Control of manufacturing systems can be defined in terms of synchronizing physical objects. These objects typically belong to a limited number of classes, exhibiting similar behavior whithin each class, examples inclu...
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Control of manufacturing systems can be defined in terms of synchronizing physical objects. These objects typically belong to a limited number of classes, exhibiting similar behavior whithin each class, examples include machines and buffers. In this paper we propose the following for feasible development of fabrication systems control: • Separate the control of the individual device from the synchronization of the whole system. • This can be achieved by bulding internal objects, software models of the physical devices, the external objects. • Encapsulate the control of the physical device, by building these objects in two distinct parts, a general and a specific part. • The internal objects communicate by messages, specially designed for expressing the synchronizing aspects, including prioritys and various addressing formats. • One object needs to be application specific, a controller that administers the message handling. Furthermore, we discuss this approch in relation to MMS, which utilizes a similar scheme, though not so intent on handling the synchronizing functions of a discrete event manufacturing system. Lastly, we illustrate our method by describing an FMS workcell involving buffers, robots and machines.
A fault-tolerant resource allocation procedure aimed at automatic modification of Petri net-based control models is presented. The recovery scheme is based on the assumption that some of the system shared resources ma...
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A fault-tolerant resource allocation procedure aimed at automatic modification of Petri net-based control models is presented. The recovery scheme is based on the assumption that some of the system shared resources may be replaced by others, e.g. in case of their malfunctioning. The method encompasses a new deadlock avoidance algorithm which guarantees deadlock freedom of the control models. Its application for development of controls for computer integrated assembly cells is shown in an example.
This article presents a rigorous system development process promoting formal specifications of functional requirements of process control software. These specifications provide the grounds for specification-based test...
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This article presents a rigorous system development process promoting formal specifications of functional requirements of process control software. These specifications provide the grounds for specification-based testing of abstract designs and computer-assisted proofs of the conformance of program code to its requirements. Specifications are formulated in the algebraic specification language OBJ. The pertinent OBJ3 environment is used as a proof checker performing all clerical work related to correctness proofs. To illustrate the design and validation method, the specification and control program for a simple function block is provided and a few properties and assumptions about its functional behavior are proved.
This paper describes a software tool for the automatic generation of ladder diagrams used in sequence control problems with programmable controllers. Input to the system consists of precedence relationships among acti...
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This paper describes a software tool for the automatic generation of ladder diagrams used in sequence control problems with programmable controllers. Input to the system consists of precedence relationships among activities and a functional description of input and output devices. A network representation of sequence control problems is introduced. The status of the control system at different instances of the operational cycle is progressively constructed based on input information. Two methods for the deduction of ladder diagrams using the notions of event and activity states are described. The concepts are illustrated with an example.
An object oriented language for distributed control, which supports hierarchical modularization and reuse of control solutions is introduced. Module descriptions include animated pictures, control equations and sequen...
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An object oriented language for distributed control, which supports hierarchical modularization and reuse of control solutions is introduced. Module descriptions include animated pictures, control equations and sequential flow charts. The cooperation between modules is described by graphical connections. A production line with roller tables and robots is presented as an example. It shows that proper design of module structure and interfaces allows distribution of the intelligence to local programs within each module. The principles of distributed execution in a network of computers is presented. The module decomposition is naturally utilized for the distribution of the program over the network. The data-flow through the network is determined automatically by analysis of the distributed program.
This paper describes the Direct Drive Manipulator Research and Development Package, which includes a two link direct drive manipulator, amplifiers, a multi-processing controls workstation, a mathematical model of the ...
