Page 376 - Control Theory in Biomedical Engineering

342 Control theory in biomedical engineering

Fig. 22 Changes in the available spaces before and after folding of the structure.
(A) Flexible structure because of the availability of open spaces. (B) Rigid structure as
the spaces are closed. (C) Stiffened and closed structure can carry loads.

and bending is no longer possible because of the rigid nature of the base
material (Fig. 22B).
This interesting observation can be applied to developing a variable stiff-
ness mechanism.
Based on our observations, we reasoned that we could make a tube that
would be flexible when the spaces were open but rigid and capable of car-
rying weight when the spaces were closed. The mechanics of such a load-
bearing structure can be assumed to follow that of a hollow triangular beam
fixed on one end and free on the other end (Fig. 23). The maximum load
that the structure can carry can be estimated as follows.