Inertial Measurement System For Spinning Projectile Application

Spinning projectile provides the navies with a quick reaction, high firepower defense against anti-ship missile. In order to improve its precision strike ability, there is a need to equip a navigation system for its all-way guidance. It is the high spin of the projectile that the traditional inertial navigation system cannot be applied easy. On the other hand, there is a volume restriction of the navigation system comparing to the projectile small size. To realize an Inertial Measurement System (IMS) for spinning projectile rolling angel reference, this thesis focused on designing a novel IMS which operates in high spin condition and has a miniature size.To settle the problem of gyroscope for high spin application, this thesis put forward a gyro-free inertial measurement system (GFISM) with accelerometers only. The difficulty of the GFISM is its output error accumulating quickly, this thesis designed several methods as follows to overcome it: (1) Considering the configuration about the accelerometers. A nine accelerometers structure was designed providing all the attitude information with improved practicability, as which can eliminate the fixing error incurred by the size of the accelerometers. On the other hand, an eight accelerometers structure was designed specially for spinning projectile rolling angel reference application to provide rolling angel only. This structure was fixed in a plane. Without a three-dimensional fixing, this structure decreased the fixing errors effectively. (2) Using the accelerometers'redundant output information as an observation equation, a self-filtered system was built to improve the system output precision. (3) An integrated GFISM was designed adding magnetometers to suppress the system accumulated errors. (4) Considering the accurate and real-time attitude calculation, the state equation and observation equation were built up based on quaternion, and a second-order interpolation filter was proposed to process information fusion. In a word, the system improved its precision and practicality by these means. Simulation results verified the feasibility of these designs. To achieve a miniature sized GFIMS, dual-axis MEMS accelerometers were adopted to get a high integration for GFIMS. At the same time, a digital part of micro Inertial Measurement Calculation System (IMCS) was designed. This IMCS needed to consider the balance among size, power consumption and process speed. An optimal novel hardware configuration and software working flow were designed sophisticated, and an IMCS was finally realized with DSP controlling AD directly.To improve and validate the performance of the developed GFISM, calibration and error compensation were undertaken. Since the accelerometers had large output range and low sensitivity, the traditional static calibration and error compensation results were not satisfying. Based on the lab designed high speed turntable, the spinning projective simulation experiment was carried on. A novel dynamic calibration and error compensation method was designed. With calibrating the dynamic error models at several single high rotated speeds and subsection curve fitting method, the whole dynamic error model was established even included the turntable speedup stage. Finally, experiments had done repeatedly and verities the effectively and reliability of the proposed method and the established model.