Development of bio-inspired underwater robot with adaptive morphology capable of multiple swimming modes

Abstract

Abstract-Bio-inspired underwater robots have several benefits compared to traditional underwater vehicles such as agility, efficiency, and an environmentally friendly body. However, the bio-inspired underwater robots developed so far have a single swimming mode, which may limit their capability to perform different tasks. This paper presents a reconfigurable bio-inspired underwater robot that changes morphology to enable multiple swimming modes: octopusmode and fish-mode. The robot is 60 cm long and 50 cm wide, weighing 2.1 kg, and consists of a re-configurable body and 8 compliant arms that can be actuated independently. While the octopus-mode is expected to have unique abilities, question is if the fish-mode has distinctive advantages. With this platform, we investigate effectiveness of adaptive morphology in bioinspired underwater robots. For this purpose, we evaluate the robot in terms of the cost of transport and the swimming efficiency of both the morphologies. The fish-mode exhibited a lower cost of transport of 2.2 and higher efficiency of 1.2 % compared to the octopus-mode, illustrating the effect of the multiple swimming modes by adaptive morphology. I. INTRODUCTIONRecently, the scope of underwater robots expands to increasingly demanding applications such as environmental monitoring, marine ecosystems study, and inspection of submerged structures.Bio inspiration is a promising design method for underwater robots given that bio-inspired locomotion can provide benefits not achievable by traditional marine propellers. Aquatic animals resulting of million years of evolution are endowed with a variety of morphological features for moving through water with high speed, agility and efficiency [1]. In addition, aquatic animals have environmentally friendly body. Thus, recent years have witnessed significant research work in the development of bio-inspired underwater robots in various swimming morphologies. These robots include fish and manta-ray that are driven by soft pneumatic actuators With the many underwater applications the world faces, it becomes required for underwater robots to have high capabilities and be multitasking. However, bio-inspired underwater robots developed up to now have a single morphology resulting in the use of a specific swimming locomotion. This may limit their capability to deal with different tasks. For example, octopus-inspired robots are advantageous for activities at relatively low speed such as point observation, manipulating object and ground locomotion [9], but may not be suitable for traveling a long distance with high swimming speed and efficiency. Similarly, fish-inspired robots may have advantage on efficient, fast steady swimming, but their non-holonomic movement may have a difficulty when they are required to perform precise manoeuvring at low or zero forward speed. In this context, adaptation of morphology [10] to suitable swimming locomotion mode could be a solution to increase the range of manageable tasks. This paper aims to investigate effectiveness of adaptive m...

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Shape morphing mechanical metamaterials through reversible plasticity

“…This combination of properties is enabling for deployable robots, which must exist in a slim, easily transportable form factor before being deployed to perform tasks. Morphing mechanisms can allow underwater machines to achieve advanced functions and deploy from a packed state (37,38). Different approaches to create underwater morphing robots have been shown; however, morphing has been predominantly used for locomotion (38)(39)(40)(41).…”

“…Morphing mechanisms can allow underwater machines to achieve advanced functions and deploy from a packed state (37,38). Different approaches to create underwater morphing robots have been shown; however, morphing has been predominantly used for locomotion (38)(39)(40)(41). Creating a reversibly deployable machine with locomotion and sufficient mechanical stability to perform functions and practically interact with the environment remains a challenge (42)(43)(44)(45).…”