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Aerospace and Electronics Conference, 1994. NAECON 1994., Proceedings of the IEEE 1994 National

Date 23-27 May 1994

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Displaying Results 1 - 25 of 199
  • Proceedings of National Aerospace and Electronics Conference (NAECON'94)

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    Freely Available from IEEE
  • Unconventional algorithm for emitter position location in three-dimensional space using data from two-dimensional direction finding

    Page(s): 246 - 250 vol.1
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    Various papers have been published concerning emitter position location using angle measurements. The so called triangulation algorithms were formulated mostly for position estimation on the plane. These algorithms are widely applied in Electronic Intelligence (ELINT) and Electronic Warfare (EW) operations. Conventional (classical) algorithms for emitter position determination in three-dimensional space use the horizontal bearing (azimuth of an emitter) and the vertical bearing (elevation angle) obtained from real measurements. Such algorithms need these measurement magnitudes without any primary processing. The unconventional (non-classical) algorithm presented here uses the both above-mentioned bearings, however these real observations are linked up within the singular pseudo-observation called the generalized bearing (or slant azimuth). Thus real angle measurements are preprocessed here. Such approach yields double reduction of matrix and vector dimensions as well as provide homogeneity or measurement equations and in consequence give homogeneous form of the gradient matrix. This algorithm shows good statistical and computational properties. It provides slightly higher accuracy of position estimation and requires essentially smaller storage for data acquisition than the conventional one View full abstract»

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  • Application of neural control to active structural load alleviation

    Page(s): 532 - 539 vol.1
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    Modern large transport aircrafts are subject to considerable structural flexibility during flight. In order to improve the dynamic response of such aircraft the use of active control technology is proposed which will alleviate the structural loads to which the airframe is subjected as a result of manoeuvre demands or encountering atmospheric turbulence. A number of methods, including linear optimal control theory, have been proposed as a solution of the structural load alleviation problem. This paper presents a method based on the use of intelligent neural controllers. Some comparisons of the effectiveness of different types of neural networks in this application are provided, and the resulting controlled responses obtained from digital simulation are compared with a baseline design based on linear quadratic regulator theory. The paper concludes with a recommendation for the use of one particular type of neural controller which provides superior performance for this application View full abstract»

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  • An air-to-air Situationally Interactive Combat Model (SICM)

    Page(s): 960 - 967 vol.2
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    This paper discusses the Situationally Interactive Combat Model (SICM), a user-friendly air-to-air combat engagement model that is used to perform analyses of offensive and defensive tactics employment, changes to avionics suite components and aircraft capabilities, and changes of air-to-air armament systems. The inputs to the model are the performance parameters of the many disparate elements that comprise airborne weapon systems, and the outputs are various types of measures of engagement-level effectiveness. SICM supports the modeling of all sensor systems and the fusion of sensor data. The modeling techniques allow for rapid prototyping and for the very low cost method of evaluating new ideas and development strategies. Although originally designed for beyond visual range (BVR) engagements, improvements in graphical display of the engagements and maneuvering of aircraft have expanded SICM's capabilities to include the performance and display of close in combat (CIC). This model has supported the Advanced Tactical Fighter (ATF) Milestone I Cost and Operational Effectiveness Analysis (COEA), the Integrated Electronic Warfare System (INEWS) Milestone I COEA, the Mark XV Identification Friend or Foe (IFF) Milestone II COEA, and a number of marginal utility analyses for Wright Laboratory, WPAFB, Ohio. SICM is the model of choice for analysts due to its ease of use, user interactivity, speed of execution, sensor identification capabilities, and engagement modeling fidelity View full abstract»

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  • Ada programming language for numerical computation

    Page(s): 853 - 859 vol.2
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    The goal of scientific computation is reliability, accuracy, and efficiency. From the programming point of view, to provide reliable computation is to prevent overflow, underflow, and other exceptional conditions so that a program can be executed safely, completely, and efficiently. From the precision aspect, accurate computation eliminates or reduces possible computational errors that include: inherent error, error is present at the outset in original data, truncation error, error replacing finite terms for a function of infinite terms, and rounding error, an error due to finite binary internal representation of a computer system. Efficient computation is to develop an effective computational algorithm for the given problem using proper programming language features for computation. This paper addresses the use of the Ada programming to accomplish the goal of scientific computation View full abstract»

