Abstract:
A system for controlling activation of a payload, particularly a high value, high consequence payload, such as a weapon of mass destruction, cannot be activated until it confirms that it has arrived at the correct destination. The system stores information that sufficiently identifies the location where the system should be activated or detonated. Sensors identify characteristics of the current location of the payload. A correlation is performed between the measured characteristics of the current location and the information stored that identifies the desired activation location. When the information sufficiently correlates, the system is allowed to activate.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS  
       [0001] This invention was made with Government support under government contract no. DE-AC04-94AL85000 awarded by the U.S. Department of Energy to Sandia Corporation. The Government has certain rights in the invention, including a paid-up license and the right, in limited circumstances, to require the owner of any patent issuing in this invention to license others on reasonable terms. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    Devices exist which are deployed from a first location and are activated at a second location. Systems with payloads delivered by air, such as launched weapons systems, provide one example of such types of systems. Other examples of systems which are designed to be delivered to a remote location and exploded could include devices used in mining operations. Weather and climate sensing systems and other remote exploration systems, which upon arrival at a predetermined location deploy assets such as scientific instruments, provide another example of systems deployed from a first location and activated at a second location. Similarly, surveillance equipment could be deployed from a first location and activated at a remote location. Malfunctions in delivery apparatus or guidance systems for such delivery apparatus can result in assets being deployed, activated or detonated at inopportune times or locations. For example, a surveillance device which begins to transmit information after being delivered to the wrong location could expose itself to detection and capture. A weapons device which detonates when delivered to the wrong location could harm innocent third parties or destroy friendly assets. If the weapon is one of mass destruction, such as a nuclear weapon, the consequences could be catastrophic. Even exploration or scientific monitoring could be wasted and destroyed if deployed in an improper environment.  
         SUMMARY OF THE INVENTION  
         [0003]    In view of the above characteristics of such devices, it is an object of the invention to provide a system and method for determining that an asset has arrived at its destination before the asset is activated, detonated or otherwise deployed. According to the invention a system for controlling activation of a device at a remote location comprises a memory location for storing a representation of externally generated intent to deploy information and a memory location for storing within said device information identifying an activation location. The system also has a location sensing system that generates information concerning the location of the device. The location system may include any suitable location detection system and corresponding sensors. By way of example and not limitation, the location sensing system could be one or more of a radar fuze system, a global positioning system receiver, an inertial navigation system or a target imaging system. Indeed, a system according to the invention can be made more robust and effective by combining several such systems and correlating their results before activating a device or weapon. A system according to the invention would also include a processor within the device to process the location information to determine the current location of the device. The processor correlates the current location of said device with the information identifying the activation location to determine whether they correlate. The processor also commands activation of said device when the correlation indicates that the device is present at the activation location. Those of ordinary skill will recognize that the processor and the memories that perform the functions disclosed herein could be one or more conventional memories and processors responsive to stored program indicia of any type, including software and hardware driven systems, hard wired logic, data processing and other computational devices, random access and read only memories and other memory and computational devices of any form, including mechanical and electronic forms. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]    The above and other features of the invention are described herein with reference to the figures in which:  
         [0005]    [0005]FIG. 1 is a functional diagram of a conventional safety system used, for example, to control detonation of a nuclear weapon;  
         [0006]    [0006]FIG. 2 is a functional block diagram of a system according to the invention;  
         [0007]    [0007]FIG. 3 is a flow diagram illustrating the steps performed according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0008]    Preventing detonation of a weapon, particularly a weapon of mass destruction, at a location other than its target illustrates the features of the invention and will be used as an example to describe these inventive features. Those of ordinary skill will recognize that the invention has application to any system which requires that a device be deployed from a first location and activated at a target location.  
