Research On Dynamic Characteristics And Attitude Solution For Non-driven Silicon Micromechanical Gyroscope

Non-driven silicon micromechanical gyroscope is a new type of angular rate sensor. The gyroscope, which is installed on the rotating aircraft, obtains the angular momentum by using aircraft spin. When the carrier occurs pitch and yaw, Coriolis force is produced and makes sensing element vibrating. And the gyroscope outputs signal to sense carrier transverse angular velocity, and automatically tunes carrier roll. Because it has no driving structure, it has simple structure, low cost, strong ability of anti-overload, etc. In addition, the output signal contains rolling angular velocity, pitching angular velocity and yawing angular velocity about carrier. So it can be widely used in single channel control system and multiple channel control system. Therefore, the study on non-driven silicon micromechanical gyroscope has important theoretical significance and practical value.Based on dynamic characteristics and attitude solution, this paper will carry out research. The main research contents are summarized as follows:(1) According to the Euler’s equations of the rotation of a rigid body, the equation of angle vibration of sensing element has been derived for non-driven silicon micromechanical gyroscope, and the kinetic parameters have been analyzed and calculated. In view of all kinds of attitude motion of rotating aircraft, the mathematical model of gyro’s output signal has been established. Through three axis precision rate table, the simulation has validated the mathematical model.(2) Based on the feature of capacitance detection for the silicon micromechanical gyroscope, the detection circuit of low noise was designed for sensing signal. The detailed formula derivation was worked on the detection circuit, and the test had been done. With transfer function, the signal processing circuits were designed. Both the Bode analysis and circuit simulation have shown that the design can meet the demands of technology.(3) According to the error model and the actual test, the change of carrier spin frequency is main reason why the instability of the gyro’s scale factor occurs for non-driven silicon micromechanical gyroscope. In view of the affect, two kinds of algorithm have been put forward for compensating the error. Test results have shown that the methods can effectively improve the stability of the gyro’s scale factor.(4) From the point of view of frequency characteristics, amplitude-frequency characteristics and phase-frequency characteristics of the silicon micromechanical gyroscope were studied. The amplitude-frequency characteristics was calibrated on the angular vibration table. Using three axis precision rate table as a benchmark, the curve of phase-frequency characteristics was tested and ploted. From the point of view of time domain characteristics, the key dynamic performances, which are resistance to the rudder partial hit, anti-shock and the startup time, were studied. The shock isolator has been designed. The method has been proposed for resistance to the rudder partial hit. The startup time has been decreased.(5) Based on the mathematical model of output signal of the silicon micromechanical gyroscope, carrier frequency of the gyro’s output signal corresponds to the spin frequency of the aircraft, and envelope is proportional to the transverse angular velocity. Some extraction algorithms of the spin frequency were designed and compared. Based on the analytical signal of gyro’s output signal, Demodulation algorithm of transverse angular velocity was designed. The algorithm was put forward for solving the deflection angle of transverse angular velocity. Through the deflection Angle, transverse angular velocity is orthogonally decomposed to pitching angular velocity and yawing angular velocity with respect to the quasi body coordinate system. With respect to the inertial system, phase difference between the gyro’s output signal and the gravity accelerometer output signal is calculated. Using the phase difference, transverse angular velocity is orthogonally decomposed to pitching angular velocity and yawing angular velocity.(6) On the basis of analyzing the signal processing circuit, the circuit was improved and the integrated gyroscope designed for damping of single channel control system. Performance test had showed that it can meet the requirements of the application. According to the relevant algorithms of attitude solution, modularized programs had been designed based on Verilog HDL and C language. On the three axis precision rate table, the program modules have been tested respectively.