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  • An overview of cost and operational effectiveness analysis (COEA)

    Page(s): 1188 - 1194 vol.2
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    This paper contains an overview on one of the most talked about topics in the Department of Defense, the cost and operational effectiveness analysis (COEA) and discusses performance of a COEA in support of the DoD material acquisition system. The material outlines the suggested analysis approach described in today's governmental regulations and provides in detail the methodology needed to perform these studies, a requirement which has been passed down to the analysis “shops” of the military services. The paper defines the purpose and scope of the COEA and overviews the important factors and techniques needed to perform these studies. Highlighted are the planning requirements, modeling issues, and the need for various forms of verified and validated data. Discussed is the establishment of measures of merit used to distinguish the worth of the various alternatives under consideration, as well as the simulation tools used to define and evaluate the effectiveness of operations and costs in the envisioned environment. Topics covered range from those discerning the political study environment, to the techniques for presenting the analytical results View full abstract»

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  • Computer emulator applications

    Page(s): 991 - 997 vol.2
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    This paper investigates the use of emulators for computer testing and integration applications in comparison with application specific computers. The performance requirements of each application are identified and evaluated against a variety of emulator implementation approaches. The relative emulator development cost, production cost, and performance levels are compared to flight computers and evaluated for key roles in trainer and OFP Integration Support Facilities (ISF) View full abstract»

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  • The location method and accuracy analysis for bistatic systems

    Page(s): 62 - 65 vol.1
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    The bistatic system discussed in this paper consists of one transmitter and one receiver at different sites, in which the transmitter only emits radar signal, and the receiver measures range sum, azimuth and elevation angles. In this paper, the location method and position errors of targets are analysed. By analyzing the region distribution of target position accuracy (GDOP) in the controlled airspace, the location performances of bistatic systems is illustrated. In this paper, the location method and its position accuracy for netted bistatic systems is analysed. The algorithm WLS is used for data fusion in the netted bistatic systems. The location performances of netted bistatic systems is discussed and it is shown that the position accuracy is improved greatly in comparison with bistatic systems View full abstract»

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  • High resolution 2-D ISAR image collection and processing

    Page(s): 371 - 377 vol.1
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    This paper goes into the practical and theoretical foundations of 2-D ISAR (inverse synthetic aperture radar) image collection and processing. Its application to validate high definition aircraft geometry models is also discussed. The ISAR data is collected by a Ground-to-Air Measurement System (GTAMS) at Tyndall Air Force Base, Florida. The GTAMS System consists of a ultra high range resolution (UHRR) radar system to collect all aspect radar signatures. The GTAMS facility ties into an ACMI system (aircraft combat maneuvering instrumentation system) that provides real-time aircraft position, attitude, and velocity parameters each time the GTAMS system collects a radar target signature. This paper details the methodology of collecting ISAR images at the GTAMS facility as well as their processing into focused 2-D ISAR images. The use of ACMI aircraft position information to derive the image focusing parameters is also discussed. The raw data required to form an ISAR image consist of 512 pulses of UHRR radar I/Q video data collected during the dwell, or “look” at the aircraft. The ACMI tracking data are also collected and include position, velocity, and attitude information. These data are converted into an ISAR image in a multistep process including range and Doppler focusing, weighting for sidelobe reduction, and 2-dimensional Fourier transformation. Examples of the results of these various processing steps are shown View full abstract»

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  • Integrated mission precision attack cockpit technology (IMPACT) role playing

    Page(s): 720 - 725 vol.2
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    The Cockpit Integration Division within Wright Laboratory at WPAFB, is exploring the Pilot Vehicle Interface (PVI) requirements for performing a precision strike mission against multiple mobile and fixed targets, at night and in adverse weather, in a single seat fighter. Such a mission has the potential for dramatically increasing pilot workload and compromising mission effectiveness. To address these issues, an exploratory simulation evaluation was conducted, using a “role playing” methodology to assess pilot workload associated with an air interdiction mission in a single seat aircraft. The role playing methodology was based on previous studies which used the Subjective Workload Analysis Technique (SWAT) “in a projective manner in order to estimate the workload implications of system configurations during the conceptual design stage of development” (Eggleston, 1984). An air interdiction scenario was developed in which the pilot was re-tasked inflight to attack a SCUD missile launcher. Pilots were asked to role play this mission in an F-15E with and without a Weapon System Officer (WSO). PROjective Subjective Workload Analysis Technique (PROSWAT) ratings were obtained for six critical mission events for each of two scenarios (i.e., with and without a WSO). The pilots were presented with a briefing of seven potential cockpit technologies, and a narrative including a potential scenario in a single seat Advanced Technology Cockpit (ATC) aircraft with those technologies incorporated. PROSWAT ratings were obtained based upon the ATC narrative. Results of the study quantified differences according to cockpit configuration, mission function, and aircraft type. Utility of the role playing methodology was substantiated View full abstract»

