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Autonomous Underwater Vehicles, 1998. AUV'98. Proceedings of the 1998 Workshop on

Date 21-21 Aug. 1998

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Displaying Results 1 - 19 of 19
  • Proceedings of the 1998 Workshop on Autonomous Underwater Vehicles (Cat. No.98CH36290)

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    Freely Available from IEEE
  • Making difficult decisions autonomously: the impact of integrated mapping and navigation

    Page(s): 123 - 132
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    The role of navigation is changing. The forces of increased autonomy, less prior knowledge, and larger missions are extending the navigation problem from the requirement of absolute localization to the larger question of context determination. Current technologies are inadequate in the face of such circumstances. The key to an evolved navigation technology begins with the ability to reason, in an integrated way, about the models used to determine vehicle context: physical models, dynamic models, sensor models, and behavior models. The integrated mapping and localization (IMAN) algorithm provides a hybrid estimation scheme to integrate decision-making about navigation events with navigation and mapping. An overview of IMAN is presented, along with an initial analysis of its performance. While IMAN is sensitive to the complexity of ambiguous situations, the algorithm demonstrates superior performance when complexity does not lead to failure. These results are used to examine the emerging set of technological needs for advanced navigation and mapping applications, including map representation, multiscale modeling, map fusion, and cross-model correlation View full abstract»

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  • Using the ST725 sonar for AUV feature based navigation and correction

    Page(s): 149 - 166
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    This paper reports on a previous experimental investigation of the Tritech ST725 high resolution sonar system used onboard the NPS Phoenix and a possible extension of the results to an underwater feature based navigation and correction system. The ST725 sonar was used in progressively complex static environments to clearly image objects. Scanline analysis of the ST725 data was conducted and shown to be useful in extracting stationary target information on vertically oriented mine-like objects as well as a small sphere. Raw scanline processing using a “gating and thresholding” method was used to determine range, bearing, and approximate size/orientation. Additionally, by capturing the range of the first return, the sonar was shown to be capable of emulating a “profiling” sonar. Future synthesis of known underwater features with range and bearing information and scanline analysis may provide the underwater vehicle systems designer with an alternate method of navigation. The value of this topic in the advancement of understanding underwater technology is that actual experimental data were used and useful results were obtained View full abstract»

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  • The Doppler inertial acoustic system for littoral navigation (DIAS)

    Page(s): 27 - 33
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    The Doppler inertial acoustic system (DIAS) is a compact, low-power, inertially-aided Doppler velocity navigation system which was developed to enhance the navigation capabilities of an unmanned underwater vehicle (UUV) in search, reacquisition, and inspection applications. Based on experience gained in the employment of long-baseline acoustic navigation approach using the divers acoustic navigation system (DANS) in support of the explosive ordnance disposal remote work packages program (EODRWP), DIAS provides for navigation of small subsea vehicles operating in shallow water without requiring reliance on external reference points reducing operational complexity. The primary navigation components in DIAS include a recently developed high-frequency (1200 kHz) Doppler velocity log and a relatively low-cost, low-power, miniature solid-state inertial package. Sensor data collection, prefiltering and integration is accomplished using a low-power digital signal processor (DSP) based single board computer (SBC) resulting in a system that requires less than 14 Watts power dissipation. Data is integrated using Kalman filtering techniques reducing long term errors introduced by the Doppler and short-term errors introduced by the inertial sensors. The paper describes DIAS development and testing and contrasts the accuracies of the developed system versus the previously employed long-baseline approach. The integration of DIAS within the EODRWP and at-sea employment using the Cetus AUV completes the paper View full abstract»

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  • An aided navigation post processing filter for detailed seabed mapping UUVs

