Biomedical Engineering Reference
In-Depth Information
Fig. 9.5
TreadPort
treadmills, one inside of the other. Each belt is made from approximately 3400
separate rollers, woven together into a mechanical fabric. Motion of the lower belt
is transmitted by the rollers to a walker. This mechanism enables omni-directional
walking [
6
]. In another instance, the “Ball Array Treadmill”, employs small balls,
which move the walker in any direction. The balls are driven by a belt mounted on
a turntable. The combination of balls, belt and turntable enables omni-directional
walking [
20
].
An important limitation of these methods is that rollers or balls are hazardous
when the walker falls down. The durability of the structure supporting the rollers or
balls is also a problem.
Another approach for realizing omni-directional walking is to use a large sphere
in which a walker stand. One of the examples is a product developed by Virtusphere
Inc. The sphere rotates freely in any direction according to the walker's steps. The
major problem of this method is that the inertia of the sphere is so large that the
walker cannot stop while he/she is walking fast. Also, a curved walking area is not
natural.
9.3.2 Torus Treadmill
An ideal solution for a treadmill-based locomotion interface is to create an omni-
directional infinite, moving floor. In order to realize an infinite walking area, the
geometric configuration of an active floor must be chosen. A closed surface driven
by actuators has an ability to simulate an unlimited floor. The following requirements
for implementation of the closed surface must be considered:
(1) The walker and actuators must be put outside the surface.
(2) The walking area must be a plane surface.
(3) The surface must be made of a material that stretches very little.
