| To address the issue of missed seeds during the seeding caused by the mechanical precision seeder during its operations,a seed miss prevention system for the mechanical precision seeder was designed with the goal of real-time seed monitoring,real-time feedback in case of the missing seeds,and automatic seed compensation for missing seeds.The research focused on using laser detection to identify missing seeds and increasing the speed of the seed metering wheel as a means of seed compensation(seed miss prevention).The design and testing scheme of the seed miss prevention system was determined through theoretical analysis,MATLAB simulation modeling analysis,feasibility verification experiments,and bench tests.This study provides theoretical and technical support for the development of missing sowing detection and seed miss prevention system.The main research contents and conclusions are as follows:1.Modeling and simulation analysis of seed miss preventions system.A physical domain model,a multi-body simulation model,and a control algorithm model for the seed miss preventions system were established using MATLAB/Simulink software.Step or sinusoidal speed mode was used to simulate the missing sowing of one or two seeds,and the simulation results showed that the method of continuous seeding by increasing the rotational speed to skip the missing groove can effectively solve the problem of missing seeds,validate the feasibility of the seed miss preventions system.2.Design of the structure of the seed miss prevention system and laboratory equipment.Based on the theoretical model of the seed miss prevention system and the speed variation seed miss prevention method,a laboratory device was designed to test the effect of the selfseed miss prevention system.The device mainly includes a groove-based mechanical precision metering device driven by a stepper motor(with through-holes on the grooved wheel for laser scanning),a microcontroller unit(MCU)that receives the missing seeding signal from the sensor and controls the stepper motor for speed-up action,and a horizontally placed laser sensor to detect the missed seeds.This platform provides technical support for conducting performance tests of the seed miss prevention system.3.Analysis of the performance of the seed miss prevention system.The number of seed misses,the rotational speed of the seed metering device,the number of consecutive seed misses,and the variable speed mode were taken as experimental factors,and the seeding time interval was taken as the experimental indicator to conduct feasibility verification experiments on the seed miss prevention system.Specifically,(1)when testing with polyoxymethylene balls,the enabled system can effectively maintain the frequency of seeding time intervals showing a normal distribution trend,and the overall amplitude of the variation of the seeding time interval error is smaller than that when the system is not enabled;(2)when testing with pea seeds,disabling the system resulted in the seed release time interval being significantly higher than the theoretical value,and 203 seed miss occurred in 6 control treatments.When the system is enabled,the seed release time interval is close to the theoretical value,and only1 seed miss occurred in 12 tests.The overall experiment shows that the seed miss prevention system can effectively prevent the occurrence of seed misses through the speed variation compensation method.4.Design and evaluation of seed monitoring system for single seed precision metering devices.The monitoring device is mainly composed of a housing,a planar laser,7photoelectric transistors,and a printed circuit board(PCB).It can form a scanning plane through the planar laser and 7 photoelectric transistors to capture seed release interval data and send the obtained data to the corresponding device for automatic storage via low-energy Bluetooth technology.When verifying the performance of the seed monitoring device,soybean seeds,and polyoxymethylene balls were used to test the monitoring device,and the results showed that the monitoring device is suitable for rapid seeding monitoring of precision seed metering devices or Internet of Things(IoT)devices in seeding machines.5.Design and testing of a new seed miss prevention system.Based on the previous research,the second-generation seed miss prevention system was designed to better adapt to real crop seeds.The system consists of a seed metering device and electrical hardware,which is integrated into a PCB board developed with Proteus.The laser emitter and micro-sensing device were embedded in the housing,and the hardware design was simplified by supplying power to the stepper motor and controlling electronic devices through an independent power supply.The software was developed using Kotlin programming language and Android Studio,which integrates control,detection,and feedback functions.The software can communicate with the microcontroller unit(MCU)in the seed miss prevention system through low-power Bluetooth technology,making it easy to remotely turn on/off the device,set the speed of the seed metering device,and count the number of missed seeds on a mobile phone.Through testing with soybean seeds,it was found that there were no missed seeds in both the systemenabled and system-disabled conditions at 2 r/min.At 5 r/min,the missed seed index dropped from 0.2%(system-disabled)to 0%(system-enabled).At 10 r/min,the missed seed index dropped from 0.2%(system-disabled)to 0%(system-enabled).At 15 r/min,the missed seed index dropped from 1.3%(system-disabled)to 0.1%(system-enabled).At 20 r/min,it dropped from 1%(system-disabled)to 0%(system-enabled).At 25 r/min,it dropped from 3.3%(system-disabled)to 0.03%(system-enabled).Overall,the system has a good speed selfcompensation effect,and the seed miss prevention becomes more obvious as the speed of the seed metering device increases. |
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