PID-Design-Delay: A MATLAB Toolbox for Stability Parameter-Space Characterization

In this paper, the problems of stabilization for interval type-2 fuzzy systems with time-varying delay and parameter uncertainties are investigated. The objective is to design an interval type-2 fuzzy controller such that the closed-loop control system is asymptotically stable. The conditions for the existence of such a controller are delay dependent and membership function dependent in terms of linear matrix inequalities (LMIs). Based on a basic lemma, we formulate and solve the problem with more flexibility due to imperfect premise matching that the number of rules and premise membership functions are not necessary the same between the interval type-2 fuzzy model and interval type-2 fuzzy controller. A systematic approach making use of the information embedded in the lower and upper membership functions is employed to facilitate the stability analysis. A numerical example indicates the effectiveness of the derived results.

The problem of stabilization for time-delay systems with time-varying parametric perturbations is considered in this paper. Two delay-independent stability criteria and a family of memoryless state feedback controllers are proposed. The main feature of the present result is that both the criteria and the controllers do not involve any Riccati equations and are easy to he tested and be implemented. A numerical example is given to demonstrate the effectiveness of the present schemes.

Time delays are inherent in modern motion-control and electric-drive loops due to sensing, filtering, sampling and computation, communication, and actuation scheduling. When such delays are only partially known, they can markedly reduce stability margins and narrow the admissible range of state-feedback gains, especially in high-bandwidth servo applications. This paper develops a design-oriented state-feedback framework for delay-affected plants based on the Manabe polynomial concept and the Coefficient Diagram Method (CDM). The plant is represented as a chain of integrators of order two to four with an effective input gain, and the feedback gain is synthesized for the nominal delay-free model by matching a standard Manabe/CDM characteristic polynomial using the classical CDM stability-index pattern. When an unmodeled input delay is present, the closed loop is governed by a delay-dependent characteristic equation. By introducing a normalized representation, the analysis yields explicit delay-stability limits that directly translate into a lower bound on the equivalent time constant used for tuning. The degradation of the phase margin and gain margin with increasing normalized delay is quantified as design charts, and a simple phase-margin-based inequality is proposed for selecting the tuning time constant, with gain-margin checks recommended as a verification step.

Heat exchanger control trainer is a device that helps to demonstrate process control of process variables and simulates real world industrial plant system whereas the implementation of Internet of things (IoT) technology allows wireless communication. This paper describes a work to develop an IoT based heat exchanger control trainer for undergraduate process control programme with the implement Proportional-Integral-Derivative (PID) controller and fuzzy logic controller into the control trainer system together. The work started up with the development of graphical user interface (GUI) for the control trainer followed by the construction and coding of the control trainer prototype. The work has developed a heat exchanger control trainer GUI with PID and fuzzy logic controller. Information was able to be transmitted wirelessly between the GUI and control trainer prototype using Wi-Fi modules. The tested maximum signal strength was -90 dBm in 50 m when connected to indoor Wi-Fi router. The control trainer was able to achieve simple temperature feedback control of the cold side of the heat exchanger. The user manual included the basic user guide of the developed control trainer user interface. Kp, Ki, Kd of Ziegler-Nichols tuning method obtained in Offline case studies are 90,18, 112.5 whereas 7.2009, 1.1473, and 7.3163 for Cohen-Coon tuning method. The Offline test result shows a better accuracy of control using the fuzzy logic controller with -0.07% of steady-state error. Further improvement could be made to by adding cooling system into the control trainer prototype and apply modern techniques in the GUI control systems.

DC motors are the most widely used electrical motors since their ease of use. Controlling a DC motor can be done by adjusting amount of voltage and current supplied to the motor. In this design the controlling is done using proportional integral derivative (PID) control, applied for movement in XY plane. Ziegler-Nichols method is used to determine PID constants. A Raspberry Pi is used to receive and process input from the user through a graphical user interface (GUI). The data input consists of two values, i.e. position and velocity. The GUI also shows the actual coordinate position on the screen. Two motors are controlled simultaneously by the Raspberry Pi through serial peripheral interface (SPI) with one microcontroller for each motor axis. The program contains a PID control algorithm to stabilize the motor speed. The coordination of the two stabilized motor speed is used to draw a sloping line. Sloping lines are drawn in order to determine the performance of the PID controller.

