4 research outputs found

    Global motion planner for curve-tracing robots, A

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    Includes bibliographical references.We present a global motion planner for tracing curves in three dimensions with robot manipulator tool frames. This planner generates an efficient motion satisfying three types of constraints: constraints on the tool tip for curve tracing, robot kinematic constraints and robot link collision constraints. Motions are planned using a global search algorithm and a local planner based on a potential-field approach. This planner can be used with any robots including redundant manipulators, and can control the trade-offs between its algorithmic completeness and computation time. It can be applied in many robotic tasks such as seam welding, caulking, edge deburring and chamfering, and is expected to reduce motion programming times from days to minutes.This work has been performed at Sandia National Laboratories and supported by the U.S. Department of Energy under Contract DE-AC04-76DP00789

    Synthetic studies of the HIV-1 protease inhibitive didemnaketals: Stereocontrolled synthetic approach to the key mother spiroketals

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    [GRAPHICS] The stereocontrolled synthesis of (2S,4R,6R,8S,10S,1'R,1"R)-2(acetylhydroxymethyl)-4, 10-dimethyl-8(isopropenylhydroxymethyl)-1, 7-dioxaspiro[5,5]-undecane (4a) and its C1"-epimer (4b), the key mother spiroketals of the HIV-1 protease inhibitive didemnaketals from the ascidian Didemnum sp., has been carried out through multisteps from the natural (R)-(+)-pulegone, which involved the diastereoselective construction of four chiral carbon centers(C-2, C-6, C-8, and C-1') by intramolecular chiral induce
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