# Research on a Combined Harvester Grain Loss Detection Sensor Based on Vibration Characteristic Optimization

## TL;DR

This paper improves grain loss detection in harvesters by optimizing sensor design and signal processing for better accuracy and reliability.

## Contribution

A novel sensor design and signal processing method are introduced to enhance grain loss detection accuracy in combine harvesters.

## Key findings

- Circular stainless steel sensing plates outperform rectangular plates in natural frequency and sensitivity.
- The developed sensor effectively distinguishes grains from impurities using FFT and high-level duration counting.
- Field experiments confirm the sensor's high accuracy and anti-interference ability in real-world conditions.

## Abstract

This article aims to improve the real-time monitoring accuracy of the loss rate for grain combine harvesters by optimizing the sensor-sensitive plate structure, thereby addressing the problem of low detection efficiency in existing equipment. Based on Kirchhoff’s thin plate theory, COMSOL 6.0 software was utilized to conduct modal analysis and single-grain impact tests on rectangular and circular sensing plates fabricated from three materials: stainless steel, aluminum alloy, and cupronickel. The circular stainless steel sensing plate was identified as the optimal structure, whose natural frequency and sensitivity significantly outperform those of traditional rectangular plates. By integrating a signal processing strategy based on FFT (Fast Fourier Transform) spectrum analysis (band-pass filtering: 1.0~3.0 kHz, voltage threshold: 3.5 V) and a high-level duration counting algorithm, the system effectively distinguishes between grains and impurities and resolves the counting errors caused by multi-grain impacts and secondary rebounds. Field experiments demonstrate that the developed sensor exhibits strong anti-interference ability and high measurement accuracy, providing reliable technical support for reducing harvesting losses.