Computer-aided Control Research Articles

Computer-aided automatic control education with a real-time development system

This article deals with the development of a real-time digital experimental setup for reinforcement of control education, using available components such as prototyping system and a DC motor module for graduate research activities. The prototyping system called prototyper is a flexible development system to control designs of a real plant without manual programming. The DC motor module is a bench-scale analog system and it was modified to be used as a hardware in the loop (HIL) in the implementation of the experimental setup. The design of PID controllers and the frequency response tests were conducted. It is demonstrated that the design of PID controllers and frequency response tests can easily be conducted on the developed experimental setup. This work aims to train student practically in the education of real-time digital controller in automatic control and mechatronic courses. © 2005 Wiley Periodicals, Inc. Comput Appl Eng Educ 13: 181–191, 2005; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20045

Optimization of Structure and Composition of Information Protection Systems in the Computer-Aided Control Systems

Optimization of Structure and Composition of Information Protection Systems in the Computer-Aided Control Systems

CAutoCSD-evolutionary search and optimisation enabled computer automated control system design

This paper attempts to set a unified scene for various linear time-invariant (LTI) control system design schemes, by transforming the existing concept of “computer-aided control system design” (CACSD) to novel “computer-automated control system design” (CAutoCSD). The first step towards this goal is to accommodate, under practical constraints, various design objectives that are desirable in both time and frequency domains. Such performance-prioritised unification is aimed at relieving practising engineers from having to select a particular control scheme and from sacrificing certain performance goals resulting from pre-commitment to such schemes. With recent progress in evolutionary computing based extra-numeric, multi-criterion search and optimisation techniques, such unification of LTI control schemes becomes feasible, analytical and practical, and the resultant designs can be creative. The techniques developed are applied to, and illustrated by, three design problems. The unified approach automatically provides an integrator for zero-steady state error in velocity control of a DC motor, and meets multiple objectives in the design of an LTI controller for a non-minimum phase plant and offers a high-performance LTI controller network for a non-linear chemical process.

Repulsive force control based on distance computation algorithm

Computer-aided repulsive force control of collision avoidance is presented in this paper. A repulsive force is artificially created using the distances between the robot links and obstacles, which are generated by a simplified distance computation algorithm. This distance computation algorithm is based on the Gilbert-Johnson-Keerthi algorithm. Control gains in the repulsive force control model are selected based on traditional control design and genetic algorithms. Results on shortest distance computation and collision detection are presented. Real-time manipulator collision avoidance control has achieved. A repulsive force gain is introduced through the approaches for definition of link coordinate frames and kinematics computations. The safety distance between objects is affected by the repulsive force gain. Safety zone can be adjustable by the repulsive force gain which is selected by a specified fitness function of the genetic algorithm.

A Web-based, collaborative, computer-aided sequential control design tool

A Web-based, collaborative, computer-aided design software tool has been developed for sequential control system design. The software includes functions for specifying a sequential control system using icons for electrical devices and circuits. With the software, users can automatically generate electrical circuit designs by inputting the required motion sequences. The software's animated simulation function helps users verify or modify their designs. The software is designed to allow multiple users to work together in a collaborative mode over the Internet. During a collaboration session, only the user who "owns" a virtual token can modify the design. Other users can only view, but not modify, the current design. The software is written in Java and thus can be used on any computer with a Java virtual machine.

Simulation System to Design Two-Level Computer-Aided Railway Control Systems

Consideration was given to the general principles underlying the ISTRA simulation system and enabling one to reproduce (simulate) to a large extent the technology and the processes of information and control of the objects of various kinds of transport. In the two-level computer-aided control system where the dynamic flow models of strict optimization represent the upper level, the ISTRA performs the checking function. Attention was focused on the possibility of representing complex hierarchical processes in a model realizing situational control. Described was construction of the simulation model of a railway junction which is built using the technological, information, and control operations. Economic efficiency of the two-level computer-aided control system for transport optimization at an industrial node was demonstrated.

Modeling and Optimization of the Throughput of the Processing Nodes in Computer-aided Control Systems of Distributed Production of Printer Matter

A computer-aided control system of distributed production of printed matter which is interpreted as an open queuing network was considered. Optimal resource allocation to the processing network nodes is one of the key problems in this class of systems. An algorithm based on a combination of the branch-and-bound method and simulation was proposed for determining the optimal solution. The branch-and-bound method enables one to establish the direction of search, and simulation is used to verify each step of search. High convergence of the algorithm was corroborated by numerical experiments.

Using Group Technology to Plan Data Processing in Computer-aided Control Systems

For the computer-aided control system of an enterprise, consideration was given to the methods of task grouping on the basis of Q-analysis. The methods and algorithms can be used to improve the procedure of task allocation to the general resources of a corporate network.

Computer-Aided Learning of Controller Design: Focus on Fuzzy Logic Control

A computer-aided controller design package is developed in this paper. The package provides a simulated environment for simulating the action of a controller under different parameter settings in order to achieve optimal system performance. The designed controller is then applied to a process plant for on-line control.

Experience of using of instruments MAXI for computer-aided control of the casting structure from annealed and high-test cast iron by magnetic method

Experience of using of instruments MAXI for computer-aided control of the casting structure from annealed and high-test cast iron by magnetic method

Method of time Petri net analysis for analysis of fault trees with time dependencies

In order to make computer-aided control systems as safe as possible, a number of analysis techniques have been developed. One of these is fault tree analysis. A fault tree (FT) represents causal and generalisation relations between events (e.g. a hazard and its causes). However, it can express neither time relations between events nor detection and protection times. Time Petri nets (TPNs) can model all the above aspects. Thus, TPNs can be used for analysing and verifying time-dependent fault trees (FTs). One of the limitations of classical TPN analysis is the large number of TPN states. Even for a small FT this number can turn out to be vast. The authors introduce a new method for analysing such TPNs that model FTs. We do not consider all states that are reachable from the initial marking in classical TPN analysis but only those that lead to the occurrence of a hazard. Such an approach simplifies the procedure and results in cleaner final conclusions. If the hazard is reachable there is a need for safety measures to be taken. FT analysis and modelling of protection using TPNs will be illustrated using an example.

