Functionality of a new
mechanical hand, able to grasp objects of generic shape. In its morphology
it is similar to the human hand; in its functionality it is adaptable as a
robot extremity or, with some specific devices, as a prosthesis. The
mechanical aspects of this mechanism point out some basic characteristics.
Its properties might be considered for a development of its adaptability
to multiple functions, in robotics and maybe in orthopaedics.
Different principles of grasping
are performed, with respect to the system, which is made of linkages with
rods, springs, and a platform, with functions similar to the fingers and
to the palm of the human land. The study of the mechanics of prehension
shows that elastic energy stored in the system represents a term of
stabilization of the grasping process. The joint (at the upper extremity
of the hand) which reproduces the hyperextension is here used as prototype
in a mechanical extremity, with analogy to the human hand functionality.
It constitutes an element of stabilization, also for a prosthesis,
because, when forces exceed a threshold value, the hand enlarges its
amplitude and the object is grasped with greater efficiency.
By dynamic equations, torques
applied at every joint may be determined, and the geometrical
configuration of the system is obtained. The elastic torque in every joint
is function of the relative angular rotations. It must be considered that.
while in grasping systems with rigid connections the grasping force is
exerted directly by an actuator, in the mechanical hand here presented the
force to be applied is consequence of the obtained configuration of the
system, and may be determined by means of the dynamic basic equations. The
configuration is defined by a set of angles and by the position of the
Future possible developments
mechanical hand here examined in its functionality shows its adaptability
to prehension of objects of generic shape. Principles of biomechanics and
of mechanical optimisation, considered in robotics and in prosthetics.
might cause developments in the mechanics and in the hierarchic control.