Download Mc cBILE Version 1.3 User's Guide

Section 5.1: Basic Methods of Formulating Loop Closure Conditions
(C1) Body Assembly
(C2) Joint Assembly
(C3) Segment Assembly
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Figure 5.2: Three basic methods for modeling loops in M BILE
of the cut, where the term pose stands for displacement and rotation. This kind
of assembly is applicable to any type of loop. In may however perform only poorly
both in terms of computational eciency and in terms of numerical stability of the
computed solution. In M BILE, pose closure conditions are generated by objects
of type \MoChord3DPose".
C2 Joint Assembly Method. The loop is dissected at a joint . The loop closure
condition consists in the equality of the geometric elements left invariant by the
joint for the two reference frames at both sides of the cut. Currently, this type
of assembly is only applicable to loops featuring a spherical joint; the cut is then
performed at the spherical joint and the closure condition is produced by an object
of type \MoChord3DTranslation".
C3 Segment Assembly Method. The loop is dissected at two joints . The loop
closure condition is formulated by taking characteristic measurements between the
end frames of the two resulting segments and setting these measurements equal.
The characteristic measurements depend on the type of the two cut joints; the
types of measurements currently supplied with the M BILE software are described
in Section 5.2.5. This type of assembly is only applicable to systems of constraint
equations that are solvable in closed form. It is the most involved of all methods
described here; however, its numerical advantages, such as computational eciency
and numerical stability, make it a good choice for advanced modeling. Currently,
M BILE is the only multibody package supporting this kind of modeling.
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M BILE 1.3 User's Guide
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