Various types of cellular neural networks (CNNs) are summarized, and a taxonomy of CNNs is given according to the different types of grids, processors, interactions, and modes of operation. The CNN universal machine i...
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Various types of cellular neural networks (CNNs) are summarized, and a taxonomy of CNNs is given according to the different types of grids, processors, interactions, and modes of operation. The CNN universal machine is introduced. The architecture and the key features of the CNN universal machine are outlined. An exhaustive list of references is given.< >
For pt.I, see ibid., p.1-10 (1992). The programmability (as a stored program) of the CNN universal machine is discussed. It is shown why and in which sense this machine is universal. The analogic type of algorithm is ...
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For pt.I, see ibid., p.1-10 (1992). The programmability (as a stored program) of the CNN universal machine is discussed. It is shown why and in which sense this machine is universal. The analogic type of algorithm is introduced. The application potential is reviewed and the biological relevance is analyzed. It is shown that the architecture is optimal not only for silicon implementations, but also for many biological information processing organs that have the same structure.< >
An algorithm based on the transduction method and implemented in the ProperCAD environment is described. The parallel ProperSYN algorithm attempts to make the execution time manageably small. The algorithm uses an asy...
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An algorithm based on the transduction method and implemented in the ProperCAD environment is described. The parallel ProperSYN algorithm attempts to make the execution time manageably small. The algorithm uses an asynchronous message driven computing model with no synchronizing barriers, and hence it is scalable to a larger number of processors. Also, the algorithm is portable across a wide variety parallel machines. Experimental results on various parallel machines are presented. The algorithm is built around a well-defined sequential algorithm interface such that there can be benefits from future expansion of the sequential algorithm.< >
This paper addresses the problem of scheduling job operations in an automatic assembly line used for manufacturing a small to medium volume of mixed workparts. The assembly line model used here differs from the classi...
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This paper addresses the problem of scheduling job operations in an automatic assembly line used for manufacturing a small to medium volume of mixed workparts. The assembly line model used here differs from the classical flow shop model in the following three aspects: 1) there are no buffers at machine stations, 2) constraints associated with the material transport system are included, and 3) for each batch of production, workparts are distinguished in groups, rather than individually. An "optimal" algorithm that requires very little computation is derived first by minimizing the total finish time for two machine assembly lines. This result is then generalized to the problem of scheduling an assembly line with m > 2 machines processing single-operation jobs. In order to reduce the computational complexity of the latter problem, heuristic algorithms are also proposed and shown to work quite well for all the cases considered. Finally, a heuristic solution to the problem of scheduling an assembly line with m > 2 machines processing multioperation jobs is discussed.
A computer-integrated manufacturing (CIM) system is composed of several workcells, each of which contains robots, NC machines, sensors, and a transport mechanism. Each CIM workcell is controlled by multiple processors...
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A computer-integrated manufacturing (CIM) system is composed of several workcells, each of which contains robots, NC machines, sensors, and a transport mechanism. Each CIM workcell is controlled by multiple processors interconnected by an intracell bus, but the individual cells are interconnected by an arbitrary network. This paper considers a communication subsystem that is designed to support real-time control and coordination of devices in each CIM cell. The concept of a poll number is proposed to control the access to the intracell bus. The bus access mechanism with the poll number is intended to minimize the probability of real-time messages missing their deadlines. When a CIM task generates a time-constrained message, a poll number is computed for this message according to the message's deadline and the task's prority. When the intracell bus is free, the various tasks at a workcell that desire to use the bus write the poll number onto the bus and read it back, one bit at a time, starting from the most significant bit. If at any time the bit read back is different from the bit written, then the corresponding task drops out of the contention for the bus. Use of a poll number provides not only for decentralized control of the intracell bus, but also a high degree of flexibility in scheduling messages. The performance of the bus access mechanism with a poll number is analyzed and compared with that of a token bus, which is widely used in CIM systems such as MAP networks. The probability of a real-time message missing its deadline in a token bus is found to be much higher than that of the proposed mechanism.
Many control applications require cooperation of two or more independently designed, separately located, but mutually affecting, subsystems. In addition to the good behavior of each subsystem, effective coordination o...
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Many control applications require cooperation of two or more independently designed, separately located, but mutually affecting, subsystems. In addition to the good behavior of each subsystem, effective coordination of these subsystems is very important to achieve the desired overall system performance. However, such coordination is very difficult to accomplish due mainly to the lack of precise system models and/or dynamic parameters as well as the lack of efficient tools for system analysis, design, and real-time computation of optimal solutions. A new multiple-system coordinator that combines the techniques of intelligent control and neural networks, and forms the high-level coordinator in a hierarchical structure, is proposed. The basic idea is to estimate the effects of the control commands to subsystems using a predictor and modify these commands using a knowledge-based coordinator so as to achieve the desired performance. The predictor is designed for multiple-input, multiple-output systems using neural networks. The knowledge-based coordinator is responsible for a goal-oriented search in its knowledge base and the overall system stability. Because the internal structure and parameters of the low level are not affected by using the proposed method, some commercially designed servo controllers for single systems can be coordinated to perform more sophisticated tasks for multiple systems than originally intended.
A hierarchical knowledge-based controller is proposed to improve the performance of complex control systems, such as robots. Unlike parameter- and performance- adaptive controllers, this controller is designed only to...
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A hierarchical knowledge-based controller is proposed to improve the performance of complex control systems, such as robots. Unlike parameter- and performance- adaptive controllers, this controller is designed only to modify the reference input of a lower-level servo controller. Because the internal parameters and structure of the lower-level controller are not affected, commercial servo controllers can be made to perform more sophisticated tasks than originally intended. The principle of the knowledge-based controller, modification of the reference input, knowledge representation, existence of the solution, and analyses of the controller's stability and tracking error are described in detail. A self-tuning multiple-step predictor is designed as part of the controller to eliminate the undesirable effects of system time delay. Both linear and nonlinear example control systems are tested via extensive simulations and have all shown promising performances.
In hard real-time systems, the problem of scheduling periodic tasks to meet their deadlines has been studied extensively, but scheduling aperiodic tasks has been addressed far less, due mainly to their uncertain arriv...
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Two important issues associated with load sharing (LS) in hypercube multicomputers are discussed and analysed: (i) ordering fault-free nodes as preferred receivers of overflow tasks and (ii) developing an LS mechanism...
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Two important issues associated with load sharing (LS) in hypercube multicomputers are discussed and analysed: (i) ordering fault-free nodes as preferred receivers of overflow tasks and (ii) developing an LS mechanism to handle node failures. The authors previously (1989) proposed to order the nodes in each node's proximity into its preferred list of receivers for the purpose of LS in distributed real-time systems. However, the occurrence of node failures will destroy the original structure of a preferred list if the failed nodes are simply dropped from the list. Three algorithms are proposed to modify the preferred list to retain its original features. Based on the modified preferred lists, node failures can be tolerated by equipping each node with a backup queue which stores and updates the arriving/completing tasks at its most preferred node. Simulation results show that this approach, despite its simplicity, can greatly reduce the number of task losses compared to approaches that do not use backup queues.< >
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