Gripper Control Design and Simulation for OpenROV Submarine Robot

In this work, a design of a gripper for the underwater OpenROV vehicle is presented. OpenROV is an open-source underwater vehicle design for remote underwater exploration. It can enable systems of underwater internet of things and real-time monitoring. Mechanical aspects of the presented gripper design are discussed including actuation, motion transmission, kinematics and general arrangement, which resembles a delta robot. The Denavit-Hartenberg (DH) notation will be employed to define reference frames on one of the fingers in order to build transformation matrices and the forward kinematics matrix. The results from the forward kinematics are used to define the workspace that can be covered by each finger. The maximum force from the fingertip is estimated using Newton-Euler equations. Finally, the transfer function and the mass moment of inertia of the second link in the finger, that is, the fingertip is calculated for control simulations. A control stability analysis is provided and shows a stable system.

A SURVEY ON UNDERWATER WIRELESS SENSOR NETWORKS REQUIREMENTS

Underwater wireless sensor networks are currently conducting substantial research in a different environment for benefit of humans. UWSNs are known to be one of the fastest-growing technical fields, due to the many advantages of their application. UWSNs consist of underwater sensors with minimal resources and use the acoustic connection as a communications medium. Current technical advancements have given rise to opportunities for underwater exploration by using sensors at all levels. However, this article provide an overview of the major requirements of UWSNs to accomplish the crucial services. This article also provides an overview of underwater wireless communications.

Unpaired Underwater Image Synthesis with a Disentangled Representation for Underwater Depth Map Prediction

As one of the key requirements for underwater exploration, underwater depth map estimation is of great importance in underwater vision research. Although significant progress has been achieved in the fields of image-to-image translation and depth map estimation, a gap between normal depth map estimation and underwater depth map estimation still remains. Additionally, it is a great challenge to build a mapping function that converts a single underwater image into an underwater depth map due to the lack of paired data. Moreover, the ever-changing underwater environment further intensifies the difficulty of finding an optimal mapping solution. To eliminate these bottlenecks, we developed a novel image-to-image framework for underwater image synthesis and depth map estimation in underwater conditions. For the problem of the lack of paired data, by translating hazy in-air images (with a depth map) into underwater images, we initially obtained a paired dataset of underwater images and corresponding depth maps. To enrich our synthesized underwater dataset, we further translated hazy in-air images into a series of continuously changing underwater images with a specified style. For the depth map estimation, we included a coarse-to-fine network to provide a precise depth map estimation result. We evaluated the efficiency of our framework for a real underwater RGB-D dataset. The experimental results show that our method can provide a diversity of underwater images and the best depth map estimation precision.

HOLD HEADING POSITION SYSTEM OF UNDERWATER REMOTELY OPERATED VEHICLE BASED ON PID

Underwater remotely operated vehicle mainly used to help human for underwater activities such as underwater exploration, underwater maintenance, and underwater search and rescue. Underwater remotely operated vehicle also used for education, entertainment, and competitions. In some case especially for an important or highly risk tasks, the ROV applied some functions to improve and optimize the use of the ROV for some missions. This paper presents a heading hold system which is applied in the ROV to maintain heading position or pose of the robot. Using a GY-271 compass sensor to read the data of ROV heading position, microcontroller Arduino mega 2560 as a central processing unit and PID controller as a feedback controller to maintain ROV on desired position by controlling thruster speed and direction. The experiments give a result of the control system using PID by 5% error for the ROV to maintain heading position in steady position.

Bio-Inspired Design of An Underwater Robot Exploiting Fin Undulation Propulsion

Interest in autonomous underwater vehicles is constantly increasing following the emerging needs of underwater exploration and military purposes. Thus, several new propulsion mechanisms are studied and developed. Fish swimming is a promising source of inspiration because they outperform conventional propellers in terms of energy efficiency and maneuvrability. Their advantages are not only due to the streamlined shape and their low-drag skin but also, above all, due to the particular fin motion, which makes thrust generation possible with small energy dissipation. This paper analyses the motion of batoid fishes that are considered highly efficient by biologists. Their motion is reproduced by different linkage mechanisms optimized to fit underwater robots. A bioinspired robot mimicking cownose ray locomotion is, then, designed and built. Numerical analysis of its dynamics allows us to measure the size of actuators and to estimate the robot behavior. Finally, the control algorithm that maintains the mechanism synchronization according to different strategies is described and some experimental results are presented.

HOLD HEADING POSITION SYSTEM OF UNDERWATER REMOTELY OPERATED VEHICLE BASED ON PID

Underwater remotely operated vehicle mainly used to help human for underwater activities such as underwater exploration, underwater maintenance, and underwater search and rescue. Underwater remotely operated vehicle also used for education, entertainment, and competitions. In some case especially for an important or highly risk tasks, the ROV applied some functions to improve and optimize the use of the ROV for some missions. This paper presents a heading hold system which is applied in the ROV to maintain heading position or pose of the robot. Using a GY-271 compass sensor to read the data of ROV heading position, microcontroller Arduino mega 2560 as a central processing unit and PID controller as a feedback controller to maintain ROV on desired position by controlling thruster speed and direction. The experiments give a result of the control system using PID by 5% error for the ROV to maintain heading position in steady position.

Optimal Design of the Shell Structure of a Disk-Shaped Water-Spraying Robot

Underwater exploration tasks in a narrow environment have stringent requirements related to the dynamic mode and shell design of underwater submersibles. Specifically, these submersibles should have horizontal maneuverability to move in a narrow environment. A certain degree of stability in the vertical direction should also be maintained to realize the stability of these submersibles at a certain depth for observation. A disk-shaped shell has the mobility of a spherical shell in the horizontal direction and the stability of a pancake-shaped shell in the vertical direction. Therefore, a design scheme for a disk-shaped shell of a water-spraying underwater robot was formulated through a comparative analysis of various shell shapes. To achieve movement in different directions, the Fluent fluid simulation software was used to continuously simulate and optimize these shell shapes. Relevant parameters, such as total pressure and force, that were obtained from the simulation were analyzed through horizontal and vertical comparisons. The maneuverability of the disk-shaped shell on the horizontal plane and its stability on the vertical plane were subsequently verified. Based on the measured maneuverability, the system of the disk-shaped water-spraying robot was designed, and a movement experiment was conducted to examine the straight and rotational motions of this robot. This study provides new ideas and theoretical support for designing the shape of submersibles in narrow underwater environments and promotes the development of underwater exploration technologies for narrow spaces.

Kraken: A wirelessly controlled octopus-like hybrid robot utilizing stepper motors and fishing line artificial muscle for grasping underwater

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 a coiled fishing line polymer muscle (TCP FL ). TCPs are becoming one of the promising actuation technologies due to their high actuation stroke, high force, light weight, 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 TCP FL actuated tentacles in a laboratory setting. This is the first time that an embedded TCP FL actuator within elastomer has been proposed for the tentacles of an octopus-like robot along with the performance of the structures. Further, as a case study, we showed the functionality of the robot in grasping objects underwater for field robotics applications.