Underwater Robotic Arm Research Articles

MURA: a Multipurpose Underwater Robotic Arm mounted on Kalypso UUV in aquaculture

Underwater vehicles utilized in net cages at aquaculture facilities are commonly utilized for the purpose of examining the deterioration of nets and the accumulation of biofouling. The implementation of a robotic system for repairing damages has the potential to decrease the expenses associated with employing divers while reducing the risk of their injury. This study details the development, fabrication, and simulation of a cost-effective subaquatic manipulator, denoted as MURA, which can be seamlessly incorporated into submersible vehicles. The Kalypso unmanned underwater vehicle (UUV) is utilized in this study. MURA exhibits a high degree of modularity, enabling seamless alteration of the end-effector tool. Additionally, its low-cost nature renders it a viable option for integration with any underwater vehicle. Three end-effectors were subjected to testing, one designed for the purpose of disposing fish morts, another intended for removing litters from net cages in fisheries, and a third for repairing net tears. This study outlines the MURA design, including the arm’s fabrication and constituent components. In addition, the modeling of the manipulator is presented accompanied by a water flow simulation of the three manipulators. Ultimately, the experimental findings are analyzed and evaluated. These include the field experiments performed at Kefalonia fisheries, along with the duration to complete each task. For instance, the capture of fish morts typically necessitates approximately 30 s, encompassing the entire process from initial targeting to actual capture. In a similar vein, the procedure of mending tears in a net necessitates an approximate duration of 70 s on average, encompassing the stages of initial identification and subsequent detachment. The suggested design exhibits adaptability and durability while upholding affordability when utilized in aquaculture.

Transient hydrodynamic coefficients for a single DOF underwater manipulator of a square cross-section

Drag and added inertia coefficients for an underwater manipulator of revolute joints are time and shape dependent. This study proposes an extension of the method to determine transient hydrodynamic coefficients, which was originally developed for a single degree-of-freedom (SDOF) underwater manipulator of a cylindrical arm, for the arm of a square cross-section. This method is based on the normalization of coefficients using the dimensionless distance traveled by the centroid of water displaced by the arm. This results in simple approximation functions independent of kinematic conditions and dependent only on the dimensionless distance traveled. Surrogate model creation via machine learning methods requires many data sets obtained as a result of experiments or numerical simulations. The proposed normalization simplifies and speeds up the process of creating metamodels for drag and added inertia torques for SDOF manipulators because only a few time histories of the hydrodynamic load are required for regression. The results of this study indicate that the method based on such a normalization can be applied to a SDOF underwater robotic arm of a square cross-section with good accuracy, thus widening the scope of the original method.

Simplified dynamical model and experimental verification of an underwater hydraulic soft robotic arm

Inherent compliance equips soft robotic arms with such advantages as incomparable flexibility, good adaptability, and safe interaction with the environment, etc. However, the strong nonlinearity also brings challenges to predict their dynamic behaviors. This work presents a simplified dynamic model of an underwater soft robotic arm which has three fiber-reinforced hydraulic chambers distributed symmetrically in each section. By controlling the pressures in the chambers, the soft robotic arm can perform complex spatial motion with multiple degrees of freedom. The model is based on Lagrangian method and piecewise constant curvature hypothesis, and considers the nonlinear viscoelasticity of soft material. The model accuracy is verified by the experiments of a two-section soft robotic arm with different actuation modes. The effects of geometrical features on dynamic response are also investigated through model-based simulation and test verification, which can provide guidance to parameter optimization. The proposed dynamic model can be extended to multiple sections and contribute to behavior analysis, performance prediction, and motion control of the soft robotic arm.

Development of an underwater robotic arm using multibody dynamics approach

Underwater robotic arms are important devices that enables workers to carry out tasks remotely from a safe distance reducing or eliminating the risks that are involved with the task. The primary objective of the robotic manipulator is to perform maintenance and cleaning activities of the hull of a ship. However, the control of these devices underwater is quite complicated due to the numerous factors that make these systems unstable and non-linear. The aim of this study is to develop a multibody dynamic robotic manipulator model, integrated with a control strategy to optimize and obtain stable kinematics solutions. The hydrodynamic forces are integrated to the manipulator model considering buoyancy forces and surface drag forces. A basic algorithm is used to generate the joint angles using 7 geometrical parameters. The control of the manipulator was done to simply follow any path that represents the given coordinates. The P, I and D parameters are tuned individually to optimize the kinematic solution of the manipulator. 3-DOF articulated manipulator is the commonly used manipulator configuration. However, a 6-DOF manipulator configuration was selected in this study to allow for change in orientation using wrist motions.

