Fig. 1. Flow chart of wavelet noise reduction

Fig. 2. Hard threshold function

Fig. 3. Soft threshold function

Fig. 4. Adaptive threshold function

Fig. 5. Curves comparison of different functions

Fig. 6. Process of determining optimal number of decomposition levels

Fig. 7. Signal data collected by three-axis laser gyroscope. (a) X-axis; (b) Y-axis; (c) Z-axis

Fig. 8. Allan variance logarithm curves of static raw data

Fig. 9. Comparison of effects of commonly used noise reduction methods. (a) Original signal; (b) TAWF; (c) standard KF; (d) IAWF

Fig. 10. Allan variance curves of noise reduction signal under different methods

Fig. 11. Effect of IAWF method after processing noise

Fig. 12. Test device for experimental car

Fig. 13. Noise reduction effect of different filtering methods

Fig. 14. Calculation results of entropy values. (a) Energy entropy of detail coefficient; (b) energy entropy of approximate coefficient; (c) energy entropy of detail ratio

Fig. 15. Dynamic noise reduction effect under different decomposition layers

Fig. 16. Detailed enlarged view of Fig. 15