To exploit instruction level parallelism in programs over multiple basic blocks, programs should have reducible control flow graphs. However not all programs satisfy this property. A new method, called Controlled Node...
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In this paper, we address the problem of suggesting corrections to terms that are ill-typed in the Curry System. For this, we convert the term into a set of constraints over type expressions, and use a method due to C...
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Next generation radar systems, with phase-controlled array antennas, will have to process data that is many times larger than in current systems. This requires an enormous computing power. Even in a relatively small a...
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Next generation radar systems, with phase-controlled array antennas, will have to process data that is many times larger than in current systems. This requires an enormous computing power. Even in a relatively small airborne radar system, with hard size and power consumption constraints, a sustained computing power of 40 GOPS (or 40 GFLOPS, if floating point calculations are used) will be needed to perform only the subset of the calculations known as the space-time adaptive processing (STAP). Consequently, there is a need for new parallel computing modules, as well as new overall system architectures and application development environments. In this paper a modular architecture with highly parallel SIMD-modules is presented as a promising solution, capable of handling STAP. A version of the architecture, equipped with bit-serial floating point processing elements, is described and evaluated. Implementation technology aspects are discussed.
In massively parallel computersystems for embedded real-time applications there are normally very high bandwidth demands on the interconnection network. Other important properties are time-deterministic latency and s...
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In massively parallel computersystems for embedded real-time applications there are normally very high bandwidth demands on the interconnection network. Other important properties are time-deterministic latency and services to guarantee that deadlines are met. In this paper we analyze how these properties vary with the design parameters for a passive optical star network, specifically when used in a massively parallel radar signal processing system. The aggregated bandwidth and computational power of the radar system are approximately 45 Gb/s and 100 GOPS, respectively. The analysis is focused on the medium access control protocol, called TD-TWDMA, for the time and wavelength multiplexed network. It is concluded that the proposed network is very well suited to this kind of signal-processing applications. We also present a new distributed slot-allocation algorithm with real-time properties.
TETROBOT is a modular system for the design, implementation, and control of a class of highly redundant parallel robotic mechanisms. This paper describes new experimental results based on evaluation of prototype confi...
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TETROBOT is a modular system for the design, implementation, and control of a class of highly redundant parallel robotic mechanisms. This paper describes new experimental results based on evaluation of prototype configurations with up to 18 nodes, 48 links and 15 actuators. TETROBOT is an actuated robotic structure which may be reassembled into many different configurations while still being controlled by the same hardware and software architecture. Implementations of a double octahedral platform, a tetrahedral arm and a six-legged walker, constructed from the same set of parts, are described. The TETROBOT system addresses the needs of application domains, such as space, undersea, mining, and construction, where adaptation to unstructured and changing environments and custom design for rapid implementation are required.
Parallel robots can be built by linking together unit cells in configurations which retain the static determinacy of the overall structure. In the Tetrobot system, the kinematics of these concatenated structures can b...
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Parallel robots can be built by linking together unit cells in configurations which retain the static determinacy of the overall structure. In the Tetrobot system, the kinematics of these concatenated structures can be solved by propagation of solutions through connected graphs of linked modules. In this paper, we examine the synthesis of unit cells which could be used in creating these structures and retain the ability to compute the kinematics for control of the actuated system. Admissible unit cells are shown to form families in two- and three-dimensions, and a set of synthesis rules is described which generates the members of these families recursively for each generations. The resulting set of modules comprises a broad set of useful cells which can be used to design parallel robots and guarantee the computability of their kinematics on a cell-by-cell basis.
This paper presents an application of feature-based visual servoing to achieve accurate and robust 3D filament alignment. Two orthogonal cameras are used to localize the five degrees of freedom of an axi-symmetric fil...
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This paper presents an application of feature-based visual servoing to achieve accurate and robust 3D filament alignment. Two orthogonal cameras are used to localize the five degrees of freedom of an axi-symmetric filament. An algorithm for precisely estimating the center and orientation features of a filament in a camera view is described. The use of feature-based servoing overcomes the difficulty of 3D camera calibration in a factory environment. These features drive a PID control loop for each view. The two views are coupled in one degree of freedom, and the multiple-view controller switches between two single-view controllers to achieve 3D servoing. The overall accuracy achieved is in thousandths of an inch. Experimental results on the performance of the control algorithm are discussed. Models explaining the system behavior are presented. The use of visual servoing in this application far exceeds the positioning accuracy and the repeatability of human operators.
This paper introduces a new feedback algorithm for steering a point robot through an obstacle field. The key innovation is the use of a circulatory field to rotate the robot path around the obstacles instead of the co...
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This paper introduces a new feedback algorithm for steering a point robot through an obstacle field. The key innovation is the use of a circulatory field to rotate the robot path around the obstacles instead of the common potential field which repels the robot. This idea is motivated by a charged particle in a magnetic field generated by a current flowing around the obstacle. In constrast, the potential field approach is associated with a repulsive static electric field generated by charges of the same polarity as the robot, on the obstacle. The circulatory field does not generate any spurious local minimum as it does not change the total energy of the system. By combining with an attractive potential field associated with the desired destination, this method achieves global convergence while avoiding collisions with obstacles.
We present a new type of Petri net called "control and integration net" (CIN) utilized for simulation and evaluation of CIMOSA (computer integrated manufacturing open system architecture) models. We discuss ...
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We present a new type of Petri net called "control and integration net" (CIN) utilized for simulation and evaluation of CIMOSA (computer integrated manufacturing open system architecture) models. We discuss the definition of a set of rules for mapping CIMOSA models to CIN structure, a formal language to describe the CIN structures, and the graphical representation extended from the conventional Petri nets. We also present an engineering environment for cellular manufacturing, in which simulation results will guide the modeller to optimize CIMOSA models with help of the CIN interpreter and simulator according to user requirements.
An object-oriented modular approach to the engineering of complex robotic systems emphasizes reliability, reusability, ease of development, and user and network interfaces. This modular approach integrates many archit...
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An object-oriented modular approach to the engineering of complex robotic systems emphasizes reliability, reusability, ease of development, and user and network interfaces. This modular approach integrates many architectural principles and computational techniques which support adaptive and learning capability at the local, modular level. The TETROBOT is a modular and reconfigurable robotic system which was developed to demonstrate the reliable performance in a wide variety of task domains through reconfiguration of the same fundamental hardware and software components. Such a modular approach emphasizes the synthesis and integration of engineering modules and takes advantage of object-oriented engineering principles to design for a family of tasks. This paper provides an overview of the TETROBOT modular system and describes three modular systems in other applications domains.
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