Development of an Underwater Robotic Arm with Back Drivability

Development of an Underwater Robotic Arm with Back Drivability

The Minimum Agriculture-Chunk as an Elementary Data Science Component in ADAM, a Micro Targeted, Trainable, Modular, Multipurpose System for Land Farming

The poor Data Science support of agriculture brought us to our main idea of the research is to analyze all micro-works for every plant or tree. Then we proceed to specify targeted actions for harvest collection, micro spraying and hundreds similar simple actions. Initially we collect data from the farm. The airborne, land and underwater unmanned vehicles scan the field area with customized various sensors and cameras in various multi spectral modes. The result is minimum agro-chunk Four-Dimensional model. The unmanned vehicle on the field area receives target data. It is equipped with a general-purpose robotic arm, an absorbing bellow, a robotic pruner, a liquid spraying pipe, an underwater robotic arm and hundreds of others. It moves there and performs the commanded action. Action is flower or nuts collection, insect suction pruning and hundred more. All operations are high trainable by human intervention and the system stores its approach and logic for future action correction.

Design, prototyping and testing of a modular small-sized underwater robotic arm controlled through a Master-Slave approach

Underwater exploration, in the last years, has evolved toward a wide adoption of increasingly smaller ROVs (Remotely Operated Vehicle). As a consequence, the need to equip these underwater vehicles with robotic arms is currently rising as well.According to this demand, the paper presents three innovative solutions achieved in the UVMS (Underwater Vehicle-Manipulator System) field. Firstly, the paper proposes a modular architecture for a lightweight underwater robotic arm, which can be mounted on small-sized ROVs. The modular concept of the arm enables several different configurations, each one characterized by the related DOFs, deployed according to the type of application to be performed.Secondly, the arm has been equipped with an adaptive gripper that, taking advantage of the additive manufacturing techniques, is able to easily grip differently shaped objects. Lastly, the underwater arm is controlled through a Master–Slave approach, designed for commercial off-the-shelf electronics, that on the one hand, entailed a significant reduction of the bill of materials, but, on the other hand, required a greater effort in the software development. Experimental tests have been carried out to measure and evaluate the gripping and manipulation capability of the robotic arm and the performance of the proposed control system.

ホールセンサ利用による関節トルク計測可能水中ロボットアーム開発

ホールセンサ利用による関節トルク計測可能水中ロボットアーム開発

Development of arm and leg for seabed walking robot CRABSTER200

This paper presents the development of arm and leg of seabed walking robot named CRABSTER200 (CR200) for precise seabed exploration and underwater works in coastal area with strong tidal current. For seabed walking and precise underwater works, CR200 uses six legs and front two legs can be transformed to manipulators. In order to design robotic arm and leg, the parameters such as the degree of freedom (D.O.F), dimensions, motion range, joint structure, and mass are determined. Then, suitable joint actuators and reduction gears are selected through a simple force analysis. In addition, a communication method between legs and main controller, actuator controllers, and sensors are selected. The detailed mechanical design for 200m class pressure–resistance as well as watertight is performed. Also, the arms and legs are built by assembled fabricating the mechanical parts. Finally, in order to verify the performance of the arm and leg, the watertight test with 25bar pressure–resistance and joints operating test through posture control of CR200 are performed. This paper describes the whole design and implementation process of the underwater robotic arm and leg of the seabed robot CR200.

Effect of Bubbles Around an Underwater Robot Arm on Thrust During the Crawl Stroke Motion

The objective of this study was to clarify the effect of bubbles on thrust by means of an underwater robot arm. The underwater robot arm had five degrees-of-freedom (three for the shoulder and two for the elbow) which were actuated by five electric motors. The size was almost the same as human. On the top of the robot, a dynamometer was installed to measure the thrust. The robot arm was mounted in a circulating water tank. Two types of stroke of the crawl, that is, I-shaped and S-shaped, were performed. In order to distribute artificial bubbles around the arm, an elastic porous stick was attached to the arm. The stick was connected to an air compressor. Two attaching positions of the stick, that is, palm side and the back side of the palm, were tested. The following findings were obtained from the experiment: For the I-shaped stroke, the effect of bubbles became significant when the thrust became maximum. The thrust decreased when the porous stick was attached to the back side of the palm. On the other hand, the thrust increased when the stick was attached to the palm side. For the S-shaped stroke, the effect of bubbles exhibited more complicated behavior than for the I-shaped stroke, and clear tendency of the effect could not be seen.

Grasping for the Seabed: Developing a New Underwater Robot Arm for Shallow-Water Intervention

A new underwater robot arm was developed through intensive cooperation between different academic institutions and an industrial company. The manipulator, which was initially designed to be teleoperated, was adapted for our autonomy needs. Its dimensions and weight were reduced, and its kinematic model was developed so that autonomous control can be performed with it. We compare several commercially available underwater manipulators and describe the development of the new one, from its initial configuration to its mechanical adaptation, modeling, control, and final assembly on an autonomous underwater vehicle (AUV). The feasibility and reliability of this arm is demonstrated in water tank conditions, where various innovative autonomous object-recovery operations are successfully performed, both in stand-alone operation and integrated in an AUV prototype.

