Research On Stochastic Resonance Characteristics And Vortex Signal Processing Of A Bistable System With Adjustable Focus

Stochastic resonance uses the positive synergy of noise in nonlinear system to transfer noise energy to signal energy,improve the signal-to-noise ratio(SNR)of output signal,and realize weak signal detection.Stochastic resonance effect is closely related to the energy accumulation of potential function.In this paper,a bistable potential function with adjustable focus was proposed.The energy accumulation and stochastic resonance characteristics of the potential function,especially the relationship between the focal length adjustment and stochastic resonance effect,were researched.The small flow detection of vortex flowmeter was taken as the engineering application object.The system parameters such as focal length were optimized by quantum genetic algorithm to generate strong stochastic resonance.The vortex frequency could be obtained accurately to realize small flow measurement,and improve the detection ability of small flow.The main works are as follows:(1)The nonlinear characteristics of different potential functions were discussed.A new bistable potential function with adjustable focus was constructed.The approximate analytical relationship between the focal length of potential function and Kramers escape rate and system output SNR was established.Theoretical analysis and numerical simulation results show that the bistable potential function with adjustable focus can change the energy accumulation of the system by adjusting the focal length,and effectively control the interaction between weak signals and noise.The output signal can accumulate more energy and the output SNR of the system can be improved.(2)According to the change characteristics of amplitude and frequency of vortex signal,the quantum genetic algorithm was used after the vortex signal preprocessing to optimize the parameters of the bistable system with adjustable focus.The optimal focal length can be obtained to make the signal match with the system.Compared with the classical bistable system,the bistable system with adjustable focus can enhance vortex signal more effectively.(3)The experimental device of vortex flowmeter was built,and the vortex signal amplification and acquisition hardware system was designed.Through the joint programming of Lab VIEW and MATLAB,the vortex signal processing software based on the bistable system with adjustable focus was developed to collect the output signals of vortex flowmeter under different flow rates,especially small flow rates.The experimental results manifest that adjusting the focal length of the bistable system and optimizing the parameters can effectively enhance the stochastic resonance effect of the vortex signal.The vortex frequency of small flow rate can be obtained accurately,and the lower measurement limit of vortex flowmeter is extended.