A time-delay unsaturated bistable stochastic resonance system and its application in weak signal detection

Weak signal detection methods, which extract specific frequency signals submerged in strong noise, are closely related to multiple applications, such as early bearing fault diagnosis of large machinery. The stochastic resonance (SR) method is a nonlinear weak signal detection method that can enhance the energy of weak signals by utilizing noise energy. Unlike other traditional methods that suppress noise energy, the SR method still has good detection performance at an extremely low signal-to-noise ratio (SNR). However, the output saturation problem of the classic bistable SR (CBSR) limits further improvements in detection ability. Therefore, in this paper, a piecewise unsaturated bistable potential function is constructed to solve this output saturation issue. Then, based on this proposed unsaturated potential function, a time-delay SR system is proposed to improve the weak signal detection ability. The theoretical output SNR and weak signal detection performance of the proposed SR system under different system parameters are analyzed. Furthermore, the experiment results of weak bearing fault signal detection also show that the proposed SR system is better than the CBSR system.