A
n unidentified flying object
floats several metres above the
ground, moving silently and
gracefully. A geometrical band
made from transparent prisms constant-
ly turns itself inside out. It contracts,
closes to form a compact shape, then
opens and turns itself inside out. Sus-
pended in and on air, it pushes off and
achieves forward propulsion through
rotation. To the observer’s eye, it is a
fascinating spectacle, though in his
mind he can’t quite believe what he is
looking at. Until now, the inversion drive
only existed in theory or as a model.
A fascinating discovery
The two classic drive systems are easy
to visualise. A linear drive can be com-
pared to a cue which moves a billiard
ball in a straight line in one direction.
We use rotary motion when cycling. The
third kind of drive based on inversion,
with its idiosyncratic sequence of move-
ment, really tests our powers of percep-
tion and reasoning. It was identified by
Swiss artist and engineer Paul Schatz,
who discovered the geometrical band at
the beginning of the 20
th
century. What
makes it unique is the “forced movement”,
whereby when one part of the system
moves, the entire system moves with
it. Festo engineers used this basic
principle in the development of Smart-
Inversion.
Freely floating prisms
With SmartInversion, the intelligent com-
bination of extremely lightweight
design, electric drives and open- and
closed-loop control makes endless
inversion in the air possible. Move-
ment is divided into four phases, two of
which generate propulsion. The prisms
are filled with helium so that they can
float freely in the air. Carbon-fibre rods
form an ultra-light framework, which
is enclosed by a gas-tight membrane.
The fascinating shape is set in rotation
by three servo motors, which move the
connecting axes forwards or backwards
depending on the drive phase. Smart-
Inversion can be controlled from a
smartphone using software specially
developed by Festo.
Four coordinated phases
In order to achieve inversion of the
geometrical band, the three servo mo-
tors are coordinated by an on-board
unit. Two of the servos run forwards
and one in reverse, depending on the