Patent Publication Number: US-6666123-B1

Title: Method and apparatus for energy and data retention in a guided projectile

Description:
TECHNICAL FIELD 
     The present invention pertains to energy and data transfer, and in one embodiment, the present invention pertains to energy and mission data retention in guided weapons. 
     BACKGROUND 
     Guided projectiles, including fuses, missiles and other weapons, generally need to be activated quickly. Conventional guided projectiles use a data interface to download mission data prior to launch and deployment. The mission data may include navigation data as well as initialization data for use by the projectile&#39;s Global Positioning System (GPS). The data may be downloaded quickly in order to launch projectiles at a rapid rate. Circuitry on the guided projectile is conventionally connected to a data-hold battery. The data-hold battery supplies power to the GPS circuitry and other circuitry prior to and during an initial portion of the projectile&#39;s deployment. The data-hold battery may be a chemical battery designed for a one-time initiation and may be ignited after mission data transfer by mixing or combining chemicals. Chemically ignited data-hold batteries may be dormant until activated allowing for a longer shelf life. 
     One disadvantage with the use of data-hold batteries is that they require the projectile be deployed relatively soon after the mission data has been transferred. One reason for this is that data-hold batteries generally do not allow for recharging without degradation in performance. For example, in some combat situations, a data-hold battery may be required to hold the mission data and power the GPS circuitry for many days on one charge. If the projectile is not deployed within a certain time frame, the data-hold battery must be replaced and the mission data may have to be transferred again to the projectile. 
     Another disadvantage with the use of data-hold batteries in guided projectiles is safety. A chemically ignited data-hold battery requires the combining and/or mixing of typically hazardous chemicals. Another disadvantage with the use of data-hold batteries is their high-cost. 
     Thus there is general need for improved method and apparatus for energy storage and data retention suitable for use in guided projectiles. There is also a need for a system and method for energy storage and data retention that permits recharging without performance degradation. There is also a need for a system and method for energy storage and data retention suitable for use in a guided projectile that does not require replacement of a data-hold battery when the projectile is not deployed within a certain time frame. There is also a need for a system and method for energy storage and data retention that does not use a data-hold battery. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The appended claims point out different embodiments of the invention with particularity. However, the detailed description presents a more complete understanding of the present invention when considered in connection with the figures, wherein like reference numbers refer to similar items throughout the figures and: 
     FIG. 1 is a functional block diagram of a system for transferring energy and mission data in accordance with an embodiment of the present invention; 
     FIG. 2 illustrates an example projectile setter and portion of a guided projectile in accordance with an embodiment of the present invention; 
     FIG. 3 is a functional block diagram of projectile circuitry in accordance with an embodiment of the present invention; and 
     FIG. 4 is a flow chart of a data and energy transfer procedure in accordance with an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     The following description and the drawings illustrate specific embodiments of the invention sufficiently to enable those skilled in the art to practice it. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in or substituted for those of others. The scope of the invention encompasses the full ambit of the claims and all available equivalents. 
     In one embodiment, the present invention provides an apparatus to retain energy and data in a guided projectile. In this embodiment, energy and mission data for the guided projectile are transferred from a projectile setter over an inductive interface. The projectile may include a capacitive energy storage element to store the energy and a data storage element to store the mission data. Precision GPS clock circuitry of the projectile may receive power from the capacitive energy storage element during projectile loading and launching operations until a flight battery is activated. In one embodiment, the capacitive energy storage element includes at least one super capacitor and a second capacitor, which may be a gun-hardened capacitor. The clock circuitry may receive power from the gun-hardened capacitor if the super capacitor fails during the launching operation. The capacitive energy storage element may include one-way energy transfer elements coupled between the super capacitor and the gun-hardened capacitor to help prevent discharge of the gun-hardened capacitor into the super capacitor, which may be damaged by the launch environment. A regulator may be coupled to an output of the capacitive storage element to regulate an output voltage. 
