In the past few years, many efficient rendering and surface reconstruction algorithms for point clouds have been developed. However collision detection of point clouds has not been considered until now, although this ...
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In the past few years, many efficient rendering and surface reconstruction algorithms for point clouds have been developed. However collision detection of point clouds has not been considered until now, although this is a prerequisite to use them for interactive or animated 3D graphics. We present a novel approach for time-critical collision detection of point clouds. Based solely on the point representation, it can detect intersections of the underlying implicit surfaces. The surfaces do not need to be closed. We construct a point hierarchy where each node stores a sufficient sample of the points plus a sphere covering of a part of the surface. These are used to derive criteria that guide our hierarchy traversal so as to increase convergence. One of them can be used to prune pairs of nodes, the other one is used to prioritize still to be visited pairs of nodes. At the leaves we efficiently determine an intersection by estimating the smallest distance. We have tested our implementation for several large point cloud models. The results show that a very fast and precise answer to collision detection queries can always be given.
Modern automotive applications such as Drive-by-Wire are implemented over distributed architectures where electronic control units (ECU's) communicate via broadcast buses. In this paper, we present the concept of ...
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Modern automotive applications such as Drive-by-Wire are implemented over distributed architectures where electronic control units (ECU's) communicate via broadcast buses. In this paper, we present the concept of virtual integration platform for automotive applications. The platform provides the basis for early analysis and validation of distributed applications, therefore enhancing the current model based development process techniques that are applied to one ECU at a time. The virtual prototype includes both functional and performance (time) models of the application software, scheduling policies, and the bus communication protocols. As a result, since design errors can be found earlier in the design process before the different sub-systems are integrated in the car, savings in both production and development costs can be achieved. The virtual integration platform concept is supported by an integrated IP-based tool environment for authoring, integration, and validation. First, a model of the distributed application is built by composing models of HW and SW components. The models can be either authored or imported from different tools. Functional simulation of the overall distributed control algorithm can be carried out first. Then, the mapping phase can take place: sub-functions of the control algorithm are mapped to architectural resources (CPUs), and zero-time communication links between the sub-functions are mapped to bus protocol delay models. Changing mappings, parameters such as task priorities, and bus schedule enables the exploration of alternative implementations. The validation is carried out by simulating the resulted virtual prototype of the distributed control algorithm running on the ECU network. The design environment shortens design turn-around time by supporting (semi)-automatic configuration of the architecture model (e.g. frame packaging, redundancy level, communication matrix, bus and RTOS scheduling, etc.). (C) 2003 Elsevier Inc. All rights re
In the future, it may be possible to employ large numbers of autonomous marine vehicles to perform tedious and dangerous tasks, such as minesweeping. Hypothetically, groups of vehicles may leverage their numbers by co...
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ISBN:
(纸本)0780385438
In the future, it may be possible to employ large numbers of autonomous marine vehicles to perform tedious and dangerous tasks, such as minesweeping. Hypothetically, groups of vehicles may leverage their numbers by cooperating. A fundamental form of cooperation is to perform tasks while maintaining a geometric formation. The formation behavior can then enable other cooperative behaviors. In this paper, we describe a leader-follower formation-flying control algorithm. This algorithm can be applied to one-, two-, and three-dimensional formations, and contains a degree of built-in robustness. Simulations and experiments are described that characterize the performance of the formation control algorithm. The experiments utilized surface craft that were equipped with an acoustic navigation and communication system, representative of the technologies that constrain the operation of underwater autonomous vehicles. The simulations likewise included the discrete-time nature of the communication and navigation.
Steam parameters control problem in power plants with coal fired boilers is one of the most challenging problems. The steam parameters are extreme at the boiler outlet. The large time constants and nonlinearities are ...
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ISBN:
(纸本)0780383354
Steam parameters control problem in power plants with coal fired boilers is one of the most challenging problems. The steam parameters are extreme at the boiler outlet. The large time constants and nonlinearities are involved in the process model. In this paper, it was shown that the feedback linearization method can be applied to synthesise control system for this process. The derivation of the linearizing transformation is not an easy task. It requires symbolic solutions for ordinary differential equations. The proposed method was compared with PI and proportional state feedback control algorithms. Simulation experiments were carried out in different points of operation, with different heat distribution and in presence of unmodelled dynamics.
Objective: The aim of this survey was to determine improved diagnostics through digital mammography with assistance of computer algorithms and new investigation techniques. Material and methods: In general, the presen...
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Objective: The aim of this survey was to determine improved diagnostics through digital mammography with assistance of computer algorithms and new investigation techniques. Material and methods: In general, the presented procedures are practicable with all digital mammography procedures. In our clinic the largest clinical experience exists with the only FDA certified full field mammography device Senographe 2000D (GE Medical Systems). Results: First results from initial studies are shown, which are to evaluate the new procedures. The so-called post processing with visualization of microcalcifications, computer-assisted diagnosis, tomosynthesis, energy subtraction, contrast media in mammography and teleradiology are considered in particular. Conclusion: Digital mammography represents a promising procedure, opening new possibilities for improved diagnostic in mammography.
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