The US Air Force Maui Space Surveillance System includes a 1.6 meter telescope located at the summit of Haleakala. This telescope has long played a key role in Space Object Identification (SOI) and other scientific research projects. The unique configuration of the 1.6m telescope and its suite of instruments make it ideally suited for high speed, extra-atmospheric Satellite and Missile tracking. However, because of the uniquely designed narrow field of the 1.6m telescope, acquisition of daytime objects presents a challenge. In the past, the 1.6 meter system relied primarily on offsite radar handoffs to provide FOV object placement. This reliance on radar based handoffs increased system operational complexity and decreased system reliability. Recognizing the value of improving mission operational availability and success the US Air Force Research Laboratory and contractor Boeing worked together to design a low cost system to improve the wide field acquisition of daylight objects. This instrument, known as the Daylight Acquisition Sensor (DAS), was developed using a COTS NIR Camera with custom NIR optics assemblies controlled with an integrated COTS embedded computer interface. The design that was implemented is a modification to the existing 0.56 meter nighttime only acquisition telescope, which now, because of the new NIR imaging sensor is capable of both daytime and nighttime acquisition. The system has been in operation for over 1 year and has significantly improved the acquisition capabilities of the 1.6m telescope while at the same time greatly reducing dependency on radar handoff. This paper discusses the design of the NIR Daylight Acquisition Sensor and some of the results from missions it has supported.
A heliostat has been designed and built for use in optical remote sensing of the atmosphere. The heliostat uses two flat mirrors to track the sun and direct the sunlight to optical instruments. A stepper motor driven horizontal turntable is used to track the sun in azimuth and support an elevation assembly and a mechanical tower. The stepper motor driven elevation assembly drives an acquisition mirror that tracks the sun in elevation. This mirror directs the solar beam to a secondary mirror fixed on the mechanical tower. The secondary mirror then directs the solar beam along the axis of the tracker for use in measurements.
A sensitive, high resolution CCD camera, receives a small part of the solar beam to analyze for fine servo-control. Ground based tests have demonstrated this instrument’s tracking capability for the sun, the moon, stars and for long pathlength sources. Presently, this system is coupled with a high-resolution Brucker 120M spectrometer used to obtain solar absorption spectra.
The heliostat directs the solar radiation along the spectrometer optical axis. The pointing precision was measured to be better than 0.5 arcsec. A description of the heliostat is presented, as well as the results of ground tests.
The strengths and weaknesses of centimetre, (I Band), millimetric (Ka band) and EO systems (daylight TV, Thermal Imager Sensors) are discussed, as applied to both the problems of acquiring and tracking naval threats, in order to achieve optimum engagements with Command to Line of Sight (CLOS) weapons. The limitations of the centimetre, millimetre and EO bands with varying target heights, seastates and visibility conditions are identified, including multipath geometry, filtering to counter multipath and utilisation of EO sensors in the Naval environment worldwide. Mechanisms of combining both Radar and EO Sensors to produce an accurate differential tracking output (target to missile), in order to control a CLOS missile are described, together with filter configurations allowing a true differential output to be produced, de-coupled from sensor sightline motion. This includes the application of sensor merging, Kalman filtering and Command Off the Line of Sight (COLOS) techniques. Finally there is a description of both an in-service and projected fire control system controlling a Point Defence Missile System (PDMS), including the results from a practical demonstration of multi-sensor tracking of an air target in a sea going environment.
In this paper we present an algorithm to track a convoy of several targets in a scene using acoustic sensor array data. The tracking algorithm is based on template of the direction of arrival (DOA) angles for the leading target. Often the first target is the closest target to the sensor array and hence the loudest with good signal to noise ratio. Several steps were used to generate a template of the DOA angle for the leading target, namely, (a) the angle at the present instant should be close to the angle at the previous instant and (b) the angle at the present instant should be within error bounds
of the predicted value based on the previous values. Once the template of the DOA angles of the leading target is developed, it is used to predict the DOA angle tracks of the remaining targets. In order to generate the tracks for the remaining targets, a track is established if the angles correspond to the initial track values of the first target. Second the time delay between the first track and the remaining tracks are estimated at the highest correlation points between the first track and the remaining tracks. As the vehicles move at different speeds the tracks either compress or expand
depending on whether a target is moving fast or slow compared to the first target. The expansion and compression ratios are estimated and used to estimate the predicted DOA angle values of the remaining targets. Based on these predicted DOA angles of the remaining targets the DOA angles obtained from the MVDR or Incoherent MUSIC will be
appropriately assigned to proper tracks. Several other rules were developed to avoid mixing the tracks.
