Noise Reduction Study of Signal Detection in Hall Sensors by Modal Analysis

Nowadays, based on the collected magnetic signals by sensors, mineral sorting machines can separate iron ore rapidly. However, there are too many interfering signals to reduce the accuracy of the ore separation. For mineral sorting machines, frame resonance is one common factor and it generates interference signal such that the collected magnetic signals contain many noise. Thus, to batter collect the signal from sensors, it is necessary to reduce the frame resonance. To deal with this problem, this paper establishes a finite element assembly model of the mineral sorting frame by SolidWorks. Then, ANSYS Workbench is adopted to obtain the natural frequency and vibration mode of the mineral sorting frame in the free-state. Besides, the effectiveness of the theoretical analysis is verified by comparing the modal test and simulation results. Based on the characteristics of external excitation frequency, the motor parameters and frame structure are adjusted respectively. The results show that, when the motor speed is 200 r/min, the corresponding meshing excitation of chain-driven frequency is 66.670Hz. Further, to reduce the meshing excitation frequencies of the chain-driven, the connecting beam is installed on the upper level of the frame. In this way, the frame resonance could be avoided effectively such that the related noise is removed and sensors can collect high quality signals.