Direct dither control without external feedback for ring laser gyro

To avoid the lock-in effect, a body dither is introduced for the ring laser gyro (RLG). A dither feedback signal is necessary to control the dither drive signal. In the current dither control method, a piezoelectric or electromagnetic transducer is often used to obtain the dither feedback. The read-out signal of the RLG contains all dither-related information; hence, dither feedback can be obtained from the read-out signal, and external feedback can be reduced. A novel dither controlling method without external feedback is introduced in the present paper. How to control the dither amplitude and track the resonant frequency of the dither motor is described in detail. A comparative experiment is conducted between the old dither control method and the new one. Results show that the output of RLG using the new method has the same accuracy as that using the old method, aside from having more compact circuit dimensions.

► New dither control method for ring laser gyro that does not need external feedback is developed.
► The dither feedback is evaluated from the read-out signal rather than piezoelectric transducer.
► The amplitude control and frequency tracking are realized using digital signal processing.
► The evaluation of dither amplitude is more accurate than that using piezoelectric transducer.
► The circuit dimension of the new dither control method is smaller.