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Volume 3692 Acquisition, Tracking, and Pointing XIII

Michael K. Masten, Larry A. Stockum July 1999

Conference Location: Orlando, FL, USA Conference Date: Wednesday 07 April 1999

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System-Level Applications

Select this Article		Ground support equipment (GSE) for testing precision ATP payloads Henry R. Sebesta, Gary E. DeMuth, Michael A. Dillow, Martin C. Rost, and Darren R. Laughlin Proc. SPIE 3692, 2 (1999); http://dx.doi.org/10.1117/12.352848 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract This paper focuses on the ground support technologies, instrumentation, and the analysis approaches employed to verify that the HABE ATP payload is correctly performing its state-of-the-art alignment, stabilization, and tracking functions. A specially constructed Laboratory Test Component (LTC) includes scoring sensors that measure the payload's LOS pointing errors by receiving and measuring the motion of the transmitted marker laser. Motion sensors with high sensitivity and broad bandwidth prove signals that are recorded simultaneously with other payload telemetry signals from the stabilized reference platform, the fast steering mirror alignment systems, and from the image track loops. The combined signals facilitate understanding and evaluation of the payload's tracking and pointing errors. With properly constructed laboratory tests and full instrumentation of the vibration and atmosphere contributed disturbances, it is possible to confirm that a sophisticated ATP payload like HABE is able to operate with residual pointing errors under a microradian.

Select this Article		HABE real-time image processing Joseph C. Krainak Proc. SPIE 3692, 14 (1999); http://dx.doi.org/10.1117/12.352878 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The HABE system performs real-time autonomous acquisition, pointing and tracking (ATP). The goal of the experiment, sponsored by the Ballistic Missile Defense Organization and administered by the US Air Force Research Laboratory, Kirtland AFB, Albuquerque, NM, is to demonstrate the acquisition, tracking and pointing technologies needed for an effective space-based missile defense system. The three sensor tracking system includes two IR cameras for passive tracking of a missile plume and an intensified visible camera used to capture the return of a high-energy laser pulse reflected by the missile's nose. The HABE real-time image processor uses the images captured by each sensor to find a track point. The VME-based hardware includes four Compaq Computer Corporation Alpha processors and seven Texas Instruments TMS320C4X processors. The C4x comports and the VME bus provide the pathways needed for inter-processor communications. The software design implements a list processing approach to command and control which provides for flexible task redefinition, addition, and deletion while minimizing the need for code changes. The design is implemented in C. Several system performance metrics are described and tabulated.

Select this Article		Pointing and stabilization system for use in a high-altitude hovering helicopter Kevin Murphy, Scott Goldblatt, Jeffery W. Warren, Rickey Chapman, James B. Hemler, Craig A. Mitchell, and George W. Moe Proc. SPIE 3692, 23 (1999); http://dx.doi.org/10.1117/12.352885 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract A pointing and stabilization system has been developed and flight tested which permits an optical payload to be operated for an extended time period from a nearly stationary point in the air aboard a hovering helicopter. The system is assembled primarily from commercial 'off the shelf' components and is capable of pointing the payload as desired to image geo-referenced aim points on the earth's surface. The payload contains two digital cameras and laser illuminator. The payload is mounted in a 20-inch diameter, two axis stabilized ball gimbal available form a previous program. The payload also contains a dynamically tuned gyro- based inertial measurement unit, which with GPS-aiding provides ball gimbal position and pointing information. The processed data is used to accurately register images in ground coordinates. The inertial measurement data is also used in real time to control pointing of the ball gimbal and to generate a hover display for the pilots of the SH-60 helicopter. The system has been successfully flight tested. The longest test sequence to data is a 30 minute long hover at 7000 ft altitude during which the payload was staring at a fixed aim point. During this half-hour period, pilots maintained the helicopter at its hover point within a circle of approximately 150 meters radius. Similar hover accuracy is routinely obtained. This system provides a unique research capability to observe ground phenomena from a fixed airborne perspective and to register the resulting data into fixed ground coordinates.

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Sensors for ATP Applications

Select this Article		Dynamic range selection in image processing hardware to maximize SNR while avoiding image saturation William B. Boucher and Michael R. Michnovicz Proc. SPIE 3692, 34 (1999); http://dx.doi.org/10.1117/12.352858 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract An image processing system has been designed and implemented which can accommodate a wide a range of image brightness, ranging in intensity from a dim star to the very bright exhaust plume of a boosting missile. The system seeks to maintain the maximum allowable gain in the image processor while not saturating the image. The implemented system uses two stages. The first is an image processing system, which selects the proper 8 bits out of a 12-bit image and achieves the above algorithm using a programmable lookup table. An 8- bit path is an artifact of the chosen image processing hardware. The image intensity to prevent saturation in the image processing system for brighter images. Both the programmable lookup table and the filter wheel can be set in response to the statistics collected for a given target image frame. This paper describes the algorithm used to achieve the required dynamic range compression. In operation, the dynamic range compression algorithm is used in a 'set and forget' fashion, where the algorithm is run for the first few frames of target imagery during a mission, and once the algorithm has settled, it is switched out and the resultant setting are employed for the remainder of the engagement. This research is being tuned by Ballistic Missile Defense Organization and conducted by the Air Force Research Laboratory.

