In the interest of enhancing the capabilities of autonomous underwater vehicles US Naval Operations, controlling vehicle position to follow depth contours presents exciting potential for navigation. Use of a contour tracking control algorithm in lieu of preprogrammed waypoint navigation offers distinct advantages within new challenges. The difficult nature of this problem lies in the non-trivial connection between the necessary corrective action and the feedback error used in traditional control methods. Stated simply, modern vehicle control algorithms separate horizontal and vertical plane navigation. The autonomous vehicle senses heading error and applies rudder to steer the vehicle to a desired heading. Simultaneously, the vehicle might sense altitude and apply stern plane angles to maintain a safe height above ground. This thesis research examines the new problem of sensing depth and altitude in the vertical plane while steering the vehicle horizontally to find a specified bathymetry contour. While more remains to understand, this research proves the existence of a solution and suggests similar approaches may facilitate tying vehicle navigation to other indirect sensors. This thesis presents two contour tracking control algorithms and examines the performance of each by simulating the response of the REMUS underwater vehicle to ideal and real-world bathymetry models.

CIVINS / This thesis presents a simulation of autonomous underwater vehicle navigation using a single transponder to create a virtual long baseline (VLBL). Similarly to LBL systems, ranges in a VLBL are calculated between the vehicle and the transponder, but the vehicle position is determined by advancing multiple ranges from a single transponder along the vehicles dead reckoning track. Vehicle position is then triangulated using these successive ranges in a manner analogous to a 'running fix' in surface ship navigation. Navigation data from bottom survey operations of an underwater vehicle called the Autonomous Benthic Explorer (ABE) were used in the simulation. The results of this simulation are presented along with a discussion of the benefits, limitations, and implications of its extension to real-time operations. A cost savings analysis was also conducted based both on the idea that a single surveyed beacon could be deployed for underwater navigation and on the further extension of this problem that the 'single beacon' used for navigation could be located on the ship itself. / Contract number: N62271-97-G-0026. / CIVINS / US Navy (USN) author.

Autonomous underwater vehicle navigation is a complex problem of state estimation. Accurate navigation is made difficult due to a lack of reference navigation aids or use of the Global Positioning System (GPS) that could establish the vehicles position. Accurate navigation is critical due to the level of autonomy and range of missions and environments into which an underwater vehicle may be deployed. Navigational accuracy depends not only on the initialization and drift errors of the low cost Inertial Motion Unit (IMU) gyros and the speed over ground sensor, but also on the performance of the sensor fusion filter used. This thesis will present the method by which an Extended Kalman Filter (EKF) was tuned after installation of an IMU in the ARIES Autonomous Underwater Vehicle. The goal of installing the IMU, analyzing the navigational results and tuning the EKF was to achieve navigational accuracy in the horizontal plane with a position error of less than one percent of distance traveled when compared to GPS. The research consisted of IMU installation and software modifications within the vehicle to fully realize the design goal. Data collection and analysis was conducted through field experiments and computer simulation. A significant result of this work was development of a pseudo-adaptive algorithm to vary the measurement noise values in selected channels to for a desired response in the filter and improve accuracy and precision in the state estimates.

The objective of the Small Robot Technology (SMART) initiative at the Naval Post Graduate School (NPS) is to develop robots for military uses. One of the goals of this program is to create a surf--zone reconnaissance robot to do beachhead surveillance and mine detection. To this end, a prototype robot was created to test the locomotion and navigation functions which will be used on the surf--zone robot. This work consisted of redesigning the steering mechanism, strengthen the structure, improving the electrical distribution and upgrading the communications hardware. Several tests were conducted on both grass and soft sand to evaluate the performance of the locomotion system and the navigation software. The results demonstrated that the robot functions best in soft sand as expected. However, several serious mechanical design flaws were noticed in the body construction and mechanical systems. These flaws, while not detrimental, did negatively impact the performance of the system. Finally, some suggestions for improving future prototypes are discussed. / US Navy (USN) author.

No description available.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Gonzalo Arce, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

<p>Safe winter navigation is a hot topic. Not only is the traffic density increasing but theenvironmental considerations are also getting bigger. An oil leakage from a big oiltanker can be of catastrophic proportions in the wrong area and more trafficincreases the risk of an accident. A project that aims for safer winter navigation isSafeWIN. The aim of this project is to develop a forecasting system for compressiveice and thus make winter navigation safer.This thesis is part of above mentioned project and aims to investigate what influenceice compression and ice class has on winter navigation. Vessels are exclusivelyAFRAMAX size tankers sailing on Primorsk in the Gulf of Finland during 2006. Transitdata comes from AIS tracks recorded by the Swedish Maritime Administration. Adatabase with tanker transits has been created and this information is the source forthe studies in this thesis. Included in the database are wind data, ice particulars andtransit information such as speed, and time at different activities during the transit.Average values for a transit has been investigated for comparison and to get a pictureof an average transit.Velocity, waiting time and time with assisting icebreaker are parameters that arebelieved to show how a tanker performs in winter navigation. These parameters arecompared with ice compression and ice class separately to see if there is acorrelation. Ice compression has also been investigated for correlation towards windforce to see if stronger wind generates stronger compression.Using the velocity in different ice compressions an estimate of ice resistance that stemfrom ice compression has been extracted by means of Lindqvist’s formula.</p>

