IEEE Robotics & Automation Magazine - December 2017 - 96

(a)

(b)

(f)

(c)

(g)

(d)

(h)

(e)

(i)

Figure 6. The SHPH is used several types of activities, including: physical labor, e.g., (a) handling an axe, (b) using a saw, and (c) lifting
a wheelbarrow; sports, e.g., (d) handling a climbing rope, (e) riding a bike, and (f) paddling; and hobbies, e.g., (g) playing the guitar,
(h) painting, and (i) throwing a ball.

the potential benefits of the presence of active joints in
the overall prosthetic setup. The task itself does not require hand dexterity but rather wrist, elbow, and shoulder coordination. There are two important aspects that
could be highlighted from the execution of this task:
the capacity of the user to control the hand in the presence of strong compensation movements (e.g., avoiding
false activations) and the possibility to have grasps where
the object is in line with the main axis of the user's
forearm (to minimize compensation movements). Most of
the hands at the competition did not have a powered wrist
and, thus, required compensatory movements to navigate
the course. Because of the flexible closure of the SHPH,
our pilot was able to grasp the handle of the wire loop
between the index and middle fingers, allowing the
wire-loop handle to be in line with the rest of his arm,
thus minimizing awkward compensatory movements
[Figure 7(e)-(h)]. Moreover, the normally closed modality of the hand allowed our pilot to effectively grasp
the wire-loop handle and attend not to the grasp stability but to the precision and joint coordination in the
execution of the task.
Shelf and Tray
Two steps in this task were particularly challenging: removing silverware from a drawer organizer and screwing in a
light bulb. For the former, the narrow drawer opening and
size of the hand (which approximates a large male hand)
made it difficult to comfortably reach into the drawer. This
difficulty was partly ameliorated by the flexibility of the fingers, e.g., allowing the ring and pinky fingers to bend out of
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DECEMBER 2017

the way while the others picked up the silverware [Figure 7(i)]. For the latter, our pilot removed the bulb from its
box by turning it upside down into his partially opened
SHPH, then set the bulb in the socket and secured it by
turning at the shoulders and waist. Our pilot, after securing
the bulb [Figure 7(l)], tended to make a fist and twist the
bulb into the socket by touching the fist to the bulb and
pulling his arm toward himself.
Breakfast Table
Two subtasks of particular interest were cutting the loaf of
bread and opening the can. For the former, our pilot made a
fist, placed it on top of the loaf of bread, and used the flexible wrist to secure the loaf [Figure 7(m)] while cutting a
slice with his other hand. The can opener proved challenging for many pilots, in part because it required the continuous exertion of downward force from the stabilizing hand
(most pilots used their prosthesis) while the active hand
turned the lever [Figure 7(o)]. Our pilot struggled with this
subtask on the qualification round but performed well in the
final race.
Hang Up
Two components of this task of particular interest were
engaging and closing the zipper and manipulating the
clothespins. Our pilot chose to lay the zippered jacket
on the floor, holding the bottom stop with the SHPH
and engaging the zipper pull with his other hand. To
increase speed and stability, he held the jacket in place
with the SHPH in a fist [Figure 7(q)]. In practice sessions, our pilot trained in grasping the clothespins in two
Table of Contents for the Digital Edition of IEEE Robotics & Automation Magazine - December 2017