Select this Article		Acquisition, tracking, and pointing systems of OICETS for free space laser communications Takashi Jono, Masahiro Toyoda, Keizo Nakagawa, Akio Yamamoto, Koichi Shiratama, Toshihiro Kurii, and Yoshisada Koyama Proc. SPIE 3692, 41 (1999); http://dx.doi.org/10.1117/12.352886 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Optical Inter-orbit Communications Engineering Test Satellite (OICETS) is under development by NASDA to verify the laser communications technology in space. The in-orbit experiment will be done by establishing inter-orbit communication between the OICETS and European geostationary satellite ARTEMIS in cooperation with ESA. These satellites will be launched in to the orbit in 2000. Laser communications system in space is a promising technology for future space activities, but it has many research matters. Acquisition tracking and pointing system of a laser terminal performs a prominent role to keep the laser communication. This paper describes the ATP system strategy of the laser terminal.

Select this Article		Airborne system for testing multispectral reconnaissance technologies Dirk-Roger Schmitt, Heinrich Doergeloh, Heiko Keil, and Wilfried Wetjen Proc. SPIE 3692, 51 (1999); http://dx.doi.org/10.1117/12.352887 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract There is an increasing demand for future airborne reconnaissance systems to obtain aerial images for tactical or peacekeeping operations. Especially Unmanned Aerial Vehicles (UAVs) equipped with multispectral sensor system and with real time jam resistant data transmission capabilities are of high interest. An airborne experimental platform has been developed as testbed to investigate different concepts of reconnaissance systems before their application in UAVs. It is based on a Dornier DO 228 aircraft, which is used as flying platform. Great care has been taken to achieve the possibility to test different kinds of multispectral sensors. Hence basically it is capable to be equipped with an IR sensor head, high resolution aerial cameras of the whole optical spectrum and radar systems. The onboard equipment further includes system for digital image processing, compression, coding, and storage. The data are RF transmitted to the ground station using technologies with high jam resistance. The images, after merging with enhanced vision components, are delivered to the observer who has an uplink data channel available to control flight and imaging parameters.

Select this Article		Analytic boresight calibration of a line-of-sight sensor Spiro P. Karatsinides and Mark L. Darnell Proc. SPIE 3692, 64 (1999); http://dx.doi.org/10.1117/12.352888 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Ground based boresighting techniques are used to install a line-of-sight sensor on an aircraft in order to align the sensor axes with the aircraft body axes. Due to the limitations of the calibration equipment, residual boresight errors often remain which degraded the system performance. This paper presents a method for in-flight calibration of the boresight errors of a line-of-sight sensor as an alternative to the less precise and more expensive conventional methods. This in-flight method employs a Kalman filter to estimate the boresight errors based on the difference between the expected and measured line of sight of a sight, and the azimuth and elevation angles of the sensor gimbals define the measured line of sight. The accuracy of the shipboard INS/GPS navigator is sufficient to make the analytic calibration practical. The results from flight tests show the benefit of this application of Kalman filter technology.

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Stabilization and Control Applications

Select this Article		Gunfire performance of stabilized electro-optical sights Jesse J. Ortega Proc. SPIE 3692, 74 (1999); http://dx.doi.org/10.1117/12.352849 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The design of stabilized electro-optical sights is a fairly mature technology. As such, many if not most of the major design tradeoffs are well know and characterized. These include basic gimbal configuration, gyroscope technology, servo control configuration, friction and inertia relationships, and structural-servo interactions. Most of these considerations and effects can be adequately treated with the classic design sequence: Design in the linear world, simulate in the non-linear world, and test in the real world. Experience has shown, however, that behavior of a stabilized sight during gunshock is difficult to predict, and the classic design sequence may ont predict gunshock problems until the late-in-the-cycle test phase. Further, evidence indicates that the system that provide excellent nominal stabilization performance may not perform well during gunshock. A discussion of a system in this regard is presented. Tradeoffs in stabilization versus gunshock performance are discussed. A section on suggested risk- reduction activities is also given.

Select this Article		Application of high-power pulse-width-modulated hybrid motor controllers to stabilized gimbal systems Jim R. Clemenger and James C. DeBruin Proc. SPIE 3692, 84 (1999); http://dx.doi.org/10.1117/12.352850 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Once available only as expensive custom designs, high-power hybrid PWM controllers are now available as commercial-off- the-shelf items from several suppliers at competitive prices. These units are hybrids in the sense that they provide analog front-ends, digital switching logic, and power output drivers in one package. The space and parts- count reduction provided by high-power PWM hybrids is substantial, making these parts attractive to use in large stabilized gimbal systems. Unfortunately, not all PWM hybrid designs are well suited to this application. Motor control for stabilization is discussed generally, and PWM design for stabilization application is discussed specifically. Key features of good design are identified and described in detail. Implementation issues are addressed.

Select this Article		Dynamically tuned gyroscopes in stabilized electro-optical sights James C. DeBruin Proc. SPIE 3692, 94 (1999); http://dx.doi.org/10.1117/12.352851 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The dynamically tuned gyroscope (DTG) has been marketed primarily as a low-cost, small-package, two-axis rate sensors for tactical missiles and is used widely in this application. The DTG is also suitable for application to stabilized electro-optical sights, though little appears in the literature on this subject. At first glance, this gyro appears to be controllable with the same capture-loop technology used for the once-ubiquitous single-axis rate- integrating gyro. Subtle but very important distinctions exist however, and inattention to these differences can result in poor or disastrous gyro performance. These and other issues pertaining to use of the DTG in sight stabilization systems are discussed. Topics covered include theory of operation, interface electronics, capture-loop design, and a discussion of error sources typically found in electro-optical systems.

