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The application of aerial and satellite imagery for mobile robot path planning and navigation has shown potential in recent years. Their uses vary from identifying terrain properties for creating traversability maps to extracting landmarks for autonomous navigation. With the freely available differential positioning system, Wide Area Augmentation System (WAAS)/European Geostationary Navigation Overlay Service (EGNOS), the use of the GPS with aerial images providing valuable contextual data demonstrates potential in waypoint-based navigation of mobile robots. However, important issues relating to the spatial accuracies of image, waypoint, and GPS-derived data, vital for obtaining accurate navigation results, are often overseen. This paper defines the causes of spatial inaccuracies in order to develop optimal waypoint navigation parameters and provides researchers with sufficient knowledge to reproduce similar results. An improvement of up to 48% in the number of waypoints reached, depending on the radius, was determined for the positional correction of the GPS. The results are shown with a simulated synchronous drive robot in Matlab's Simulink environment. The reader is presented with a method for easily creating waypoints from aerial images, yielding results to a similar level of accuracy to conventional and often tedious manual methods.

The Federal Aviation Administration (FAA) is currently leading a team consisting of members from industry, government, and academia to provide guidance to the policy makers in their evaluation of the future of Loran-C in the United States. In a recently completed Navigation Transition Study, the FAA concluded that Loran-C, as an independent radio navigation (RNAV) system, is theoretically the best backup for the global positioning system (GPS). However, for Loran-C to be considered a viable backup system to GPS, it must be able to meet the requirements for non-precision approaches (NPAs) for the aviation community, and the Harbor Entrance and Approach (HEA) requirements for the maritime community. Through FAA sponsoring, the US Coast Guard Academy (USCGA) is responsible for conducting some of the tests and evaluations to help determine whether Loran can provide the accuracy, availability, integrity, and continuity to meet these requirements. A major part of assessing the suitability of Loran is in understanding the nature of Loran ground wave propagation over paths of varying conductivities and terrain. Propagation time adjustments, called "additional secondary factors" (ASFs), are used to adjust receiver times of arrival (TOAs) to account for propagation over non-seawater path(s). These ASFs vary both spatially and temporally, and unless understood and/or modeled, we lose accuracy and may not be able to guarantee a hazardously misleading information (HMI) probability of less than 1times 10-7. During the summer of 2003, the Coast Guard Academy, with flight support from the FAA Technical Center, conducted a series of tests to measure ASF variations in the vicinity of several selected airfields in Colorado, Arkansas, Florida, and California. In addition, approaches were flown at several airports in each of these areas. ASF and TOA data collected during these trials has been analyzed through post-processing to determine the Loran position accuracy during approaches. The accuracy of raw (uncorrected Loran) as well as ASF-corrected Loran positions are shown for a variety of ASF profiles. Using the BALOR ASF modeling software produced by the University of Wales at Bangor, we have also done some simulations of best-case performance analysis for receivers with little or no noise. In addition, we present some ideas for using a Kalman-filtered integrated Loran-INS receiver to smooth out Loran position errors. Finally, how all of these efforts lead toward meeting the accuracy requirements is shown

We address the issue of autonomous navigation, that is, the ability for a navigation system to provide information about the states of a vehicle without the need for a priori infrastructure such as GPS, beacons, or a map. The algorithm is known as simultaneous localisation and mapping (SLAM) and it is a terrain aided navigation system (TANS) which has the capability for online map building, and simultaneously utilising the generated map to bound the errors in the navigation solution. Since the algorithm does not require any a priori terrain information or initial knowledge of the vehicle location, it presents a powerful navigation augmentation system or more importantly, it can be implemented as an independent navigation system. Results are first provided using computer simulation which analyses the effect of the spatial density of landmarks as well as the quality of observation and inertial navigation data, and then finally the real time implementation of the algorithm on an unmanned aerial vehicle (UAV).

In this paper, flight-path deviation in the navigation of unmanned space vehicles by global positioning system (GPS) is analyzed. A new method to calculate flight-path deviation by means of coordinate transforming is presented and the software of navigation and control is designed. This software is practical and effective for navigation by GPS with some characteristics including high-speed, high accuracy, real-time positioning and the use of digital mapping technique.

How animals navigate in their cross-continental migration has puzzled scientists for centuries. To date, the mechanism behind this mysterious navigation remains unclear. In this paper, a hypothesis is developed and computer simulations have been performed to investigate long-distance animal navigation. Simulation results show that animals may be able to complete their long-distance navigation by observing a spatial angle included by the geomagnetic field line and a geographic direction, without necessarily knowing any prior landmark information. Our results not only match existing observation reports in detail on the long-distance migration routes of animals, but also are able to explain the conflicting evidence on the role of geomagnetic field in animal navigation. We think our results could help reveal the actual mechanism of animal navigation. This paper also provides a potential solution for global and local area navigation of mankind and machines assisted by artificial sensors.

The International Civil Aviation Organization (ICAO) Standards and Recommended Practices (SARPS) states that the Time Reference Scanning Beam (TRSB) Microwave Landing System will supplant the existing Instrument Landing System (ILS) as the recognized international standard as early as 1995. The MLS provides the ability to determine the aircraft's position in three dimensional space over a large coverage volume in the airport terminal area. This affords the capability to navigate and execute approaches throughout this volume of coverage. This technique is known as Microwave Landing System Area Navigation (MLS RNAV). In order to assess and further develop the potential capabilities of MLS RNAV, the FAA Technical Center has undertaken the tasks of performing analytical studies, as well as the development of a prototype MLS RNAV system.