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  • Real-time parameter identification for self-designing flight control

    Page(s): 526 - 531 vol.1
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    A self-designing flight control system (SDFCS) could provide a cost-effective means for developing controllers for new aircraft by eliminating analyst-intensive design of numerous individual controllers, each optimized for a single flight condition. Additionally, the SDFCS could improve the capabilities of existing aircraft by enhancing control performance in new flight regimes such as high angle-of-attack or post-stall maneuvers. Finally, the SDFCS could automatically reconfigure the control system to account for sudden changes such as may result from airframe and/or effector impairment(s). Rapid identification of time-varying, nonlinear plants is an important enabling technology for most SDFCS concepts. In this paper, the authors present a modified sequential least squares (MSLS) parameter identification method and compare its performance to that of standard RLS techniques using a simulated nonlinear F-16 with multiaxes thrust-vectoring (MATV) aircraft. It is shown that MSLS offers significant improvement in performance over conventional RLS parameter identification by providing: (1) a recursive estimation algorithm that penalizes noisy estimates and is less subject to ill-conditioning as ifs forgetting factor is reduced, (2) detection of airframe and effector impairments and corresponding adjustments of the algorithm settings, and (3) an intelligent supervisor that injects a minimum level of effector random activity to ensure identifiability View full abstract»

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  • GEM-contemporary system support solutions

    Page(s): 1158 - 1164 vol.2
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    The Department of Defense (DoD) and Original Equipment Manufacturers (OEMs) face an increasingly difficult time supporting fielded systems due to a variety of factors. The generalized emulation microcircuit (GEM) program applies modern technology to provide an economical, rapid alternative to traditional redesign approaches. GEM provides form, fit, and function (FFF) replacement devices for unavailable microcircuits. GEM employs a modern BiCMOS gate array technology to produce these nonavailable devices. The GEM program utilizes specially designed gate arrays covering the range of specification requirements of the original device families. GEM parts are fabricated using modern, industry standard fabrication equipment employing statistical process control methods. The GEM design system employs commercial computer aided design, simulation, and verification tools in all phases of design View full abstract»

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  • Mutual coupling calibration using a single source in near field

    Page(s): 424 - 426 vol.1
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    In this paper a mutual coupling calibration method suitable for uniform linear arrays (ULA) and circular arrays (UCA) is presented where only one known calibration source in the near field is necessary for effective calibration. The paper has also discussed the position error influence of the source on the calibration, and the optimum azimuth of the source is analyzed. Finally some simulation results are given to show the advantage of the new method View full abstract»

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  • A technology audit: key to technology planning

    Page(s): 1241 - 1247 vol.2
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    The technology possessed by an organization may be even more valuable than the resources evaluated in a financial audit. What technology does an organization possess, both product and process? How much of it is the same technology the organization's competitors possess? How much of it gives the organization a competitive edge? How much of it will provide a competitive edge in the future? Is the technology on which the organization depends for competitive status verging on obsolescence? A technology audit is intended to evaluate the state of the organization's technology resources. These can be classified as base technologies, possessed by every firm in the industry, key technologies those which provide the firm with a competitive edge, and pacing technologies (those needed to provide a competitive edge in the future). This paper presents a methodology for conducting a technology audit. The paper identifies the critical issues which must be addressed in a technology audit. A systematic procedure is then presented for identifying the technologies involved in the organizations products and processes. Methods for evaluating these technologies for competitive status are then described. Finally, a method is presented for preparing a profile of the organization's technological status View full abstract»