W051001 水泳動作を行うロボットに作用する非定常流体力の計測とモデル化(【W05100】EFDワークショップ『流体力とせん断応力の計測』,流体工学部門企画,ワークショップ)

The measurement and modeling of unsteady fluid forces acting on robots in swimming motions are introduced in this paper. Two robots were developed for this purpose. One is an underwater robot arm for the fluid forces acting on limbs and the other is a swimmer mannequin for those acting on body trunk. For both cases, the fluid forces were modeled and formulated as the sum of the drag forces and the inertial force due to the added mass of fluid. The fluid force coefficients in the fluid force model were determined so that the simulated force became consistent with the measured one as well as possible. The simulated forces were found to consistent with the measured ones sufficiently both for the underwater robot arm and the swimmer mannequin. In particular, it was found that the determined fluid force model could estimate the fluid forces for the various different swimming motions.

7자유도 탁상식 마스터 암의 설계 연구

In this research, a novel mater arm was studied as a teaching device for an underwater revolute robot arm used as a slave arm. The master arm was designed to be a seven-degree-of-freedom (DOF) structure, with a structure similar to that of the slave arm, and to be desktop size to allow it to be worn on a human arm. The master arm with encoders on the joints was used as an input device for teaching a slave robot arm. In addition, small electric magnets were installed at the joints of the master arm to generate the haptic force. A control system was designed to sense excessive force and torque in the joints of the master arm and protect it by controlling the position and velocity of the slave arm through the encoder signal of the master arm.

Clarification of Unsteady Fluid Forces Acting on Limbs in Swimming Using an Underwater Robot Arm

Clarification of Unsteady Fluid Forces Acting on Limbs in Swimming Using an Underwater Robot Arm

Clarification of Unsteady Fluid Forces Acting on Limbs in Swimming Using an Underwater Robot Arm

Clarification of Unsteady Fluid Forces Acting on Limbs in Swimming Using an Underwater Robot Arm

水中ロボットアームを用いた水泳時の四肢に働く非定常流体力の解明 : 第2報,実験結果に基づく流体力のモデル化(流体工学,流体機械)

水中ロボットアームを用いた水泳時の四肢に働く非定常流体力の解明 : 第2報,実験結果に基づく流体力のモデル化(流体工学,流体機械)

2A2-C13 水圧人工筋で駆動する柔軟関節を持つ水中ロボットアームの開発

2A2-C13 水圧人工筋で駆動する柔軟関節を持つ水中ロボットアームの開発

水中ロボットアームを用いた水泳時の四肢に働く非定常流体力の解明 : 水中ロボットアームの開発と流体力測定実験(流体工学,流体機械)

The objective of this study was to clarify the unsteady characteristics of the fluid force acting on limbs during swimming. For this objective, an underwater robot arm was developed in this paper. The robot arm has five degrees-of-freedom in order to perform the various complicated limb motions during swimming. In addition, by changing the hand model into the foot one, the robot also can perform the lower limb motions. The joint torques and the resultant thrust can be measured by the force sensors attached to the robot. In a circulating water tank, an experiment to measure the fluid force was conducted for four swimming strokes of the upper and lower limbs. From the experiment, it was found that even the slight difference of the fluid forces between slightly different swimming motions can be quantified by the developed experimental system. In addition, it was suggested that 'nipping' the water by both lower limbs during the kick of the breaststroke almost does not affect the thrust generation. The developed experimental system with the robot arm is useful not only for measuring the unsteady fluid force, but also for the flow visualization in the future studies.

The design and control on intelligent underwater cleaning robot for power plant condenser

A novel method for online steam condenser fouling cleaning is proposed in this paper. In the approach, high pressure cleaning is chosen as the main method, chemical cleaning is applied to complement and this cleaning method is achieved by a new autonomous cleaning robot. In this paper, firstly, the robot system structure is designed which consists of mechanical and electrical structure. Secondly, the distributed control system is used to improve cleaning efficiency. Based on these, the cleaning control strategy based on fuzzy-gaussian neural network is presented and the BP algorithm is adopted to train the network weights. Then, the simulation results show that the proposed control strategy has better robustness and dynamic performance than traditional fuzzy control, which can not only reduce the phenomenon of chattering in effect, but also has good robustness and dynamic performance. Hence, the control strategy is very fit for underwater robotic arm control.

1548 水中ロボットアーム実験に基づく水泳時の四肢に働く非定常流体力のモデル化(S31 スポーツ流体工学,S31 スポーツ流体工学)

The objective of this study was to model the unsteady fluid force acting on limbs in swimming, based on the experiments using an underwater robot arm. First, overview of the robot arm and the experiments were briefly described. Next, the modeling method of the robot arm and the unsteady fluid force, as well as the identification method of the coefficients in the fluid force model were described. The significantly large values of the identified coefficients for the arm suggest the possibility of underestimating the contribution of the arm to the thrust in the previous studies. The good agreement between the experiment and simulation for all strokes shows the validity of the model.