The algorithm is tested on data collected at Aberdeen Proving Ground with a convoy of 3, 4 and 5 vehicles. Some of the vehicles are tracked and some are wheeled vehicles. The tracking algorithm results are found to be good. The results will be presented at the conference and in the paper.
Passive magnetic measurements may be used to determine the azimuth, bearing and range to the target in real time using suitable signal processing without illuminating the target. Collision and even close approach must be avoided for classes of targets such as proximity fuzed mines. This paper describes a simple safety algorithm that monitors data from such a tensor magnetometer system and overrides the normal autopilot to ensure a minimum radius is always maintained
from all magnetic targets encountered.
This paper presents an Extended Kalman Filter for tracking a
maneuvering target, where the kinematics of a typical target aircraft maneuver have been incorporated into the filter state equations. Such a formulation allows the target's motion to be accurately determined through estimation of heading and lateral acceleration. This is an improvement over the the typical approach of modeling target motion with acceleration terms represented by random processes,
such as that used in the Singer model. In the following pages,
a three-dimensional target maneuver model is formulated in conjunction with the kinematic equations of a sensor tracking a target in spherical coordinates. Three degree-of-freedom simulation results of the proposed filter, simplified for planar target maneuvers, are compared to a filter modeling target motion with the Singer model.
Tracking maneuvering target using multiple models is an attractive approach that is an alternative to a design that needs logic for both maneuver detection and filter re-initialization. Common current practice in multiple model tracking uses a switching Markov model. This paper also uses a multiple model approach to tracking maneuvering targets, but without using a switching Markov model. The models used work independently, while the process noise of each is adjusted online based on a relative likelihood function. The performance of the newly developed filter will be compared to an IMM tracker.
The information requirements for missile guidance are treated from simple parameter descriptions of a missile and a target. Their maximum accelerations and the maneuver response time of the missile characterize the description of the maneuverability of the missile and the target. Other parameters are the lethal range of the warhead, the closing velocity, the time to go etc. The requirements are reflected within the parameters such as the level of uncertainty before and after a measurement, the measuring times or the instantaneous measurement frequency, the total number of measurements
etc. For the most part, the study is not associated with any particular measuring method. The study focus is on the endgame of missile guidance where we apply a simple maneuver model. We suppose that all accelerations are perpendicular to the initial line of sight. A specific case therefore shows a constant closing velocity
and a known time to go. The missile is also characterized by a time delay between the start of the measurement and the effectuation of the acceleration command. The result includes the calculation of the amount of information needed for a certain case and some parameter
dependencies. We have studied the minimum information due to the acceleration ratio between missile and target and also the maximum delay limit due to the acceleration capabilities of the target and missile along with other parameters. The result also indicates the dependence of the information requirement on the time to go.
Tracking accuracy will be improved greatly and stability of control system will not be affected by input velocity of moving target in electro-optical theodolite. However, the velocity of moving target can’t be obtained directly from video or infrared data in electro-optical theodolite. This paper designed two effective forecast filters, Kalman filter and finite-memory smooth filter, to obtain the velocity of moving target. The simulated and test results shows that velocity of moving target can be estimated by fitting the proper position quantity of electro-optical theodolite to the target-missing quantity and using forecast filters. The tracking accuracy of electro-optical theodolite can be improved effectively in this way.
This paper presents a multi-mode fusion algorithm for detection and tracking of dim, point-like target. The key contribution of this paper includes the effective fusion approach to harvest the advantages and complement the disadvantages of various algorithms using conditional voting. From qualitative analysis, these algorithms are separated into two classes, i.e. main and supporting algorithms. In the multi-mode fusion algorithm high confidence is placed on the main algorithms with supporting algorithms used to further reduce the false alarm. The main algorithms trigger a voting process and detection is confirmed true if any of the supporting algorithms report detection. The multi-modal fusion algorithm has lower false alarm and moderate true detection rate compared to any individual algorithm namely, Triple Temporal Filter, Frame Differencing, Continuous Wavelet Transform, Max-median and 2-D Mexican hat filter. Besides, a novel variability filter is proposed to remove strong glint thus reduces false alarm. Kalman filter is used to track the detected targets. A novel track decision algorithm to continue or
terminate the track when target disappears is proposed. Prior knowledge of target in Kalman filter is fed forward to an Adaptive 3-D Matched filter to improve the performance. Three sets of real-world infrared image sequences with very different background and target characteristics were used to test the robustness of the multi-modal fusion algorithm. The algorithm performs satisfactorily in all the image sequences. Video clips will also be presented.
