A -- A REQUEST FOR INFORMATION-MINIATURE INTEGRATED NAVIGATION TECHNOLOGY (MINT) : The Air Force is actively investigating the development of small precision guided conventional munitions that are able to meet or exceed performance goals associated with existing larger munitions (500, 1000 and 2000 lb classes). By decreasing size, delivery aircraft will be able to carry more munitions per sortie thereby increasing the effectiveness of each sortie. The need for small munitions has become more pointed due to the imminent release of the next generation of fighter-bomber aircraft which, to decrease observability, have installed small, internal bomb bays. The Air Force Research Laboratory Munitions Directorate (AFRL/MN) is currently developing miniature munition technologies that support air-to-surface engagements, for both fixed and mobile target types. Precision guidance will be a critical need for all future weapons, including miniature versions. Consequently, the Advanced Guidance Division (AFRL/MNG) is investigating technologies that will enable precision engagement with and without a seeker on a cylindrical munition that is less than 6 inches in diameter. A major aspect of this research is focused on reducing the size of the Navigation subsystem. Inertial Navigation Systems (INS) for precision munitions have typically been developed on a three gyro three accelerometer strapdown mechanization. The raw rate and acceleration data is processed in a co-located Kalman filter to retrieve local level position of the munition. To achieve the accuracy desired for a precision guided munition, the INS sensors are required to meet tactical grade error specifications, that is, gyro bias drift less than one degree per hour and acceleration bias less than 500 milli-g_s. The obvious approach to achieving size reduction goals is to miniaturize the sensors using MEMS technologies, which is being pursued by the DOD on many fronts. However, this sensor focus is not enough to reduce the size of a system that incorporates the Global Positioning System (GPS). Recently, GPS navigation has been integrated withan INS on stand-off munitions with the objective of correcting INS drift so that the weapon engagement range can be extended without making even more accurate (and expensive) INS sensors. A GPS receiver subsystem measures pseudoranges to several satellites and processes a navigation solution in a local level frame. GPS and INS systems have been coupled in increasingly integrated methods. Originally, the GPS receiver simply provided one-way measurements to the INS filter that bounded the navigation drift. Later, the INS measurements were provided back to the GPS filter providing satellite tracking robustness during high dynamics and RF interference environments. The combination of measurements formed a type of _loose_ coupling of the two navigation systems that allowed better navigation performance that either on its own. Munitions designers are concerned with reducing the size and cost of the navigation subsystem, while increasing its robustness. By _tightly_ coupling the GPS psuedorange and inertial sensor measurements within a single navigation filter, cost and size are reduced. Furthermore, the inertial and GPS components cooperate on a much higher level, providing a more robust and accurate navigation system. Additional satellite tracking robustness has been provided via adaptive techniques in the antenna portion of the GPS receiver. AFRL/MNGN is interested in going beyond tight coupling such that raw inertial sensor measurements and GPS receiver code phase measurements are directly included together within a single navigation filter. The advantages of what is defined as an _ultra tightly coupled system_ include increased accuracy of the navigation solution, decreased complexity and cost of the navigation sub system, improved robustness in an RF challenged environment, and most importantly (from the perspective of miniature munitions developers) reduction in the size of the GPS/INS navigator. Ideally, an ultra tightly coupled system would reside within a single cylindrical package less than 35 cubic inches in volume and 5 inches in diameter that would include three rate sensors, three acceleration sensors, a GPS receiver, power conditioning, and a single navigation filter. The Navigation and Control Branch (AFRL/MNGN) is requesting information from the defense industry to determine what progress has been made in ultra tightly coupled navigation systems. The government will use this information to determine the maturity of ultra tightly coupled technologies. If it is determined that the technology is not mature, an RFP will follow which will solicit proposals for the development of a breadboard demonstration system. If the technology is mature, a flight demonstration may be solicited. This RFI provides interested contractors an opportunity to present to the government their ideas, an approach, and progress made towards developing ultra tightly coupled navigation systems. Responses to this RFI are due by close of business 16 August 1999 to the Contract Specialist, Ms. MiMi Martin at (850) 882-4294, Ext. 3409. At aminimum, the submitted packages should include one (1) hard copy and an electronic copy compatible with Word 97. Following submission of the packages, the program office will host two-hour presentations by interested contractors. The level of detail for each RFI response and optional briefing should be compatible with a presentation of no more than a two-hours in duration. For more detailed technical information and for scheduling contractor briefings, please contact Lt Jae Yang, (850) 882-5388 x1256. This RFI is for informational and planning purposes only and does not constitute an Invitation for Bids or a Request for Proposals, nor is it a commitment by the Government. The Government will use this information to determine an acquisition approach for MINT. The government will not pay for any effort expended in responding to this notice. Please refer all other questions and comments to the Contract Specialist, Ms. MiMi Martin at (850) 882-4294, Ext. 3409, or e-mail her at martinmd@eglin.af.mil, or to the Contracting Officer, Ms. Brenda Soler at (850) 882-4294, Ext. 3399, or e-mail her at solerb@eglin.af.mil. If the government decides to solicit offers for the MINT, an Ombudsman will be appointed to address concerns from potential offerors during the proposal development phase of the acquisition. See Note 26 WEB: Visit this URL for the latest information about this, http://www.eps.gov/cgi-bin/WebObjects/EPS?ACode=S&;ProjID=MNK-99-038&Lo cID=1362. E-MAIL: Brenda Soler, solerb@eglin.af.mil. Posted 07/22/99 (D-SN357997).

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