Five Fingers Artificial Hand
The artificial hand was built uniquely to test the force feedback
glove in a dextrous telemanipulation. We have therefore opted for
a simple and functional creation.
The mechanism of the artificial hand is redundant and identical
to that of the force feedback glove. It has 5 fingers with 14
dof. The presence of a mechanical redundancy in a prehensor
allows one to carry out different types of grasps appropriate for
different types of objects according to the tasks. Furthermore,
the resemblance of the artificial hand to the human hand allows
one to avoid the difficulties of planning a strategy of grasping
and manipulating objects.
Photo
Principle of the artificial hand
Natural grasps are carried out by the inner part of the hand :
the hand squeezes an object from the exterior towards the
interior. It is from this that the idea comes to design an
artificial hand where one can uniquely control the closing, while
its opening is ensured by a passive system. Consequently
unidirectional actuators, already perfected for the force
feedback glove may be used.
In view of simplifying the transformation of movement for a
telemanipulation task between the human hand and the artificial
hand we have chosen to use a similar mechanical structures for
both of them. The structure of the artificial hand is equivalent
to the structure of the human hand when its equipeed with the
force feedback glove. Thus the general structure of the
artificial hand is obtained by replacing the joints of the human
hand with those the mechanical joints.
The analogy between the master system and the slave system is
also respected in terms of the placement of the force and
position sensors. The correspondence between the angles and the
forces of the two systems is thus more simple. The only
difference between the two mechanisms resides in the trajectory
of the cable (We assume that the length of the human phalanxes
are identical to the corresponding phalanxes of the artificial
hand). The application points of the motor forces are thus
different.
Briefly, in the glove mechanism, the motor action must oppose the
closing of the human fingers while in the mechanism of the
artificial hand the action of the motor must oppose the opening
of the hand.
Prototype
Video Demonstraion ( 67.4Mo, avi)
Video Demonstraion ( 11.4Mo, mpeg)
