Research For Small Strap-down Inertial Navigation System Based On FPGA

Inertial navigation system(INS) is a significant navigation system in the field of aerospace and military, it is with such characteristics as autonomous, high concealment and anti-interference. Other navigation systems are not comparable with it. The new generation of micro-gyroscope and micro-accelerometer are approached with the rapid development of Micro-Electro-Mechanical System(MEMS). The prospect of INS is bright thanks to the reduced manufacturing cost of the inertial sensor. In order to rapidly promoting INS in civilian field, the design of a low-power, more convenient and human-interactive small navigation system is necessary to be issued. To solve this problem, a novel navigation hardware platform is designed to construct the Strapdown INS(SINS). This system takes the MEMS-sensor as the primary sensor, and the FPGA as the processor.Firstly, the algorithm of SINS is discussed via analyzing Maneuvering principle of inertial sensor. The calculation model of SINS is further proposed.Then, taking the FPGA as controller, a set of small navigation platform is designed. This platform includes sensors module, communication module, power module and display module.Auxiliary navigation sensors, consisted of magnetometer and GPS receiver, are integrated in the hardware system for the sake of the accumulated error derived from INS. Further, taking MicroBlaze as processor, System on a chip(SOC) is built on FPGA for algorithm process.Data acquisition of sensors is realized as well as peripheral communication, corresponding control by adding IP core on SOC.The third, the software of navigation system is developed using c language. Aiming at solving boot-loader problem of FPGA, a structure of double-software project is made. This plan can achieves copying the code of software to SDRAM from FLASH after powering.Considering the code of double-software project would be stored in the same FLASH, the storage method of configuration files based synchronization word is proposed. This method is convenient for read block data from FLASH in addition to reducing the conflict probability of multiple data.Further, we study the data fusion algorithm called complementary filter, to eliminate theaccumulated error in attitude determination of INS, the filter module is built based on second order low-pass filter. The data fusion algorithm aimed at calculating position by GPS and INS is also designed based on Kalman filter.Finally, a set of tri-dimensional attitude test platform is established to validate feasibility of complementary filter. Meanwhile, carrier-car experiments are conducted, the results show that the navigation system designed in this paper meets the design request, and be characterized by exercise and long-time stabilization.