Patent Application
20190056201
The present disclosure relates to precision guidance and more particularly to using digital light processing (DLP) in a precision guidance system.
There are a number of guidance systems that aid in the accurate delivery of an air-borne device to its target. Certain airborne devices, such as drones, can carry extensive and expensive hardware and software to allow the delivery and return of the drone. These devices tend to leverage global positioning system (GPS) information for location, routing and accurate delivery. Other air-borne devices such as missiles, rockets and other precision guided munitions tend to travel at high speeds and have weight, space and cost constraints. Such devices have particular characteristics for accuracy and proper deployment. These may also operate in hostile environments such as GPS-denied areas and be subject to jamming. Despite the adversity, it is desired to have the air-borne device accurately arrive at the target destination.
Some conventional guidance systems comprise beam riders. These beam rider systems rely on a scanning laser to generate a digital pattern in which the air-borne device, such as a precision guided munition, decodes the pattern and then determines its location within the pattern. It can then use that information to aid in reaching the target destination. These scanners tend to have moving parts and tend to be costly. Additionally, these conventional systems consume bandwidth due to the need to scan, thereby increasing latency and reducing bandwidth.
Wherefore it is an object of the present disclosure to overcome the above-mentioned shortcomings and drawbacks associated with the conventional guidance systems. These aspects of the disclosure are not meant to be exclusive and other features, aspects, and advantages of the present disclosure will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description and accompanying drawings.
One aspect of the present disclosure is a digital light processing guided system comprising a laser source configured to generate a plurality of pulsed signals comprising pulse repetition interval information; a controller configured to guide a munition using the plurality of pulsed signals comprising pulse repetition interval information; a retro reflector located on the munition; and a laser range finder comprising a digital light processing mirror array configured to detect the plurality of pulsed signals returned by the retroreflector.
One embodiment of the digital light processing guided system is wherein the laser source is a 1.57 μm micro laser. In some cases a portion of the plurality of pulsed signals indicate elevation and azimuth information. In certain embodiments, the azimuth and elevation information are coded separately.
Another embodiment of the digital light processing guided system is wherein the laser range finder comprises an avalanche photodiode.
Another aspect of the present disclosure is a digital light processing method of guiding a munition comprising generating, with a laser source, a plurality of pulsed signals comprising pulse repetition interval information; guiding a munition, with a controller using pulse repetition interval information in the plurality of pulsed signals; and detecting, with a laser range finder comprising a digital light processing mirror array, the plurality of pulsed signals returned by a retroreflector located on the munition.
One embodiment of the digital light processing method is wherein the laser source is a 1.57 μm micro laser. In some cases a portion of the plurality of pulsed signals indicate elevation and azimuth information. In certain embodiments, the azimuth and elevation information are coded separately.
Another embodiment of the digital light processing method is wherein the laser range finder comprises an avalanche photodiode.
These aspects of the disclosure are not meant to be exclusive and other features, aspects, and advantages of the present disclosure will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description, appended claims, and accompanying drawings.
The foregoing and other objects, features, and advantages of the disclosure will be apparent from the following description of particular embodiments of the disclosure, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure.
According to some embodiments, the present system provides the ability to track in-coming threats in a small form factor. By using a digital light processing (DLP) mirror array at the laser source, the control receiver tracks location of the air-borne device such as a munition using a retro reflector on a pulse-to-pulse basis. The DLP tracks the munition with a non-scanning beam and immediately provides a correction update to the airborne device using a pulse repetition interval (PRI) varying code.
The seeker and beam riding laser architecture can be packaged in a small format, at a lower cost, and with a higher reliability. There are no moving parts other than the micro mirrors in the array. The cost of the DLP scanner is reduced considerably and in one example can be packaged in about 2 in3.