Select this Article		Modeling the dynamically tuned gyroscope in support of high-bandwidth capture loop design David May Proc. SPIE 3692, 101 (1999); http://dx.doi.org/10.1117/12.352852 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The 'dynamic tuning' of a dynamically tuned gyroscope (DTG) refers to a clever gimbal configuration that balances the torques from the support flexures with dynamic spring torques created by gimbal 'flutter' while the gyro rotor spins. This configuration allows the gyro rotor to spin to a 'free' rotor in two axes. The dynamics of a free rotor are widely known and easily summarized in the right-hand rule for gyro precession and a simple second order system equation with a natural frequency, known as the nutation frequency, as a function of the angular momentum and transverse inertia. Not much more is needed for design of capture loops for the DTG, as long as the bandwidth of the capture loop does not approach the nutation frequency of the gyro. However, the complete dynamical equations of motion of the DTG include other parameters such as windage, mistuning and friction torques that must be considered when designing capture loops with higher than nominal bandwidths. These equations, which are well known and widely published, are discussed in regard to capture loop design. The application of active nutation damping in the capture loop compensation is outlined. Typically results are presented.

Select this Article		Micro-electro-mechanical system (MEMS) component research and development for army missile applications Tracy D. Hudson, Deanna K. McMillen, Paul R. Ashley, Paul B. Ruffin, and Janet Baeder Proc. SPIE 3692, 112 (1999); http://dx.doi.org/10.1117/12.352853 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The US Army Aviation and Missile Command Missile Research, Development and Engineering Center has identified MEMS as an emerging technology with high potential for fulfilling the mission of future missiles. The technology holds the promise of reducing the size, weight, cost, and power requirements for performing existing functions in Army missile systems, as well las providing opportunities for new computing, sensing, and actuation functions that cannot be achieved with conventional electromechanical technology. MEMS will enable the Army's next generation of smaller and lighter missiles. The military market drives the thrust for development of miniature sensor with applications such as: competent and smart munitions, aircraft and missile autopilots, tactical missile guidance, fire control system, platform stabilization, smart structures with embedded inertial sensors, missile system health monitoring, missile and ground-based radar, radio frequency seekers, aerodynamic flow control, IR imagers, and multiple intelligent small projectiles. Current efforts at AMCOM include the development of MEMS-based inertial components to include accelerometers with wide dynamic range, tactical grade gyros with high rate range, and miniature three-axis inertial measurement unit with common interface electronics. Performance requirements of such components will be presented in terms of current and future Army missile systems. Additional MEMS based efforts under investigation at AMCOM include missile storage health monitoring, RF MEMS components, encoders for actuators, and aerodynamic flow control will also be discussed.

Select this Article		Impact of hydrostatic bearings on the design and performance of telescopes Donald R. Chivens and David E. Chivens Proc. SPIE 3692, 123 (1999); http://dx.doi.org/10.1117/12.352854 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The use of hydrostatic bearings for the support of the azimuth and elevation axes of telescopes offers a number of optical performance advantages. In addition to the benefits resulting from exceedingly low friction, the integration of hydrostatic bearings into the conceptual design of a telescope mount widens the range of geometric possibilities, particularly for larger telescopes. Mount stiffness and tracking accuracy are major advantages. This paper presents an overview of some of the design opportunities made possible by the use of hydrostatic bearings in addition to a discussion of the features and factor that are necessary for the their successful application.

Select this Article		Influence of base support on large gimbal performance Robert D. Sobek and James E. Kimbrell Proc. SPIE 3692, 129 (1999); http://dx.doi.org/10.1117/12.352855 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Large gimbal systems often demand high accuracy pointing and smooth travel. Feedback control is employed to guarantee this performance in the face of wind, bearing and other disturbances. Both small and large gimbal performance is affected by many common factors. However, in smaller gimbal system, the foundation has little impact on the performance of the gimbal feedback control and can be neglected. For larger gimbal systems, this is not the case. Fortunately, the control system designer can use simplified analytical models to characterize foundation designs assess the impact on the system. This information can be coupled with modern control design techniques to improve the performance under less than ideal foundations. Analytical work is supplemented with test results from two large terrestrial gimbal telescopes with significantly different foundation designs.

Select this Article		Nonlinear control of the optical delay line pathlength Boris J. Lurie, John J. Hench, Asif Ahmed, and Fred Y. Hadaegh Proc. SPIE 3692, 139 (1999); http://dx.doi.org/10.1117/12.352856 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract This paper discusses the problem of designing a control system for an interferometer delay line which contains coarse-vernier loops. The vernier loop compensator has nonlinear dynamics and includes a local feedback path containing a deadzone. This accomplishes two objectives: global stability and good transient response to large signals. In addition, by ensuring global stability in the vernier loop, the gain of the coarse loop may be increased thus providing greater disturbance rejection in the overall loop.