In this paper, we present a technique for object tracking in image sequences, which makes use of an active contour framework that moves vertices of a polygon. In this approach, upon capturing boundaries of an object by a polygon from the first few frames of the image sequence, both the spatial segmentation and motion segmentation of a polygonal object can be achieved quickly by involving only the vertex locations and the adjacent edges in the computations. We carry out velocity field estimation at an active polygon vertex using the optical flow constraint on its two adjacent edges. A spatial segmentation phase follows to further refine object’s vertex locations estimated by the optical flow. The advantage of our region-based active polygons over continuous active contours in object tracking in video applications is highlighted by its provision of a compact representation of object features, particularly for simply connected target shapes, hence will be essential for their tracking. Application of the method to target tracking in IR image sequences is illustrated.
Searching for the faint target is thought as a very difficult subject in imaging track system. The target shows the complex characteristics, for example low S/N ratio, low contrast, small size, blurry edge, even flicker, discontinuous image, changeful brightness during the target’s moving. It’s difficult to track the target with high-precision and wellstability. In this paper, a new algorithm searching for the target adaptively was proposed. This method fully uses the correlation of target’s multi-characteristics fusion as criterion and fitness function during searching. Then calculate its
position coordinate using global and adaptive genetic algorithm by searching for it. Experimental results demonstrate that this method improve not only detection precision, but also stability and intelligence strategy in tracking.
An automatic target detection algorithm is developed for infrared image small target in complicate background of sea and sky. Wavelet multiresolution edge detection algorithm is adopted to detect the sea-level line from coarse to fine. A strip can be decided accordingly as the potential area where the naval vessel targets in infrared images usually appear. We realized target detection by defining an energy function that integrated the results of horizontal wavelet transform. We complete the detection by marking the position where the energy is assumed the maximum and improving the target location precision by comparing the dissimilarity between a couple of windows. Experiment results indicate that the method can detect and locate small targets precisely in an infrared image with high detection probability.
Printronix, Inc. uses scanner-based image systems to perform print quality measurements for line-matrix printers.
The size of the image samples and image definition required make commercial scanners convenient to use.
The image processing is relatively well defined, and we are able to simplify many of the calculations into hardware equations and "c" code.
The process of rapidly prototyping the system using DSP based "c" code gets the algorithms well defined early in the development cycle.
Once a working system is defined, the rest of the process involves splitting the task up for the FPGA and the DSP implementation. Deciding which of the two to use, the DSP or the FPGA, is a simple matter of trial benchmarking.
There are two kinds of benchmarking: One for speed, and the other for memory. The more memory intensive algorithms should run in the DSP, and the simple real time tasks can use the FPGA most effectively.
Once the task is split, we can decide which platform the algorithm should be executed. This involves prototyping all the code in the DSP, then timing various blocks of the algorithm.
Slow routines can be optimized using the compiler tools, and if further reduction in time is needed, into tasks that the FPGA can perform.
This paper is a tutorial on factors affecting the detectability and tracking of targets using visible and IR sensor systems. Topics to be addressed are the effects associated with atmospheric attenuation, sensor system parameters, and target characteristics including reflectivity, size and range. Also considered are servo and optical system characteristics and their effects on tracking system performance. This paper complements a paper presented at Acquisition, Tracking and Pointing III, which addressed the performance and design parameters for electro-optical tracking systems.
Many future infantry weapons will incorporate a laser range finder. There is often a requirement to measure the range of small targets at distances of over one kilometre, which means that the necessary pointing accuracy is in the order of milliradians. The weapon is being aimed by a soldier who could be cold, tired and suffering from combat stress. Trials have shown that the stability of a hand held weapon is unlikely to allow an accurate range measurement on small moving targets at long range, using a standard laser range finder. Octec have been investigating the use of a video tracker to control the firing or processing of a laser range finder in an attempt to significantly improve the probability of reporting the correct range. This paper presents the results of trials carried out to measure the drift or 'wobble' of a soldier's aim and goes on to demonstrate how the use of angular information provided by a tracker could help provide an accurate range from small moving targets. The equipment necessary to test a tracker controlled laser range finder in the field will be described as well as the results of simulations indicating an increase in the probability of a correct lase on small, moving targets.