The purpose for writing this thesis is to prove the automatic carrier landing system (ACLS) a valuable Operational Risk Management (ORM) tool for recovering F/A-18A-D aircraft aboard the modern aircraft carrier. ORM is itself a subset of human factors and worthy of exploration in the aviation systems field. In proving the value of the ACLS, the author presents the following objectives: 1) describe the major components of the F/A-18A-D and modern aircraft carrier ACLS, 2) describe the current Mode I approach procedures, and the Precision Approach Landing Systems (PALS) certification process, 3) promote an increase in automatic landings during night time and low ceiling/visibility environments through an analysis of ACLS strengths and weaknesses, and 4) advocate the continued use of fully automatic carrier landings amidst addressing deeply rooted fleet squadron paradigms and the advent of future technologies. The information gathered for this thesis came primarily from the author’s own direct flight and test experiences as well as documentation of standardized Navy flight and test publications. Detailed background information on the ACLS and future landing programs along with data from the Naval Safety Center and the VX-23 Carrier Suitability department were used as evidence to support the findings. The author concludes that the Mode I ACLS capability is extremely vital to the safe and expeditious recovery of the F/A-18A-D Hornet aircraft onboard the modern aircraft carrier that the Mode I automatic carrier landing system as currently structured and utilized is a highly effective risk management tool for naval aviation. The routine testing and certification of the precision approach equipment, all-weather capability, redundant cockpit data and voice safety network, plus enhanced aircraft carrier mobility through the use of Mode I approaches are all strengths of the ACLS system. To enhance the effectiveness of the ACLS for future carrier operations, the author recommends: 1) creating RAG and fleet squadron command climates that promote and support the use of Mode I approaches, 2) increasing ACLS training for aircrew and maintainers, and 3) establishing a new CV-1 approach that can capitalize on JPALS functionality in order to improve upon automatic landings.

A self-contained, portable, inertial and positional measurement system was developed and tested for an HGU-55 model fighter pilot helmet. The system, designated the Portable Helmet Instrumentation System (PHIS), demonstrated the recording of accelerations and rotational rates experienced by the human head in a flight environment. A compact, self-contained, “knee-board” sized computer recorded these accelerations and rotational rates during flight. The present research presents the results of a limited evaluation of this helmet-mounted instrumentation system flown in an Extra 300 fully aerobatic aircraft. The accuracy of the helmet-mounted, inertial head tracker system was compared to the aircraft-mounted referenced system. The ability of the Portable Helmet Instrumentation System to record position, orientation and inertial information in ground and flight conditions was evaluated. The capability of the Portable Helmet Instrumentation System to provide position, orientation and inertial information with sufficient fidelity was evaluated. The concepts demonstrated in this system are: 1) calibration of the inertial sensing element without external equipment 2) the use of differential inertial sensing equipment to remove the accelerations and rotational rates of a moving vehicle from the pilot’s head-tracking measurements 3) the determination of three-dimensional position and orientation from three corresponding points using a range sensor. The range sensor did not operate as planned. The helmet only managed to remain within the range sensor’s field of view for 37% of flight time. Vertical accelerations showed the greatest correlation when comparing helmet measurements to aircraft measurements. The PHIS operated well during level flight.

Naval aviation is on the brink of taking advantage of a 12 year old capability. Naval commercial derivative aircraft have had the ability to navigate in instrument meteorological conditions using global positioning technology for nearly as long as civil commercial-for-hire aircraft. However, tactical naval aircraft, like the E-2C Hawkeye, are now only beginning to obtain and install the necessary technology to meet federal aviation regulations for satellite based area navigation. Worldwide airspace controlling agencies have mandated the use of navigation equipment that meets highly specific performance standards prior to entry in required navigation performance airspace. Aircraft not compliant with these standards are denied flight clearance or experience clearance delays. The Department of Defense has issued policy guidance that allows military aviation organizations to self-certify satellite based navigation technologies to meet required navigation performance standards. In many ways, military navigation technologies far exceed the performance requirements for civil and international airspace use. These technologies, however, are highly specific in their mission orientation and must demonstrate their compatibility with civil aviation standards. This study focused on the source and the specifics of navigation performance requirements. Domestic and international regulations and policies were reviewed as they pertain to civil aviation, and then applied to military aviation. Critical technical standards documents were reviewed to determine the best strategy for complying with civil and international regulations. Lessons learned from previous E-2C navigation system evaluations were also reviewed and incorporated within this compliance strategy. Compliance and self-certification responsibilities belong to aircraft specific program managers within the Navy’s acquisition organization. Sophisticated navigation systems incorporating satellite positioning technology require a tailored approach toward compliance demonstration. Military receivers with precise positioning capability satisfy many of the required availability, accuracy and containment standards. To satisfy civil requirements, correctly keyed, military navigation systems may be evaluated according to standards typically applied to the most highly augmented standard civil systems. This thesis contains a comprehensive list of compliance items selected for their applicability to the E-2C Hawkeye mission.