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  • Neural solution to multitarget tracking in clutter with velocity measurements

    Page(s): 204 - 211 vol.1
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    The problem of tracking multitarget in clutter environment in a track while scan (TWS) system is considered. In such an environment, missed detections and false alarms make it impossible to decide, with certainty, the origin of received report. The two main functions of the TWS algorithm are : 1) plot-to-track (state predicted estimate) association, and 2) the filtering algorithm that uses the associated plot for recursive estimation. In this paper, ANN (artificial-neural-network based data association method approximate to NNPDA (nearest neighbour probabilistic data association) is used to realize plot-to-track association, while filtering algorithm suitable to tracking with radial velocity measurements is introduced. Simulation results included in this paper show a great improvement of tracking performance when radial velocity measurements are used View full abstract»

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  • Analysis of a buck PWM DC-DC converter in discontinuous conduction mode

    Page(s): 35 - 42 vol.1
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    A buck pulse width modulated (PWM) dc-dc converter operating in discontinuous conduction mode (DCM) has been analyzed based on the principles of energy conservation. Efficiency equations have been developed and compared to an experimental circuit. Results demonstrate acceptable agreement between calculated and experimental values View full abstract»

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  • Feature extraction and feature selection of microwave scattering images

    Page(s): 57 - 61 vol.1
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    An ISAR object recognition system has been described. The feature extraction of ISAR object images is achieved by two-dimensional FFT processing,and a square window which is located on the center of the spectrum is used for feature selection, and the classifier of the system is a nearest neighbor classifier. Through experiments on ISAR object recognition, the effect of the feature window length on the system recognition rate has been investigated. The experimental results show that the feature selection window with the low-pass form is the optimum feature selection approach, and an optimum feature window length is existing for this feature selection method, which can be determined by training sample set itself View full abstract»

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  • Multi-sensor analysis of the effects of fire in the Alaskan boreal forest

    Page(s): 1085 - 1089 vol.2
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    Fire is a significant natural process throughout the world's boreal forests, with 10 to 25 million acres burning annually. These fires tend to cover large areas. During severe fire years, forest fires >100,000 acres in size are the norm, and fires >1 million acres are not uncommon. Because of the remote location of boreal forests and the large size of fires, satellite-based imaging remote sensors are ideal for mapping and studying spatial characteristics of fire scars. Research has been conducted over the past several years for NASA and the Environmental Protection Agency to study fires in the Alaskan boreal forests with a variety of remote sensors. Research has also been directed towards conducting field surveys of the effects of fires in order to better understand the characteristics of fire signatures. Examples of fire signatures are presented from three different satellite remote sensing systems, one operating in the visible and near-infrared region of the electromagnetic spectrum (AVHRR) and two operating in the microwave region of the electromagnetic spectrum (the ERS- and JERS-1 synthetic aperture radars). In this paper, the signatures from the various remote sensors are presented and compared to field measurements View full abstract»

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  • Computation of moment invariants and Hadamard transform using neural net

    Page(s): 367 - 370 vol.1
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    In this paper, computation of moment invariants and Hadamard transform using the Tank and Hopfield linear programming neural net is proposed. First, the relationship between the one-dimensional moments and the one-dimensional Hadamard transform (1D HT) is derived. One can compute the moments of grey level image through 2N 1D HT's except for a negligible amount of addition, shift and multiplication operations. Then, the neural net to compute the 1D HT is shown. Because the HT matrix H satisfies H=HT and H2=NI, a closed-form solution of the time evolution of the neural net can be found. A proof is given that the neural net will find a result arbitrarily close to the correct HT of the input data in hundreds of nanoseconds. The proposed HT implementation is speedy, simple and robust. The proposed approach will be expected to find wide practical applications that require computing moments and HT View full abstract»

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  • Task simulation using human figure models

    Page(s): 765 - 770 vol.2
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    Modern design evaluation technologies based on human figure simulations are helping us to make fuller and more accurate assessments of human/machine and workplace interfaces. As computer graphics and related digital technologies advance, one will be able to illustrate, predict, evaluate, and document a wider array of human performance issues involving system useability concurrently with design development. The Design Evaluation for Personnel, Training, and Human Factors (DEPTH) program is developing and integrating many of these technologies for engineering applications. This paper provides an overview of current and planned DEPTH technology developments View full abstract»

