A transfer alignment algorithm study based on actual flight test data from a tactical air-to-ground weapon launch

The paper provides results from a joint study of various transfer/alignment (T/A) techniques including velocity matching, integrated velocity matching, and doubly integrated velocity matching approaches. The goal is to determine how the various algorithms perform when driven with actual flight test data. The study addresses key T/A Kalman filter issues such as the effect of wing flexure vibration on instrument error estimation and rapid alignment concepts. A description of how a T/A Kalman filter is implemented and used in inertially guided weapons is included. The data used in the study was acquired from the Air Force Operational Concept Demonstration (OCD) Program. The OCD effort was performed by the Air-To-Surface Weapons System Program Office (SPO) at Eglin AFB in late 1992 and early 1993. The Eglin SPO initiated the flight test program to demonstrate the effectiveness of GPS/INS integration in a tactical weapon. The test was conducted using a Honeywell Integrated Flight Management Unit (IFMU) and an Interstate Electronics 5-channel P-code GPS receiver in a GBU-15 airframe on board a block 40 F-16 aircraft. Telemetry data from this OCD weapon was transmitted continuously from the beginning of weapon alignment to final impact on the ground. The OCD telemetry stream contained INS and GPS data from both the aircraft and weapon during captive carriage T/A maneuvers. After launch, the weapon data alone was transmitted during the free flight to the target. These messages provide the data set used in the T/A study