MEMS Vibration Sensor for Foreign Body Detection in Harvesting Machines
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Solution Overview
Problem
Existing foreign body detection systems in agricultural harvesting machines are inadequate in distinguishing vibrations caused by non-ferromagnetic objects from background noise, particularly due to the use of sensors with low upper limit frequencies and sensitivity to airborne noise, which leads to unreliable detection.
Innovation Solution
A device utilizing a micro-mechanical-electrical system (MEMS) vibration sensor connected to the axle of a conveyor roller, with a metal housing and circuit board for low-damping vibration transmission, allowing detection of high-frequency vibrations generated by foreign bodies, and an evaluation device that emits a warning signal when such impacts are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microphone or conventional vibration sensor is used to detect foreign bodies, then the detection system can identify foreign objects, but the sensor cannot distinguish vibration signals from background noise generated by moving machine elements
Solution Approach 1:
The patent changes the frequency parameter of the vibration sensor, selecting a sensor with an upper limit frequency of at least 4 kHz. This parameter change allows the sensor to detect high-frequency vibrations caused by foreign body impacts while filtering out lower-frequency background noise from machine operation, thereby improving both detection reliability and signal discrimination capability
Solution Approach 2:
The patent replaces conventional microphones or macroscopic vibration sensors with a micro-mechanical-electrical system (MEMS) vibration sensor. This substitution enables the system to capture high-frequency vibration signals with greater precision and reliability, as MEMS sensors have superior frequency response characteristics compared to traditional sensing devices
2Measurement precision
If a vibration sensor with low upper limit frequency is used, then the sensor structure can be simpler, but the sensor cannot detect high-frequency vibrations from hard foreign bodies
Solution Approach 1:
The patent employs a micro-mechanical-electrical system (MEMS) vibration sensor that integrates high-frequency detection capabilities into a compact structure. The MEMS technology enables the sensor to achieve an upper limit frequency of at least 4 kHz without proportionally increasing structural complexity, as the micro-scale construction inherently provides high natural frequencies while maintaining a compact form factor
3Ease of manufacture
If a macroscopic vibration sensor is used, then the sensor can be easily manufactured, but the sensor has low upper limit frequency and cannot detect high-frequency impacts
Solution Approach 1:
The patent replaces macroscopic vibration sensors with micro-mechanical-electrical system (MEMS) sensors. MEMS sensors are manufactured using standard semiconductor fabrication processes, making them equally easy to manufacture as conventional sensors while providing superior frequency response. The micro-scale construction allows these sensors to achieve upper limit frequencies of at least 4 kHz, enabling detection of high-frequency impacts from hard foreign bodies
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the signal-to-noise ratio and improves the reliability of detecting non-ferromagnetic foreign objects by focusing on the frequency range of vibrations caused by hard foreign bodies, reducing contamination and damage to the harvesting machine.
Implementation Method 1
The vibration sensor is connected in a vibration-conducting manner to the axle of a conveyor roller... vibrations excited by a foreign body impacting the conveyor roller are transmitted via the bearing of the conveyor roller to the axle and from there to the vibration pickup
Implementation Method 2
The vibration sensor is designed as a micro-mechanical-electrical system (MEMS). Such systems have dimensions in the micrometer range. Its upper limit frequency (-3 dB) is above 4 kHz
Implementation Method 3
In order to enable low-damping transmission of the high-frequency vibrations from the housing to the circuit board, the circuit board is glued to the housing
Data Source
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AI summary
The device has a vibration sensor such as micro-mechanical-electrical systems (MEMS) which is conductively connected to a vibration axis (58) of a conveyor roller (30) that is arranged relative to a rotatable drum (40). An evaluation device connected to vibration sensor, emits a warning signal if vibration sensor detects the penetration of foreign material into conveying roller. The sensitive frequency range of vibration sensor is above 4 kHz. An independent claim is included for harvesting machine.