The control system, software design and implementation issues for a large, 15,000 pounds, high accuracy, high dynamics, low jitter multi-axis gimbal set, optical Beam director Assembly are discussed in this paper. The definite success of the Contraves Brashear Systems approach to design and implement these unique systems is discussed and results shown.

The VIGILANTE project is a planned vision system capable of tracking and recognizing targets in real time, on a small airborne platform. The project consists of two parts: (1) the viewing imager/gimballed instrumentation laboratory (VIGIL), which is an IR and visible sensor platform with appropriate optics and (2) the analog neural 3D processing experiment (ANTE), a massive parallel, neural based, high- speed processor. The VIGIL platform is mounted on a helicopter equipped with Global Position System (GPS), Inertia Measurement Unit (IMU), gimbal, radio-link and anti- vibration platform. Also, a jet powered, radio controlled VIGILANTE Target Vehicle (VTV) has been manufactured and equipped with GPS. In the first stages of the project, the VIGIL system is used to acquire image sequences of the VTV for training and testing of the ANTE image recognition processor. Based on GPS and IMU input, the gimbal is pointed toward the VTV and acquires images. This paper describes the VIGIL system in detail. It discusses position-based pointing, tracking algorithms and the alignment procedure. Test imagery and an evaluation of the system will be presented.

A state-of-the-art acquisition/tracking/positioning (ATP) system for vehicle protection and area defense application is presently being developed. The ATP system, referred to as the high performance laser fire control system, has been designed to automatically acquire, track, rangefind and designate top attack weapons, such as mortars and artillery, as well as line-of-sight type weapons, such as anti-tank guided missiles and anti-tank projectiles. The ATP mission scenario requires full hemispherical coverage, extremely high acceleration capabilities, precision stabilization, and precision pointing.

This paper describes the embedded systems software design and computer architecture for a high performance laser pointing and fire control system (HPFCS). The HPFCS, is a stabilized, high bandwidth target acquisition, tracking and laser pointing system.

This paper describes the mechanical and control system upgrades performed on the IFLOTS trailer mounted optical tracking system. It will begin by briefly describing the original configuration of the mount and performing a 'before' FEA analysis of the pedestal structure. I will then outline the upgrades performed and discuss the net effect of the improvements on system performance.

The Shuttle Radar Topography Mission (SRTM), scheduled for an 11 day Space Shuttle flight in 1999, will use an Interferometric Synthetic Aperture Radar instrument to produce a near-global digital elevation map of the earth's land surface with 16 m absolute vertical height accuracy at 30 meter postings. SRTM will achieve the required interferometric baseline by extending a receive-only radar antenna on a 60 meter deployable mast from the shuttle payload bay. Continuous measurement of the interferometric baseline length, attitude, and position is required at the 2 mm, 9 arcsec, and 1 m levels, respectively, in order to obtain the desired height accuracy. The attitude and orbit determination avionics (AODA) subsystem will provide these functions for SRTM. The AODA flight sensor complement includes electro-optical metrology sensor, a star tracker, an inertial reference unit, GPS receivers, plus supporting electronics and computers. AODA ground processing computers will support SRTM system performance evaluation during the mission and baseline reconstruction after the mission. The final AODA data products will be combined with the radar data to reconstruct the height information necessary for topographic map generation. A description of the AODA system architecture, error budgets, and the major issues involved with measuring large space structures are presented.

In this paper we describe an approach for designing a pointing and stabilization system for an unbalanced, flexible gun. Our approach is based upon classical control techniques as well as system identification and adaptive feedforward techniques. Adaptive algorithms identify the flexible modes of the system and estimate the dynamics unbalance. This information is used to update the control law in order to improve the stabilization accuracy of the system.

In determining the processing requirements for a track processor, which is most easily specified in terms of processing delay, it is necessary to have a relationship between the system requirement of track loop bandwidth, the sensor sample frequency and all the delays in the track loop processing. These delays include the sensor integration time, the sensor integration time, the sensor readout time, the time for A/D conversion and reformatting, the track processor delay and any D/A conversion and transportation delays associated with getting the rate commands to the servo system. This paper documents a methodology used in determining the relationship between bandwidth, sample frequency and system delays. This is done algebraically in terms of an 'effective' sampling frequency that takes into account the phase loss due to system delays. While more sophisticated analysis can be done, the simplified methods presented here will often be helpful to the systems analyst without the need for more direct control system analysis.

