Expanding the measuring range of MPS by n-order wave-array interference

To strengthen the signal intensity and expand the measuring range of the magnetostrictive position sensor (MPS), a new method using the interference of the wave array (IWA) was proposed in this study. Usually, a torsion strain wave was generated within the waveguide wire of MPS due to the Wiedemann effect. On the basis of the conventional MPS structure with single pulse and single cursor, we further developed a new structure that consists of multi-pulses and multi-cursors to generate a wave array with order n. Then, the wave interference occurred by adjusting the time interval of pulses and the space interval of cursors, which led the signal intensity and measuring range of MPS to be increased n times. After the analysis of the IWA work principle, a signal model was presented, and several experiments were performed to verify the feasibility of the new method. The signal of torsion strain wave at 28 m could be observed clearly in the experimental system with the IWA method of 12-order. According to the IWA method, the measuring range could still be increased with the increase in order n. Finally, the mechanism of how the IWA could enhance the signal and resolve the magnetostrictive nonlinear problem was further discussed. Moreover, the relationship between the limit of order n and the elasticity modulus E of the wire material was also discussed.