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Figure 8.5 Different robot architecture
8.3.3 Technical constraints
To the extent possible, the haptic interfaces must be designed to match the abilities of
the users. However, in most cases, technological limitations hinder the achievement of
these values. It is thus necessary to compromise, for example, between a very stiff but
very heavy interface and a lighter but more flexible interface. In order to be able to
make the correct choices, it is necessary to know the technologies used most frequently
on the existing force feedback interfaces.
8.3.3.1 Mechanical architecture of the force feedback interface
We can think of all kinds of mechanical architectures to build a robot. It is necessary and
sufficient that these structures provide adequate mobility vis à vis the planned tasks.
In the literature, numerous authors have tried to list and classify the architecture of
robots. For example, we will cite the work of Jean Pierre Merlet on parallel robots
(1997). However, if these works provide a complete list of the existing structures,
only a few authors provide an exhaustive comparison of their performance (Stocco &
Salcudean, 1996; Gosselin, 2000). On the whole, we can distinguish between four
types of structures: serial, fully parallel (the fixed base is connected to the mobile
platform by a number of branches as per the number of degrees of freedom of this
platform), two stages mixed (a parallel translation structure with a serial or parallel
wrist) and parallel mixed (the fixed base is connected to the mobile platform by several
branches with several degrees of freedom each) (Figure 8.5).
A special case of fully parallel interfaces is represented by tight rope interfaces on
which the robot gripper is connected to the fixed base only by cables (Ishii & Sato,
1994).
A serial structure provides the advantage of a significant work space, mainly in
rotation. On the other hand, it has the major drawback of requiring the actuation
of segments located far from the fixed base. There are two solutions. The motors on
the industrial robots are located at the level of each articulation, which increases the
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