The gimbal and control system for a high performance, acquisition, tracking and pointing system is described. This system provides full hemispherical coverage, precision stabilization, rapid position response, and precision laser pointing. The high performance laser pointing system (HPLPS) receives position and rate cues form an integrated threat- warning-system, slews to the predicted target location, acquires, tracks, and designates the target. The azimuth and elevation axes of the HPLPS are inertially stabilized with independent, high bandwidth, inertial rate loops. The cue to position control loop is implemented using a time-optimal control algorithm which slews each axis of the platform to the predicted target location with high accuracy and zero overshoot in minimum time. After cuing to position,m auto- track mode engages with a type 4, high bandwidth track loop. Track loop integrators are initialized to keep the platform moving at the cued target rate as control transfers from position cue to auto-track mode. After initially tracking with a narrow field of view tracking sensor, an active laser track is performed with a narrower field of view laser-spot- tracking sensor. The gimbal electronics use a Texas Instruments TMS320C30 digital signal processor and proprietary software executive to achieve the performance required for the 960 Hz control loop sample rates. Optical encoder, resolver, and high bandwidth fiver-optic-gyro sensors are used. Linear amplifiers drive the azimuth and elevation mirror motors and a sine wave commutated amplifier drives the outer gimbal motor.

We describe the design and performance of the pointing and aspect reconstruction system on the Gamma-Ray Arcminute Telescope Imaging System. The payload consists of a 4m long gamma-ray telescope, capable of producing images of the gamma-ray sky at an angular resolution of 2 arcminutes. The telescope is operated at an altitude of 40km in azimuth/elevation pointing mode. Using a variety of sensor, including attitude GPS, fiber optic gyroscopes, star and sun trackers, the system is capable of pointing the gamma-ray payload to within an arc-minute from the balloon borne platform. The system is designed for long-term autonomous operation and performed to specification throughout a recent 36 hour flight from Alice Springs, Australia. A star tracker and pattern recognition software developed for the mission permit aspect reconstruction to better than 10 arcseconds. The narrow field star tracker system is capable of acquiring and identifying a star field without external input. We present flight data form all sensors and the resultant gamma-ray source localizations.

This paper investigates the existence and design of optimal, multiple model filters for target tracking using different local models. Two models are used: a constant velocity and a constant acceleration model. Sufficient conditions are derived that guarantee the existence of optimal multiple model filters. The problem is then solved for the case where the switching gains are diagonal matrices. The performance of the derived multiple model filter is evaluated using a simulated target trajectory.

Consider two sensors tracking a single target and the two tracks of this target, one from each sensor, that are generated. For some time, it has been recognized that these two tracks are correlated and that this correlation is due to the common process noise of the target. A MMSE solution has been derived that accounts for this correlation between tracks when fusing tracks from synchronous sensors. Here, synchronous means that the sensor take measurements of the target's position at the same time and that they arrive at the fusion center with no communications delays. This paper extends the previous work in correlated track fusion to include asynchronous sensors, i.e., the sensor do not measure the target's position at the same time, and the possibility of communications delays.

The measurements for two targets will be merged when the targets are closely-spaced with respect to the resolution of the radar. Improved monopulse processing techniques for an electronically scanned array (ESA) can be used to compute a measurement for each target and used to update the state estimates. However, a substantial amount of radar resources is required to perform this operation. The integration of the ESA with additional sensors has the potential to enhance the tracking and reduce the resource allocation requirements of the ESA when targets are unresolved. A complementary sensor would provide measurements for both targets and can be employed to form a composite track for the ESA. The tracks will not be merged and the ESA can better utilize its resources. This paper presents algorithms for the tracking of maneuvering targets and multisensor integration for effective ESA resource management when tracking of maneuvering targets and multisensor integration for effective ESA resource management when tracking unresolved targets. The sensor suite includes an ESA and an IR Search and Track sensor. The effect of sensor integration on tracking performance and ESA resource allocation will be presented for single and multiple sensor configurations.

This paper presents a novel approach for tracking maneuvering target in the X-Y plane. The algorithm uses the fuzzy if-then rules and the exponential decaying for tuning the process noise covariance in its upscaling and downscaling respectively. A new method of estimating the turn rate is also proposed. This algorithm is compared with the IMM filter using simulated and real data.

A number of 'bearing-only' target motion analysis algorithms have appeared in the literature over the years, all suited to track an object based solely on noisy measurements of its angular position. In their paper 'Utilization of Modified Polar (MP) Coordinates for Bearings-Only Tracking' Aidala and Hammel advocate a filter in which the observable and unobservable states are naturally decoupled. While the MP filter has certain advantages over Cartesian and pseudolinear extended Kalman filters, it does not escape the requirement for the observer to steer an optimum maneuvering course to guarantee acceptable performance. This paper demonstrates by simulation the consequence if the observer deviates from this profile, even if it is sufficient to produce full state observability.

