Game Development Reference
Figure 8.19 Interface IKD. (Illustration: F. Jannin/CEA-LIST, with permission)
index finger). Its peak force capacity is close to 5N at the centre of the work space.
Its weight of 1 kg requires the use of a spring static balancing unit.
Amongst the other interfaces of this type, we shall cite the interface prototype
developed by the Robotics Centre of the Ecole des Mines de Paris (Stergiopoulos,
2003) which provides a satisfactory level of perception of the forces and shapes by
the user, even if the mechanical device is sub-actuated (a motor per finger) and does
not allow forces to be produced at the fingertips in all directions, and the Pure Form
HandExoskeleton or PFHE developed by the PERCRO laboratory, Scuola Superiore
SantaAnna of the University of Pisa in Italy (Bergamasco et al., 2002; Frisoli et al.,
2002). The latter interface is also composed of 2 robots with 6 degrees of freedom
including 3 with force feedback, which helps to interact with the thumb and the index
finger (Figure 8.20). The force capacity reaches more than 10N, but its weight and
overall dimensions require integrating it on an exoskeleton for the arm in such a way
that the user does not need to carry it.
A solution for reducing the mass consists of motorising only one axis, generally
the one that is connected to the closing of the hand. If the information restored is not
very detailed, the weight can be drastically reduced. This is the solution used on the
Rutgers Master II ND of the University of New Jersey in Rutgers in the United States
(Figure 8.21). To further reduce the mass, this interface, of which several successive
versions have been developed, uses pneumatic actuators (Burdea & Speeter, 1989;
Burdea et al., 1992; Bouzit et al., 2002). Its performance is summarised in table 8.8.
The use of pneumatic jacks helps to obtain a very light interface (its mass is lower
than 100 g). This interface is thus really portable, even if the air supply cables limit
the work space to a 2m radius hemisphere and hinder the movements of the user.
In addition, its travel is limited (the hand cannot be completely closed because of the