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Low Cost Competent Munitions

Neither "brilliant" nor "dumb", Competent Munitions are good enough to do a job effectively and are expected to cost much less than terminally guided munitions. By effectively managing their assignment to target, it is possible to optimize their force multiplier effect.

Rockwell Collins has developed many GPS receivers designed to place GPS navigation into artillery shells. The receivers are miniaturized to fit into existing artillery fuzes and are ruggedized to withstand severe gun launch dynamics. They incorporate full 12-channel, all-in-view capability and fast direct-Y code signal acquisition, which is crucial for the short flight times of artillery.

The company has supplied a variety of receivers for artillery applications on both domestic and international programs. These receivers have been successfully tested on many programs, including Extended Range Guided Munition-Risk Reduction (ERGM RR), Competent Munition Advanced Technology Demonstration (CMATD), the United Kingdom's Smart Trajectory Artillery Round (Team STAR) and Low Cost Course Corrected Munitions (LCCCM).

Recent development of micromechanical Inertial Management Units (IMUs) and Global Positioning Systems (GPS) capable of withstanding more than 16,000 g's has spawned renewed interest in unpowered guided munitions. Guidance schemes seek to increase the static targeting accuracy by decreasing the Circular Error Probability (CEP). In mass production, these guidance and control units could potentially be manufactured for less than $3,000 each and affixed to all current NATO standard projectiles.

In order to retain the usefulness of the vast stock piles of Army/Navy/USMC ammunition, numbering in the tens of millions of rounds, a fuze replacement is sought which incorporates all the necessary additions to transform these unguided shells into guided, or competent munitions. In particular, competent munitions require aerodynamic control actuation to effect trajectory control. Investigations focus on replacement fuzes for trajectory control by modulated roll control of a fixed magnitude lift vector.

The Army TACOM-ARDEC Low Cost Competent Munitions (LCCM) program seeks to improve artillery accuracy by creating a low cost device which could automatically adjust a round's in-flight trajectory. Enabling MEMS technologies include RF MEMS for GPS transceivers, inertial measurement units (IMU's) for safing and arming, and miniature actuation systems. The Army's goal is to improve artillery accuracy by over 50%. The US Army Armament Research, Development, & Engineering Center (ARDEC) is located at the Picatinny Arsenal in Morris County, New Jersey. ARDEC is a sub-command of the U.S. Army Tank-Automotive and Armaments Command (TACOM).

With the advances in microelectronics, sensor technology, and packaging design, the reality of a range correction device for artillery is conceivable. One of the main objectives of the range correction device concept is to contain all the mechanical and electrical components within a fuze-like envelope, while maintaining certain constraints that would allow the fuze to fit into a variety of artillery shells used by North Atlantic Treaty Organization (NATO) countries. Another objective of the range correction device concept is to avoid any changes within the ogive of any of the projectiles in the existing stockpile.

The U.S. Army Research Laboratory (ARL) and the U.S. Army Armament Research, Development, and Engineering Center (ARDEC) have been working on various LCCM concepts. The LCCM concept dictates that the design of a trajectory correction module will fit into an artillery shell like any of the fuzes used by NATO. An initial 1996 design process identified potentially critical problems in the mechanical design of a trajectory control device. The design process concentrated on the current level of technologies and the electro-mechanical requirements for a D-ring range correction module. The D-ring correction module is a one- dimensional, self-correction device concept for providing sufficient change in drag, to achieve the needed correction, given the constraints of size, power, and other necessary components and technologies. An LCCM range correction module appears to be a very viable concept without requiring aggressive technologies or high-risk approaches. The efficient use of the available volume for electrical and mechanical components will he crucial.

In 1996 the Army Research Laboratory Aberdeen Proving Ground undertook an analysis of a Fuze-Configurable Range Correction Device for an Artillery Projectile. This effort included design iterations, numerical analyses, shock tests, and actual cannon launchings. Structural analyses indicated that the overall prototype design was durable enough to withstand the most severe artillery cannon launching available today. The design should be capable of withstanding a 15,000 g inertial set-back load with 150,000 rad/s2 of angular acceleration. In addition, the design should be capable of deploying while the projectile has velocity of 650 m/s and is spinning at 250 cycles per second.