    Page(s): 19 - 25
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    HUGIN is an untethered underwater vehicle (UUV) intended for bathymetric data collection for detailed seabed surveying. The HUGIN sensor suite, consisting of standard commercially available navigation sensors and a multibeam echosounder, is briefly presented. A Kalman filter based post processing integration of UUV sensors and survey vessel sensors is discussed. Resulting UUV position and heading accuracy and important characteristics of the post processing filter is shown with simulation results and results from a commercial survey operation. Finally, we briefly show how the claimed position and heading accuracy has been verified View full abstract»

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  • Online compensation of heading sensor bias for low cost AUVs

    Page(s): 35 - 42
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    Presents a study of the effects of compass bias on navigational accuracy of autonomous underwater vehicles. Low cost vehicle systems utilize a magnetometer, and Doppler sonar for dead reckoning, and a DGPS fix when surfaced. By learning the compass bias from a few DGPS fixes, the navigational errors can be bounded with only a small number of fixes. The study is conducted using the Florida Atlantic University OEX vehicle and a large set of data obtained from a 3.5 Km run including several segments at different headings so that the dependency of compass error on actual heading could be evaluated View full abstract»

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  • Acoustic positioning systems. A practical overview of current systems

    Page(s): 5 - 17
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    There are existing commercial sources that provide acoustic positioning systems with some capability to navigate unmanned underwater vehicles (UUVs). Some of these systems can be applied to autonomous underwater vehicles (AUVs). Systems are currently available to provide full ocean depth positioning to an absolute accuracy of 5 m and a relative accuracy of <2 m. Also available from these and other sources are shorter range, higher resolution acoustic positioning systems. The paper discusses how these systems are configured and what capabilities they have. A definition of conventional systems and frequency bands is included. In addition to system types, some of the more common problems associated with acoustic positioning systems and some solutions to these problems are outlined. The paper concludes that although some systems, or components readily exist for the AUV community, additional development is required View full abstract»

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  • Demonstration of a vision-based dead-reckoning system for navigation of an underwater vehicle

    Page(s): 185 - 189
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    This paper describes a dead-reckoning navigation system for hover-capable underwater vehicles operating close to the ocean floor. Navigation is presented as an extension of underwater station-keeping and mosaicking. It combines real-time vision-processing to build a mosaic of the area of interest, an image-based user interface to specify desired vehicle locations, and vision-based dead-reckoning to compute the robot's position in the mosaic. This system provides a high-level interface between the vehicle and the pilot, who specifies the goal (e.g., go to and hover over this feature) instead of the commands to execute the task (e.g., rotate to the left, go forward, stop). Thus, it is an enabling technology for autonomous underwater vehicles (AUV)-for which commanding actuators directly is not feasible-and a useful high-level interface for remotely operated vehicles (ROV). This new capability is the result of our on-going research with the Monterey Bay Aquarium Research Institute (MBARI) View full abstract»

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  • Trends in acoustic velocity log technology at RD Instruments

    Page(s): 89 - 101
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    RD Instruments (RDI) has been the leading manufacturer of acoustic Doppler current profilers (ADCP) for many years. Sales of our products for use primarily as navigation sonars or Doppler velocity logs (DVL) have been limited until recently by issues of size, weight, and cost. In 1995, RDI introduced the Workhorse product line which dramatically reduced the size, weight, and cost of ADCPs. This was followed closely by the Navigator DVLs which are based on the same technology. The Navigators have received an excellent reception by the small AUV community and are in use on many of the prominent vehicles in the world today. In addition to AUV builders, the ROV community is beginning to discover the value of incorporating a DVL into the vehicle's navigation and control system. In this paper, we discuss some of the applications in which our DVLs are being used and the technical issues which have been addressed. We also present our views on the directions in which the acoustic velocity log technology is moving and some of the constraints on that technology. The issues discussed include further reduction of size, weight and cost, the use of phased array technology to reduce further the transducer size, and the progress which we have made in correlation velocity logs as a deep water alternative to DVLs View full abstract»

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  • Inertial sensor technology trends