     In another embodiment, the present invention provides a method for storing energy and data. The method may include receiving energy and data over an interface, charging a capacitive storage element with the received energy, and storing the received data in a data storage element. The energy may be provided to clock circuitry until another energy source is activated. In one embodiment, the energy and data may be received over an inductive interface of a guided projectile. In this embodiment, the data may be mission data for the guided projectile and the other energy source may include a flight battery of the guided projectile. The receiving, charging and storing may be performed during projectile setting operations, and the energy may be provided to precision GPS clock circuitry subsequent to the projectile setting operations and during loading and launching operations of the guided projectile. In this embodiment, the capacitive storage element may comprise a super capacitor and a secondary capacitor. Energy stored in the secondary capacitor may be provided to the clock circuitry if the super capacitor fails during the launching operation. 
     FIG. 1 is a functional block diagram of a system for transferring energy and mission data in accordance with an embodiment of the present invention. System  100  may be used to transfer data and/or energy to an apparatus, such as a guided projectile. Guided projectiles include, for example, fuses, missiles and other guided weapons, which may be configured to use mission data. System  100  may include setter circuitry  102 , interface  104  and projectile circuitry  106 . Setter circuitry  102  may transfer mission data  108  and energy  110  to interface  104 . Projectile circuitry  106  receives the mission data and/or energy from interface  104  and may store the mission data in data storage element  112  and the energy in energy storage element  114 . Energy in energy storage element  114  may provide power to load  116  until another power source becomes available. In one embodiment, energy from energy storage element  114  may also provide power to data storage element  112  for data retention until another power source becomes available. 
     Setter circuitry  102  may include other functional elements (not illustrated) to configure the data and energy for transfer across interface  104 , depending on whether interface  104  is a mechanical-type interface or, for example, an inductive interface. In the case of an inductive interface, setter circuitry  102  may include functional elements to convert energy  110 , for example, to an alternating current waveform. Setter circuitry  102  may also include functional elements to modulate data  108  on the waveform. 
     In a guided projectile embodiment of the present invention, mission data  108  may include GPS information and navigational information, and load  116  may include a precision clock, such as a GPS clock or precision oscillator. In this embodiment, energy in energy storage element  114  provides power to load  116  until a flight energy source, such as a flight battery becomes available shortly after deployment of the projectile. 
     Interface  104  may be a connector-less interface, such as inductive interface  118 , comprised of one or more sets of windings on the projectile setter and one or more sets of windings on the projectile. Data and energy may be transferred from the one or more sets of windings of the projectile setter to the one or more sets of windings of the projectile during projectile setting operations when, for example, the projectile setter is brought in close proximity to the projectile. Alternatively, interface  104  may be an electrical or mechanical interface comprising one or more mechanical and/or electrical connectors. 
     Although interface  104  is illustrated as a separate functional element from setter circuitry  102  and projectile circuitry  106 , a first portion of interface  104  may be fabricated as part of a projectile setter, while a second portion of interface may be fabricated as part of the projectile. In the case of an inductive interface, the first portion may include, for example, first sets of windings and a magnetic core located on the projectile setter, and the second portion may include, for example, second sets of windings and a magnetic core located on the projectile. 
     FIG. 2 illustrates an example projectile setter and portion of a guided projectile in accordance with an embodiment of the present invention. Projectile setter  202  and projectile portion  204  may form connector-less interface  200  across which data and/or energy may be transferred. Connector-less interface  200  is one example of an inductive interface suitable for use as interface  118  (FIG.  1 ), although other interfaces are also suitable. Connector-less interface  200  may be comprised of one or more sets of windings  206  on projectile portion  204  and one or more sets of windings  208  in projectile setter  202 . Windings  206  may be wound directly on magnetic cores  210  which may be separated by spacer  212 . Windings  208  of setter  202 , similarly, may be wound on magnetic cores (not illustrated). During energy and data transfer operations, projectile portion  204  may be inserted, or disposed, into setter  202  to form a transformer allowing the transfer of energy and data. One suitable inductive interface may be found in U.S. Pat. No. 6,268,785, which is incorporated herein by reference. 
