IEEE Robotics & Automation Magazine - December 2018 - 47

other underwater operations require a gentle grasp or working
with tools made for the human hand, as in subsea inspection,
repair, and maintenance of offshore structure components,
e.g., pipelines and umbilicals [see Figure 2(e) and (f)].
The industrial nature of existing underwater robotic
manipulation technology does not allow for the performance of such fine activities. Attempts at object grasping
often result in damage through the unwitting application of
excessive contact forces; this introduces expensive delays or
complete failure in task execution. Human skills are still
needed and are mostly provided by scuba divers in shallow
water or by ADS operators equipped with either unpractical
pressurized gloves or primitive lobster-like claws, as shown
in Figure 2(g)-(j). These approaches present risks for human
life and are highly inefficient.

de monstrates excellent
grasping skills in many
Human skills are still
different situations. In [11],
the hand, controlled by a
needed and are mostly
human operator, successfully grasped a total of 107
provided by scuba divers
objects having different
shapes. Examples includin shallow water or by
ed a bottle, a pen, a cup, a
hammer, a book, coins,
ADS operators equipped
and so on.
This grasping ability
with either unpractical
and the soft robotic mechanical design of the Softpressurized gloves or
Hand appear to suit fine
underwater operations well,
primitive lobster-like claws.
considering in particular
the following:
1) The tendon-driven design has already been proven reliable in underwater use (as in [6], inspired by [12]).
2) The SoftHand joints are able to withstand even the severe
disarticulations that hydrostatic pressure can create without losing their adaptivity (see, e.g., [11, Fig. 15]).
3) No closed spaces are present in the grasping mechanism,
so no pressure differential exists that can cause deformations and ruptures.
Thus, we propose a solution based on the SoftHand technology, i.e., a set of two soft terminal devices, to be used in a
waterproof end effector. Such soft devices present

Proposed Solution
The Pisa/IIT SoftHand [11] is an underactuated, adaptive soft
robotic hand that constitutes a flexible-joint robot [14], i.e., its
compliance is concentrated in the joints. It is designed to be
robust and easy to control as an industrial gripper, while exhibiting high grasping versatility and a form factor similar to
that of the human hand. It has 19 joints but needs only one
actuator to activate its grasping capabilities. Such simplification
is enabled through the theory of adaptive synergies, resulting
in a series of considerable advantages both for control and
design simplification. The Pisa/IIT SoftHand implements one
adaptive synergy, actuated by a transmission system that uses a
tendon, pulleys, and a single-gear motor. The SoftHand

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(i)

(j)

Figure 2. The state of the art in underwater manipulation. Complex postures of the hand performed by scuba divers in (a)-(b)
archeological recovery; (c)-(d) biological sampling; and (e)-(f) offshore inspection, repair, and maintenance. (g) A modern ADS
pincer-like end effector, (h)-(i) typical deep-water ADS operation, and (j) extravehicular activity conducted underwater with
pressurized gloves. [Image (a) is from www.megalehellas.net, image (b) from www.nottingham.ac.uk/archaeology/underwater, image
(c) from www.livingoceansfoundation.org, image (d) from www.calacademy.org, image (e) from www.airliquide.com, image (f) from
www.antwerpunderwatersolutions.com, image (g) from www.nutyco.com, image (h) from www.oceanworks.com, image (i) from
adas.org.au, and image (j) from www.nasa.gov.]

december 2018

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IEEE ROBOTICS & AUTOMATION MAGAZINE

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47

http://www.megalehellas.net http://www.nottingham.ac.uk/archaeology/underwater http://www.livingoceansfoundation.org http://www.calacademy.org http://www.airliquide.com http://www.antwerpunderwatersolutions.com https://nuytco.com/ http://www.oceanworks.com http://adas.org.au http://www.nasa.gov

IEEE Robotics & Automation Magazine - December 2018

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