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Computer

Issue 3 • Date March 1989

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Displaying Results 1 - 9 of 9
  • Algorithmic motion planning in robotics

    Page(s): 9 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1326 KB)  

    A survey is presented of an approach to motion planning that emphasizes object-oriented, exact, and discrete (or combinatorial) algorithmic techniques in which worst-case asymptotically efficient solutions are being sought. Following a statement of the problem, motion planning in static and known environments is treated. The discussion covers general solutions, lower bounds, the projection method, the retraction method, the expanded obstacles, the single-component approach, and a mobile convex object moving in a 2D polygonal space. Variants of the motion-planning problem are then considered, namely, optimal motion planning, adaptive and exploratory motion planning, motion planning in the presence of moving obstacles, constrained motion planning, motion planning with uncertainty, and general task planning.<> View full abstract»

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  • Task-level planning of pick-and-place robot motions

    Page(s): 21 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (851 KB)  

    A task-level robot system named Handey, which is under development, is described. The current system is limited to pick-and-place operations, and it has successfully carried out dozens of such operations involving a variety of parts in relatively complex environments. The pick-and-place problem is described, and approximate approaches to the problem are examined. Heuristic motion planning in Handey is then discussed.<> View full abstract»

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  • The problems of accuracy and robustness in geometric computation

    Page(s): 31 - 39
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    Practical implementation of geometric operations remains error-prone, and the goal of implementing correct and robust systems for carrying out geometric computation remains elusive. The problem is variously characterized as a matter of achieving sufficient numerical precision, as a fundamental difficulty in dealing with interacting numeric and symbolic data, or as a problem of avoiding degenerate positions. The author examines these problems, surveys some of the approaches proposed, and assesses their potential for devising complete and efficient solutions. He restricts the analysis to objects with linear elements, since substantial problems already arise in this case. Three perturbation-free methods are considered: floating-point computation, limited-precision rational arithmetic, and purely symbolic representations. Some perturbation approaches are also examined, namely, representation and model, altering the symbolic data, and avoiding degeneracies.<> View full abstract»

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  • Exception handling in robotics

    Page(s): 43 - 49
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    The construction of robust and reliable robot systems able to handle errors arising from abnormal operating conditions is addressed. It is assumed that the robot program is logically correct but fails due to hardware or external state errors. The error-handling technique called exception handling is treated. The type of errors that can occur in a robot system and their error-handling requirements are described, and approaches to error handling and recovery are reviewed. Exception-handling facilities in Ada and AML/X are mentioned, and Exceptional C, the language chosen for exposition, is described. The use of exception-handling facilities is illustrated with two examples.<> View full abstract»

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  • Current research in robotics and automation-an intelligent grasping system

    Page(s): 50 - 52
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (394 KB)  

    A research project is described that focuses on building a comprehensive grasping environment capable of performing tasks such as locating moving objects and picking them up, manipulating man-made objects such as tools, and recognizing unknown objects through touch. In addition, an integrated programming environment is being designed that will allow grasping and grasping primitives within an overall robotic control and programming system that includes dextrous hands, vision sensors, and multiple-degree-of-freedom manipulators. A system overview is given, and the applications are discussed.<> View full abstract»

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  • Current research in robotics and automation-automated planning and programming for robotic batch mechanical assembly

    Page(s): 53 - 54
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    To overcome the difficulties of programming robots, the authors are seeking automatic programming methods, using various forms of computer-based reasoning. This overview outlines their algorithm and software-related research and development for automated mechanical assembly. Five major areas of ongoing research are briefly described: compliant motion; motion planning; machine interpretation of solid models; automatic planning of assembly sequences; and automatic programming of robotic systems.<> View full abstract»

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  • Current research in robotics and automation-electronic prototyping

    Page(s): 55 - 57
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    Electronic prototyping, i.e. building a computer model of an object to verify its design, faces a number of obstacles. The Cornell modeling and simulation project, which was created to develop the necessary science base to overcome these barriers, is discussed. In particular, the project's progress in improving robustness of solid modelers and its ongoing research in electronic prototyping are examined. A key component of the project, a model-driven simulator capable of supporting a wide range of multidisciplinary research, is described.<> View full abstract»

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  • Current research in robotics and automation-robotics research at USC

    Page(s): 58 - 60
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    A number of projects are described, and the breadth of these activities is indicated. The projects concern: skill transfer from human to robot; telerobotics; knowledge-based control of robot grasping; hand-eye coordination; robot sensors; control of flexible robot arms; low-cost robots for pick-and-place operations; and simulation of material-handling components in manufacturing cells.<> View full abstract»

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  • Secure query-processing strategies

    Page(s): 63 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (928 KB)  

    Strategies for secure query processing multilevel-security database management systems are proposed. They are carried out by query modification, a technique that has been used for enforcing integrity constraints and providing view mechanisms. The technique consists of replacing the query the user presents with one that, when evaluated, will perform the desired function. In the case of a view mechanism, the names of views referenced in the query are replaced by the definitions of the views in terms of base relations. The basic strategy and two variants-adding environmental information and using graphs-are described. The performance of the strategies is examined.<> View full abstract»

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Computer, the flagship publication of the IEEE Computer Society, publishes highly acclaimed peer-reviewed articles written for and by professionals representing the full spectrum of computing technology from hardware to software and from current research to new applications.

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Editor-in-Chief
Ron Vetter
University of North Carolina
Wilmington