Parallelism in Manipulator Dynamics
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...
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| Language: | en_US |
| Published: |
2004
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| Online Access: | http://hdl.handle.net/1721.1/6943 |
| _version_ | 1826206897114447872 |
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| author | Lathrop, Richard D. |
| author_facet | Lathrop, Richard D. |
| author_sort | Lathrop, Richard D. |
| collection | MIT |
| description | 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. |
| first_indexed | 2024-09-23T13:40:39Z |
| id | mit-1721.1/6943 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T13:40:39Z |
| publishDate | 2004 |
| record_format | dspace |
| spelling | mit-1721.1/69432019-04-12T08:33:36Z Parallelism in Manipulator Dynamics Lathrop, Richard D. 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. 2004-10-20T20:09:06Z 2004-10-20T20:09:06Z 1984-12-01 AITR-754 http://hdl.handle.net/1721.1/6943 en_US AITR-754 11807351 bytes 4399602 bytes application/postscript application/pdf application/postscript application/pdf |
| spellingShingle | Lathrop, Richard D. Parallelism in Manipulator Dynamics |
| title | Parallelism in Manipulator Dynamics |
| title_full | Parallelism in Manipulator Dynamics |
| title_fullStr | Parallelism in Manipulator Dynamics |
| title_full_unstemmed | Parallelism in Manipulator Dynamics |
| title_short | Parallelism in Manipulator Dynamics |
| title_sort | parallelism in manipulator dynamics |
| url | http://hdl.handle.net/1721.1/6943 |
| work_keys_str_mv | AT lathroprichardd parallelisminmanipulatordynamics |