  Underwater soft grippers exhibit potential for applications such as
monitoring, research, and object retrieval. However, existing underwater
gripping techniques frequently cause disturbances to ecosystems. In response to
this challenge, we present a novel underwater gripping framework comprising a
lightweight gripper affixed to a custom submarine pod deployable via drone.
This approach minimizes water disturbance and enables efficient navigation to
target areas, enhancing overall mission effectiveness. The pod allows for
underwater motion and is characterized by four degrees of freedom. It is
provided with a custom buoyancy system, two water pumps for differential thrust
and two for pitching. The system allows for buoyancy adjustments up to a depth
of 6 meters, as well as motion in the plane. The 3-fingered gripper is
manufactured out of silicone and was successfully tested on objects with
different shapes and sizes, demonstrating a maximum pulling force of up to 8 N
when underwater. The reliability of the submarine pod was tested in a water
tank by tracking its attitude and energy consumption during grasping maneuvers.
The system also accomplished a successful mission in a lake, where it was
deployed on a hexacopter. Overall, the integration of this system expands the
operational capabilities of underwater grasping, makes grasping missions more
efficient and easy to automate, as well as causing less disturbance to the
water ecosystem.
