AN INNOVATIVE GUIDENCE SYSTEM TO TRACK AND ATTACK MOVING TARGETS
BESTOWED BY
B.SUBASHRI
PRE Final year CSE
P.PRIYADHARSHINI
Pre-final year CSE
Contact:subashathriya7@ymail.com
ABSTRACT
In this paper, we propose a new missile guidance technique that is an ideal support for surface-to-air and air-to-air cruise missile attack. Our technique exemplifies the usage of real time video camera for target tracking which is once impossible to attain due to the lack of real time video processing techniques. But several advancements have been made in the field of digital video processing that promises to provide reliable support for real time systems. Recent innovation in discovering objects in videos provides solution for unsupervised object discovery which was believed impossible a decade earlier. Our paper focuses narrowly on the way the targets are being identified rather the whole system itself. Though our technique works complimentary to the present guidance systems, it’s possible to use it as a standalone technique under certain threshold conditions which we reveal later.
INTRODUCTION
A Missile is a rocket carrying a warhead of conventional or nuclear explosives; may be ballistic or directed by remote control. A missile is not just a carrier of military warheads but it’s more than that. A missile could be anything from a rock that you pick up off the ground and throw at an enemy, to a spear, an arrow, a bullet, up to a multi-staged rocket carrying multiple MIRV-type nuclear weapons. Basically there are two types of missiles.
• Ballistic Missiles
• Cruise Missiles
A ballistic missile is a missile that follows a sub-orbital ballistic flight path with the objective of delivering a warhead to a predetermined target. The missile is only guided during the relatively brief initial powered phase of flight and its course is subsequently governed by the laws of orbital mechanics and ballistics.
A cruise missile is a guided missile that carries an explosive payload and uses a lifting wing and a propulsion system, usually a jet engine, to allow sustained flight; it is essentially a flying bomb. Cruise missiles are generally designed to carry a large conventional or nuclear warhead many hundreds of miles with high accuracy. Modern cruise missiles can travel at supersonic or high subsonic speeds, are self-navigating, and fly on a non-ballistic very low altitude trajectory in order to avoid radar detection.
Obviously Cruise missiles possess greater power and threat to military and defense attacks. But designing a Cruise missile posts numerous challenges since its being semi-autonomous in various aspects. Especially guidance techniques used differentiates the capability of the missile under concern.
ROLE OF GUIDANCE SYSTEMS IN MISSILES
Missile guidance refers to a variety of methods of guiding a missile or a guided bomb to its intended target. The missile's target accuracy is a critical factor for its effectiveness. Guidance systems improve missile accuracy by improving its "Single Shot Kill Probability" (SSKP).
These guidance technologies can generally be divided up into a number of categories, with the broadest categories being "active," "passive" and "preset" guidance’s. Missiles and guided bombs generally use similar types of guidance system, the difference between the two being that missiles are powered by an onboard engine, whereas guided bombs rely on the speed and height of the launch aircraft for propulsion.
CATEGORIES OF GUIDANCE SYSTEMS
Guidance systems are divided into different categories according to what type of target they are designed for – either fixed targets or moving targets. The weapons can be divided into two broad categories.
• Go-Onto-Target (GOT)
• Go-Onto-Location-in-Space (GOLIS)
A GOT missile can target either a moving or fixed target. The trajectory that a missile takes while attacking a moving target is dependent upon the movement of the target. Also, a moving target can be an immediate threat to the sender of the missile. The target needs to be eliminated in a timely fashion in order to preserve the integrity of the sender.
A GOLIS missile is limited to a stationary or near-stationary target. In GOLIS systems the problem is simpler because the target is not moving.
EXISTING GUIDANCE SYSTEM OVERVIEW
1) BEAM RIDER GUIDANCE
The beam rider concept relies on an external ground- or ship-based radar station that transmits a beam of radar energy towards the target. The surface radar tracks the target and also transmits a guidance beam that adjusts its angle as the target moves across the sky. The missile is launched into this guidance beam and uses it for direction. Scanning systems onboard the missile detects the presence of the beam and determine how close the missile is to the edges of it. This information is used to send command signals to control surfaces to keep the missile within the beam. In this way, the missile "rides" the external radar beam to the target.
2) COMMAND GUIDANCE
Command guidance is similar to beam riding in that the target is tracked by external radar. However, second radar also tracks the missile itself. The tracking data from both radars are fed into a ground based computer that calculates the paths of the two vehicles.