Select this Article		Generalized ideal proportional navigation Pin-Jar Yuan, Ming-Ghow Chen, and Jeng-Shing Chern Proc. SPIE 3692, 150 (1999); http://dx.doi.org/10.1117/12.352857 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Some generalized proportional navigation were studied before under the assumption that the magnitude of commanded acceleration is proportional to the product of line-of-sight rate and closing speed or line-of-sight rate and it is applied in the direction with a bias angle to the normal direction of line-of-sight. Now in this article, the generalized ideal proportional navigation is introduced, in which the commanded acceleration is applied in a direction with a bias angle to the normal direction of relative velocity and its magnitude is proportional to the product of relative speed and line-of-sight rate between interceptor and its target. The exact and compete closed-form solutions are derived under this modified guidance scheme for both maneuvering and non-maneuvering targets. Some related important characteristics, such as capture capability and energy cost, are investigated and discussed. The variation of bias angle will induce the change of capture area and energy coast required. Also, a typical example of target maneuver is introduced to describe the effect of target maneuver easily. It shows that the target maneuver will decrease the capture area and increase the energy cost for effective intercept of target.

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Signal Processing Applications

Select this Article		Single-model asynchronous fusion of correlated tracks Theodore R. Rice and Ali T. Alouani Proc. SPIE 3692, 164 (1999); http://dx.doi.org/10.1117/12.352859 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The theory behind the fusion of two asynchronous track updates has been derived by the authors in a previous paper. However, the result were incomplete since there was not sufficient information to actually implement the fusion theory as an algorithm. In this paper, the information necessary to implement the theory is provided. Additionally, simulated data in the form of tracks from two sensors having different update rates and communications delays is used to compare this technique to the result obtained using the standard sequential updating of a Kalman filter.

Select this Article		Comparison of the PMHT and PDAF tracking algorithms based on their model CRLBs Yanhua Ruan, Peter K. Willett, and Roy L. Streit Proc. SPIE 3692, 177 (1999); http://dx.doi.org/10.1117/12.352860 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The PMHT is a very nice tracking algorithm for a number of implementational reasons. However, it relies on a modification on the usual data association assumption, specifically that the event that a target can generate more than one measurement in a given scan is made feasible. In this paper we examine the ramifications of this from the point of view of theoretical estimation accuracy - the Cramer-Rao lower bound. We find that the CRLB behavior for the PMHT is much like that for the PDAF: there is a scalar 'information reduction factor' (IRF) relating the loss of accuracy from measurement-origin-uncertainty. This IRF ix explored in a number of ways, and in particular it is found that the IRF for the PMHT is significantly degraded relative to that for the standard measurement model when clutter is heavy. Other topics include the effect of 'homothetic' measurements; data fusion; and non-Gaussian measurement.

Select this Article		Tracking and recognition of airborne targets via commercial television and FM radio signals Aaron D. Lanterman Proc. SPIE 3692, 189 (1999); http://dx.doi.org/10.1117/12.352861 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract We formulate a Bayesian approach to the joint tracking and recognition of airborne targets via reflected commercial television and FM radio signals measured by an array of sensors. Such passive system may remain covert, whereas traditional active systems must reveal their presence and location by their transmissions. Since the number of aircraft in the scene is not known a priori, and targets may enter and leave the scene at unknown times, the parameters space is a union of subspaces of varying dimensions as well as varying target classes. Targets tracks are parameterized via both positions and orientations, with the orientations naturally represented as elements of the special orthogonal group. A prior on target tracks is constructed from Newtonian equations of motion. This prior results in a coupling between the position and orientation estimates, yielding a coupling between the tracking and recognition problems.

Select this Article		Perception-net-based maneuvering target tracking Jae W. Choi, Tae H. Fang, and Keum S. Hong Proc. SPIE 3692, 199 (1999); http://dx.doi.org/10.1117/12.352862 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The IMM estimator is known as a suboptimal hybrid filter that has been shown to be one of the most cost-effective hybrid state estimation schemes. The value of hybrid models for tracking algorithm is that the occurrence of target maneuvers can be explicitly included in the kinematic equations through regime jumps. However, the model probabilities of IMM filter trend to be slowly adapted from the non-maneuver mode to maneuver mode or from maneuver to non-maneuver, although sudden maneuver can take place in the true system. This is why the model probability is dependent on the past model probabilities. In order to track a suddenly and highly maneuvering target, the technique which combines IMM filter with error monitoring and recovery technique of perception nit is proposed in this paper. The perception net, as a structural representation of the sensing capabilities of system, is formed by the interconnection of logical senor with three types of modules: feature transformation module, data fusion module (DFM), and constraint satisfaction module. Observing the output and input of DFM, we can detect an error of input data. Error monitoring and recovery technique based on this function makes it possible to detect and identity errors, and to calibrate possible biases involved in sensed data and extracted features. Both detecting maneuver and compensating the estimated state can be achieved by employing the properly implemented error monitoring and recovery technique reduces the maximum values of estimation errors when maneuvering starts and finishes, and shows higher tracking performance especially for a highly maneuvering target. Its effectiveness is demonstrated through Monte-Carlo simulations.

