Online high-precision identification method for ship propeller thrust

Abstract

ObjectiveThe weak deformation signal generated by propeller thrust on a shaft system is easily overshadowed by interfering noise, making it challenging to accurately measure the thrust. Therefore, this study proposes a new method for accurately measuring the thrust of propellers under low signal-to-noise ratio conditions. MethodsBy taking into consideration the influence of measurement data errors and the underlying mechanical mechanisms, a thrust identification model is established based on a combination of Kalman filtering, and the thrust-displacement state equation. Thrust measurement research is conducted under three different operating conditions: constant rotational speed, variable rotational speed and low-frequency fluctuating rotational speed. The precision and robustness of the proposed method are then analyzed under different signal-to-noise ratios.ResultsThe results demonstrate that even at a signal-to-noise ratio of only 20 dB, the maxi-mum relative error in thrust identification is only 3.56%. Thus, the proposed method exhibits highly accurate and robust thrust identification performance under low signal-to-noise ratio conditions. Conclusion The findings of this study can provide valuable insights for the real-time and high-precision monitoring of propeller thrust and shaft system status in actual ship environments.

Keywords

• kalman filtering
• thrust identification
• propulsion shaft
• displacement measurement
• online monitoring