     FIG. 3 is a functional block diagram of projectile circuitry in accordance with an embodiment of the present invention. Projectile circuitry  300  may be suitable for use as projectile circuitry  106  (FIG. 1) although other circuitry is also suitable. Projectile circuitry  300  may include rectifier  302  to rectify a waveform received from an interface, such as interface  104  (FIG.  1 ), and capacitive storage element  304  to store energy extracted from the rectified waveform. Projectile circuitry  300  may also include data extractor  306  to extract data from a waveform received from an interface, such as interface  104  (FIG.  1 ), and data storage element  308  to store the extracted data. Regulator  310  may regulate the voltage of the waveform for data extractor  306 . 
     Data storage element  308  may be correspond with data storage element  112  (FIG.  1 ). Data storage element  308  may be comprised of volatile and/or non-volatile semiconductor memory devices, as well as other elements suitable for storage of digital information including, for example, magnetic memory and magnetic storage elements. 
     Capacitive energy storage element  304  may be suitable for use as energy storage element  114  (FIG. 1) although other energy storage elements are also suitable. Capacitive storage element  304  may provide an output voltage through regulator  312  for circuitry  316 . Circuitry  316  may include precision clock and/or oscillator circuitry including, for example, a GPS time-synchronization clock. In one embodiment, regulator  312  may provide power to data storage element  308  for use in retaining stored data. For example, when data storage element  308  includes volatile memory, regulator  312  may provide a voltage to element  308 . In one embodiment, capacitive storage element  304  may replace a data-hold battery conventionally used in guided projectiles. 
     In one embodiment of the present invention, data received over an interface may include mission data for use by a guided projectile. In this embodiment, energy and data may be transferred very rapidly over the interface. Capacitive energy storage element  304  may be charged rapidly and the mission data may be stored in data storage element  308  during projectile setting operations. During projectile setting operations, power may be supplied to elements of projectile circuitry  300  including guidance electronics  318 . After projection setting operations and during firing, capacitive energy storage element  304  may provide power to precision clock circuitry  316  until chemical energy storage element  320  is activated after launch. Chemical energy storage element  320  may be a flight battery for use in powering guidance electronics  318  and precision clock  316 , among other things, during projectile deployment. In one embodiment, the flight battery may be chemically ignited during launch. A controller (not illustrated) may control the operations of the various functional elements of projectile circuitry  300 . 
     Capacitive energy storage element  304  may include primary capacitive energy storage elements, such as at least one super capacitor  322  for storing energy received from rectifier  302 . In one embodiment, capacitive energy storage element  304  may include a backup-energy storage element, such as gun-hardened capacitor (GHC)  324 , and one-way energy transfer elements  326  between super capacitor  322  and gun-hardened capacitor  324 . Gun-hardened capacitor  324  may be a tantalum capacitor or surface mount capacitor, for example that may be gun hardened. One-way energy transfer elements  326  may be diodes. Gun-hardened capacitor  324  may serve as a back up energy storage element and in one embodiment, clock circuitry  316  may receive energy from gun-hardened capacitor  324  if super capacitor  322  fails during projectile launching (e.g., in the event super capacitor  322  may not be “gun hardened”). Capacitive energy storage element  304  may include other functional elements (not illustrated) to allow for charging energy storage elements  322  and  324  with a rectified waveform received from rectifier  302 . 
     In one embodiment, regulator  312  may be a boost-type voltage regulator that provides an input voltage to circuitry  316  which may be greater than the voltage level received from capacitive energy storage element  304 . In this embodiment, only one super capacitor  322  may be needed, although more than one super capacitor may be configured in a parallel arrangement. 
     In another embodiment, regulator  312  may be a linear voltage regulator or a switching voltage regulator that provides an input voltage to circuitry  316  which may be less than or about equal to a voltage level received from capacitive energy storage element  304 . In this embodiment, more than one super capacitor  322  may be used, and the super capacitors may be arranged in a series configuration (as illustrated) to provide a higher combined voltage. Additional super capacitors may be added (e.g., in parallel) to provide additional current capacity. In these embodiments, regulator  312  may provide a regulated output voltage to circuitry  316 , which may be in the range of approximately two to four volts, for example. 