Select this Article		Continuously high accurate positioning algorithm for integration of a GPS and an INS Jingying Chen, Guoyou Wang, and Haiqing Chen Proc. SPIE 3692, 209 (1999); http://dx.doi.org/10.1117/12.352863 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract In order to solve the slowly modified rate of 1 Hz of a GPS and the infinite position error of an INS, a continuously high accurate positioning algorithm of a linear convex combination of a linear-two-point and a quadratic-five-point polynomial to filter and predict GPS and INS positioning data is presented in this paper. The integration experiment of real GPS data and simulated INS data has shown the validity of this method. It provides a new approach of continuously high accurate real-time positioning under medium or highly dynamic environment.

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Imaging Trackers I

Select this Article		Reconfigurable video tracker Gillian K. Groves, Spencer W. White, Michael D. Vahey, and John A. Harding Proc. SPIE 3692, 216 (1999); http://dx.doi.org/10.1117/12.352864 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Reconfigurable computing using SRAM-based field programmable gate arrays (FPGAs) can achieve significant computational performance advantage over conventional programmable processors. Since FPGAs can be customized, reconfigurable computers can provide optimal logic-circuitry for distinct phases of an application resulting in superior performance compared to generic multi-purpose hardware implementations. This performance improvement can be accomplished by reallocating logic resources to address the critical task at-hand. Consequently, not only can reconfigurable processors provide higher performance than programmable processors; they also enable common module architectures useful for multiple application or programs. In this paper, we will describe a fielded, ruggedized, fully programmable, single card, image-based tracking system using a reconfigurable computing module. The reconfigurable computing board contains multiple FPGAs, which can be customized at-request by loading configuration data from the host processor to the module over the Peripheral Component Interface (PCI) bus. Configurations can be selectively loaded to a specific FPGA or multiple configurations can be loaded simultaneously to different devices. This system provides multiple video tracking algorithms, automatic and manual target acquisition, RS-170 video input/output, and command/data I/O on a single 6U VME format card. While the initial application for this reconfigurable system was image-based target tracking, its hardware reconfigurability allows it to be applied to a wide variety of image and signal processing applications, such as automatic target recognition, IR search and track, and image enhancement.

Select this Article		Real-time multistage IR image-based tracker Teresa L. P. Olson and Carl W. Sanford Proc. SPIE 3692, 226 (1999); http://dx.doi.org/10.1117/12.352865 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract In this paper we describe a real time algorithm for a missile-based IR tracking system. A correlation-based tracker is considered to be the primary tracker, while a feature-based is chosen to provide support on a secondary level. A prescreener runs concurrently with the trackers to provide a list of probable target centroids. This information is used to provide a level a confidence to the tracker. The tracker subfunctions are implemented in both programmable logic hardware and software operating on digital signal processors. The maximum sustained pixel data rate that can be processed is 10 MHz, which will provide a 60 Hz tracker with a 256 X 256 input image and a 30 Hz tracker for a 512 X 512 input image. The prescreener functions is implemented in reprogrammable hardware subfunctions that operate up to the full 10 MHz pixel rate producing target centroids.

Select this Article		Comparison of image processing algorithms for tracking illuminated targets Jerry W. Bukley and Robert M. Cramblitt Proc. SPIE 3692, 234 (1999); http://dx.doi.org/10.1117/12.352866 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Pointing the line-of-sight of an acquisition, tracking and pointing (ATP) system at a target requires designation of a reference line of sight (LOS) based principally on the target image. For many system, this will also include registration of a specific fiducial on the target for precision pointing. It is difficult to select a track reference because of algorithm sensitivity to modeling of the image. The selection of a track reference ins further complicated by image variations associated with changes in the viewing geometry and target characteristics. This paper compares several image-processing algorithms for the precision pointing of a near-space ATP platform that is viewing missile targets. The platform has state-of-the-art alignment, stabilization and tracking functions. The algorithms are tested in a full imaging and control system simulation that models an illuminating laser beam, target reflectance, optical effects, the sensor, a high order control system and pointing dynamics. The target models are based on flight dynamics, orientation, measured drawings and surface reflectivity. The simulation results are compared by calculating bias, drift and jitter characteristics of the error incurred when attempting to point the optical line-of- sight at the target. Several algorithms have been identified that provide a pointing reference capable of sustaining sub- microradian error. This paper describes the calculation of the fiducials for the algorithms and compares their relative merits.

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Imaging Trackers II

Select this Article		Handoff between track-while-scan and image tracking Stacy H. Roszkowski Proc. SPIE 3692, 246 (1999); http://dx.doi.org/10.1117/12.352867 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The handoff between track-while-scan (TWS) mode and image based tracking raises some important questions for the systems designer. TWS is used for point targets and image tracking is used for resolved targets; during any given scenario there are times when both methods may work. An optimal point for handoff must be found. The target may oscillate between a state where TWS is optimal and a state where image based tracking is optimal; reacquisition of the target by one mode after breaklock in another is another problem that must be addressed. The limitations of both modes need to be considered: detection of a point target with 2D spatial algorithms is dependent on the apparent size of both the target and the filter. Performance of the image based tracker is also highly dependent on target size and shape. This paper will describe the detection algorithms used to detect point targets for a typical TWS mode, give a brief description of a typical image based tracker and show results for several different scenarios.