3) HOMING GUIDANCE
Homing guidance is the most common form of guidance used in anti-air missiles today. Three primary forms of guidance fall under the homing guidance umbrella--semi active, active, and passive.
i) SEMI-ACTIVE HOMING GUIDANCE
A semi-active system is similar to command guidance since the missile relies on an external source to illuminate the target. The energy reflected by this target is intercepted by a receiver on the missile. The difference between command guidance and semi-active homing is that the missile has an onboard computer in this case. The computer uses the energy collected by its radar receiver to determine the target's relative trajectory and send correcting commands to control surfaces so that the missile will intercept the target.
ii) ACTIVE HOMING GUIDANCE
Active homing works just like semi-active except that the tracking energy is now both transmitted by and received by the missile itself. No external source is needed. It is for this reason that active homing missiles are often called "fire-and-forget" because the launch aircraft does not need to continue illuminating the target after the missile is launched.
iii) PASSIVE HOMING GUIDANCE
A passive homing system is like active in that the missile is independent of any external guidance system and like semi-active in that it only receives signals and cannot transmit. Passive missiles instead rely on some form of energy that is transmitted by the target and can be tracked by the missile seeker.
iv) RETRANSMISSION HOMING GUIDANCE
A more unusual example of homing guidance is the retransmission method. This technique is largely similar to command guidance but with a unique twist. The target is tracked via an external radar, but the reflected signal is intercepted by a receiver onboard the missile, as in semi-active homing. However, the missile has no onboard computer to process these signals. The signals are instead transmitted back to the launch platform for processing. The subsequent commands are then retransmitted back to the missile so that it can deflect control surfaces to adjust its trajectory.
BEAM RIDER GUIDANCE
COMMAND GUIDANCE
HOMING GUIDANCE
SEMI-ACTIVE HOME GUIDANCE
ACTIVE HOMING GUIDANCE
PASSIVE GUIDANCE
RETRANSMISSION HOMING GUIDANCE
DIFFICULTIES IN SURFACE-TO-AIR AND AIR-TO-AIR MISSILE IMPLEMENTATION
Setting multiple target and simultaneous missile attacks is almost impossible.
Both attacker and target will be in motion.
Possibility of Self-attack.
Probability of success is minimum
PROPOSED SYSTEM
Considering the flaws of the above listed guidance systems we developed yet another missile guidance system that overcomes most of the limitations mentioned.
BRIEF OVERVIEW
Our system makes use of a fully automated high resolution digital camera for the purpose of tracking the target body. The video obtained will be processed to detect the motion of the target. The guidance system will send a hardware trap after finalizing the motion change. The Interrupt is nothing but a command to the guidance computer to turn the missile to respective degree focussing the target. Thus the target body is tracked effectively without any external signalling as well as with full automation. Detailed discussion about the guidance system is as follows.
ARCHITECTURE OF OUR PROPOSED VIDEO GUIDANCE SYSTEM
As shown in the figure, Our Guidance system consists of the following important functional blocks.
• Real-Time Capturing Device
• Location and Scale Estimation
• Motion Modelling
• Guidance Centre
REAL-TIME CAPTURING DEVICE
The missile consists of a high resolution camera that captures the target body with maximum frames per second. As soon as the camera captures the video it immediately split into individual frames for processing. The camera’s zooming power is the critical factor which determines the performance measure in our case. Suitable camera selection solves such a problem.
LOCATION AND SCALE ESTIMATION
After splitting the video into frames the next step is to find a number of patches to generate the visual words. In this paper, we have adapted a robust operator called Maximally Stable Extremal regions (MSER) operator. MSERs are a part of image where the local contrast is high. Features are then extracted from the MSERs by Scale-Invariant feature transform (SIFT). The SIFT descriptor is collected from all the images and are vector quantized using k-means clustering. The resulting cluster centres form the dictionary of visual words. The visual words is represented as w = { w1, w2, w3, ...., wn} , here we take n=50. The visual words are nothing but the Estimates for Location and scale of the desired target object. Note that the acquisition of visual words does not require any labelled data, which shows the unsupervised nature of this system.
calculation. Thus the prediction will be right as long as the target exhibits the constant directional motion. Only if there is a deviation the system’s will go wrong (for only one instance).By the next prediction it will correct the guidance information and send immediately to the guidance computer. A probability data Association problem is there while comparing the predicted and observed results. This PDA problem is solved by using a PDA filter. A PDA filter is a fuzzy logic that calculates correction values to the guidance system.
