| According to stochastic resonance system theory,the control method of stochastic resonance on nonlinear bistable system was investigated with combination of numerical calculation and experimental method.Moreover,the control method was used to engineering signal especially vortex flowmeter signal processing.The noise signal in vortex signal is influencing the measuring accuracy and also leading to difficulty in low flowrate measurement.This presents a stochastic resonance detection method for vortex signal processing and the mainly work as follow.1?The relationship between signal and parameters of nonlinear bistable system is discussed.The matching relation of signal amplitude and system threshold value,signal frequency and Kramers rate are analyzed quantitively.The control method based on dual modulation with adjustable amplitude and frequency is proposed to realize signal matching with bistable system.The numerical simulation results manifest that the control method is feasible and effective for generating stochastic resonance by input signal with different parameters.2?The adaptive method specific to vortex signal is proposed to determine control parameters based on standard deviation.The vortex signal feature is used to estimate the flow velocity and reduce the control parameters scope by standard deviation,the matching efficiency between signal and bistable system is improved.3?The experimental device was set up and the output signals of vortex flowmeter mixed with noises were sampled and processed by stochastic resonance control method.The emphasis is on the vortex shedding signal under lower flowrate.The results indicate that noisy energy transfer to vortex shedding,the SNR was improved.The vortex shedding frequency can be obtained accurately to realize flowrate measurement and extend the measurement lower limit. |
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