A New Method for Eliminating the Lock-in Error of Mechanically Dithered Ring Laser Gyro

The origin of tock-in error of the mechanically dithered ring laser gyroscopes(MDRLG)is theoretically analyzed.It is obtained that the lock-in error relates to the input angular velocity,the dither frequency and the dither magnitude.According to the limitation of pulse count decoder caused hy the readout circuit,a new method for eliminating the lock-in error of RLG is presented.At first,the phase character at the zero rate of crossing is described by a parabola equation.Secondly,the fractional angular signal that is smaller than a pulse count is compensated.Finally,by utilizing the values of sine,cosine and the second derivate of the phase at the zero rate of crossing,the lock-in error is eliminating.The simulation results show that the maximum output error of RLG is reduced from 6.25% to 0.622%.So this method improves the detection precision of RLG,and the output signal of RLG has preferably stability and repetition.