Select this Article		Development of an infrared imaging seeker emulator for countermeasure studies Andre Morin and Pierre Lessard Proc. SPIE 3692, 255 (1999); http://dx.doi.org/10.1117/12.352868 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract An IR imagin tracker has been developed by the Defence Research Establishment Valcartier to emulate IR seekers representative of the next generation of anti-aircraft missiles. The main application of this tracker is to perform research on the susceptibility of IR imaging seekers to countermeasures such as decoy flares and jamming by modulated sources. The tracker is composed of a 3-to-5 micrometers IR focal plane array camera and fixed optics mounted on a motorized gimbaled platform. High-speed processors are used to process in real time the IR images to detect and discriminate the targets in the tracker's FOV. The digital tracking loop provides tracker stabilization. A multitude of image processing and target discrimination algorithms can be implemented in the tracker. The complexity of these algorithm must take into account the potential processing limitation of the seeker on-board processor. A specific tracking algorithm has been developed to reject false targets such as decoy flares. Its performance has been evaluated in the presence of counterparts by means of a hardware-in-the-loop simulation facility.

Select this Article		Multimode algorithm for detection and tracking of point targets Ronda Venkateswarlu, Meng H. Er, Suyog D. Deshpande, and Philip Chan Proc. SPIE 3692, 269 (1999); http://dx.doi.org/10.1117/12.352869 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract This paper deals with the problem of detection and tracking of point-targets from a sequence of IR images against slowly moving clouds as well as structural background. Many algorithms are reported in the literature for tracking sizeable targets with good result. However, the difficulties in tracking point-targets arise from the fact that they are not easily discernible from point like clutter. Though the point-targets are moving, it is very difficult to detect and track them with reduced false alarm rates, because of the non-stationary of the IR clutter, changing target statistics and sensor motion. The focus of research in this area is to reduce false alarm rate to an acceptable level. In certain situations not detecting a true target is acceptable, but declaring a false target as a true one may not be acceptable. Although, there are many approaches to tackle this problem, no single method works well in all the situations. In this paper, we present a multi-mode algorithm involving scene stabilization using image registration, 2D spatial filtering based on continuous wavelet transform, adaptive threshold, accumulation of the threshold frames and processing of the accumulated frame to get the final target trajectories. It is assumed that most of the targets occupy a couple of pixels. Head-on moving and maneuvering targets are not considered. It has been tested successfully with the available database and the results are presented.

Select this Article		Fusion algorithm for multisensor target tracking in nonlinear systems Chunling Yang, Quan-Zhan Zheng, and Guo-Sui Liu Proc. SPIE 3692, 279 (1999); http://dx.doi.org/10.1117/12.352870 \| Cited 1 time Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Mainly studies multisensor data fusion algorithm for target tracking in nonlinear systems. Proposes the distributed fusion algorithm based on Converted Measurement Kalman Filter (CMKF). From theory, it is derived that distributed converted CMKF algorithm (DCMKFA) can nearly reconstruct centralized fusion estimate based on CMKF. Simulations proved this conclusion. So DCMKFA is a better distributed fusion algorithm for target tracking in nonlinear systems.

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Image Processing Applications

Select this Article		Detection and tracking of multiple targets in infrared images Joao Dinis, Pedro Ribau, and Bento A. B. Correia Proc. SPIE 3692, 290 (1999); http://dx.doi.org/10.1117/12.352871 \| Cited 1 time Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Multitarget tracking in cluttered environments has to deal with noisy measurements from ambiguous origins, which leads to a process of hypotheses generation and evaluation in addition to the traditional estimation problem. The multiple hypothesis tracking (MHT) algorithm is a statistical data association that provides a high level of support for false alarms and temporary occlusion at the cost of high processing requirements. This paper describes a methodology developed for the detection of moving and stationary point targets that feeds the MHT based tracking algorithm implemented. The time filtering approach developed for target detection is based on a combined spatio-temporal analysis approach optimized for clutter driven situations. The analysis of the local variance behavior within a time window is followed by a spatial processing stage based on motion segmentation by region growing. Moving regions presenting similar properties are thus clustered into single entities. Furthermore, a background estimation algorithm is also used, aiming to increase the robustness of the detection method. Multitarget tracking is then achieved through a MHT methodology based on the spatial features of the segmented motion regions. Special attention is given to the evaluation of performance of the method in real IR image sequences.

Select this Article		Real-time reconfigurable foveal target acquisition and tracking system David J. Stack, Cesar Bandera, Christopher J. Wrigley, and Bedabrata Pain Proc. SPIE 3692, 300 (1999); http://dx.doi.org/10.1117/12.352872 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents a target acquisition and tracking system based on the biomimetic concept of foveal vision. The system electronically reconfigures the resolution, sizes, shape, and focal plane position of visual acuity to meet time- varying operational requirements while maximizing the relevance of acquired video. A reconfigurable multiresolution active pixel CMOS imaging array is integrated in a closed-loop fashion with video processing and configuration control. Imager and algorithm configuration is updated frame-by-frame and reactively to target and scene conditions. By dynamically tailoring the visual acuity of the senor itself, the relevance and acquired visual information is maximized and a fast update rate is achieved with reduced communications bandwidth and processing requirements throughout the entire system. The system also features small size and less power consumption, and does not require a pointing mechanism. The distinguishing features of reconfigurable foveal machine vision are presented, and the hardware and software architecture of the target acquisition and tracking system is discussed. Real-time experimental result for automated target search, detection, interrogation, and tracking are then presented.