The Advanced Airborne Interceptor Simulator (AAIS) is a pod- mounted system that simulates RF emission of an airborne tracking radar. The simulator does not contain a receiver. It is a 'smart' emitter which uses the time, space and position information (TSPI) received form a target carrying a RAJPO GPS datalink pod. The TSPI essentially replaces outputs typically seen in a radar receiver, namely angle, range and range rate of a target. Since the update rate of this information is dictated by the slow transmission rate of the RAJPO datalink, the signal must be extrapolated and filtered at a much faster rate, close to that of the simulated airborne interceptor. This is necessary to accurately track and faithfully emit radar signals to maintain track on an airborne target. The received TSPI rate is 10 Hz. A second order (alpha) -(beta) filter is chosen to optimize the tracking performance of the AAIS. This paper discusses various rates of the filter, the need for extrapolation and the optimal values of the (alpha) and (beta) factors for this airborne application.

A rosette scanning IR seeker is the device mounted on the IR guided missile. It offers the positions and images of target to missiles' servo system by scanning a total field of view (TFOV) in a rosette pattern with a single detector. An instantaneous field of view (IFOV) is a diameter of the detector moving along the path of the rosette pattern. The IFOV has the property that its smaller size provides the less interference of background signals and detector noise. If its size is too small to cover the TFOV, however, it produces the invisible regions in the TFOV and decreases the performance of the seeker. For full scan coverage, it is necessary to design the small IFOV without the invisible regions as possible. In this paper, we propose a new method to design the smaller IFOV than the conventional one. The IFOV of the proposed method is defined as a distance between two points, which are selected among the intersected points between any petal and its neighbors. By comparing a noise equivalent flux density of the proposed method with that of the conventional, we confirm that the former is better than the latter in terms of performance. To evaluate the designed IFOV dynamically, we simulate the rosette scanning IR seeker using MATLAB-SIMULINK.

This paper presents a dynamic simulation loop that gives tracking results of 2-color concentric annular ring (CAR) reticle seeker. Our simulation tool includes the target/flare model and a proportional navigation guidance loop. The CAR reticle system performance and the flare effects are analyzed in various cases. When a flare is presented in the field of view (FOV), the simulation results show that the reticle seeker cannot keep a precise target tracking. In this paper, we propose a 2-color counter- countermeasure using the least mean square method to cope with a presence of IR flare. The proposed method makes a simultaneous process in two IR wavelength bands: (i) the modulation output in FWIR, (ii) the output in MWIR. The simulation result have shown that our adaptive IRCCM algorithm achieves an effective cancellation of the flare signal with a relatively high intensity.

This paper describes an airborne opto-electronic tracking and imaging gimbals that can support several sensor. The gimbals is driven by a multi-loop controlling unit, which supplies controlling signals to track targets and to stabilize the LOS. The test result show that the tracking error is less than 1.7' and the stability of LOS reaches 100 (mu) rad.

In previous studies of optimal proportional navigation, the problem are most formulated to obtain the optimal magnitude of applied commanded acceleration under pure or true proportional navigation. Recently, the optimal direction of applied commanded acceleration is derived and discussed under conventional proportional navigation. Now in this article, the optimal guidance of modified proportional navigation is studied with maneuvering or nonmaneuvering target, in which the energy expenditure till intercept is minimized. From the result of this study, it shows that true proportional navigation is the exact optimal solution for a nonmaneuvering target or near-optimal solution for a maneuvering target. Some related important characteristics, such as capture criterion and energy expenditure, are investigated and discussed in detail. Also, a typical example of target maneuver is introduced to illustrate 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.

In this paper we propose a new motion simulator base don tendon controlled tensegrity structures. The simulator is equipped with a robust nonlinear controller which achieves robust tracking by the simulator of a desired motion. The controller parameters can be tuned to guarantee tracking to within a prespecified tolerance and with a prescribed rate of exponential convergence. The design is verified through numerical simulations for specific longitudinal motions of a symmetric aircraft.