    Page(s): 55 - 62
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    This paper presents the status of inertial sensor technology in underwater navigation applications, followed by a prediction of where inertial instrument technology is heading and in which applications the future sensor technologies will find a niche. Many kinds of sensors have been developed. The GPS is cheap and ubiquitous, but it is uncertain whether it would be continuously available in military scenarios View full abstract»

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  • 3-D motion and depth estimation from sea-floor images for mosaic-based station-keeping and navigation of ROVs/AUVs and high-resolution sea-floor mapping

    Page(s): 191 - 200
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    A vision system has been developed in order to support the autonomous operation or operated-assisted missions of AUV and ROV near the ocean bottom. The sea-floor images, acquired by a down-look camera installed on the vehicle, are processed by the vision system in order to detect and estimate its motion in real time. This information is utilized to realize a number of capabilities, including automatic station keeping, navigation and trajectory following, and the construction of a composite (mosaic) image of the sea floor. We describe the system and provide sample results from various experiments for evaluating performance. We also provide examples from ongoing work, planned for implementation on the real-time vision system View full abstract»

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  • Precision gravity gradiometer/AUV system

    Page(s): 167 - 174
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    Unprecedented stealth in navigation at sea, both long and short term, is now achievable through the integration of a gradiometer/gravimeter inertial navigation system into an appropriate submersible platform. Several key accomplishments have advanced the technology of gravity and gradiometry. Highly accurate gradiometer tensor measurements of 1.0 Eotvos or better were made at sea using a fully integrated GPS/DGPS/INS/gradiometer system. These measurements are part of the ongoing oil exploration surveys by Bell Geospace, Inc. (BGI) using its retrofitted surface vessel Seacor Surf. Through a reversal in roˆles, whereby gravity gradient signatures are used as references, instead of oil deposit signatures, reference mapping can be accomplished, enabling stealth navigation to the order of 30 m. Additionally, to handle the rough sea condition that affects the fidelity and resolution of gravity gradient detection, a nonpowered submersible has been developed and built for BGI, which can house the presently sized full tensor gradiometer (FTG) system View full abstract»

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  • Incorporating environmental measurements in navigation

    Page(s): 115 - 122
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    Extended missions in unknown regions present a significant navigational challenge for autonomous underwater vehicles (AUV). This paper investigates the long-term performance of a concurrent mapping and localization (CML) algorithm for the scenario of an AUV making observations of point features in the environment with a forward look sonar. Simulation results demonstrate that position estimates with long-term bounded errors of a few meters can be achieved under realistic assumptions about the vehicle, its sensors, and the environment. Potential failure modes of the algorithm, such as divergence and map slip, are discussed. CML technology can provide a significant improvement in the navigational capabilities of AUVs and can enable new missions in unmapped regions without reliance on acoustic beacons or surfacing for GPS resets View full abstract»

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  • GIB buoys: an interface between space and depths of the oceans

    Page(s): 181 - 184
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    Unmanned underwater vehicles having no umbilical can be successfully used for defense and commercial applications only if answers are found to the two most critical technical challenges: accurate positioning, and communications at a reasonable cost. The author states that, as new OEM GPS receivers achieve metric accuracy, LEO satellites will soon offer real-time two-way data communications anywhere over the oceans. DSP chips offer tremendous signal processing power. The question that raises is how those new technologies will be assembled together to make practical, operational and efficient underwater positioning and guidance systems. GIB (GPS intelligent buoys) involve groups of buoys that calculate their own position from the GPS and then send acoustic signals to the underwater vehicle as a basis for calculation of its position View full abstract»

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  • An integrated GPS/INS navigation system for small AUVs using an asynchronous Kalman filter

    Page(s): 43 - 49
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    A small AUV navigation system (SANS) is being developed at the Naval Postgraduate School. The SANS is an integrated GPS/INS navigation system composed of low-cost, small-size components. It is designed to demonstrate the feasibility of using a low-cost inertial measurement unit (IMU) to navigate between intermittent GPS fixes. The paper reports improvements to the SANS hardware, latest testing results after compensating heading-dependent derivations in the TCM-2 compass measurements, and development of an asynchronous Kalman filter for improved position estimation View full abstract»

