Design and Testing of an Impact Sensor Using Two Crossed Polyvinylidene Fluoride (PVDF) Films

Impact sensors are widely used to detect grain losses in harvesters. Using polyvinylidene fluoride (PVDF) films as sensing elements is a promising way to improve sensor performance due to their high sensitivity, stability, and flexibility. However, the overlap of collision signals significantly reduces the accuracy of a sensor. To solve this problem, a novel impact sensor with two crossed PVDF films was designed and investigated. This sensor has two orthogonal layers of sensing elements that both respond to impacts, which creates positioning information for the impacts. Because of the sensor's structure, a signal processing method was designed based on multisensor fusion theory. Tests were performed to verify the performance of the proposed impact sensor. The average signal-to-noise ratios (SNRs) for impacted PVDF films were 34.79 and 20.23 dB, respectively, for the upper and lower layers, while the average signal-to-clutter ratios (SCRs) for nonimpacted films were 21.90 and 10.05 dB, respectively. The sensor also has an extremely high detection efficiency of at least 1528 collisions per second and can identify particles that impact at the same time.