124 The Bricard linkages
One of the issues associated with the threefold- symmetric Bricard
linkage with twists of π/3 or 2π/3 is the existence of bifurcation points.
Kinematic bifurcation is a situation where the number of mobilities of a
mechanism increases at a particular configuration.
1
Here the corresponding
configurations are at points (π, π), (π, –π), (–π, –π) and (π, –π). This can be
seen in Figure 6.2 as the points where the input–output curves cross. In
these configurations, the linkage folds to a bundle where all of the links are
(a)
(b)
Figure 6.10 Model showing connectivity of two basic elements with a type II
pair. (a) Fully expanded and (b) during deployment.
Figure 6.11 Portion of an assembly of threefold-symmetric Bricard linkages.
One of the issues associated with the threefold- symmetric Bricard
linkage with twists of π/3 or 2π/3 is the existence of bifurcation points.
Kinematic bifurcation is a situation where the number of mobilities of a
mechanism increases at a particular configuration.
1
Here the corresponding
configurations are at points (π, π), (π, –π), (–π, –π) and (π, –π). This can be
seen in Figure 6.2 as the points where the input–output curves cross. In
these configurations, the linkage folds to a bundle where all of the links are
(a)
(b)
Figure 6.10 Model showing connectivity of two basic elements with a type II
pair. (a) Fully expanded and (b) during deployment.
Figure 6.11 Portion of an assembly of threefold-symmetric Bricard linkages.