The Competent Munitions Advanced Technology Demonstration (CM-ATD) was started in 1996, to demonstrate that a lower cost Guidance, Navigation and Control (GN & C) Inertial Navigation System (INS) system based on MEMS could provide improved impact geo-location performance at ranges greater than 9 nautical miles when compared to standard artillery unguided spinning rounds. The demonstration hardware used a GPS receiver and a complete MEMS-based, inertial measurement unit to navigate the projectile to preset coordinates. All of the required GN & C electronic hardware is contained in a volume of 13 cubic inches which is approximately 30 times smaller than any existing concept for gun launch.

The CM-ATD GN & C section, designed to withstand more than 15,000 Gs of launch acceleration, is essentially a "smart fuse" replacement for the "dumb" unguided fuzz sections used by the Navy, Army, Marines and many NATO countries.

The final test of the Office of Naval Research Competent Munitions Advanced Technology Demonstration (CM-ATD) was successfully completed in early 2000 at the Army's Yuma Proving Ground in Arizona. The test proved that a micro-electromechanical sensor (MEMS) and Global Positioning System (GPS)-based guidance package on a conventional spinning Naval gun projectile could be steered toward a designated GPS coordinate impact location.

In the final test, the Navy's 5"/54 caliber MK 45 gun fired a spinning projectile that was successfully guided toward a designated target by a GPS/MEMS coupled INS. The test projectile was modified to carry power and telemetry equipment, required to transmit flight data to ground recording stations. The GPS/MEMS INS system altered in mid-flight the normal ballistic flight path of the projectile and steered the projectile toward the target through the use of a set of nose-mounted tilting canard fins.

The Naval Surface Warfare Center Guns and Munitions Division in Dahlgren, Va., provided technical direction of the CM-ATD. The Charles Stark Draper Laboratory coupled their development of a MEMS roll-rate gyroscope with MEMS accelerometers and a Rockwell Collins GPS to design and build the INS. The U.S. Army Armament Research Development and Engineering Center, Picatinny Arsenal, N.J., provided technical support to the CM-ATD.

Microelectromechanical Systems (MEMS) is one of the three core enabling technologies within the Microsystems Technology Office (MTO) of the Defense Advanced Research Projects Agency (DARPA). MEMS technology uses the materials and processes of semiconductor electronics to create integrated electromechanical systems that merge computation with sensing and actuation. MEMS technology merges the functions of compute, communicate and power together with sense, actuate and control to change completely the way people and machines interact with the physical world. Using an ever-expanding set of fabrication processes and materials, MEMS will provide the advantages of small size, low-power, low-mass, low-cost and high-functionality to integrated electromechanical systems both on the micro as well as on the macro scales. Further, demands for increased performance, reliability, robustness, lifetime, maintainability and capability of military equipment of all kinds can be met by the integration of MEMS into macro devices and systems.

MEMS is based on a manufacturing technology that has had roots in microelectronics, but MEMS has gone beyond this initial set of processes as it became more intimately integrated into macro devices and systems. MEMS will be successful in all applications where size, weight and power must decrease simultaneously with functionality increases, and all while done under extreme cost pressure.

Experiences in recent conflicts and the evolving role of the US military in rapid response to new kinds of missions have demonstrated the compelling advantage of securing accurate and timely information. Coupled with smart weapons systems, the resulting combination of awareness and lethality is key to increasing and projecting military capability in the 21st century at reduced cost. MEMS embedded into weapons systems, ranging from competent munitions and sensor networks to high-maneuverability aircraft and identify-friend-or-foe systems, will bring to the military new levels of situational awareness, information to the warrior, precision strike capability, and weapons performance/reliability. These heightened capabilities will translate directly into tactical and strategic military advantage, reduced casualties and reduced material loss.

MEMS will make high-end functionality affordable to low-end military systems and extend the operational performance and lifetimes of existing weapons platforms. Because devices and systems that will be produced or enabled by this program can be expected to be deployed in significant numbers, affordability and manufacturing issues are key to DoD use. With a strong MEMS technology base, a growing MEMS manufacturing capability, and coordinated federal and industry investments, the U.S. can cost-effectively leverage its semiconductor industry leadership into industry leadership in MEMS. To continued Access to MEMS technology, DoD's strategy is focusing on developing advanced MEMS devices and systems; developing support and access technologies for further development of MEMS; and accelerating insertion of presently available or near-term commercial MEMS products into military systems and operations.

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