David A. Mindell

Iron age shipwrecks in deep water off Ashkelon, Israel

In 1997, two shipwrecks were first discovered in the Mediterranean Sea west of Israel by the U.S. Navys research Submarine NR-1. Further investigation in 1999 with the remotely operated vehicle system Medea/Jason found the wrecks to be from the eighth century B.C., the earliest known shipwrecks to be found in the deep sea. Both ships appear to be of Phoenician origin, laden with cargoes of fine wine destined for either Egypt or Carthage, when they were lost in a storm on the high seas. The ships lie upright on the seafloor at a depth of 400 m in a depression formed by the scour of bottom currents. Their discovery suggests that ancient mariners took direct routes to their destinations even if it meant traveling beyond sight of land.

Towards Precision Robotic Maneuvering, Survey, and Manipulation in Unstructured Undersea Environments

This paper reports recent advances in the precision control of underwater robotic vehicles for survey and manipulation missions. A new underwater vehicle navigation and control system employing a new commercially available 1,200 kHz doppler sonar is reported. Comparative experimental trials compare the performance of the new system to conventional 12 kHz and 300 kHz long baseline (LBL) acoustic navigation systems. The results demonstrate a hybrid system incorporating both doppler and LBL to provide superior tracking in comparison to doppler or LBL alone.

Robotic Tools for Deep Water Archaeology : Surveying an Ancient Shipwreck with an Autonomous Underwater Vehicle

The goals of this article are twofold. First, we detail the operations and discuss the results of the 2005 Chios ancient shipwreck survey. This survey was conducted by an international team of engineers, archaeologists, and natural scientists off the Greek island of Chios in the northeastern Aegean Sea using an autonomous underwater vehicle (AUV) built specifically for high‐resolution site inspection and characterization. Second, using the survey operations as context, we identify the specific challenges of adapting AUV technology for deep water archaeology and describe how our team addressed these challenges during the Chios expedition. After identifying the state of the art in robotic tools for deep water archaeology, we discuss opportunities in which new developments and research (e.g., AUV platforms, underwater imaging, remote sensing, and navigation techniques) will improve the rapid assessment of deep water archaeological sites. It is our hope that by reporting on the Chios field expedition we can both describe the opportunities that AUVs bring to fine‐resolution seafloor site surveys and elucidate future opportunities for collaborations between roboticists and ocean scientists. (Less)

Imaging Underwater for Archaeology

Abstract In this paper we examine underwater imaging for archaeology and especially the use of multiple acoustic and optical sensors at varying degrees of resolution for reconnaissance and mapping sites on the seafloor. Specifically, we look at the role of side-scan sonar for locating suitable sites of interest, which may then be mapped quantitatively with bathymetric sonars. We also discuss the role of conventional digital and video cameras in providing high resolution redundant imagery, and how, after compensating for lighting and other artifacts, such imagery may be assembled into a photomosaic of a large site.

Integrating Precision Relative Positioning into JASON/MEDEA ROV Operations

Advances in navigation continue to add precision and robustness to undersea operations. Two challenges limit navigation of the JASON/MEDEA two-vehicle ROV system: acoustic noise from JASON’s hydraulic systems and lack of a direct relative position measurement between the two vehicles. This paper describes successful integration of the SHARPS ranging system—enabling precise relative positioning that is robust with respect to acoustic noise. We discuss four aspects of the installation: the capabilities of SHARPS as installed on the ROVs, the estimation theory predicted performance of the system design, the proof-of-concept navigation results from field deployments, and the operational utility of the SHARPS capability. The SHARPS installation integrates an important capability into the ROV system, enhancing the data product for science while adding safety and flexibility to the at-sea operations. hangs below the dynamically positioned (DP) surface ship via an armored cable carrying fiber-optic communications and electric power. The vehicle’s large, concentrated mass decouples the ROV, JASON, from the surface ship’s motion, keeping the armored cable vertical and reducing the chance of snap-loading from surface heave. A 35 m neutrally buoyant tether connects the two vehicles, extending the communication and electric power to JASON. Operators move the ship to position MEDEA vertically over-top of JASON, maintaining visual contact using a down-looking low-light camera on MEDEA and adjusting the vertical separation between the two vehicles. During lowerings lasting as long as 72 hours, JASON samples and surveys the seafloor at depths of up to 6,500 m. One of the most important data products of this work is the record of navigation estimates. These records allow scientists to systematically and quantitatively explore the seafloor. Because of the JASON/MEDEA two-body configuration, short baseline (SBL) relative positioning improves the navigation solution, allowing safer, more flexible operation. Operators navigate the JASON/MEDEA ROV system using a combination of long baseline (LBL) positioning and Doppler velocity log (DVL) dead-reckoning. Both JASON and MEDEA have LBL receivers, but only JASON has a DVL to measure velocity relative to the seafloor. There are two challenges with the current navigation solution. First, LBL reception at JASON’s receiver is inconsistent or non-existent due to acoustic noise and limited line-of-sight. JASON’s hydraulic motors power much of the on-board utilities: the two manipulators, tool basket, suction pumps, etc. The associated acoustic

