Assessment of a GPS Guided Spinning Projectile Using an Accelerometer -Only IMU

This paper describes the system design and a preliminary performance assessment of a Global Positioning System (GPS) guided spinning projectile known as the Autonomous Naval Support Round (ANSR). The ANSR is a rolling 5 inch gun launched rocket assisted guided projectile being considered for development by the US Navy that utilizes the GPS and a gyro -less “accelerometer only” inertial measurement unit (AO IMU) for guidance and navigation purposes. The ANSR guidance, navigation and control (GNC) concept (initia lly proposed by NSWC Dahlgren) is based on being able to exploit commercial off the shelf components (COTS) for lower cost, while providing a projectile with an extended range capability. The proposed GNC concept for ANSR is based on using GPS measurement s to provide the onboard guidance system with position and velocity states and using a Forward Integrated Terminal States (FITS) guidance policy to guide the projectile to stationary ground based targets. A traditional Inertial Navigation System (INS) is n ot used. This is in contrast to previous assessment studies which assume an integrated GPS/INS system in a tightly coupled configuration. The ANSR functions with an open loop autopilot that generates deflection commands for a single pair of canards. The pe rformance analysis for this paper is done using a six degree of freedom simulation, and the primary metric used for the terminal navigation performance is the circular error probable (CEP).