GUIDANCE CENTRE
Guidance centre is nothing but a computer that includes a fuzzy circuit which selects the missile path according to the predicted and observed values. Suppose if the target’s motion is the same as that of the predicted direction and displacement, the Guidance computer maintains the previous command to the missile tracker. Otherwise, depending upon the displacement, the guidance computer calculates the turning angle and optimal speed to the missile tracker.
HOW TO MAINTAIN THE RELATIVE SIZE OF THE TARGET IN THE CAMERA FRAME?
Let us review the important critical issue in our guidance system i.e How to maintain the optimal size of the target body in our capturing device?
This can be achieved by robustly automating the camera focus handle. Let’s explain the facts using some simulation.
Let,
The camera’s total angle is 360’ (single rotational focuser)
The maximum range of the camera is X km
The feasibility distance be Y m (The distance at which the target relies at the centre)
Current position of the target is Z km
Then,
Focus angle F = {[Z/(X – Y)]*360’}
- if and if only Z
The distance between the target and the missile can be easily achieved by Doppler Effect of stationary waves.
WORKING SCENARIO OF OUR PROPOSED SYSTEM:
Let’s simulate the working scenario of our proposed system. Consider a Target T is in motion and assume we need perform a surface-to-air attack. Initially the camera is controlled by a ground system that contains radar for initially locating the target. Once the missile’s camera is able to capture the target, it sends a trap to the ground controller. Now the Ground controller will issue a launch of the missile. The missile, with its onboard camera predicts and approaches the target. Once the target is liable to be attacked, the missile fires.
The following diagrams show how the frames after extraction being processed and the missiles intelligence in deciding the targets path.
We simulate the tracking functionality of our system using some snapshots from the camera virtually. We have taken a case where the camera’s angle is limited to 8 angles namely North, South, West, East, Northeast, Northwest, Southeast, and Southwest.
FRAME 1
Let the camera has been initialized to focus the target body at the centre of the frame position. This can be done before missile launch using a ground radar station.
FRAME 2
Let the target moves along Northeast direction (45*).
FRAME 3
Now our Guidance system compares the 1st and the current (2nd) frame and predicts the direction and velocity model of the moving target. Then it will give instruction about the direction and angle to which the camera should be turned. Note that the camera performs a ‘Double jump’ in order to capture the target at its centre. Meanwhile it calculates the next move using the PDA (predictive filter).
FRAME 4
The missile’s prediction is correct and hence it needs no correction thereby it predicts for the next position in the same manner. Assume that the target deviates from the predicted position by an angle x*.
FRAME 5
Now the System’s prediction is obviously wrong. The centre part of our frame corresponds to a wrong position since the target deviates. Hence a correction is needed to be done in the inputs. This is done by the correction filter in the diagram shown earlier.
FRAME 6
Now the System performs a correction over its prediction parameters (i.e) in terms of angle and in terms of velocity model. Now the guidance system again issues a ‘double jump’ in order to track the current position of the target at the centre.
ADVANTAGES OF OUR PROPOSED SYSTEM
Cost effective
Reliable performance
Implementation complexity is being reduced
Robust
Scalable
OTHER RELATIVE APPLICATIONS OF OUR PROPOSED SYSTEM
This Video object discovery technique can be applied to variety of fields even though the breakthrough application will be on Defence purpose. Some of them are….
a. High Level Video Content analysis
i. Content based Multimedia Search
ii. Automated High level video editing technology
iii. Forensic video analysis systems
b. Fully automated Cricket Cameras
c. Spatial data mining
CONCLUSION
We presented a new innovative guidance system for cruise missiles. We justified that our system increases performance and robustness when used as a complementary with the existing guidance systems. Also we proved that our approach can be operated standalone at certain instances without compromising the performance metrics. With the innovation in camera techniques and video object discovery techniques, our system will also evolve. It’s not our aim to increase violation by increasing ballistic weapons, but, our current scenario demands great advancements in Military and defence area to meet the challenges that are upcoming from terrorist attacks and other countries.
REFERENCES
1. “Missile Survey: Ballistic and Cruise Missiles” by Andrew Feickert, CSS report, 2007
2. “Multimedia Image and Video Processing” by Ling Guan, Sun-Yuan kung, 2001
3. “DISCOV: A Framework for discovering objects in videos” by David Liu and Tsuhan Chen, IEEE transactions on Multimedia, feb-2008
4. “Video retrieval based on Object discovery” by David Liu and Tsuhan Chen, Science direct, 2007
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