Vibration Control Of MEMs Strapdown Inertial Navigation System

MEMS strapdown inertial navigation system(SINS) is a device that directly fixed on the carrier. By using MEMS accelerometers and MEMS gyros, it can measure line movement and angular movement parameters of carriers relative to inertia space. After calculation of these parameters, MEMS SINS can manage lots of navigation tasks. MEMS SINS has many advantages such as smaller size, higher automation, etc. Since the MEMS SINS are fixed directly on carrier, the vibration and noise of carrier will directly act on the inertial components, serious measurement errors will be produced, this will lead to a lower accuracy of MEMS SINS? navigation system. Especially when the system was used in missiles, abundant of factors like engine vibrations, disturbs of air would make inertial devices produces dynamic measuring error. It?s important to design an excellent vibration isolate system to reduce the effect of environment vibrations.Based on analysis of a large number of relevant references at home and abroad, to satisfy the particular requirement of missile vibration environment, through extensively study of little size, light loading vibration isolate system, MEMS SINS vibration isolate system were designed by using method of combining theoretical analysis and experimental testing. The results of simulation and experiment indicate the designed system performed well at vibration isolation and noise suppression. The main contents of the dissertation are expressed as follows:First of all, mathematical models of MEMS gyro output error under line vibration based on the working principle of gyro were set up. And parameters of these models were got through sine sweep vibration test. Analysis of these models indicate the cut-off frequency of line vibration must as low as possible when the vibration isolation system is designed merely for MEMS gyros.Then, consult MEMS gyro output error model under line vibration and engineering use the output performance of MEMS SINS were determined. Through the performance demand and amplitude-frequency curve of accelerometer in MEMS SINS got by sine scanning vibration experiment, isolate system design of single degree-of-freedom were complete. To fit the designed result of single degree-of-freedom and reduce the coupling between line and angular vibration, the decoupling design of isolate system were complete.After that, According to single degree-of-freedom requirement for stiffness and damping coefficient, combining with the super elastic constitutive equation, vibration isolator of rubber were designed. The simulation results of Radioss indicate, designed shock absorber can fit the stiffness requirement of vibration isolate system.Finally, we verify the performance and vibration isolation effect of MEMS SINS system through experiments. The sine sweep vibration test result shows that, after vibration isolation, the X Y direction(axial and lateral) cutoff frequency of MEMS SINS is 125?15 Hz?105?10 Hz and their magnification is about 6.024 dB, 5.47 dB, respectively. Since the lateral structure of isolator is fully symmetrical, on a three axis vibration direction, the vibration isolation system designed can basically fulfill the performance requirements. Under incentive of Y direction sine sweep vibration, by comparing the before and after isolation output curve and the output error of different inertial devices, we can make a conclusion that the vibration isolation system designed has good vibration and noise isolation effect. Especially in terms of gyro noise isolation, after isolation, the gyro?s output standard deviation of X, Y, Z decreased to 43.5%, 40.2% and 34.6%, respectively.