Underwater Manipulator Research Articles

Position Control of a Flexible Rotating Arm with a Thruster in Water.

Stress is applied to an underwater manipulator driven by a DC motor by fluid forces due to the added mass and the drag. Especially, the stress at the clamped end of manipulator with the motor shaft is very large. To suppress the stress, this study proposes the manipulation of the arm driven by a thruster installed at the tip of the arm, and develops a position control system of the underwater flexible rotating arm with a thruster using the optimal control theory. A model of an underwater flexible rotating arm driven by a thruster is made and control experiments are carried out. Using this model, the performance of the developed control system is evaluated. Using experiments and computer simulations, it is clarified that the maximum stress of the arm driven by a thruster is under 20% compared to that by a DC motor.

Design issues for underwater manipulator systems

Underwater manipulators have developed from the crude grabbers first fitted to submersibles in the 1970s to become advanced systems capable of a diverse range of tasks, operating dependably in a hostile and unstructured environment. However, many difficulties still exist in this field and new manipulators with enhanced capabilities, particularly in terms of intelligent control, will be required within the next few years if the efforts to replace the diver are to continue to advance. The wide range of technologies embodied in manipulator systems, together with inherent non-quantifiable and human factors considerations, necessitates a mechatronics approach to design for all but the crudest of arms. Many of the design criteria for underwater systems contrast sharply with those in the better known industrial robotics context. This paper provides an overview of underwater manipulator technology, and discusses the broad range of design problems associated with subsea operation which must be considered for any new design.

The formation of a complex skill in Black Sea dolphins under free choice conditions.

A free choice situation, characterized by the fact that any sequence of actions of dolphins on manipulators set up in a pen was reinforced, providing that they pressed on three specific levers in a required order, independent of the number of "superfluous" reactions before and between the required actions, was created in the experiment. No sequence of actions leading to reinforcement was formed in the dolphin in the first series of experiments using eight above-water levers. In the second series, using eight under-water manipulators, both experimental dolphins regularly acquired reinforcement. Stereotypical trajectories of movements about the pen, which included swimming passed the levers and sequential actions on them, were formed in these dolphins. The formation of a minimal chain of motoric reactions did not take place, although presses on some of the "superfluous" levers did stop. During the accomplishment of the task, the phenomenon of efferent generalization was manifested in two ways in the dolphins in both series of experiments: the animals acted in different ways on the very same manipulator and performed presses on various levers.

Design and performance evaluation of an actively compliant underwater manipulator for full‐ocean depth

AbstractAn underwater manipulator is described that can exhibit a wide range of compliance through a combination of mechanical design and software control and its performance characterized. The manipulator has been used in conjunction with the JASON Remotely Operated Vehicle at full‐ocean depth. The major goal of the design was to produce a manipulator that can actively control the interaction forces with the work task in the hostile deep‐ocean environment. The manipulator's performance has been characterized in the lab and its overall operational utility has been confirmed during tests to depths of approximately 4000 meters, including an archaeological excavation at 700 meters depth in the Mediterranean. The manipulator uses high performance brushless DC servomotors driving the joints though low‐friction, zero‐backlash reductions of moderate ratio consisting of cables and pulleys. Each joint is highly backdriveable and has a large range of rotation. This approach permits a variety of force control schemes such as impedance control to be implemented with no sensors other than the displacement sensors integrated with the brushless motor. It also permits high‐quality torque servomechanisms to be directly implemented. This article outlines the design and illustrates the performance of a single joint in terms of friction, stiffness, and in implementing variable compliance and as a closed‐loop torque servo.

Modelling and simulation of an underwater manipulator

Recently, applications of articulated manipulators have increased to include extreme environments such as underwater and space. Simulation systems to support the design and control of industrial robots have been developed in many laboratories, and some high-speed calculation methods for inverse dynamics analysis of manipulators with series connections have been proposed. This paper deals with the dynamic simulation and modelling of underwater articulated manipulators. The dynamics of the above manipulators are formulated to evaluate the influence of the added mass tensor, the added inertia tensor, and fluid drag, and the lift on each arm according to classical Newton-Euler mechanics. Moreover, by generalizing this model, we can discuss the dynamics of a manipulator with dual arms and simulate some constrained motion of an end-effector. As an example of inverse dynamics analysis, the force and moment of a nine degrees of freedom (d.o.f.) manipulator with dual arms are analysed. As an example of direct dyna...

水中マニピュレータの動揺補償型位置・力ハイブリッド制御

水中マニピュレータの動揺補償型位置・力ハイブリッド制御

Neural networks for robotic control

Conventional underwater manipulation is performed by a remotely operated vehicle (ROV) equipped with a rigidly connected multi-link arm. However, accurate manipulation requires the ROV to have excellent maneuverability, which limits the design flexibility and capabilities of the vehicle. This paper instead proposes the use of a small, deployable, and highly maneuverable agent ROV as an end effector, which is connected to the main vehicle by a flexible smart cable. This cable tracks the relative position of the agent, thus eliminating the need for additional positioning sensors and allowing significant size reduction for the agent. In addition, to compensate for the limited lifting capability of the small agent, it is equipped with active buoyancy control. The proposed system can be applied to common autonomous underwater vehicles (AUVs) with minimal modification for coarse station-keeping. The whole system is operated as a conventional AUV under normal operating conditions, but the agent is deployed when manipulation or precise monitoring is necessary. Numerical simulations were performed for dynamic analysis and prototype design of the agent vehicle, and this design was implemented as a model-scale system for experiments in a test tank. This implementation confirmed the feasibility and potential capabilities of the proposed manipulation system concept.