Tracking multiple targets in a cluttered environment using Electro-Optical (EO) and IR imagery is important to airborne video surveillance (AVS). However, existing system often fail when a target encounters occlusion, changes in direction, or stops in transit. To counter this problem, a new software package named GATOR has been developed, which can automatically initiate, maintain, terminate, and reacquire tracking of multiple targets under these challenging conditions. The tracking performance of the system is measured by the discriminative signal to noise ratio and the peak sharpness. The system is implemented in C/C⁺⁺. Using caches for memory addressing the pipeline programing, high speed processing and dynamic target handling are achieved simultaneously. Compared with other multiple target tracking systems, the distinguishing feature of GATOR is that it integrates a suite of tightly structured advanced computer vision algorithms to achieve very rugged performance and fast processing speed. The strength of the system resides in its ruggedness and automation, which is fundamental to many demanding applications such as video image exploitation for UAV, border control, treaty enforcement, and other large area surveillance systems.

Implementation of a target acquisition tracker on real time video images can be made to run with more modest processors by using intensity thresholds. Pixels are ignored in real- time based on this threshold setting, hence reducing processor time. This paper considers issues when a real-time histogram is presented to a user and how the decision can be made rapidly by a user. This paper also describes a common tracking algorithm adapted to using this threshold, and a hybrid mode. The paper will also show how a system's user interface is designed to rapidly gather this information without overloading the user.

The Aspect Camera Assembly (ACA) is a 'state-of-the-art' star tracker that provides real-time attitude information to the Advanced X-ray Astrophysics Facility (AXAF), and provides imaging data for 'post-facto' ground processing. The ACA consists of a telescope with a CCD focal plane, associated focal plane read-out electronics, and an on-board processor that processes the focal plane data to produce star image location reports. On-board star image locations are resolved to <EQ 0.8 arcsec, and post-facto algorithms yield <EQ arcsec star location accuracies. The protoflight ACA has been built, along with a high accuracy vacuum test facility. Image position determination has been verified to <EQ 0.2 arcsec accuracy. This paper is a follow-on paper to one presented by the author at the AeroSense '95 conference. This paper presents the 'as built' configuration, the tested performance, and the test facility's design and demonstrated accuracy. The ACA has been delivered in anticipation of a 1998 shuttle launch of AXAF.

Tracking in real-time is a complex problem handled by researchers in may different manners. In a general way, a tracking system can be organized in some pipelined modules: the first one provides sensorial capabilities using some different technologies such as radar, ultrasonic, IR or CCD cameras, etc. The second one works as a pre-processing device, usually in real time, and supplies filtered information. The third step usually deals with algorithms, supplying information to the last and most important phase: scene understanding and taking decisions. This paper describes a whole computer vision system for tracking moving objects in real-time. First, a high-speed image processing hardware for computing 2D positions is presented. This hardware is the basic sensor of a higher-level system where the integration of several views of the scene allows the computation of 3D positions. Then, the mathematical formulation to solve the trinocular problem is pointed out.

In several recent papers and a new book, Mathematics of Data FUsion, we have shown how finite-set statistics (FISST), a special case of random set theory, provides a theoretically rigorous foundation for many aspects of data fusion. In particular, we demonstrated that this theory provides a fundamental new approach to the problem of determining optimal dwell allocations, mode selections, and servo parameters for reassignable and/or multimode sensor. The basic approach relied on the fact that FISST provides a means of mathematically transforming multisensor, multitarget sensor management problems into conventional nonlinear optimal control problems. In this paper we show that the approach can be extended to include the possibility that the sensor may be distributed among many platforms. We also briefly describe a special cases of finite-set statistics called 'joint multitarget probabilities' or 'JMP', which has been applied to another sensor management approach by Musick, Kastella, and Mahler.

A Bayesian technique is applied to the target acquisition problem at handover from the fire control to the missile seeker. This is a multiple hypothesis scheme which includes an explicit model of the possible misalignment or bias between the fire control and seeker coordinate frames. This method is compared with a linear least cost assignment technique which may be implemented via the Munkres fast search algorithm.