Stability analysis and control design of LTI discrete-time systems by the direct use of time series data

This study presents the development of a mechatronic device for an additively manufactured Pneumatic Artificial Muscle (PAM) rehabilitation orthosis. Within this scope, the system's electro-pneumatic, mechanical, control, and software designs have been designed and implemented. The device, intended to directly interact with both patients and therapists within the bio-mechatronic process, is equipped with an intuitive graphical user interface (GUI). Utilizing a FlexSensor to measure hand flexion/extension angles, the device employs a solenoid valve, along with a trigger relay, for the inflation and deflation of the orthosis. During the electronic design phase, challenges such as interference and latency were mitigated through the implementation of isolations in the design. Employing a PD (Proportion-Derivative) control loop on the ATmega328 microcontroller, control parameters were determined empirically. By excluding a compressor pump inside the device, a lightweight, portable, and cost-effective system was accomplished. While potential enhancements discussed in the conclusion will be considered in future studies, the current prototype effectively fulfills the project objectives.

This paper considers the problem of iterative learning control design for linear systems with data quantization. It is assumed that the control input update signals are quantized before they are transmitted to the iterative learning controller. A logarithmic quantizer is used to decode the signal with a number of quantization levels. Then, a 2‐D Roesser model is established to describe the entire dynamics of the iterative learning control (ILC) system. By using the sector bound method, a sufficient asymptotic stability condition for such a 2‐D system is established and then the ILC design is given simultaneously. The result is also extended to more general cases where the system matrices contain uncertain parameters. The effectiveness of the proposed method is illustrated by a numerical example.

Mobile applications use Accessibility Services to assist users with disabilities (UWDs) in using Graphical User Interface (GUI)-based apps. However, such mobile assistive technologies are not fully secure as these can obtain data from the GUI objects, enhance this data for UWDs and transmit it to a server, thereby potentially exposing sensitive data to the external world. SEAPHISH (SEcuring Accessibility using PHISHing) is a platform aimed towards protecting against such an attack by providing defense by deception. This platform generates a phishing app i.e. an app similar to the original app installed on the user’s smartphone by extracting GUI elements and properties from the original app. A simulation for SEAPHISH can help determine the situations when an attack against a particular app can be performed with a high degree of probability. But performing effective simulations requires a fundamental understanding of the properties of GUI layouts of apps at large. This thesis aims at providing a framework that analyzes GUI layouts and their transitions using a large base of approximately three million Android apps. Various state-of-the-art tools that use different strategies in traversing layouts are explored. We created a framework where the tool Backstage performs static analysis and another tool AndroidRipper performs dynamic analysis of the layouts to help build a GUI model of the app. Using these models, we investigate the layouts of Android apps by collecting statistics on various GUI elements and screens. This investigation enhances SEAPHISH with statistically significant real-world constraints thereby providing defense against malwares and reducing the security vulnerabilities faced by UWDs.

Visual and aural are two most important channels of information processing. While most of the interaction with computers have been designed around the visual channel, there are circumstances where voice based man-machine interaction becomes preferable, and in some cases, necessary, given that voice based interaction comes naturally to humans and can be used by illiterate people easily.

The contemporary theory of metaphor defines the metaphor as a major and indispensable part of our ordinary, conventional way of conceptualizing the world and it asserts that the metaphors are used to define our relationship with the physical environment and to create a context of communication. The metaphors are the core idioms of the contemporary graphical user interface (GUI) and have an important role in helping users interact with computer systems. The desktop metaphor began with the first GUI Xerox Star and was popularized by the Lisa of Apple Macintosh. Realizing the physical-office metaphor and reflecting the familiar world of the potential users by using icons of file, folder and trashcan, the metaphor-based GUIs made it relatively easy for all to use the computer productively. Nowadays almost all of the software industry is based on the desktop metaphor paradigm. However, besides the researchers that favor the use of metaphors in the development of the system image by accentuating their assistance to learning, there are also other researchers, who reject the metaphor-based design approach in GUIs by referring to their limitations. Considering these discussions and various approaches, this study aims to make an outline of the historical development of metaphor-based GUIs; to determine the current state of metaphor within GUI design by brief examples and finally to identify future prospects and research themes. The study claims that metaphor still remains to be an inevitable part of the GUI to communicate it with the users and despite its potential limitations -rather than rejecting the metaphor totally- it seems better-to try compatible and supplementary solutions like visual formalism.