         [0009]    By way of example, location enablement according to the invention prevents detonation of a weapon system if that weapons system fails to reach its intended target. Conventional and nuclear weapons, while the subject of several procedures and technical safeguards against inadvertent detonation, do not verify that they are in the correct location prior to detonation. Location enablement according to the invention uses navigation and/or imaging technologies to preclude detonation until the weapon system is at the target. In this way, location enablement according to the invention also allows discriminating between inadvertent and commanded launch.  
         [0010]    Conventional nuclear safety systems rely on isolation, incompatibility, inoperability and independence to prevent inadvertent detonation. The critical components for nuclear detonation are isolated from their surroundings by placing them in an energy barrier, which forms an enclosed exclusion region. To initiate detonation, energy is permitted to enter the exclusion region by opening a shutter. A stronglink, which operates under extreme environmental conditions, is a mechanical or electromechanical device that allows the shutter to open upon receipt of a correct signal. The stronglink provides a lock whose combination is based on a complex pattern of binary signals, such that detection of only the correct pattern of binary signals allows the shutter to open. Since the binary pattern is designed to be incompatible with naturally occurring signals, such signals are known as “unique” signals. Two stronglinks in series are typically employed in each weapon, with each stronglink using different patterns in order to be independent. One stronglink is known as the intent stronglink, the other is a trajectory stronglink.  
         [0011]    Conventional weapons systems also include “weaklinks” which provide functions required to make a weapon operate and which fail at relatively less extreme environment conditions, such that a weapon is rendered inoperable under such conditions. In this way, even if the strong link fails, the redundant failure of the weaklink prevents detonation.  
         [0012]    [0012]FIG. 1 functionally illustrates such a system. Those of ordinary skill will recognize that FIG. 1 illustrates one possible implementation of a nuclear weapon device. However, similar devices could be constructed in other configurations. Devices with other purposes also have applicability to the invention disclosed herein, such that the invention is not limited to nuclear weapons applications, but has broad applicability to systems which must be deployed from a first location and activated at a second remote location. In FIG. 1, a stronglink  101  has a prime mover or energy transducer, such as a solenoid  103 , which converts electrical pulses in a unique signal  105  into mechanical motion. The solenoid  103  creates discrete motion in the same pattern as that in the unique signal  105  and is tied to discriminator  107 . The unique signal is embedded in the discriminator, for example, as notches on a pattern wheel. The stronglink remains locked until it has received and processed the entire unique signal. If one of the instructions received by the discriminator is not correct, the discriminator locks permanently and disables the weapon until it is dismantled. If all the instructions are correct, i.e. correspond to the pattern built into the discriminator, the discriminator  107  can form one portion of the signal required to allow the energy coupling element  109  or shutter to be moved from a position blocking energy from source  111  entering critical component enclosure  113  into a second position where the energy from source  111  can enter the enclosure  113  and the weapon can be activated.  
         [0013]    The intent unique signal  105  for the stronglink cannot be stored in the weapon and must be entered by a person. Essentially this is an enabling code from an operator, such as a pilot or other authorized weapons deployment specialist that indicates a positive intent to use the weapon. Another element required for detonation is the trajectory stronglink, also shown in FIG. 1. A trajectory sensing signal generator uses the intent unique signal  105  and signals from environmental sensors to develop a trajectory unique signal (TUQS)  117  which drives solenoid  119  and discriminator  121  in a manner similar to that previously discussed herein. The signals from both stronglinks, as functionally indicated in FIG. 1 by AND functional block  123  are required to move coupling element  109  from the weapon inactive to the weapon active position. The trajectory sensing signal generator determines that the weapon has been launched and is on a trajectory, but cannot determine if a weapon is at the desired target location. Thus, there is a risk that a device which fails to arrive at the desired location may be detonated or activated.  