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  • 3-D cockpit simulator displays-achieving precise depth placement of objects in graphic images

    Page(s): 709 - 714 vol.2
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    The authors have developed software routines to produce 3-D images that can be used with any application. Each graphics application tends to have unique features such as the size of objects being drawn or the coordinate system in which these objects are displayed. For example, one application may display objects such as aircraft in a situational display while another displays aircraft system status information. Clearly, coordinate systems and object sizes will differ between these two applications. The stereographic software techniques described are compatible with any coordinate system or size of object and are also compatible with other graphic transformations such as rotation and translation. Stereographic theory is explained in the context of these software procedures as applied in a study of a 3-D situational display. Ultimately, the combination of this software and respective explanation will enable any user to develop and display 3-D images, reliably placing graphic objects in space View full abstract»

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  • Two robust homing missile guidance laws based on sliding mode control theory

    Page(s): 540 - 547 vol.1
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    Two new guidance laws for short range homing missiles are developed by invoking the sliding mode control (SMC) theory. Guidance law 1 as structured around the basic proportional navigation (PN), with an additive switching term, which is a function of the line of sight (LOS) rate alone. An adaptive procedure is suggested to select the gain of the switching term, in order to reduce chattering. This guidance law is nearly as simple to implement as the PN itself and does not require any explicit target maneuver estimation. Guidance law 2, based on a first order sliding surface, is designed such that it results in a continuous acceleration law, thereby reducing the chattering problem. While explicitly taking into account the effect of aerodynamic drag, it requires the second derivatives of LOS angle and range, which are not directly measured. An estimation scheme, again based on sliding mode theory, is presented to estimate these quantities. Simulation results clearly demonstrate the superior performance of these schemes View full abstract»

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  • Integration of the AN/ALQ-131(V) electronic countermeasures pod on tactical aircraft using a MIL-STD-1553B interface

    Page(s): 1150 - 1157 vol.2
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    This paper describes the development and integration of a MIL-STD-1553B interface for the AN/ALQ-131(V) Terminal Threat Electronic Countermeasures (ECM) pod. Integrated circuit devices and the Ada programming language were used to develop a low risk, highly flexible design. The fully programmable interface can communicate with any aircraft electronic system with a MIL-STD-1553B interface. Potential Electronic Warfare (EW) and general purpose avionics bus system architecture interfaces are discussed. Required aircraft and pod modifications to support the interface are described View full abstract»

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  • Rapid and accurate timing simulation of radiation-hardened digital microelectronics using VHDL

    Page(s): 378 - 385 vol.1
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    The development of a fast, yet accurate, timing simulation capability based on VHSIC Hardware Description Language (VHDL) without the use of back annotation of timing delay information is presented. This simulator is intended, primarily, for use with radiation-hardened microelectronic circuits in simulating timing of circuit operation in the pre-radiation and post-radiation environment. Additionally, this simulator works well, using simplified models, for conducting timing estimates of circuit operation in cases where radiation effects are not a concern. Development of the timing models used in the VHDL timing simulator are presented. The timing models are based on a gate output drive capability being represented as an equivalent drive resistance. The loads of the driving gate and the input gates are correspondingly represented by equivalent capacitance values. The resultant gate delays are calculated from the drive resistance and the combined load capacitances. The implementation of the timing models are incorporated into a VHDL library composed of logic gates, latches, and flip-flops. Simulations of circuits were run in SPICE and VHDL to assess the timing accuracy and simulation run time of the VHDL-based timing simulator versus SPICE, and results are presented. Final evaluation of the simulator included testing of a microprocessor control unit. In all cases, the VHDL-based simulation runs over two orders of magnitude quicker than the equivalent SPICE simulation. In the pre- and post-radiation environment, accuracy estimates are usually within five percent and always within 12 percent View full abstract»

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  • Lane position tracking

    Page(s): 483 - 489 vol.1
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    This paper describes a proposed low risk, low cost, electro-optical lane tracking sensor for vehicle guidance and control. The S*R sensor is capable of measuring the lateral position of the vehicle with respect to highway lane markers with a high degree of accuracy. These sensor outputs can be used to automatically guide the vehicle along the interstate highway system in both the lateral direction as well as velocity View full abstract»

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