Page 90 - Human Inspired Dexterity in Robotic Manipulation

88 Human Inspired Dexterity in Robotic Manipulation

losthanddexterity.Althoughthereisstillnoconsensusaboutthedefinitionof
human hand dexterity, the biological variations found in the length of bones,
branching of tendons, and insertion of muscles [1] all suggest that dexterity is a
highly personal property that is not only shaped by an individual’s motor con-
trol ability, but also inherently bonded to the unique biomechanical charac-
teristics of its very owner, and therefore cannot be generalized without
considering the biological differences between individuals.
The conventional approach to designing anthropomorphic robotic
hands often involves mechanizing biological parts with hinges, linkages,
and gimbals to simplify the seemingly complicated human counterparts.
This approach is helpful for understanding and approximating the kinemat-
ics of the human hand in general, but inevitably introduces undesirable dis-
crepancies between human and robotic hands. The unique biomechanics of
any abled human being, which includes complicated shapes of the bones,
varied rotational axes, and other biomechanical advantages, can be seen as
a validated physical system as a whole. But most of these salient features
are discarded in the mechanizing process. Although a significant amount
of effort has been made by researchers to solve this mismatch from the con-
trol and sensing aspects, very limited work has been done to reduce the gap
from the biomechanical point of view.
The general approach of our proposed method is first to identify the
important biomechanical information of the human hand and then biomi-
metically replicate it. This allows a close replica that possesses the same kine-
matic and even dynamic properties of its human counterpart. Our design
benefits from several important rapid prototyping technologies: the shape
of the bones could be first captured with a laser/MRI scanner and then
3D printed with detailed surface features such as joint shapes and tendon
insertion sites; soft tissues can then be mimicked by using compliant silicone
rubbers whose mechanical properties match that of the skin.
As shown in Fig. 6.1, our approach resulted in a highly biomimetic
anthropomorphic design, which will have potential impact on studies in
both robotics and biology fields. Besides the obvious application in telema-
nipulation in which a human operator can directly transfer his/her own dex-
terity to the robotic hand, it could also help medical and biology research in
terms of physically preserving personal biomechanical data and serving as the
3D scaffolds for limb regeneration research.
In the following sections, we first review related work and introduce our
design motivation. Then we reinterpret the important biomechanics of