Select this Article		Stabilization of infrared image sequence with differential invariants and M-estimators Daniel McReynolds, Pascal Marchand, Yunlong Sheng, Langis Gagnon, and Leandre Sevigny Proc. SPIE 3692, 311 (1999); http://dx.doi.org/10.1117/12.352873 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract We investigate computer vision techniques for the stabilization of image sequences from a single image sensor. Image stabilization is required to improve the performance of human operators for evaluating surveillance imagery in real-time. Non-trivial rotation and scale changes of the input images could be important. Furthermore, for many operations such as airborne surveillance, perspective distortion induces an image transformation that is typically not handled well by classical registration techniques such as cross-correlation. We focus on the issue of rotation, scale and projective invariance for point feature detection and verification. It is often the case that hypothesized point matches are incorrect or poorly localized so we investigate solutions incorporating robust estimators. Feature points are detected with the Harris-Stephens corner detector. We use the greylevel differential invariant (GDI) matching due to Schmid and Mohr which is invariant to rotation and scaling. Extensions to the basic GDI method are introduced that improve the performance of the method. We verify the point correspondences under orthographic projection using the epipolar constraint via M-estimators and least median of squares on real-world and synthesized IR sequences.

Select this Article		Ground-to-ground automatic target detection and tracking system: human factors performance evaluation (phase IV) Mike Greenley, Holger Lange, and Jeremy Brooks Proc. SPIE 3692, 322 (1999); http://dx.doi.org/10.1117/12.352874 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Fire Control and Surveillance in the ground-to-ground environment has traditionally relied on the operator for the detection and tracking of targets. Significant performance improvements can be realized with the introduce of a ground- to-ground ATDT system. Computing Devices Canada (CDC) is developing an ATDT system to provide a high performance, cost effective solution for ground-to-ground applications. The development of the ATDT system is being carried out in 5 phases. The objective of Phase I was to select and develop the Image Processing algorithms. Phase II implemented a new generation of image processing algorithms in the form of a prototype syste. Phase III developed the ATDT system applying proper object oriented software design. In Phase IV the core ATDT system has been integrated into a full motion Armored Fighting Vehicle (AFV) simulator, a high fidelity simulation facility used for design and development. A critical component of Phase IV is the evaluation of the core ATDT system with the human-in-the-loop. This paper describes the method and result of the human performance evaluation of the core ATDT system. These evaluations have been conducted with the ATDT system integrated with an advanced Fire Control System and a Defensive Aids Suite in the high fidelity AFV simulation using both Visual and Thermal sights. Extensive human performance trials with active military tank crews have been carried out to measure the impact of the ATDT system on mission and task performance, and usability. Special focus has been put on measuring the impact of ATDT on AFV crew target detection and engagement performance when integrated with future vehicle systems. The performance evaluation also provided input on how the development of the ATDT system can continue to be enhanced and better integrated with other vehicle systems to optimize engagement performance and vehicle survivability.

Select this Article		Fundamentals of on-road tracking Robert H. Enders Proc. SPIE 3692, 334 (1999); http://dx.doi.org/10.1117/12.352875 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Among the various ways in which ground targets differ from air-targets, a most important one is that in order to travel substantial distances, ground targets generally need to move on roads. Alpha-beta type filters or Kalman filters, i.e., tracking filters designed for air-targets, have not dealt with constrained target motion. The use of road-constraints changes both the prediction and update steps in the tracing problem. In this paper a Bayesian framework is developed, in which the road information, in standard vector-product form, is incorporated with the predicted target location into the Bayesian prior. Both the maximum a posterior and Bayes least-squares solutions are then computed. An examination of the results shows that the MAP solutions is potentially unstable when two conditions coincide: the target is located near a road bend and the sensors return is located inside the bend. Because of this potential instability, the preferred update solution turns out to be the along-road average of the updated location probability density. Formulas for calculating or effectively approximately the solution and its along-road variance are given, as well as an association measure for multi-target tracking, track initiation, and clutter rejection by gating.

Select this Article		3D simulator for the rosette-scanning seeker using thresholding techniques SurngGabb Jahng, HyunKi Hong, Sung-Hyun Han, DongSun Seo, and Jong S. Choi Proc. SPIE 3692, 343 (1999); http://dx.doi.org/10.1117/12.352876 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The IR seeker is a device that detects heats radiated from a target and provides the target position with servo system of the missile. Among various kinds of seekers, the rosette- scanning seeker ins a tracker in which a single IR detector scans the total field of view (TFOV) in a rosette pattern, and then produces 2D image about a target. Since the detected image has various shapes according to the target position in the TFOV, it is necessary that we investigate the tracking algorithm applicable to the different shapes. In this paper, we present a comparative study of the projective and the moment technique among the various target tracking techniques. Using the 3 degree-of-freedom simulator, we evaluate two algorithms and confirm the better performance of the moment technique as a tracking one.

Select this Article		Probability of target acquisition by seeker in circular scan considering dwell time requirement Chandra B. Asthana Proc. SPIE 3692, 354 (1999); http://dx.doi.org/10.1117/12.352877 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The acquisition of moving target by an active seeker requires detection and confirmation of target leading to lock-on and tracking subsequently. The probability depends on the probability of detection and that of sighting the target in the seeker beam such that the target remains in the beam for a finite time called dwell time. The dwell time is necessary to process the signals for the confirmation of target. In order to improve upon the probability of sighting the target without search, a circular scan is generally carried out. This is accomplished by deflecting the seeker beam by half the beam width and making one rotation. This causes the beam to sweep the target and the sweep speed depends on the location of the target with respect to the point of rotation of the beam. In this paper, first the dwell time is evaluated for the circular scan in a 3D engagement. The probability of sighting the target is then worked out for a given pointing accuracy of the beam. Finally, the probability of acquisition is found as the product of the probability of detection and that of sighting the target.

