Automatic Positioning of Spinning Projectile in Trajectory Correction Fuze via GPS/IMU Integration

Abstract

In this paper, an automatic positioning system for spinning projectile in trajectory correction fuze is described in detail. Aiming at the characteristics of spinning, this system is designed through integration of GPS (Global Positioning System) and IMU (Inertial Measurement Unit). Compared with general projectiles, the signals from spinning projectile are modulated by rotation. Therefore, how to obtain valid signals from the rotation modulated ones is a key problem. With the special rotation tracking loop, GPS module in this system can demodulate the rotation-modulated signals and thus provide correct position information. This part of design is based on SDR (Software Defined Radio) and FPGA (Field Programable Gate Array) means in order to speed it up and get a small size. Meanwhile, IMU module including several accelerometers provides attitude information which gives aiding signals to GPS section for rotation demodulation. Via the integration of IMU and GPS in fuze, the system can realize automatic positioning and trajectory correction. Accordingly, the device is suitable for dynamic conditions of high G-forces and vibration and spinning rate experienced frequently by these applications. Besides, due to its advantages of low-cost and flexibility it can adapt itself to different satellite navigation systems easily.