Development of the magnetic separation device for surface cracks of delinted cottonseed

In seed processing for commercial production,the collision or friction between mechanical parts and seed is inevitable.These collisions or friction can cause cracks on the surface of the seed,which can affect germination rates and ultimately reduce crop yields.Using the difference of the seed motion trajectories with different crack degrees in the magnetic field,the grading of the surface crack seed can be realized.In this study,the motion law of seed in a non-uniform magnetic field was analyzed by taking the delinted cottonseed as an object.A magnetic separation device for crop seeds was developed.This device was essentially composed of the feed throat,magnetic roller,conveyor belt,and variable-frequency adjustable-speed motor.The magnetic powder adhering seeds enter the magnetic separation device through the feed throat and are conveyed to the magnetic roller through the conveyor belt.The magnetic roller has different adsorption forces on seeds with different degrees of cracking,and seeds fall into different outlets,thus completing the grading of the seeds.By adjusting working parameters such as the magnetic field strength and the speed of the conveyor belt,magnetic separation could be made.In order to verify the grading effect,the magnetic separation accuracy was taken as the inspection index,the magnetic powder’s mesh number,the mass mixing ratio between magnetic powder and delinted cottonseed,and the rotation speed of the magnetic roller were taken as the inspection factors.The response surface methodology was used to optimize the working parameters of the experimental device.The results showed that the optimal process parameters of the magnetic separation device were as follows:the number of magnetic powder meshes was 250,the mass mixing ratio between magnetic powder and delinted cottonseed was 1:20,and when the rotational speed of the magnetic separation roller was 20 r/min,the detection rate reached 92.5%.The designed magnetic separation device can realize the non-destructive batch detection of seed surface cracks with high work efficiency and has guiding significance for the high-precision and low-damage classification detection and classification of commercial seed.

Development of a PVDF sensor for potted seedling clamping force of vegetable transplanting

Aiming at the problems of loose bowl,nutritive bowl damage and planting leakage caused by lack of perception and detection of seedling clamping force in vegetable transplanting,a semi-micro-column structure sensor for measuring potted seedling clamping force was developed based on polyvinylidene fluoride(PVDF)piezoelectric film.The diameter of the semi-micro-column is 4 mm.The size of the force probe is 14 mm×30 mm,the encapsulation position of the force probe is 25 mm away from the tip of the seedling claw.The hardware circuit for sensor signal acquisition including pre-amplification module,power frequency notch module,low-pass filter module,processor module and power module was designed.The circuit completes charge-voltage conversion,clamping force signal amplification,power frequency signal elimination,vibration and noise elimination,and ensures the accurate acquisition of clamping force signal.In order to verify the sensor performance,sensor calibration tests and indoor experiments were carried out respectively.The calibration tests showed that the sensitivity of the clamping force sensor was 0.5264 V/N,the linearity was 4.74%,the accuracy was 6.51%,the hysteresis was 3.63%,and the range was 8 N under the impact of different waveforms and frequencies,which fully meet the accuracy requirements of the clamping force detection during transplanting.Indoor experiments showed that the clamping force sensor had good stability and adaptability under different seedling frequencies.The sensor can provide useful reference for the perception and detection of seedling clamping force and the feedback regulation of seedling clamping force.

Design and experiment of intelligent sorting and transplanting system for healthy vegetable seedlings

Healthy vegetable seedlings are surviving seedlings with good biological characteristics.Selective planting of healthy seedlings in the mechanized transplanting process can effectively avoid the reduction in yield caused by missed planting.Aiming at the current transplanting machinery that cannot achieve the selective planting of healthy seedlings,a healthy seedling intelligent sorting and transplanting system was proposed.The system consisted of a seedling delivery mechanism,sorting mechanism,photoelectric sensor,image sensor,PLC control system,and computer control system.It can realize automatic transmission of seedling trays,automatically identify the information of healthy seedlings in the trays and selectively transplant them.Also it can reduce the missed planting rate caused by the poor quality of plug seedlings after planting and the lack of seedlings in the hole.A sorting test of plug seedlings was carried out for the age-appropriate pepper plug seedlings cultivated in the factory.The results showed that the system had an average recognition accuracy rate of 89.14%and an average sorting success rate of 93.20%in the process of sorting suitable age pepper plug seedlings.The whole system can identify,sort and transplant the plug seedlings of appropriate age according to healthy information,and effectively avoid missing planting.This research can provide technical support for the intelligent upgrade of transplanting equipment.

Design and test of automatic detection platform for soil fragmentation rate in rotary tillage

As an important index of soil crushing performance of rotary tiller,the soil fragmentation rate is still limited to manual measurement.In this study,an automatic detection platform for soil fragmentation rate was designed,which integrated soil intake,screening,weighing and calculation of soil fragmentation rate.This platform can solve the problem that the index of the soil fragmentation rate cannot be detected quickly and effectively after rotary tillage,which leads to difficulty in field quality evaluation.The platform was mainly composed of a shovel soil module,conveying module,screening module,weighing module and automatic control system,which could realize single-line and multi-point automatic soil fragmentation rate detection.Based on the homogeneous dry slope model,the tilting angles of soil intake and soil feeding after rotary tillage on the platform were determined to be 30.10°and 26.67°,respectively.According to the principle of flow conservation,a rotary circulation screening module was designed to obtain soil particle size grading.A method based on the principle of multi-line and multi-point measurement was developed to detect soil fragmentation rate.The influence of screening speed on screening effect was analyzed,and the reasonable value of screening speed was determined to be 0.5 m/s.A field performance test was carried out in October 2019 to verify the detection performance of the platform.The results showed that,compared with the manual test method,the maximum test error was no more than 11%,the minimum test error was less than 4%,the maximum single test time was no more than 2 min,and the total test time of each test area was no more than 30 min.The efficiency of single-point detection was significantly better than the manual detection,which indicated that the design in this study met the requirements of rapid detection of soil fragmentation rate,and provided a new idea for the automatic detection of quality of rotary tillage.