This paper is concerned with the stability analysis and H∞ fuzzy controller design of continuous-time fuzzy interconnected systems with time-varying delays. The fuzzy interconnected system consists of N interconnected time-delay Takagi-SugenoT-S fuzzy subsystems and the delay-dependent stability analysis is based on the fuzzy weighting-dependent Lyapunov-Krasovskii functionals. It is shown that the delay-dependent stability of the time-delay fuzzy interconnected systems can be established if a fuzzy weighting-dependent Lyapunov-Krasovskii functional can be constructed, and moreover, the functional can be obtained by solving a set of linear matrix inequalities LMIs that are numerically feasible. The decentralized H∞ controllers are also designed by solving a set of LMIs based on these fuzzy weighting-dependent Lyapunov-Krasovskii functionals. It is demonstrated via numerical examples that the stability and controller synthesis results based on fuzzy weighting-dependent Lyapunov-Krasovskii functionals are less conservative than those based on the common quadratic Lyapunov-Krasovskii functionals.

Mobility for graphical user interfaces (GUIs) is a challenging problem, as different GUIs need to be constructed for different device capabilities and changing context, preferences and users’ locations. GUI developers frequently create multiple user interface versions for different devices. The solution lies in using a single, abstract, user interface description that is used later to automatically generate user interfaces for different devices. Various techniques are proposed to adapt GUIs from an abstract specification to a concrete interface. Design-time techniques have the possibility of creating better performing GUIs but, in contrast to run-time techniques, lack flexibility and mobility. Run-time techniques’ mobility and autonomy can be significantly improved by using mobile agent technology and an indirect GUI generation paradigm. Using indirect generation enables analysis of computer-human interaction and application of artificial intelligence techniques to be made at run-time, increasing GUIs’ performance and usability.

Graphical User Interfaces (GUIs) are amongst the most common user interfaces, enabling interactions with applications through mouse movements and key presses. Tools for automated testing of programs through their GUI exist, however they usually rely on operating system or framework specific knowledge to interact with an application. Due to frequent operating system updates, which can remove required information, and a large variety of different GUI frameworks using unique underlying data structures, such tools rapidly become obsolete, Consequently, for an automated GUI test generation tool, supporting many frameworks and operating systems is impractical. We propose a technique for improving GUI testing by automatically identifying GUI widgets in screen shots using machine learning techniques. As training data, we generate randomized GUIs to automatically extract widget information. The resulting model provides guidance to GUI testing tools in environments not currently supported by deriving GUI widget information from screen shots only. In our experiments, we found that identifying GUI widgets in screen shots and using this information to guide random testing achieved a significantly higher branch coverage in 18 of 20 applications, with an average increase of 42.5% when compared to conventional random testing.

Dynamic Software Product Line (DSPL) Engineering has gained interest through its promise of being able to unify software adaptation whereby software adaptation can be realised at compile time and runtime. While previous work has enabled program logic adaptation by the use of language extensions and platform support, little attention has been placed on Graphical User Interface (GUI) variability. Different design patterns including the Model View Controller are commonly used in GUI implementation, with GUI documents being used for declaring the GUI. To handle dynamic GUI variability currently, the developer needs to implement GUI refinements using multiple techniques. This paper proposes a solution for dealing with GUI document variability, statically and dynamically, in a unified way. In our approach, we currently use a compile time method for producing GUI variants, and code transformations to handle these variants within the application at runtime. To avoid GUI duplicates, only GUI variants that are unique, and related to a valid product configuration, are produced. To validate our approach, we implemented tool support to enable this for Android based applications.