Fig. 1. Flow chart of sequence threshold least square method

Fig. 2. Simplified two-mass model

Fig. 3. State change curves under different noise levels

Fig. 4. The curve of determination coefficient

Fig. 5. Principle diagram of system identification experiment

Fig. 6. Square wave input and output signal

Fig. 7. Sine input and output signal

Fig. 8. Output curve of identification system under the input of square wave signal

Fig. 9. Output curve of identification system under the input of sine signal