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 introduction of a Ground-to-Ground Automatic Target Detection and Tracking (ATDT) System. Computing Devices Canada (CDC) has developed an ATDT System designed to provide a high performance, cost effective solution for Ground-to-Ground Automatic Target Detection and Tracking. To ensure high performance and cost efficiency the development focused on the integration of the Human Factors, Hardware Development, and Algorithm Development activities. Human Factors focused on ensuring that interaction between the human and the ATDT System was realized in the form of an optimized Operator Machine Interface (OMI). Hardware development focused on maximizing the use of COTS to ensure cost efficiency. Algorithm development focused on achieving high performance in Ground Target Detection and Tracking while building in the capacity to take advantage of the future growth in hardware resources. Computing Devices Canada (CDC) has been involved in the development of image processing capabilities for Armoured Fighting Vehicles since the early 1980's. The following paper provides an overview of the CDC's ATDT System currently under development. The development is following a five phase process and this paper reflects the development status following the completion of Phase II. Details on the Human Factors, Hardware Development and Algorithm Development activities are included. Keywords: Ground-to-Ground Systems, Fire Control Systems, Surveillance Systems, Automatic Target Detection (ATD), Automatic Target Tracking (AlT), Human Factors Engineering, Commercia' of the Shelve (COTS)

Protection of high value military equipment against threats requires a robust self defense system. To meet the challenge of defending against a multitude of different types of threats, a fire control system must have the capability to detect, acquire and track, point a mechanisms and launch a device that intercept threats that present different signatures. This paper presents a multisensor optical assembly that has been developed which allows long wavelength, mid-wavelength and near IR energy to be directed to a multisensor suite. This optical assembly is incorporated in the Acquisition, Tracking and Pointing System of the Experimental Small Low-cost Interceptor Device fire control system. In addition to the optical paths the optical assembly contains calibration references for IR two- point calibration. This optical assembly works in concert with a high performance laser pointing system that has a 10,000 degrees per second per second acceleration capability. This combination of systems provides 360 degrees of hemispherical threat acquisition and tracking coverage.

The task of pattern recognition is to assign an input pattern to one of the known classes of classified patterns. The idea of the syntactic approach to pattern recognition is to decompose the complex input pattern into a hierarchy of simpler subpattems and to develop rules by which they can be combined to assemble a high-level pattern. The decomposing of the original pattern is called parsing and the rules to combine the subpattems are based on formal language theory. This theory works with concepts like words, sentences and syntactic rules which are borrowed from ordinary languages. The input patterns comprise of features. One of the steps within a pattern recognition problem is the feature extraction. The feature selection is very important for pattern recognition : the feature set is selected to ensure a good separation of pattern classes. The features are combined to form patterns according to the pattern grammar rules in a way similar to the human languages. Similarly, some combinations are allowed ,others not. The syntactic approach to the pattern recognition problem works with the following notions: S the input patterns are called words ,which are strings offeatures (same as letters from an alphabet); S there is a grammar for each class ofpatterns , which generates the objects from the class as part ofthe language. . parser is responsible to decide the validity of a pattern , seen as a word from the language generated by the grammar. What seems to be an easy way to classify the input objects based on syntactic rules, is unfortunately not. The instrumentation as well as the algorithm errors and approximations are leading to a much more complicated task. To be able to ensure a good separation of classes , the dimension ofthe feature set has to be increased ; therefore the complexity of the algorithms and the computational time will increase to unacceptable values. The paper presents a solution using the attributed grammars to reduce the feature set dimension. Each feature (seen as a letter from the grammar alphabet) has a set of attributes ; therefore the input pattern , seen as a string of concatenated features ,has a multidimensional structure. Since the grammars used are dealing with multidimensional strings ,the grammars themselves are multidimensional.

Bit error rate is a very important parameter in a system of communication, it influences communication quality. In a general communication system, there are many parameters that would influence bit error rate of the system. But in a system of intersatellite optical communications, there are some special parameters to influence the bit error rate except these parameters. In this paper, the influence on bit error rate of a system of intersatellite optical communications is discussed when a satellite's platform is shaken. By analysis, we may know which parameter is main parameter for influence on bit error rate.

Theoretical prerequisites are reviewed in the paper for providing an experiment to investigate the scattered light in the space vehicles devices for stellar attitude control, the problems related with these experiments, description of the measurement scheme and procedure and also some result of the researches are presented.

We propose an adaptive windowing algorithm that could provide a tracker with the tight reference window by adaptively adjusting its window size independently into all four side directions for enhancing the reliability of correlation-based image tracking in complex cluttered environments. When the size and shape of a moving object changes in an image, a correlator often accumulates walk-off error. A success of correlation-based tracking depends largely on choosing suitable window size and position and thus transferring the proper reference image template to the next frame. We generate sizing vectors from the corners and sides, and then decompose sizing vectors from the corner into two corresponding sides. Since our tracker is capable of adjusting a reference image size more rapidly and properly, stable tracking has been achieved minimizing the influence of complexed background and clutters. We tested performance of our method using 18 artificial image sequences made of 2160 images and 45 real image sequences made of more than 3400 images, and had the satisfied results for most of them.