Biomedical Engineering Reference
In-Depth Information
FIGURE 10-30
Terminal devices.
(a) Photograph of
the Vari-Plus Speed
Hand. (b) Electric
Greifer. (Courtesy of
Otto Bock, with
permission.)
10.9.2.1 Ultralight hand
The Ultralight hand was developed at the Forschungszentrum Karlsruhe (FZK) using
flexible fluidic actuators. These consist of a flexible chamber between two members con-
figured so that inflation of the chamber using air or a liquid results in an increasing
separation between the members or angle if they are hinged. Unlike PAMs, these actua-
tors provide a reasonably linear relationship between pressure and expansion force. They
are low cost and can be cascaded to produce very complex movements while remaining
lightweight.
The hand shown in Figure 10-31 consists of 18 miniature flexible fluidic actuators
integrated into the fingers and wrist. The fingers contain actuators, flex, and tactile sensors,
while the metacarpals each house a microcontroller, microvalves, and a small pump and
a power source. Joint extension is passive using elastomeric spring elements.
10.9.2.2 GIFU Hand
Developed at the Virtual System Laboratory and the Faculty of Engineering of GIFU
University, this hand weighs 1.4 kg and consists of an opposable thumb and four fingers
supported by a palm plate and wrist, as shown in Figure 10-32. The thumb has four joints
with four degrees of freedom, while each of the fingers has four joints and three degrees
of freedom, making 16 DOF in total. All the DC motor actuators of the joints are mounted
within the hand providing a fingertip force of up to 2.7 N. Each of the driven joints includes
FIGURE 10-31
Ultralight hand by
Forschungszentrum
Karlsruhe. (Schulz,
Pylatiuk et al., 2001)