Spatial autocorrelation with RUM (Remote Underwater Manipulator): vertical and horizontal structure of a bathyal benthic community

Abstract The RUM/ORB unmanned submersible system (Marine Physical Laboratory, Scripps Institution of Oceanography) was used at 1220-m depth to collect precisely located samples separated by distances from 0.1 to 500 m in the San Diego Trough, Southern California continental borderland. Newly developed spatial autocorrelation procedures from the field of quantitative geography were used on this irregularly spaced network of samples to test the statistical significance of the calculated autocorrelations. Scales less than 200 m showed little spatial autocorrelation in total numbers of macrofaunal individuals per sample. Density of Polyophthalamus sp. (Polychaeta, Opheliidae), however, displayed a complex autocorrelative pattern; ‘patches’ of individuals of similar size were observed. Ceratocephale pacifica (Polychaeta, Nereidae), on the other hand, showed negative spatial autocorrelation at the smallest inter-sample distance, perhaps indicative of territoriality. Vertical segregation among confamilial and congeneric species was observed in vertically sectioned subsamples. The majority (82%) of polychaetes, however, appear regularly to inhabit the uppermost centimeter of sediments, suggesting a refinement of current bioturbation models.

GE's underwater manipulator shipped to oceaneering

GE's underwater manipulator shipped to oceaneering

In situ morphologies of deep-sea and sediment bacteria

Deep-sea and sediment bacteria at the bottom of an approximately 1200-m water column were sampled by means of pressure vessels attached to a remote underwater manipulator. Cells were immediately fixed in situ with glutaraldehyde, and after processing in the laboratory their morphologies were observed with the scanning electron microscope. Most bacteria were coccoid or rod-lide and less than 0.4 mum in diameter or width. Few filamentous bacteria were observed. Bacteria were in aggregates or free-living. It is concluded that morphologies of deep-sea bacteria collected and fixed at the hydrostatic pressure of their environment are, in general, similar to the observed morphologies of deep-sea bacteria determined at 1 atm pressure after collection and decompression during ascent through the water column.

Instrumenting RUM for in situ subsea soil surveys : V. C. Anderson, J. R. Clinton, D. K. Gibson and O. H. KirstenASTM Spec. Techn. Publ. No. STP 501, 216–231 (1972)

The RUM (Remote Underwater Manipulator), one of the laboratory research vehicles of the Marine Physical Laboratory, USA, is a tracked vehicle capable of operating on the sea floor to depths of more than 6000 ft. An umbilical coaxial strain cable connects it with a surface support platform ORB (Oceanographic Research Buoy) and provides the power and data transmission required for unmanned remote sea floor operations. A brief description of this sea floor work system is presented, whose main emphasis concerns the instrumentation suite developed for in situ soil trafficability studies with RUM. RUM has been instrumented for remote operation of a 2-ft-long 3-in.-diameter corer, a vane shear meter, a cone penetrometer, an anchor-winch-tensiometer combination for the measurement of drawbar pull, and a short range, high resolution echo-sounding profiler for examination of track depression. All of these instruments are adapted for use by the manipulator arm mounted on RUM, and all telemeter their data back to ORB via the coaxial strain cable. Results of initial measurements with the system are discussed.

New research tool in ocean technology

Sea‐floor operations of a remote‐controlled, tracked vehicle called RUM have totaled more than 100 hours in running up nearly ten miles of bottom crawling in the Pacific since it was first lowered into the ocean early this year.RUM, the Remote Underwater Manipulator, is undergoing extensive tests off the California coast to determine its capability as a research tool in ocean technology.

UNDERWATER MANIPULATORS

Naval Engineers JournalVolume 78, Issue 6 p. 1003-1009 UNDERWATER MANIPULATORS First published: December 1966 https://doi.org/10.1111/j.1559-3584.1966.tb04123.xAboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume78, Issue6December 1966Pages 1003-1009 RelatedInformation

MOBOTRY: The new art of remote handling

Equipment to perform a great variety of tasks within hostile environments has been designed and built utilizing well-proven electronic techniques. Such systems perform most of the operations which would be performed manually were it possible for a man to enter the hazardous area. Examples of hostile environments include space, the ocean, nuclear laboratories, and numerous others. A simple trinary coding command system has proved quite practical and is capable of commanding mobile remote systems having 50 or more degrees of freedom. Conventional closed-circuit television systems may be used for driving and steering remotely-controlled vehicles and for accomplishing manipulative tasks. Two or more such cameras are highly desirable for obtaining good spatial perception. Examples of remotely-controlled systems for hostile environments include the Hughes Mark II Mobot system for nuclear hot laboratories, the RUM (Remote Underwater Manipulator) built by Scripps Institute of Oceanography for scientific and military operation in the depths of the ocean, and a variety of outdoor remotely-controlled vehicles designed and operated by Engineer Research and Development Laboratory at Fort Belvoir, Virginia, and by Air Force Special Weapons Center in Albuquerque, New Mexico.