The APCC system provides guidance and control (G&C) for a smart LFL Seeker projectile engaging a moving enemy target. The system consists of various algorithms for tracking targets, tracking projectiles, and providing guidance and control for projectile course correction.
The Active Projectile Course Correction System (APCC) initiative, funded by the U.S. Army’s TACOM-ARDEC, investigated the development of an APCC system that provides guidance and control (G&C) for a smart LFL Seeker projectile engaging a moving enemy target. The projectile is equipped with an onboard Long Wave Infrared (LWIR) staring sensor that provides target images for tracking, inertial sensors for projectile trajectory feedback, and side thrusters/diverters for projectile course correction. The LFL Seeker projectile is also spin stabilized; though spin provides stability to the projectile’s linear motion, it also poses the greatest challenge for the design and implementation of a G&C algorithm: the projectile motion that needs to be controlled—and the target motion that needs to be tracked—is in the inertial frame, while all onboard sensors and control mechanisms (diverters) are in the non-inertial rotating frame.
Achieving the goals of this initiative required major breakthroughs in a number of focus areas: (i) in tracking the target state, (ii) in tracking the projectile’s own state, and (iii) in trajectory guidance and control. The high spin rate of the projectile makes these goals challenging, particularly in regard to the reference frame for the onboard sensors. While the sensors are collecting sensor data in a high spinning reference frame the APCC algorithms must also determine the projectile course, the relative direction and location of the intended target, and the direction of course correction in the inertial, non-rotating frame of reference. The APCC system consists of various algorithms for tracking targets, for tracking projectiles, and for the guidance and control of the projectile course correction.
The APCC system was evaluated through off-line simulation, and the results demonstrated the APCC system’s ability to provide the LFL Seeker with a high incapacitation probability for the target. These results represent a significant advancement in guidance and control technology for smart munitions. We also anticipate that the APCC technology, in concert with technology in other relevant fields, will ultimately result in a fully autonomous projectile system with “fire and forget” capability.