompasses different onboard computer platforms and sensor configurations, allowing for easy adaptation to research experiment setups. The objective is to facilitate the transition from simulated and simplified laboratory experiments to deploying aerial robots in challenging real-world conditions. The paper explores the hardware architecture and Robot Operating System 2 (ROS2)-based communication system of the UAV and provides a weight analysis and power estimation

Type inference in flexible model-driven engineering using classification algorithms

Flexible or bottom-up model-driven engineering (MDE) is an emerging approach to domain and systems modelling. Domain experts, who have detailed domain knowledge, typically lack the technical expertise to transfer this knowledge using traditional MDE tools. Flexible MDE approaches tackle this challenge by promoting the use of simple drawing tools to increase the involvement of domain experts in the language definition process. In such approaches, no metamodel is created upfront, but instead the process starts with the definition of example models that will be used to infer the metamodel. Pre-defined metamodels created by MDE experts may miss important concepts of the domain and thus restrict their expressiveness. However, the lack of a metamodel, that encodes the semantics of conforming models has some drawbacks, among others that of having models with elements that are unintentionally left untyped. In this paper, we propose the use of classification algorithms to help with the inference of such untyped elements. We evaluate the proposed approach in a number of random generated example models from various domains. The correct type prediction varies from 23 to 100% depending on the domain, the proportion of elements that were left untyped and the prediction algorithm used

Extending William Baumol’s theory on entrepreneurship and institutions: lessons from post-Second World War Greece

This article examines William Baumol’s theory about the interaction between taxation and entrepreneurship and proposes an extension to it. The analysis shows that the traditional form of Baumol’s model, focusing mainly on the level of taxes, cannot be used in order to explain what happened in the Greek case. Utilising historical evidence from the mid 1950s to the late 1980s, this article confirms that problematic tax rules create difficulties for entrepreneurship and can lead to unproductive forms of it, as Baumol suggests. However, the focus here is on aspects of the system of taxation that Baumol’s model, examining solely tax rates and levels of taxation, neglected. It is shown that, as far as Greek entrepreneurship is concerned, the adverse effects of the system of taxation came not from the level of taxes, but mostly from a series of issues that increased its perceived unfairness and illegitimacy. Some of such issues were the complexity and frequent change of legislation, the insufficient organisation of the tax bureaus as well as the lack of adequate training and arbitrariness of the members of tax services. The evidence presented here suggests that Baumol’s model can be enriched by taking into consideration these aspects of taxation too

Optimal design of PID controllers using the QFT method

An optimisation algorithm is proposed for designing PID controllers, which minimises the asymptotic open-loop gain of a system, subject to appropriate robust stability and performance QFT constraints. The algorithm is simple and can be used to automate the loop-shaping step of the QFT design procedure. The effectiveness of the method is illustrated with an exampl