5,693 research outputs found
Wrist joint assembly
A wrist joint assembly is provided for use with a mechanical manipulator arm for finely positioning an end-effector carried by the wrist joint on the terminal end of the manipulator arm. The wrist joint assembly is pivotable about a first axis to produce a yaw motion, a second axis is to produce a pitch motion, and a third axis to produce a roll motion. The wrist joint assembly includes a disk segment affixed to the terminal end of the manipulator arm and a first housing member, a second housing member, and a third housing member. The third housing member and the mechanical end-effector are moved in the yaw, pitch, and roll motion. Drive means are provided for rotating each of the housings about their respective axis which includes a cluster of miniature motors having spur gears carried on the output drive shaft which mesh with a center drive gear affixed on the housing to be rotated
The proto-type wrist joint assembly TACPAW (Triple Axis Common Pivot Arm Wrist), phase 2
A wrist joint assembly is described for use with a mechanical manipulator arm for finely positioning an end-effector carried by the wrist joint on the terminal end of the manipulator arm. The wrist joint assembly is pivotable about a first axis to produce a yaw motion, a second axis to produce a pitch motion, and a third axis to produce a roll motion. The performance of the wrist configuration is indicative of the capability to produce the 15 ft lb torque in either one of the three motions and the smoothness of operation is notable
Triple-axis common-pivot arm wrist device for manipulative applications
A concept in manipulator development to overcome the 'weak wrist syndrome', a triple-axis common-pivot arm wrist (TACPAW), is presented. It contains torque motors for actuation, tachometers for measuring rate, and resolvers for position measurements. Furthermore, it provides three degrees of freedom, i.e., pitch, yaw, and roll, in a single manipulator joint. The advantages of this development are increased strength, compactness, and simplification of controls. Designed to be compatible with the protoflight manipulator arm, the joints of TACPAW are back-driveable with + or - 45 deg rotation in pitch, + or - 45 deg in yaw and continuous roll in either direction while delivering 20.5 N-m (15 ft-lb) torque in each of the three movements
PRISMA database machine: A distributed, main-memory approach
The PRISMA project is a large-scale research effort in the design and implementation of a highly parallel machine for data and knowledge processing. The PRISMA database machine is a distributed, main-memory database management system implemented in an object-oriented language that runs on top of a multi-computer system. A prototype that is envisioned consists of 64 processing elements
An Unfamiliar Way to Generate the Hierarchy of Standard Model Fermion Masses
While the properties of the observed Higgs boson agree with the Standard
Model predictions, the hierarchy of fermion masses lacks an explanation within
the model. In this work, we propose a fresh approach to this problem, involving
a different Higgs doublet responsible for each quark mass. We construct a model
with a gauged, non-anomalous family symmetry that fixes which fermion
couples to which doublet with an Yukawa coupling. The
hierarchy of masses is generated by the hierarchy of vacuum expectation values
of the Higgs fields. The model generically predicts a light, weakly coupled
pseudoscalar. We verify that the model satisfies constraints from flavour
changing neutral currents, Higgs phenomenology and electroweak precision tests.Comment: 31 pages incl. reference
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