In this paper we discuss synchronization techniques-and specifically their implementation at the hardware, operating system and high-level language levels-that can be used to achieve deadline satisfaction. In particul...
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In this paper we discuss synchronization techniques-and specifically their implementation at the hardware, operating system and high-level language levels-that can be used to achieve deadline satisfaction. In particular, it is shown that by endowing process control computers with fully parallel input and output mechanisms making use of exact time specifications, synchronization and deadline satisfaction can be achieved at the same time without any jitter. Continuous multimedia applications require accurate synchronization of the clocks in different processors. The available solutions have considerable accuracy or applicability. Local clock synchronization by radio transmitted time information turns out to be the only general purpose and high accuracy technique that is applicable with reasonable effort.< >
Complex systems are large applications, typically running on distributed, heterogeneous networks, driven by a number of distinct constraints and desiderata on goals such as performance, real-time behavior, and fault t...
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Complex systems are large applications, typically running on distributed, heterogeneous networks, driven by a number of distinct constraints and desiderata on goals such as performance, real-time behavior, and fault tolerance. These requirements frequently conflict, and satisfaction of these design objectives interacts strongly with assignment of system tasks to processors. The NSWC design framework DESTINATION provides an assignment module which can be used to optimize the system, as measured by the value of a weighted combination of objective cost functions. For even modest-sized systems and networks, assignment space is too large to search exhaustively. We have implemented algorithms which generate heuristically good assignments. However, compile-time evaluation of many interesting design factors, even those clearly related to assignment, is impossible without some estimate of the schedule. We therefore provide approaches for determining a reasonable “pseudo-schedule” for a given system, network, and assignment, and use this to simulate execution in evaluating cost functions.
The development of autonomous robots involves the imitation of human decision-making abilities with the aid of diverse sensor information. Fuzzy logic, which is based on fuzzy modelling and approximate reasoning, can ...
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The development of autonomous robots involves the imitation of human decision-making abilities with the aid of diverse sensor information. Fuzzy logic, which is based on fuzzy modelling and approximate reasoning, can be applied in different levels of control tasks. We first present the research results of applying fuzzy logic control in the motion execution of mobile systems and sensor-guided fine-motion of a manipulator. To realize real-time 'reactive' control, suitable hardware which supports the acceleration of fuzzy inference should be developed. The design and development of a VME-bus compatible fuzzy co-processor is also described.
A fuzzy control approach is proposed for controlling a mobile robot by effectively using the static knowledge of a partially-known environment and the dynamic sensor data. To describe the global structure of the stati...
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A fuzzy control approach is proposed for controlling a mobile robot by effectively using the static knowledge of a partially-known environment and the dynamic sensor data. To describe the global structure of the static environment, a tangent-graph is first constructed and a sequence of subgoals is generated for guiding the global path direction. During the execution of these subgoals, a motion executor using the concept of fuzzy control evaluates the sensor data and the robot current status, and adjusts the moving speed and direction of the robot.< >
In manufacturing it is often necessary to orient parts prior to packing or assembly. We say that a planar part is polygonal if its convex hull is a polygon. We consider the following problem: given a list of n vertice...
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In manufacturing it is often necessary to orient parts prior to packing or assembly. We say that a planar part is polygonal if its convex hull is a polygon. We consider the following problem: given a list of n vertices describing a polygonal part whose initial orientation is unknown, find the shortest sequence of mechanical gripper actions that is guaranteed to orient the part up to symmetry in its convex hull. We show that such a sequence exists for any polygonal part by giving an O(n2 log n) algorithm for finding the sequence. Since the gripper actions do not require feedback, this result implies that any polygonal part can be oriented without sensors.
A new product model that is particularly useful for model-based assembly planning is presented in this paper. The majority of the models used in this domain are simple approximations of the real workpiece and they are...
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A new product model that is particularly useful for model-based assembly planning is presented in this paper. The majority of the models used in this domain are simple approximations of the real workpiece and they are often dedicated to special algorithms. The model described here provides a more accurate and more flexible representation of workpieces. An increase in accuracy of the shape description was achieved by enhancing a polyhedral model with an analytical representation. The application of the model is demonstrated within the framework of assembly sequence planning.
In this paper the control architecture of the mobile robot system PRIAMOS is presented. It consists of four layers which integrate reactive and reflexive components in such a way that the robot can combine fast reacti...
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In this paper the control architecture of the mobile robot system PRIAMOS is presented. It consists of four layers which integrate reactive and reflexive components in such a way that the robot can combine fast reaction to unexpected obstacles with predictive behaviour to known components in the environnement. A solution for the problem bow to combine control layers which process information on different levels of abstraction and of increasing complexity is discussed. The reflexive part of the control architecture and the modification concerning the motion controller of the mobile robot which was necessary to apply the idea of reflexive navigation is described in more details. The architecture presented allows to execute motion tasks in partially unknown or changing environment in an efficient manner. Especially the time critical reflexive level is computationally less expensive than previous approaches
In this paper various approaches to synchronize leg movement of a walking machine are reported. Backpropagation-networks with diverse topologies, different types of encodings of information and of training methods are...
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In this paper various approaches to synchronize leg movement of a walking machine are reported. Backpropagation-networks with diverse topologies, different types of encodings of information and of training methods are investigated.
A method for recognizing a part from a set of known parts using a parallel-jaw gripper and a simple sensor that measures the distance between the jaws is described. The authors consider how empirical measurements of p...
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A method for recognizing a part from a set of known parts using a parallel-jaw gripper and a simple sensor that measures the distance between the jaws is described. The authors consider how empirical measurements of part behavior can be used to generate efficient recognition strategies. These strategies are compared to random strategies using physical experiments. It is found that the former cut error rates and recognition times by approximately 50%.< >
A new concept for navigation of mobile robots based on the planary coded environment (PLACER) is presented, which enables the coordination of several mobile robots in a real manufacturing environment. It is a path ind...
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A new concept for navigation of mobile robots based on the planary coded environment (PLACER) is presented, which enables the coordination of several mobile robots in a real manufacturing environment. It is a path independent external navigation system with passive environment structuring over the entire movement area of the robots. This area is completely covered with tiles, each containing the coordinates of its centre point inscribed using an error correcting code
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