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  • Characteristics of a small low cost inertial measurement unit

    Page(s): 75 - 87
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    The HG1700 Inertial Measurement Unit (IMU) was developed to provide low cost inertial measurement products for air-to-air missiles and air-to-surface weapons. The HG1700 IMU uses low cost miniature tactical grade ring laser gyros and linear accelerometer inertial sensors. Since the IMU was initially introduced as a production item in 1994, it has been selected by each Department of Defense service for a variety of applications, including; missiles, munitions, unmanned aerial vehicles, air targets, and unmanned underwater vehicles. Many of the applications are in Engineering and Manufacturing Development program phases so available test results are current and impressive. The HG1700 IMU is designed to use a common hardware configuration with software that can be modified to meet application specific requirements. Software modifications generally include interface protocol, data rate output and frequency response characteristics. This paper provides a history of the need for the HG1700 IMU, a summary of current applications using the HG1700 IMU and a review of recent test results. A technical overview and interface description are also included View full abstract»

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  • Concurrent mapping and localization with FLS

    Page(s): 133 - 148
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    The topic of concurrent mapping and localization (CML) using a forward look sonar (FLS) is addressed. In many AUV applications, artificial beacons are employed for long duration positioning, or Global Positioning System (GPS) data are used to provide navigation resets. There are numerous missions where these constraints are undesirable and it is the aim of CML to provide relative position by extracting information from the environment through which it is moving. A technique for CML using a multibeam FLS is presented. The method is based on forming objects based on compact regions of high-level bottom backscatter, extracting features from the objects to identify/label them to aid in the data association process, and using the objects in an extended Kalman filter (EKF). A simplified approach to the EKF is used, whereby a new and separate filter is initiated for each new object encountered. Vehicle position is then derived as a weighted sum of the outputs from the individual filters. This approach has been developed and tested using data collected with an advanced FLS referred to as the high resolution array (HRA) View full abstract»

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  • Acoustic positioning systems. New concepts-the future

    Page(s): 103 - 110
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    A clear definition of the applications and accuracies required to navigate AUV will have to be completed prior to defining future developments within acoustic positioning systems. This paper discusses these applications and then estimates the positioning accuracy and market size for these operations. Beyond these estimates a discussion of system development trends including inverted long baseline, inverted ultrashort baseline and system integration is detailed. Several incremental development trends are also outlined. This paper concludes that some basic research and significant system development is still required to provide the “ultimate” AUV acoustic positioning system View full abstract»

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  • Trends in inertial systems technology for high accuracy AUV navigation

    Page(s): 63 - 73
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    Medium accuracy inertial systems of the 1 nautical mile per hour class, enjoyed significant acceptance in the market for land survey systems in the early 1970's-prior to the introduction of GPS. This occurred because such systems could be implemented with software that capitalized on “zero velocity updates” (ZUPTS) which enabled the resultant system to achieve real-time navigation accuracies of a few meters over several hours of operation. “ZUPTS” are realized by simply bringing a land vehicle to a stop or, in the case of a helicopter, by hovering across a fixed point on the ground. Those initial inertial survey systems were large, heavy, expensive and required substantial power. Since the technology has changed dramatically, these systems have become highly suitable as the core of the navigation and control suite for small submersibles. The paper will discuss and illustrate the trend in inertial technology, from that of gimbaled spinning wheel gyro based systems initially employed for surveying, to the ring laser gyro based systems available today and the next generation of systems employing fiber optic gyros. Performance obtainable with these medium grade inertial systems will also be presented as a function of the quality of zero velocity updates. Realization of zero velocity updates by different means will also be a topic of discussion View full abstract»

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