Parallelism in Manipulator Dynamics
Item
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Title
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en_US
Parallelism in Manipulator Dynamics
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Creator
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en_US
Lathrop, Richard D.
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Date
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2004-10-20T20:09:06Z
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Date Available
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2004-10-20T20:09:06Z
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Date Issued
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en_US
1984-12-01
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Identifier
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en_US
AITR-754
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Abstract
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en_US
This paper addresses the problem of efficiently computing the motor torques required to drive a lower-pair kinematic chain (e.g., a typical manipulator arm in free motion, or a mechanical leg in the swing phase) given the desired trajectory; i.e., the Inverse Dynamics problem. It investigates the high degree of parallelism inherent in the computations, and presents two "mathematically exact" formulations especially suited to high-speed, highly parallel implementations using special-purpose hardware or VLSI devices. In principle, the formulations should permit the calculations to run at a speed bounded only by I/O. The first presented is a parallel version of the recent linear Newton-Euler recursive algorithm. The time cost is also linear in the number of joints, but the real-time coefficients are reduced by almost two orders of magnitude. The second formulation reports a new parallel algorithm which shows that it is possible to improve upon the linear time dependency. The real time required to perform the calculations increases only as the [log2] of the number of joints. Either formulation is susceptible to a systolic pipelined architecture in which complete sets of joint torques emerge at successive intervals of four floating-point operations. Hardware requirements necessary to support the algorithm are considered and found not to be excessive, and a VLSI implementation architecture is suggested. We indicate possible applications to incorporating dynamical considerations into trajectory planning, e.g. it may be possible to build an on-line trajectory optimizer.
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Extent
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11807351 bytes
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4399602 bytes
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Format
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application/postscript
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application/pdf
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Language
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en_US
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Relation
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en_US
AITR-754