Abstract
Underwater exploration or inspection requires suitable robotic systems capable of maneuvering, manipulating objects, and operating untethered in complex environmental conditions. Traditional robots have been used to perform many tasks underwater. However, they have limited degrees of freedom, manipulation capabilities, portability, and have disruptive interactions with aquatic life. Research in soft robotics seeks to incorporate ideas of the natural flexibility and agility of aquatic species into man-made technologies to improve the current capabilities of robots using biomimetics. In this paper, we present a novel design, fabrication, and testing results of an underwater robot known as Kraken that has tentacles to mimic the arm movement of an octopus. To control the arm motion, Kraken utilizes a hybrid actuation technology consisting of stepper motors and twisted and coiled polymer fishing line muscle (TCPFL). TCPs are becoming one of the promising actuation technologies due to their high actuation stroke, high force, lightweight, and low cost. We have studied different arm stiffness configurations of the tentacles tailored to operate in different modalities (curling, twisting, and bending), to control the shape of the tentacles and grasp irregular objects delicately. Kraken uses an onboard battery, a wireless programmable joystick, a buoyancy system for depth control, all housed in a three-layer 3D printed dome-like structure. Here, we present Kraken fully functioning underwater in an Olympic-size swimming pool using its servo actuated tentacles and other test results on the TCPFL actuated tentacles in a laboratory setting. In this work, an embedded TCPFL actuator within elastomer has been proposed for the tentacles of an octopus-like robot along with the performance of the structures.
Highlights
The field of robotics deals in large with inhospitable environments wherein it is either impossible or very difficult for a person to operate in
We will discuss the silicone arm configurations that provide various movements. This will be followed by the isotonic test results of the artificial muscle twisted and coiled polymer (TCP) actuators such as fishing line (TCPFL), and the embedded TCPFL in the arm that was tested in a fish tank
The results show that the flow is only affected in the close vicinity of the rigid body motion of Kraken but the magnitude and pattern of curling, circulation and other properties are essential to understand the behavior
Summary
The field of robotics deals in large with inhospitable environments wherein it is either impossible or very difficult for a person to operate in One such environment is the high-pressure aquatic environment in which human physiology makes it practically impossible for a person to operate in without the assistance of either robots or other machinery. Twisted and coiled polymer fishing line muscles have been first introduced in 2014 by Haines et al [1] as a new class of smart materials. These artificial muscles contract or expand when heated depending on the way they are manufactured. Our approach in design is to try to mimic an octopus to some extent, but not the entire anatomy and swimming principles of an octopus, instead adapting only the flexible tentacles, and test the basic motion characteristics in an underwater environment
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