     In one embodiment, super capacitor  322  may have a high storage density and may have a capacitance of one or more Farads. Super capacitor  322  may be chemically inert (i.e., not including a battery or be a battery-capacitor hybrid) and may have radially configured double layer plates. Super capacitor  322  may also be hermetically sealed and have an electrolyte that does not freeze at temperatures of up to −45 degrees F. Super capacitor  322  may also be able to withstand shock forces of up to 15,000 g&#39;s and greater during projectile launching operations without failure. The charge and/or discharge rate of super capacitor  322  may be at least 15 Joules per second allowing super capacitor  322  to store up to 15-20 watts in less than two seconds, for example. Super capacitor  322  may be referred to as a “quick-charge” capacitor. 
     Although projectile circuitry  300  is illustrated as having several functional elements  302 - 320 , one or more of these functional elements may be combined with other functional elements and may be fabricated from various combinations of hardware and software configured elements. 
     FIG. 4 is a flow chart of a data and energy transfer procedure in accordance with an embodiment of the present invention. Data and energy transfer procedure  400  may be performed by a projectile setting system, such as system  100  (FIG.  1 ), although other systems are also suitable. Although the individual operations of procedure  400  are illustrated and described as separate operations, one or more of the individual operations may be performed concurrently and nothing requires that the operations be performed in the order illustrated. 
     In operation  402 , a projectile setter may be placed over a projectile. Operation  402  may establish a connector-less or an inductive interface, such as interface  118  (FIG.  1 ), between setter circuitry  102  (FIG. 1) and projectile circuitry  106  (FIG.  1 ). Operation  402  may alternatively establish an electro-mechanical interface. In the case of an electromechanical interface, operation  402  may include electrically coupling the setter and projectile circuitry. In operation  404 , data and/or energy are transferred over the interface from the setter circuitry to the projectile. The energy may take the form of an AC waveform and the data may be modulated on the waveform. 
     In operation  406 , a capacitive energy storage element, such as energy storage element  114  (FIG.  1 ), may be charged. The charging may be performed rapidly allowing up to 25 watts or more of energy to be stored on the capacitive energy storage element in less than a few seconds. Operation  406  may include charging primary and back-up energy storage elements of the capacitive energy storage element. In operation  408 , mission data may be stored in a data storage element, such as data storage element  112  (FIG.  1 ). In one embodiment, operations  404  through  408  may be performed substantially simultaneously. During operations  404  through  408 , power to the projectile circuitry may be supplied from an external means. 
     In operation  410 , the projectile setter may be removed from over the projectile, which may terminate the interface established in operation  402 . In the case of an electro-mechanical interface, operation  410  may include electrically decoupling the setter and projectile circuitry. 
     In operation  412 , a primary storage element of the capacitive energy storage element may provide energy to circuitry, such as circuitry  316  (FIG.  3 ), until another energy source becomes available. In one embodiment, the capacitive energy storage element may provide energy to the circuitry from the time the projectile is removed from the projectile setter until after launch. This may include the time during which the projectile is transferred to a gun barrel for loading in operation  414 , and the time subsequent to launch in operation  416  until a flight battery becomes available. In this embodiment, the capacitive energy storage element may replace a data-hold battery used in conventional guided projectiles. 
     In operation  418 , a backup-energy storage element, such as a gun-hardened capacitor, may provide energy to circuitry, such as circuitry  316  (FIG.  3 ), in the event of failure  419  of the primary capacitive energy storage element. For example, if super capacitor  322  (FIG. 3) fails during launching operations, gun-hardened capacitor  324  may provide power to the clock circuitry until the flight battery becomes available. In this situation, gun-hardened capacitor  324  may provide power to the clock circuitry for a relatively short amount of time (e.g., less than two seconds) from launch until activation of the flight battery. 
     In operation  420 , another energy source, such as fight battery  320  (FIG.  3 ), may be activated and becomes available. In operation  420 , the capacitive energy storage element may refrain from providing energy to the clock circuitry. 
     The foregoing description of specific embodiments reveals the general nature of the invention sufficiently that others can, by applying current knowledge, readily modify and/or adapt it for various applications without departing from the generic concept. Therefore such adaptations and modifications are within the meaning and range of equivalents of the disclosed embodiments. The phraseology or terminology employed herein is for the purpose of description and not of limitation. Accordingly, the invention embraces all such alternatives, modifications, equivalents and variations as fall within the spirit and broad scope of the appended claims.