Swarm Of Underwater Robots Research Articles

Omnidirectional optical communication system designed for underwater swarm robotics.

In this paper, an omnidirectional underwater wireless optical communication (UWOC) system is proposed, including six lens-free transceivers. An omnidirectional communication with a data rate of 5 Mbps in a 7-m underwater channel is experimentally demonstrated. The optical communication system is integrated into a self-designed robotic fish, and the signal is processed real-time through an integrated micro-control unit (MCU). In addition, it is experimentally demonstrated that the proposed system could establish a stable communication link between two nodes, regardless of the nodes' locomotion and attitude, with a data rate of 2 Mbps and a communication range up to 7 m. In particular, the optical communication system features small footprint and low power consumption, which is suitable for integration in autonomous underwater vehicle (AUV) swarms to achieve an omnidirectional information transmission with low latency, high security, and high data rate compared with its acoustic counterpart.

Underwater Optical Wireless Communications in Swarm Robotics: A Tutorial

Underwater swarm robotics is an emerging topic. Compared to individual autonomous vehicles, high-capacity communication links are required between the mobile agents. In this tutorial, suitable communication technologies are studied, with emphasis on LED-based underwater optical wireless communications. A comprehensive overview about challenges, advances, and practical aspects of underwater swarm robotics employing optical wireless communications is provided. The tutorial includes the following topics: (1) Channel modeling fundamentals; (2) Physical layer transmission techniques for underwater optical wireless communications; (3) Data link layer aspects and hybrid transmission schemes; (4) Ambient light and interference suppression; and (5) Realization aspects. Finally, suggestions regarding future work are given. The tutorial is intended for readers with a background or interest in electrical and information engineering.

Current Algorithms, Communication Methods and Designs for Underwater Swarm Robotics: A Review

As technology advances, the places we have been able to explore have drastically increased. However, the advancements in the underwater realm have staggered behind both the exploration of surface and air domains. This is due in part to the challenges that arise when placing a robot in water. One current shift has seen the use of a swarm of robots that are cheaper and are of a lower quality, that work together to accomplish a common goal, as opposed to using a single expensive robot. Swarm robotics benefits from being more tolerant of catastrophic failure and can cover large areas in smaller time frames. However, unlike other advancements in technology, underwater swarm robotics have struggled to compete with its counterparts on the surface and in the air. This is mainly due to the problems with communication underwater, the hazardous environment, the cost and difficulties with construction of underwater robots. This article conducts a literature review into the current state of underwater swarm robotics; it covers the design of the underwater robots, the methods used by the individual robot to perceive their environment, how they can localize to said environment, the methods of communication available underwater, centralized and decentralized control, the basis of swarm algorithms, the behaviors that are exhibited when a swarm works collectively and how swarms have been applied underwater.

Computational analysis of hydrodynamic interactions in a high-density fish school

Numerical simulations are employed to study hydrodynamic interactions between two-dimensional fish-like bodies under a traveling wavy lateral motion in high-density diamond-shaped fish schools. This study focuses on two different streamwise spacings, a dense school with 0.4 body length (BL) spacing and a sparse school with 2.0 BL spacing, respectively. An immersed-boundary-method-based incompressible Navier–Strokes flow solver is then employed to quantitatively simulate the resulting flow patterns and associated propulsive performance of the schools. The results suggest that a fish in the dense school achieves higher thrust production and higher propulsive efficiency than that in the sparse school due to a strong wall effect from neighboring fishes. In addition, results from changing the lateral spacing in the dense school have shown that the wall effect is enhanced as the lateral spacing decreases. Flow analyses have shown that the wake pattern of the fish swimming diagonally behind the leading fish in a dense diamond-shaped school transfers from 2S to 2P when the lateral spacing is smaller than 0.6 BL. As a result, an angled jet is produced behind the school and brings more momentum downstream. At the same time, the appearance of the trailing fish results in a stronger pressure region behind the leading fish and leads to a higher hydrodynamic performance of the leading fish in the dense school. The insights revealed from this study will contribute to understanding physical mechanisms in fish schools and providing a new swimming strategy for bio-inspired underwater swarm robots.

Into the World of Underwater Swarm Robotics: Architecture, Communication, Applications and Challenges

Background: With the curiosity of exploring the underwater world, science has devised various technologies and machines that can help them in performing activities like exploring, navigating and plunging into the unknown world of oceanography. Underwater Robot or vehicle can be claimed as an outcome of extensive research done by the scientists who aimed at discovering the unknown mysterious world of ocean and how it can benefit humanity. Swarm robotics is an entirely new section of robotics that has been developed based on swarm intelligence. Considering the fact, swarm robotics being still in nuptial stage, researchers have provided immense contribution with an aim to develop this technology. The objective of the paper is to present a comprehensive review covering the various technical and conceptual aspects of underwater swarm robotic system. Methods: A systematic review on state-of-the-art has been performed where contributions of various researchers was considered. The study emphasis on the concepts, technical background, architecture and communication medium along with its applicability in various fields that also include various issues and challenges faced while attaining them. Results: The incorporation of swarm intelligence in underwater robotics provides a new angle altogether into the working pattern of underwater robotic system. Conclusion: The article is a systematic presentation of swarm robot technologies, their mechanisms, conceived and designed communication medium with respect to adaptability of the vehicle to the versatile nature of water. The paper delineates the various conceptual and technical details and its beneficence to humanity.