The future applicability of the Global Positioning System (GPS) to the National Airspace System (NAS) for user navigation and landing support is discussed. Functional characteristics and performance estimates are presented for several GPS enhancements, including the use of a geostationary satellite L-band repeater, a CONUS calibration network, and pseudolites. Analysis results indicate that an enhanced GPS system can meet US Federal Aviation Administration (FAA) enroute/terminal area navigation and nonprecision approach requirements under conditions which include accuracy degradation due to worst-case satellite failure, selective availability, and signal integrity. Similarly, it is shown that a Category I precision approach and landing requirement is essentially met using two pseudolites per airport. Additional analysis and extensive testing are required to validate the Category I findings. >

Statistical and operational results of extensive government field-testing of the Rockwell-Collins Global Positioning System (GPS) units are summarized. The equipment has exhibited better than 16-m spherical-error probable-position accuracy in over 6300 hours of testing conducted during the past two years. One-channel, two-channel, and five-channel receivers were subjected to thorough evaluation. Their respective signal-processing and data-processing architectures are described. Data highlighting dynamic position accuracy, static position accuracy, acquisition times, and field reliability are presented. GPS equipment integration and operation with nine different host vehicles is described. The results of mission scenarios, such as area navigation, rendezvous, and weapon delivery, are presented. >

An examination is made of old and new navigation technology that considers most factors affecting this technology, including cost, accuracy, autonomy, time-delay, global coverage, and the human interface. The author reviews cartography and the navigation of land, ship, air, and space vehicles, concluding with a forecast of navigation in the twenty-first century. An extensive annotated bibliography is included. >

The historical evolution and current status of the airborne traffic situation display concept is presented as well as a survey of related technological developments in collision-avoidance systems, area navigation equipment, and data links. Two alternative ATSD systems configurations are discussed: one deriving aircraft positions from ATC surveillance, the other deriving aircraft positions from air-to-air data exchanges. Based on the results of a Massachusetts Institute of Technology simulation study of airborne traffic situation display capabilities, a review of the many possible applications of the device is presented. Significant benefits in greater system capacity, greater safety, and an overall improvement in operational efficiency are predicted. A reduction in ATC capital and operating costs appears to be realizable if the ATSD is accepted as an integral element in future ATC system designs. Finally, the airborne computer-display capability required for the ATSD provides a fresh opportunity to combine, enhance, and integrate many of the cockpit functions that are now carried out by a proliferation of separate devices.

This paper describes the characteristics of the common system navigational aids, VOR and DME, as an area navigation system, and discusses methods for using them other than by flying along radials to or from the station. The use of pictorial displays and course line computers, either separtely or in combination, to achieve area navigation capability is distinctly possible. The choice of pictorial display or of the computer or of both will be made on considerations other than accuracy. Justification will have to be based on operational benefits such as least time and distance tracks, altitude availability or on air traffic control benefits. Cockpit space and chart provisioning are major problems in connection with pictorial displays, but can be overcome if cost benefits are sufficient. Flight evaluation in a live-traffic environment of the Bendix-modified Alternate Track VORTAC Computer in a united Air Lines DC-8F Cargoliner is described. Modification consisted of an additional function permitting operation parallel to radiais, in addition to phantom station mode of operation. Results were promising and indicate the track-keeping ability of a parallel course computer is consistent with existing airway criteria with little increase in pilot workload. Significant increases in traffic capacity of the existing airway system is possible with no required increase in number of VOR/DME facilities presently available.

This paper covers some important advances in understanding the problems associated with the VOR system, especially in connection with area navigation. Anomalies arising from airborne equipment, operating in the airborne environment, are described and analyzed. Factors contributing to overall system accuracy are treated with respect to VOR receiver response and to rate-limiting, filter means, with special attention to appropriate noise reduction systems providing zero or minimal time delay characteristics. The use of active filters in the VOR receiver is shown to be of major importance with regard to signal improvement and overall system accuracy. Active filters of the constant slew rate type have proved of significant value, both within the VOR receiver as well as in signal processing.

For future navigation systems the major problems in development will be as much concerned with the presentation and use of data as with its provision. The relationship between a stated operational requirement and the means developed to meet it are discussed on this basis. The nature of different types of navigational intelligence are considered, and a distinction is drawn between control and monitoring functions. The navigational task is analyzed, and different types of associated displays are examined. Safety considerations call for a degree of redundancy in a complete system, and the importance of avoiding dependence on a single navigational technique is emphasized.

Control of air traffic from the ground is only half the story?the airborne electronic equipment, displays, instrumentation, and human response are necessary to complete the loop in any practicable system. A few versions of collision-avoidance systems are entirely under airborne control. Based upon experience, pilots are wary of the hazards at certain major airports; in approaching other terminals, however, they have a sense of confidence that is inspired by the existence of the latest ATC equipment and facilities that afford a high degree of safety to pilots, passengers, and aircraft.

The VOR/DME/TACAN system of short distance navigation in the United States has provided service over the past decade to all civil and military air traffic. Improvements have been incorporated which have been in the nature of refinements, assuring adequate performance for all current aircraft needs. Recent analyses indicate that continued use of VOR/DME to meet increased civil air traffic demands through 1980 will require that the system demonstrate a capability for greater accuracy for terminal area operations, an improvement in signal quality to support area navigation, and the potential for increased traffic handling capacity of the DME component. Development activities now underway indicate that such improvements are feasible. Evaluation results and new techniques are described in support of this conclusion.

The author outlines some of the history of navigation and brings out the status of the navigator among the Polynesians. His theme is that life will not be the same when the sextant and the Polynesian palu's knowledge are replaced by an electronic device depending on the Global Positioning System. >