Parallelism in Manipulator Dynamics

Item

Title
en_US Parallelism in Manipulator Dynamics
Creator
en_US Lathrop, Richard D.
Date
2004-10-20T20:09:06Z
Date Available
2004-10-20T20:09:06Z
Date Issued
en_US 1984-12-01
Identifier
en_US AITR-754
uri
http://hdl.handle.net/1721.1/6943
Abstract
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.
Extent
11807351 bytes
4399602 bytes
Format
application/postscript
application/pdf
Language
en_US
Relation
en_US AITR-754
Item sets
AI Technical Reports (1964 - 2004)