Game Development Reference
In-Depth Information
Table 8.8 Features of Rutgers Master II, CyberGrasp and Cyberforce.
Rutgers Master II
CyberGrasp
Cyberforce (base)
Work space (base)
> 2m
> 1m
300 × 300 × 900mm
Work space (fingers)
28 to 44mm
Work space of the fingers
-
Position resolution
0.3mm
-
0.06 to 0.07mm
Continuous force
16N
Max. 12N
6.6 to 8.8N
Friction
0.014N
-
-
Force resolution
0.004N
0.003N
-
Apparent stiffness
-
-
-
Mass
approx. 80 g
450 g
8,620 g
a geometry that corresponds to the geometry of the articulations of the body. Numerous
interfaces of this type have been developed, for example the LRP HandMaster (Bouzit,
1996), Safire marketed in 1993 by the Exos Inc. company or the SKK Hand Master II
(Choi &Choi, 1999). These interfaces provide an independent force feedback on all the
phalanxes of the fingers, which provides an extremely enhanced interaction. However,
their architecture is complex and they use numerous motors. These interfaces are thus
relatively heavy (when the robot actuators are not offset) and bulky.
The only interface of this type that has been marketed is CyberGrasp from the
Immersion Corporation company who, in 2000, bought out Virtual Technologies Inc.,
initial designer of Cybergrasp. Its performance is summarised in table 8.8. It makes it
possible to operate using 5 fingers. However, only one actuator is associated with each
finger and CyberGrasp provides a force feedback only on closing the hand, which limits
its scope of application. Moreover, to minimise the mass of the interface, the motors
are offset and the force is transmitted to the articulations by cables passing through
the ducts. These transmissions introduce friction and flexibility that harms the quality
of the feel. The Immersion Corporation company optionally offers to integrate the
motor units in a backpack called GraspPack to provide greater freedom of movement.
Immersion Corporationa also marketed CyberForce (Figure 8.22), which combines
Cyber Grasp and an interface with 3 degrees of freedom with force feedback using a
serial structure whose performance is given in table 8.8, as well as Haptic Workstation
that integrates 2 CyberForce.
A common point between all the exoskeletons is that their articular configuration
depends on the size of the body segments that they are fixed on. They are more or
less well adapted to the size of the users and are not as universal as the carried robots.
In addition, it is indispensable to calibrate them before each use. Finally, they cannot
be taken off quickly, which may cause a safety problem.
8.4.2.4 Exoskeletons for the arm
There are exoskeletons for the arm as well. Several robots of this type have been devel-
oped and marketed by Exos Inc. (Force Arm Master, upto 1996) and Sarcos Research
(Dextrous Master, meant more for the teleoperations market (Jacobsen et al., 1991)).
Recently, the PERCRO laboratory, Scuola Superiore Santa Anna of the University of
Pisa in Italy developed the L-Exos (for Light Exoskeleton) (Frisoli et al., 2005). This
exoskeleton with 5 degrees of freedom, including 4 that are actuated, has a work space
 
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