英语翻译For 4 CO-planar contacts,Nguyen 171 gave a geometrictest

英语翻译
For 4 CO-planar contacts,Nguyen 171 gave a geometric
test for form-closure’ and showed how to check form closure
by drawing a quadrilateral covering the overlapping cones
formed by pairs of force vectors.This is equivalent to the
condition that there exists a set of four wrenches { w,li =
1,2,3,4} such that the line joining the vertices of the two
vector cones,one formed by w1 and w2,and the other by wg
and w4,goes out of and into these two cones.Nguyen also
showed how to construct grasps with four frictionless fingers
by finding 4 independent regions on the boundary of the part
such that if each region contains one contact,the part will be
in form closure.For three frictional contacts in the plane,1101
showed that comparable regions on a polygoncould be found
using linear optimization.Surveys of the grasping literature
can be found in [9,3].
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