         [0014]    A system according the invention provides location enablement and is shown in FIG. 2. The system according to the invention can be used in place of the conventional systems, such as shown in FIG. 1, or to supplement such conventional systems to provide more robust performance of such systems. In another embodiment, a location enablement system according to the invention can replace a trajectory signal sensing generator  115  as discussed above or to control a corresponding stronglink and be used with an intent stronglink system. Such a stronglink would otherwise operate as disclosed in FIG. 1 upon receipt of the activation signal, UQS, as discussed below, which would replace the signal TQUS.  
         [0015]    A system according to the invention uses navigation and/or imaging or other location specific information to generate a location unique signal (UQS) in the vicinity of the target. A successful correlation with the location specific information delivered as part of a device authorization message results in enablement of the device. An unsuccessful correlation precludes device enablement.  
         [0016]    As shown in FIG. 2, a system according to the invention has a location sensing signal generator  200  which receives an authorization message on line  201 . The authorization message includes target identification information. Target identification information could be in the form of geographic characteristics of the target, such a building heights and locations, mountains, rivers, lakes, and other identifiable location criteria. Target information in the authorization message could also be in the form of map coordinates or a place name. In this case, pertinent characteristics of the target can be retrieved from a database. Location sensing signal generator  200  has a location extraction function  203  to extract the pertinent target information. This target information from location extractor  203  is provided to a correlator  205 . Those of ordinary skill will recognize that the pertinent target information is a function of the location sensors  207  available on the device, which provide forms of location information to location sensing signal generator  200 . For example, where the location sensors  207  generate image data, the location extractor will provide target image data to correlator  205 . As noted above, this image data may be provided to location extractor  203  directly in the authorization message or the authorization message may, instead, identify the target with the location extractor retrieving the target image data from a database. Where the location sensing device  207  is a global positioning system (GPS) receiver, the location extractor  203  provides the correlator  205  with GPS compatible information.  
         [0017]    Correlator  205  correlates the target information with the information from the location sensing devices  207 . The location information can be of relatively coarse quality and need not be of targeting grade resolution. The information need only be of sufficient quality to determine that the device or weapon is at the target. Since it is only necessary to perform a correlation sufficient to determine that the device is at the target within a specified tolerance range, it is only necessary to process a sufficient number of parameters to a sufficient accuracy to determine within a defined degree of certainty that the device is at the target. For example, if the target has one or two notable features that cannot be mistaken, it is sufficient to examine parameters that indicate the presence of those particular features. If the target has few defined features, it may be necessary to process the sensor information to a higher degree of accuracy to achieve the desired level of certainty that the device is at the target. In addition, where one form of sensor information is relatively uncertain or cannot lead to a substantially certain correlation, it may be useful to use a second or third type of sensor data to support the correlation conclusion reached based on one set of sensors.  
         [0018]    The invention is not limited by the types of information that can be used to achieve the correlation. However, certain systems are known to provide data that can be used alone or in combination with other data to provide correlation.  
         [0019]    A radar fuze system provides distance to ground information as the device or weapon approaches the target. Distance to ground information is predictable, assuming that terrain features along the flight path are known. A correlation between the profile generated by the radar fuze and the profile indicated in the authorization message could produce the required activation signal.  
         [0020]    The global positioning system (GPS) can provide location accuracy to less than ten meters. GPS location correlation with the location indicated by the authorization message would produce an activation signal required for enablement of the device.  
         [0021]    A target image, such as a visual system or a synthetic aperture radar system can be used to generate a image of the target vicinity. Correlating this image with an image map of the location indicated in the authorization message could also produce the signal required for enablement of the device.  
         [0022]    Another alternative is an inertial navigation system. The accuracy of this information is a function of the time since the last update and the drift rate of the inertial navigation system. For short flight times, the accuracy may be sufficient to correlate with the location information in the authorization message to produce the necessary activation signal.  
         [0023]    Upon making the determination that the correlation between the location information derived according to the authorization message and the measured data from the sensors is sufficient, the correlator can produce a signal that will allow the device to be activated, provided other relevant system conditions are met.  