TOWARDS A DOCUMENT CENTRED COMPUTER-AIDED CONTROL SYSTEM DESIGN ENVIRONMENT

Most conventional design processes produce documentation as a by-product: design is done within an environment or collection of tools and the design outputs, models, diagrams, results, etc are gathered together along with commentary (usually with hindsight) into some kind of document at the end of the process. Inspired by ideas taken from literate programming and notebook interfaces to design tools, a prototype document centred design document has been developed. In such an environment, the document is the main product and the design is a by-product of documenting the design. By implementing the framework components of the system in Java and by using the extended markup language (XML) to encode the contents of the documents, the system is made platform neutral and therefore portable. An example document centred environment for computer-aided control system design (CACSD), that integrates Matlab and Simulink with the document-based framework, is briefly described and indications for future possibilities for this technology are given.

Fault-Tolerant Computer-Aided Control Systems with Multiversion-Threshold Adaptation: Adaptation Methods, Reliability Estimation, and Choice of an Architecture

For multiversion majority-redundant computer-aided control systems, systematization of adaptation methods that are stable to hardware and software failures, a method for estimating their reliability from an event graph model, and a method for selecting a standard architecture with regard for reliability requirements are studied.

Performance-based control system design automation via evolutionary computing

This paper develops an evolutionary algorithm (EA) based methodology for computer-aided control system design (CACSD) automation in both the time and frequency domains under performance satisfactions. The approach is automated by efficient evolution from plant step response data, bypassing the system identification or linearization stage as required by conventional designs. Intelligently guided by the evolutionary optimization, control engineers are able to obtain a near-optimal “off-the-computer” controller by feeding the developed CACSD system with plant I/O data and customer specifications without the need of a differentiable performance index. A speedup of near-linear pipelineability is also observed for the EA parallelism implemented on a network of transputers of Parsytec SuperCluster. Validation results against linear and nonlinear physical plants are convincing, with good closed-loop performance and robustness in the presence of practical constraints and perturbations.

Theoretical Control and Experimental Verification of Carded Web Density. Part IV: Computer-Aided On-Line Control of Carded Web Density

This paper presents a new on-line control system that is implemented for controlling carded web density. The control system is based on the previous controller design of the worker-stripper group presented in Parts I, II, and III of this series. Theoretically, these aforementioned control methods can make a corresponding closed-loop system for efficient and precise system control, but the design effort is meaningful only when tested by experiment. In this part of the series, the well-designed analog controller can be discretized and used as a digital controller for experimental verification. The worker-stripper group control system successfully operates based on our experimental implementation and agrees well with theoretical analyses.

Control of the state of orders on machines

Many computer-aided production and control (PPC) systems are available on the market and these systems have to be integrated into existing information systems. Experience has proven that commercial PPC systems do not provide the expected results because they do not have a closed production planning and control feedback loop. This article proposes that the basic PPC system model be expanded so as to include a system which enables control, co-ordination and management of the state of orders on machines. Detailed description is given regarding the general production control procedure, which is based on the Deming circle of continuous improvements, and the corresponding procedure for implementation of control of the state of orders, which wait on the treated machines during the selected interval. To implement the practical continuous control of the state of orders a computer software product CONTROL has been developed.

Implementation of a robust PID autotuner in a control design environment

This paper describes a robust PID autotuner embedded in a block library for constructing both simulated and real control systems. The library has been implemented in a visual programming tool and contains all the functions for building complete systems, similar to those provided by a typical CACSD (computer-aided control system design) environment. After a brief overview of the library, the paper concentrates on describing the PID autotuning tool, its implementation and operation. The underlying theoretical background is simply sketched out to permit the necessary degree of comprehension, and for its complete illustration the interested reader is referred to more specific works. Some examples of the autotuner’s operation, one of which refers to a laboratory plant, are also reported.

Computer-aided control of microstructural evolution during sintering

Computer-aided control of microstructural evolution during sintering

Theory of Machines and Mechanisms in the Electronic Era

The widely held notion ‘that most machine problems can be solved by active control’ and Machines and Mechanisms Theory can be dropped from mechanical engineering curricula is discussed and refuted, and the role of electronics and computers in machine engineering are put in their correct context. Computer-aided control of machines and mechanisms cannot replace the mechanical essence of the mechanical end-actuator, tool, etc. An in-depth knowledge of the theory of mechanisms is essential for the understanding and development of new approaches to machine design as well as for computer programming relevant to this field.

Virtual race as an examination test: models, solutions, experiences

In this paper, an idea is presented on how to motivate students to learn an exacting subject such as computer-aided control systems design (CACSD). The idea is that the exam is a virtual race or competition meaning that the students are graded according to the success achieved in the competition. The aim of the competition is set by the professor, and the students have to design a controller to achieve the best possible result they can. Four competition subjects, those used in the last four years of CACSD education at the Faculty of Electrical Engineering, University of Ljubljana, are reviewed with emphasis on the fourth one-the surf regatta. The mathematical model of the surf is then presented. In all four cases, the criterion for the competition was the shortest time. The paper concludes with the description of solutions applied by students and the faculty experiences with the course.