full Paper - Nguyen Dang Binh

Figure 5: The MORIS simulator
Figure 6: A scheme of one point attached device
mans other than those imposed from the contact, they can
generally be optimized in design for high performances. One
point attached interface are generally external to the operators.
The most common one point attached device for haptic
rendering is the PHaNToM interface [16]. The nature of the
force that can be exchanged in such type of devices make
them well suited for simple VE applications in which the
user needs to explore the environment by means of simple
probing.
Since the one point attach can render forces as they were
produced in one “virtual space”, point they are usually employed
for rendering surface profiles or the objects consistency
(stiffness).
Some haptic devices have special end-tools attached to
their extremity. These end-tools can be shaped as generic
handles as well as a copy of a specific instrument. We named
c­ The Eurographics Association 2005.
Massimo Bergamasco / Haptic Interfaces
9
these kind of interfaces Task Replica. The design complexity
of task replica devices may be different depending on the
kind of task they try to replicate. For writing (See figure 3)
two or three active force feedback information are needed
while the remaining movement are left free (This kind of
system required at least five DOFs for allowing completely
writing related movements).
Figure 7: A task replica example: an haptic interface for
writing and virtual prototyping in course of development at
PERCRO
Even if task replica interface can be less complex than
HDOF# or VHDOF#, they allow the user to share a complex
experience with the system limited to the field of application
the interface has been developed for.
Since the task replica devices are specifically designed
for a task, they can be optimized with respect to that task
and their design can be made simpler that is requested for
HDOF# or VHDOF#.
A Multipoint Attached interface shares more than one
contact with the operator. Multipoint attached are designed
for sharing complex experience such as manipulation of objects.
With respect to the other types of HIs, the multipoint
attach interfaces show much more design constraints on mechanical
development and control synthesis:
¯ from a mechanical point of view since this kind of interfaces
is “strictly” connected to the operator it is no more
conceivable the “separation of the links working spaces”.
This design concept is usually adopted in the case of simple
LDOF#/HDOF# devices for improving user safety
during the motion of the mechanical device: haptic interface
and operator shares only the contact point or tool, but
their “bodies” moves in separate spaces such that the collision
problems between structures are always avoided.
Multi point attach interfaces should be designed according
to the kinematic structure of the operator and their
mechanism should move in such a way of not interfering
with the operator movements. This physical constraint is
truly hard and often compels developers to complex designs
in order to ensure safety of operations;