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Poster Session

Select this Article		Missile angle acquisition based on total least square estimation with phased array radar Jian-Ming Qu, Chen-yang Yang, and Shiyi Mao Proc. SPIE 3692, 366 (1999); http://dx.doi.org/10.1117/12.352879 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract An angle acquisition method is proposed in this paper that is based on the total least squares (TLS) estimation with phased array radar. Not only the perturbations in the observation vector but also the perturbations in the data matrix are considered. By applying TLS estimation, the Frobenius norm of the error matrix is minimized. The simulations are given to compare the performance of the TLS acquisition method with the LS acquisition method.

Select this Article		AFMM solution to the benchmark radar tracking problem Mattias J. L. Carlsson and Mika V. Laaksonen Proc. SPIE 3692, 373 (1999); http://dx.doi.org/10.1117/12.352880 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The paper describes a new approach for an adaptive update- rate-tracking algorithm for phased array radars. Since phased array radars have the ability to perform adaptive sampling of the target by radar beam positioning, proper control of radar has the potential for significantly improving many aspects associated with tracking of multiple maneuvering targets. An adaptive multiple model filter for tracking maneuvering targets has been designed for applications to the Benchmark Tracking Problem (BTP). The first Benchmark Problem has previously been solved with (alpha) - (beta) -filters, standard Kalman filters and two and three model IMM filters. The tracking algorithm used in this paper is an Adaptive Forgetting through Multiple Model filter (AFMM). AFMM is especially suited for tracking of dynamic system with jumping and rapidly changing parameters. It can be viewed as a particular way of implementing adaptive gains or adaptive forgetting factors for tracking. Two motion models have been used: a constant velocity and a 3D turning rate. Preliminary result indicate promising capabilities of the filter in solving the BTP. This paper presents results for the BTP solved with an AFMM filter.

Select this Article		Suppress the radar target glint by an L-filter preprocessor Guoying Chen and Peikang Huang Proc. SPIE 3692, 381 (1999); http://dx.doi.org/10.1117/12.352881 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract Based on the statistical analysis of the radar target glint, the long term dependence and 1/f-type spectrum are show. Moreover, from the point of view of the long term dependence, the effectiveness of available processing techniques are explained. Since L-filters are particularly well suited to deal with the strong correlation structure signal, an L-filter preprocessor is employed in analyzing and processing the radar target glint in this paper. The results show that the glint noise can be properly reduced by the L-filter preprocessor.

Select this Article		Application of fuzzy logic in multipassive acoustic tracking Gee W. Ng Proc. SPIE 3692, 389 (1999); http://dx.doi.org/10.1117/12.352882 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, we introduce the application of fuzzy logic concepts to solve the time-delay problem in tracking moving target using passive acoustic sensors. Passive tracking which uses the direction of arrival or bearing of a target is a nontrivial task. The problem is made even more difficult to solve if the passive sensors measurement of bearing is based on acoustic signal only. This is because the acoustic signal introduce time-delay i.e. different senors spatially apart will receive the same target's acoustic signal at different time. The time-delay problem cannot be resolve easily partly because the amplitude of the acoustic signal strength cannot be modeled linearly; its behavior is nonlinear subjected to environmental conditions. To solve these problems we propose to apply the fuzzy logic concept, using information from sensors such as amplitude difference and time-stamp difference from different sensors. The defuzzified results provide one of the main factors for computing the correlation strength between different bearing tracks. The two tracks with the highest correlation strength are then used to determine the position of the target.

Select this Article		Improved AGC design for scan tracking radar using H-∞ Andres Guesalaga and Sebastian Tepper Proc. SPIE 3692, 398 (1999); http://dx.doi.org/10.1117/12.352883 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract The AGC of a conical scan tracking radar IF amplifier is designed using H_x synthesis. It is shown that this technique is particularly suited for this problem because of its loop shaping capabilities and because it can tackle particular frequencies effectively, providing a correct balance among closed loop stability, fast responses to echo changes and rejection of frequencies other than the echo modulation. Two controllers are implemented and compared to a standard controller, showing significant improvement in system tracking.

Select this Article		Converted measurement Kalman filtering algorithm for radar target tracking Chunling Yang, Quan-Zhan Zheng, and Guo-Sui Liu Proc. SPIE 3692, 410 (1999); http://dx.doi.org/10.1117/12.352884 Online Publication Date: Jul 09, 2003 Full Text: \| Download PDF
	+ -	Show Abstract In this article, the filtering-algorithm for target tracking is studied in nonlinear systems. First, the converted measurement Kalman filtering algorithm (CMKFA) is inferred in 3D space. The statistics of the errors in converted measurements conditioned on target's true position is obtained, and the statistics of the errors in converted measurements conditioned on measurement is given to. Then it is proved that the CMKF is a linear unbiased least mean square estimator of debiased converted measurements under certain conditions. Finally, from simulations, it is proved that CMKF has a higher target tracking accuracy than EKF.

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