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This paper describes the Direct Drive Manipulator Research and Development Package, which includes a two link direct drive manipulator, amplifiers, a multi-processing controls workstation, a mathematical model of the manipulator system, and software environment which is used for the development and execution of real-time control algorithms. The software provides a C-language based Robot Programming Language (RPL), control algorithm development environment, and a robot simulator. The package is based on an open architecture with full user programming capability. The user can enter the control loop at any level with the ability to modify or replace any part of the RPL, servo routine, inverse kinematics, or trajectory generation modules. The package provides a convenient workstation to develop a control algorithm, simulate, implement, and fine-tune the controller. The simulation is a unique part of this package being a “semi-active” simulation which uses a mathematical model of the mechanical system while using the actual control hardware that is used for control implementation. Mechanical nonlinearities such as dynamic coupling and Coulomb friction are taken into account. Since the actual controller is used, the simulation accounts for quantization, integer overflow, and controller dynamics. This package is ideal for an advanced robotics research program or a lab oriented graduate course in robotics or controls.
What confidence can we have in a microprocessor based control or monitoring device when the safety of people or the reliability of an industrial process is a stake ? In order to provide some objective elements in answ...
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What confidence can we have in a microprocessor based control or monitoring device when the safety of people or the reliability of an industrial process is a stake ? In order to provide some objective elements in answer to this delicate question, INRS carried out a series of tests on a dozen electronic microprocessor based devices which are widely used in industry. The tests were carried out using the *** device which allows the operating safety of the equipment to be measured. The results show that certain devices designed for specific applications have a high level of safety while others including the programmable controllers do not guarantee a sufficient safety level in applications where risks are involved.
This thesis describes the design and construction of a high performance induction motor drive, controlled by a network of parallel (INMOS) Transputer processors. The flexibility and high computational ability of the c...
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This thesis describes the design and construction of a high performance induction motor drive, controlled by a network of parallel (INMOS) Transputer processors. The flexibility and high computational ability of the controller is demonstrated by the implementation of three forms of indirect vector control for the induction motor (here termed "V-Type, "V-Type with Current Feedback" and "I-Type") on two motor drive rigs. Results show that V-Type control with current feedback is superior, and that on-line parameter estimation (namely the rotor time constant) is required.
The controller has been expanded to incorporate two parameter identification strategies for assessment. The first, termed "Reactive Power Measurement", has proved successful in matching the controller value of rotor time constant to the actual machine value of rotor time constant. The second, termed "PRBS Injection with Cross- Correlation" has proved inconclusive and is the subject of on-going research.
The performance of the transputer parallel processing network for real time control is discussed. This assessment is felt to be significant since parallel architectures are likely to become increasingly exploited as the processors become cheaper, more powerful and flexible, and with enhanced system support.
La présente norme est applicable à la couche "application" (au sens du modèle de référence d'interconnexion des systèmes ouverts de l'ISO) du bus FIP pour l'éch...
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标准号:
NF C46-602-1990
La présente norme est applicable à la couche "application" (au sens du modèle de référence d'interconnexion des systèmes ouverts de l'ISO) du bus FIP pour l'échange d'informations entre transmetteurs, actionneurs et automates à l'intérieur d'un processus *** s'insère dans un ensemble de normes donnant les spécifications du bus FIP : - C 46-601 Architecture et présentation générale ;- C 46-602 Couche application -Services périodiques et apériodiques ;- C 46-603 Couche liaison de données ;- C 46-604 Couche physique en bande de base sur paire torsadée blindée ;- C 46-605 Gestion du réseau ;- C 46-606 Couche Application - Services de messagerie ;- C 46-607 Couche physique en bande de base sur fibre optique.
Nowadays the qualification and assessment of microprocessor based safety related systems cannot be done manually. Therefore a set of tools has been developed which consists of disassemblers for an important group of m...
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Nowadays the qualification and assessment of microprocessor based safety related systems cannot be done manually. Therefore a set of tools has been developed which consists of disassemblers for an important group of microprocessors, a control flow analyser and a data flow analyser. To do the analysis unaffected by errors in the documentation, compilers or linkers it starts from the object code. The disassemblers supply direct metric survey information about the programs. Further result files of the diassemblers are processed by the control flow analyser and data flow analyser. All tools give hints on formal errors on the one hand, on the other hand they deliver accounts that allow an efficient semantic analysis of the control and data flow. A large amount of safety relevant applications can be ascertained by this method.
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