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Three axis aerodynamic control of guided munitionsRelated Patent Categories: Aeronautics And Astronautics, Missile Stabilization Or Trajectory Control, Externally Mounted Stabilizing Appendage (e.g., Fin)Three axis aerodynamic control of guided munitions description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080029641, Three axis aerodynamic control of guided munitions. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims rights under 35 USC 119(e) from U.S. application Ser. No. 60/650,705, filed Feb. 7, 2005; the contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to armaments and more particularly to guided munitions. Even more particularly, the invention relates to a three axis control system and mechanism for guided mortar shells or for other small aerodynamic bodies. [0004] 2. Background Information [0005] Mortars are one of the most commonly employed weapons in a ground combat unit. The traditional role of mortars has been to provide close and continuous fire support for maneuvering forces. Military history has repeatedly demonstrated the effectiveness of mortars. Their rapid, high-angle, plunging fires are invaluable against dug-in enemy troops and targets in defilade, which are not vulnerable to attack by direct fires. One of the major disadvantages of mortars is their comparatively low accuracy, and as a result mortars are becoming less effective in today's precision combat environment. Equipping a mortar round with a precision guidance package will increase its accuracy, enabling the mortar to be a precision munition that will be significantly more effective in wartime situations. For maximum utility, the guidance package preferably should be an inexpensive retrofit to current munitions, with a cost in production that allows its use in all situations, either as a guided or unguided weapon. [0006] Unguided munitions are subject to aim error and wind disturbances. These factors, along with other more subtle error sources, may cause the munition to miss the target completely or require many rounds to complete the fire mission due to the resulting large CEP (Circular Error Probability). Current approaches to guided weapons are expensive and are used on larger, long range weapons. The approach of the present invention results in significantly lower cost and smaller size. This allows use with small to medium caliber weapons and significantly improves CEP which also results in a significant reduction in the quantity of rounds required to complete the fire mission which in turn results in lower overall cost and improved crew survivability. In addition, another benefit to this approach is the virtual elimination of collateral damage due to errant rounds impacting non-targeted areas. Furthermore, complete integration of a seeker/guidance error can be used in a modification to the existing fuse in order to "safe" errant rounds which are failing to meet the established CEP ground rule which further controls unwanted collateral damage by preventing detonation of off target rounds. [0007] Mortars are typically unguided or guided by an expensive G&C (Guidance and Control) system. The cost is high for current guided mortars and unguided mortars may have poor accuracy. Also, unguided mortars may result in unacceptable collateral damage, excess cost due to the large number of rounds required to blanket the target area, and may expose the mortar crew to counterbattery fire due to the large time required to drop the necessary shells to saturate the target. [0008] The control of a small caliber body, (or any multi-caliber munition or Micro-Air Vehicle, MAV), necessitates a space efficient, light weight, reliable, low cost hardware embodiment. Furthermore, in order to optimize performance, a full 3-axis control system is required to maximize maneuver load capability and overall control, hence minimizing CEP (or miss distance) and for flight trajectory optimization. The combination of a full 3-axis control system using, in this case canards, (although traditional aileron, rudder, and elevator control can be incorporated), in a low cost, volumetrically efficient package which does not adversely effect center of gravity has been developed. The approach of the present invention does not require shaft encoders or resolvers and integrates feedback from other onboard sensors to effect control over the body utilizing the 3-axis control scheme. [0009] Therefore, there is a need for an accurate and cost effective means for guiding mortar munitions. There is also a need for an ultra low cost G&C approach for mortars which is compatible with a large class of rounds. Furthermore, subsequent need exists for preventing detonation of errant rounds to minimize non-target specific damage and non-combatant loss of life. Likewise, there is a need for a highly integrated control mechanism for small caliber and MAV aerodynamic bodies which provides full 3-axis control with minimal weight, cost, volume, and power impacts. BRIEF SUMMARY OF THE INVENTION [0010] In one embodiment of the present invention, a set of three miniature stepper motors, each driving a zero backlash spur gear assembly, are used to drive bevel gears attached to a set of three shafts. In another embodiment the stepper motors each drive a planetary gear assembly which drives a worm gear and a pitch gear connected to each of the three shafts. Attached to each shaft are the canards. A common shaft has a canard attached at opposite ends of the shaft. Two individual shafts each have a single canard affixed at an end thereof. In this manner, roll, pitch, and yaw steering commands can be executed through the canard frame to maneuver the munition in order to increase system accuracy. This technique is robust and also can be adapted to conventional MAV airframes to improve aerodynamic maneuvering performance. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0011] The present invention is further described with reference to the accompanying drawings wherein: [0012] FIG. 1 is a diagrammatic perspective view of the guided munition of the present invention. [0013] FIG. 2 is an exploded perspective view of the guidance control mechanism located in the nose of the munition shown in FIG. 1. [0014] FIG. 3 is a front end view of the nose of the munition of FIG. 1. [0015] FIG. 4 is a fragmentary diagrammatic sectional view taken on line 4-4, FIG. 3 showing the improved guidance control mechanism mounted in the front of the munition. [0016] FIG. 5 is a top plan view of one of the guidance canards. [0017] FIG. 5A is a side elevation of the canard of FIG. 5. [0018] FIG. 6 is a diagrammatic perspective view of a first embodiment of the guidance canards and drive mechanism. [0019] FIG. 6A is a diagrammatic top view of the guidance canard drive mechanism of FIG. 6. [0020] FIG. 7 is a diagrammatic perspective view of a second embodiment of the guidance canard and drive mechanism. Continue reading about Three axis aerodynamic control of guided munitions... Full patent description for Three axis aerodynamic control of guided munitions Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Three axis aerodynamic control of guided munitions patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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