CIMAX: collective information maximization in robotic swarms using local communication

Robotic swarms and mobile sensor networks are used for environmental monitoring in various domains and areas of operation. Especially in otherwise inaccessible environments, decentralized robotic swarms can be advantageous due to their high spatial resolution of measurements and resilience to failure of individuals in the swarm. However, such robotic swarms might need to be able to compensate misplacement during deployment or adapt to dynamical changes in the environment. Reaching a collective decision in a swarm with limited communication abilities without a central entity serving as decision-maker can be a challenging task. Here, we present the CIMAX algorithm for collective decision-making for maximizing the information gathered by the swarm as a whole. Agents negotiate based on their individual sensor readings and ultimately make a decision for collectively moving in a particular direction so that the swarm as a whole increases the amount of relevant measurements and thus accessible information. We use both simulation and real robotic experiments for presenting, testing, and validating our algorithm. CIMAX is designed to be used in underwater swarm robots for troubleshooting an oxygen depletion phenomenon known as “anoxia.”

Robust Maneuverability of a Miniature, Low-Cost Underwater Robot Using Multiple Fin Actuation

In this letter, we present the design of a miniature (100 mm) autonomous underwater robot that is low-cost ($ 100), easy to manufacture, and highly maneuverable. A key aspect of the robot design that makes this possible is the use of low-cost magnet-in-coil actuators, which have a small profile and minimal sealing requirements. This allows us to create a robot with multiple flapping fin propulsors that independently control robot motions in surge, heave, and yaw. We present several results on the robot, including 1) quantified open-loop swimming characteristics; 2) autonomous behaviors using a pressure sensor and an inertial measurement unit (IMU) to achieve controlled swimming of prescribed trajectories; 3) feedback from an optic sensor to enable homing to a light source. The robot is designed to form the basis for underwater swarm robotics testbeds, where low cost and ease of manufacture are critical, and three-dimensional (3-D) maneuverability allows testing complex coordination inspired by natural fish schools. Individually, miniature and low-cost underwater robots can also provide a platform for the study of 3-D autonomy and marine vehicle dynamics in educational and resource-constrained settings.

Division of labor in a swarm of autonomous underwater robots by improved partitioning social inhibition

In this paper, a distributed algorithm for adaptive task allocation and adaptable partitioning of a swarm into different work-groups is proposed and used in a swarm of underwater robots. The algorithm is based on local interactions of agents and is inspired by honeybee age-polyethism. It is adaptive to changes in the swarm size (workforce) and relative demands (workload) for different tasks and it limits the number of switchings of agents between different tasks enabling specialization of agents. The preliminary version of the algorithm was introduced previously. Here a fully decentralized version of the algorithm is proposed that improves the previous version by removing the need for global information. The algorithm is successfully implemented in swarms of physically-embodied underwater robots while the swarm size and the demands for the tasks change over the course of the experiments.

From honeybees to robots and back: division of labour based on partitioning social inhibition

In this paper, a distributed adaptive partitioning algorithm inspired by division of labor in honeybees is investigated for its applicability in a swarm of underwater robots in one hand and is qualitatively compared with the behavior of honeybee colonies on the other hand. The algorithm, partitioning social inhibition (PSI), is based on local interactions and uses a simple logic inspired from age-polyethism and task allocation in honeybee colonies. The algorithm is analyzed in simulation and is successfully applied here to partition a swarm of underwater robots into groups demonstrating its adaptivity to changes and applicability in real world systems. In a turn towards the inspiration origins of the algorithm, three honeybee colonies are then studied for age-polyethism behaviors and the results are contrasted with a simulated swarm running the PSI algorithm. Similar effects are detected in both the biological and simulated swarms suggesting biological plausibility of the mechanisms employed by the artificial system.

Consensus Control for a System of Underwater Swarm Robots

The control of a swarm of underwater robots requires both a control algorithm and a communication system. Unfortunately, underwater communications is difficult at the best of times and so large time delays and minimal information is a concern. The control system must be able to handle a large number of robots without a master control, i.e., a decentralized control approach. This paper describes Consensus control as a way to decentralize. Consensus control allows each robot to know the final goal and then to decide, based on the position of the other robots, its best move to help achieve the goal.