ANTHROPORMORPHIC ROBOT HAND — ABSTRACT & SEMINAS

By | December 17, 2012
                                       ANTHROPOMORPHIC ROBOT HAND   
                 
            This
paper presents an anthropomorphic robot hand called the Gifu hand
II, which has a thumb and four fingers, all the
joints of which are driven by servomotors built into the fingers
and the palm. The thumb has four joints with four-degrees-of-freedom
(DOF); the other fingers have four joints with 3-DOF; and two axes
of the joints near the palm cross orthogonally at one point, as
is the case in the human hand. The Gifu hand II can be equipped
with six-axes force sensor at each fingertip and a developed distributed
tactile sensor with 624 detecting points on its surface. The design
concepts and the specifications of the Gifu hand II, the basic characteristics
of the tactile sensor, and the pressure distributions at the time
of object grasping are described and discussed herein. Our results
demonstrate that the Gifu hand II has a high potential to perform
dexterous object manipulations like the human hand.
INTRODUCTION
            IT IS HIGHLY
expected that forthcoming humanoid robots will execute various complicated
tasks via communication with a human user. The humanoid robots will
be equipped with anthropomorphic multifingered hands very much like
the human hand. We call this a humanoid hand robot. Humanoid hand
robots will eventually supplant human labor in the execution of
intricate and dangerous tasks in areas such as manufacturing, space,
the seabed, and so on. Further, the anthropomorphic hand will be
provided as a prosthetic application for handicapped individuals.
           Many multifingered
robot hands (e.g., the Stanford-JPL hand by Salisbury et al.(1),
the Utah/MIT hand by Jacobsen et al. [2], the JPL four-fingered
hand by Jau [3], and the Anthrobot hand by Kyriakopoulos et al.
[4]) have been developed. These robot hands are driven by actuators
that are located in a place remote from the robot hand frame and
connected by tendon cables. The elasticity of the tendon cable causes
inaccurate joint angle control, and the long wiring of tendon cables
may obstruct the robot motion when the hand is attached to the tip
of the robot arm. Moreover, these hands have been problematic commercial
products, particularly in terms of maintenance, due to their mechanical
complexity.
          To solve these
problems, robot hands in which the actuators are built into the
hand (e.g., the Belgrade/USC hand by Venkataraman et al. [5], the
Omni hand by Rosheim [6], the NTU hand by Lin et al. [7], and the
DLR’s hand by Liu et al. [8]) have been developed. However, these
hands present a problem in that their movement is unlike that of
the human hand because the number of fingers and the number of joints
in the fingers are insufficient. Recently, many reports on the use
of the tactile sensor [9]-[13] have been presented, all of which
attempted to realize adequate object manipulation involving contact
with the finger and palm. The development of the hand, which combines
a 6-axial force sensor attached at the fingertip and a distributed
tactile sensor mounted on the hand surface, has been slight.
          Our group developed
the Gifu hand I [14], [15], a five-fingered hand driven by built-in
servomotors. We investigated the hand’s potential, basing the platform
of the study on dexterous grasping and manipulation of objects.
Because it had a nonnegligible backlash in the gear transmission,
we redesigned the anthropomorphic robot hand based on the finite
element analysis to reduce the backlash and enhance the output torque.
We call this version the Gifu hand II.

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