Signal Detecting And Processing Of Strapdown Inertial Navigation System With Ring Laser Gyroscope Based On FPGA

Being the main aspect of inertial navigation system, strapdown inertial navigation system (SINS) with ring laser gyroscope (RLG) has been widely applied in the land, sea, air and outer space. It is one of the current efficient ways that can improve navigation accuracy with present inertial instrument by selecting digital signal processing chips ,which are bigger in capacity and faster, to improve the course and the method of processing the signal of the inertial instruments.Firstly, the function of FPGA (Field Programmable Gate Array) and DSP (Digital Signal Processor) in the original SINS is compartmentalized renewedly. Pretreatments of all the signals from inertial navigation system are accomplished by high-powered FPGA, and only navigation calculation is done by DSP so as to speed up the navigation calculation. The phase demodulator and up/down counter used to process the signals of three RLGs have been implemented in FPGA, while digital lowpass filter is also designed to sampling the signals of three RLGs and filter out the dither signal. The results of the experiment on SINS indicate the digital lowpass implemented in FPGA can satisfy the requirements.Secondly, the floating-point operator is designed in FPGA, which can not only be applied to double precision floating-point number of IEEE754 standard, but also can be applied to other three types of floating-point number of IEEE754 standard. The simulation and the test of the floating-point operator indicate that the operator works correctly and it can be used as an IP core in FPGA.At last, an error compensation model of the RLG and another error compensation model of accelerometer are introduced, and floating-point operation of error compensation have been carried out in FPGA based on the error compensation algorithm. The compensated result is transmitted to DSP to finish navigation calculation. The result of the inertial navigation system with the new programs is validated by the result of original inertial navigation system, and the former can meet the need of navigation well.