On the Design of Direct Sequence Spread-Spectrum Signaling for Range Estimation

Precise range measurement by time-of-flight sonar is important for underwater positioning, oceanography (tomography) and marine geology (geodesy). This paper reports on the design of spread-spectrum codes for range measurement in a variety of important underwater environments. Direct sequence spread-spectrum (DSSS) signal processing has many advantages over continuous wave techniques for time-of-flight range estimation: improved precision, extended effective range, robustness to ambient or jamming noise, increased update rate, and simultaneous multi-user capability. Design of appropriate DSSS codes requires matching the code parameters to the acoustic operating environment to maximize system performance. We consider three canonical ocean environments: a laboratory test-tank, the littoral zone, and the deep water channel. The characteristics of these acoustic channel models directly influence the code design to maximize range estimate performance. We parameterize the design choices for DSSS codes by code type, code length, carrier frequency, and chip rate. The paper concludes with experimental results for spread- spectrum range estimation in a shallow water dynamic environment and on an operation ROV in deep water.

A high-frequency, narrow-beam sub bottom profiler for archaeological applications

Shipwrecks in deep water are often found by their surface expressions, such as exposed ceramic containers. Fully investigating or excavating those sites, however, requires understanding what is buried beneath, including organic materials and the remains of ship structure. This paper lays out the archaeological and technical justification for a high-frequency, narrow-beam sub-bottom profiler. It describes an ultrasonic (150 kHz) device built to image local areas of the seafloor beneath the mud. The final section presents a data set collected with the instrument operating on the ROV JASON over an 8/sup th/-century B.C. shipwreck found off the coast of Israel. Precise sub-bottom imagery can aid in characterizing a site before excavation, and enables a three-dimensional computer model of a buried structure to be built with acoustic techniques, without ever disturbing a wreck.

Anti-aircraft fire control and the development of integrated systems at Sperry, 1925-40

The dawn of the electrical age brought new types of control systems. Able to transmit data between distributed components and effect action at a distance, these systems employed feedback devices as well as human beings to close control loops at every level. By the time theories of feedback and stability began to become practical for engineers in the 1930s, a tradition of remote and automatic control engineering had developed that built distributed control systems with centralized information processors. These two strands of technology, control theory and control systems, came together to produce the large-scale integrated systems typical of World War II and after. >

Engineers, psychologists, and administrators: control systems research in wartime, 1940-45

Describes the organisation and work of 2 US wartime scientific agencies, the National Defense Research Committee (NDRC) and its successor and umbrella organization, the Office of Scientific Research and Development (OSRD). >

Integrating SHARPS II precision navigation into JASON/MEDEA two-vehicle operation

Advances in navigation continue to add precision and robustness to undersea operations. This paper describes the integration of the SHARPS II system into two-vehicle operations with the JASON/MEDEA ROV system, allowing precise relative navigation of the two vehicles. This paper details the SHARPS II system as installed on JASON and MEDEA, uses estimation theory to illustrate the potential performance enhancement over the state-of-practice and presents proof-of-concept navigation data from field deployments