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The encoded laser signal 7 from the laser 2 is directed to the air-borne device 8, wherein the air-borne device 8 includes a retro reflector (not shown) that reflects a portion of the inbound encoded laser signal 7 and provides a reflected encoded laser signal 7′. The reflected encoded laser signal 7′ is picked up by the control receiver 1. The control receiver 1 receives the reflected laser signal 7′ and it is processed by a digital laser processing (DLP) unit 4. While not shown, in one embodiment further optical elements are on the front end of the control receiver 1 to focus the reflected laser signal 7′. The DLP unit 4 in one example has micromirrors coupled to a semiconductor and forming a digital micromirror device (DMD) that processes the digital optical signals thru the DLP spatial filter represented by
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By using a polarized light source and a polarizer on the air-borne device (not shown) also referred to as a seeker that receives a portion of the reflected signal 7′ and is able to provide a vertical reference of air-borne device 8. In some cases, the air-borne receiver uses two PIN detectors, one polarized (orientation signal) and one non-polarized (reference) to establish the vertical reference. In one example the PIN detectors are InGaAs avalanche photodiodes (APD), or the like.
The air-borne device 8 includes an air-borne receiver that converts the received pulsed signal into a digital signal that aids in guiding the air-borne device to the target. One example is a rocket or rocket propelled grenade where the guidance system tracks the path of the rocket and provides correction information to the rocket in the pulsed signal that is processed on-board the rocket.
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First, a wide area 16 is used to ensure capture for the offset control from the launch point. Next, a reduced area 18 ensures a correct flight path. A tighter area 20 ensures a hit on the target 22. There can be any number of reduced areas while the air-borne device travels to the target depending upon factors such as speed, distance, and communications capabilities. In some cases, the flight controller knows the initial flight path, but correction is typically still needed for precision targeting. The system provides proper reduction to the error zones using known time and range information from the built in LRF on the control device. In
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The system bandwidth of the present disclosure in one embodiment approaches 300 Hz. In certain embodiments, the system is from about 20 Hz to about 30 Hz. The seeker utilizes a pair of PIN detectors for measuring time interval pulses and amplitude as the weapon is spinning. The spinning induces a modulation on detector 36. Detector 34 generates a received reference signal level that compensates for atmospherics amplitude variation due to scintillation (e.g., 10 to 500%). The shallow response from the offset FOV is pointing away from the ground where the laser is located thus determining upward direction.
In one embodiment of the system, a 3000 RPM spin rate results in a 50 Hz spin rate or a 18000 degrees per second rate for the spinning munition. At 3 KHz, that is a 6.0 degree rotation per pulse. With a 1 second launch profile, the system establishes up and down reference to the pulse code and a vertical reference is tracked as part of the PRI variability. With four pulse groupings, the four pulses measure a 24 degree arc swing/coupled with low cost inertia measurement unit (IMU) to establish PRI tracking and control either with an Az/E1 or LOS vector in <0.05 seconds. Variability in PRI provides commands, and with 5 groupings the vectors are determined assuming a 100 Hz update rate for each vector provides 20 data points, sufficient to determine orientation.
It will be appreciated from the above that the invention may be implemented, in part, as computer software, which may be supplied on a storage medium or via a transmission medium such as a local-area network or a wide-area network, such as the Internet. It is to be further understood that, because some of the constituent system components and method steps depicted in the accompanying Figures can be implemented in software, the actual connections between the systems components (or the process steps) may differ depending upon the manner in which the present invention is programmed. Given the teachings of the present invention provided herein, one of ordinary skill in the related art will be able to contemplate these and similar implementations or configurations of the present invention.
It is to be understood that the present invention can be implemented in various forms of hardware, software, firmware, special purpose processes, or a combination thereof. In one embodiment, the present invention can be implemented in software as an application program tangible embodied on a computer readable program storage device. The application program can be uploaded to, and executed by, a machine comprising any suitable architecture.
While various embodiments of the present invention have been described in detail, it is apparent that various modifications and alterations of those embodiments will occur to and be readily apparent to those skilled in the art. However, it is to be expressly understood that such modifications and alterations are within the scope and spirit of the present invention, as set forth in the appended claims. Further, the invention(s) described herein is capable of other embodiments and of being practiced or of being carried out in various other related ways. In addition, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items while only the terms “consisting of” and “consisting only of” are to be construed in a limitative sense.
The foregoing description of the embodiments of the present disclosure has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure to the precise form disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the present disclosure be limited not by this detailed description, but rather by the claims appended hereto.
A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the scope of the disclosure. Although operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.
While the principles of the disclosure have been described herein, it is to be understood by those skilled in the art that this description is made only by way of example and not as a limitation as to the scope of the disclosure. Other embodiments are contemplated within the scope of the present disclosure in addition to the exemplary embodiments shown and described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present disclosure.