         [0024]    [0024]FIG. 3 illustrates steps in a method according to the invention. In step  301  an authorization message is read, for example by a processor. The processor next extracts the target location information in step  302 . As noted above, the approach to extracting the target location information can vary depending on the content of the authorization message. For example, the authorization message could provide target characteristic information directly or the authorization could provide information, such a map coordinates, that the processor uses to access a database of location specific information that is compatible with the sensing capabilities of the device. At step  303 , the processor determines if the target identified is a valid target. The system may be programmed so that only valid coordinates can be specified or so that certain geographic areas are excluded. For example, as an added safety measure, a weapon system could be programmed not to treat a populated mainland U.S. target as a valid target. In this case, the system will again read the authorization message and follow a protocol designed for such circumstances without proceeding to complete the activation sequence.  
         [0025]    In step  304 , the processor reads data acquired in flight from the on board sensors and subsystems that provide current location information. At step  305 , the processor tests whether the device is approaching its target. If not, it returns control to step  304  and continues to read data. When the device is in the vicinity of the target, or other data, such as flight time, indicates that the device should be in the vicinity of the target, control passes to step  306  where the correlation takes place. In step  306 , the processor correlates the current location information received from the sensors with the expected location information derived from the location information in the authorization message. As previously indicated, the information need not be targeting quality information and may be relatively coarse, provided that the correlation is sufficient to indicate with a desired level of confidence that the device is at its target. If such a correlation is not achieved at step  307  control passes to step  308  where the device is disabled. If the correlation determines that the system is at its target location and can be activated, at step  307  control passes to step  309  to generate the activation signal required for the system in use.  
         [0026]    Those of ordinary skill will recognize that the correlation can be performed using conventional correlation techniques that are appropriate for the type of data sensed and the accuracy desired. The invention is not dependent on the selection of the correlation technique. Furthermore, the target location which is the subject of the correlation may be at any scale suitable for the application. Therefore, the correlation can be made to a highly specific location, such as geographic coordinates or a street corner, or may be to made to a much larger recognizable area, including a geographic region, a county, a country, a continent or other suitable landmark without limitation. In addition, the target location which is the subject of the correlation may instead be defined as a set of points along a path, such that the correlation may be made to determine that the device has traveled along a specified path from a source to arrive at a desired destination. For example, a correlation may be made at specific points along the path to determine that the device is still on track. In the event that the device is not on track, as determined by an inadequate correlation at one or more points, an attempt can be made to bring the device back to a correct path to arrive at the desired destination or the device can be disabled, so that it does not deploy or detonate at an incorrect location. For example, the processor of the device can be programmed to recognize from the correlation error the nature of the error and attempt to issue commands to redirect the device to the target.  
         [0027]    A system according to the invention can be implemented using one or more processors to extract the location information, perform the correlation and generate the device activation signals. Such processors may include semiconductor or optical processors which are responsive to stored programs indicia. However, those of ordinary skill will recognize that the correlator and other devices discussed herein are conventional in nature and can be implemented in hardware, software or combinations of hardware and software. Moreover, the implementation of the invention disclosed herein is not limited to electronic or semiconductor applications, as the invention can be implemented with mechanical or other types of memories and processors as are suited to the operational environment. For example, a program to operate a mechanical processor, such as a discriminator can be implemented as a sequence of positions on a rotary dial. Thus those of ordinary skill will recognize that as used herein the terms memory, processor and stored indicia have broad meaning and do not restrict the scope of the invention.  
         [0028]    Those of ordinary skill will also recognize that the weapons systems discussed herein are by way of example and not limitation. The system according to the invention can be applied in numerous application where a device is deployed from a first location and activated later at a second, remote location. Thus, the invention also has applications in such diverse fields as mining, exploration and other endeavors.  
         [0029]    While embodiments of the invention have been described modifications of the described embodiments may become apparent to those of ordinary skill in the art following the teachings of the invention, without departing from the scope of the invention as set forth in the appended claims.