| Rice is an important food crop in China,it accounts for about 1/3 of China’s total grain output,so ensuring the stability of rice production is of great significance for China’s food security.Rice diseases,insect pests and weeds may burst and grow in the whole growth cycle.Annual loss of rice yield caused by diseases,insect pests and weeds is 400-500 million tons,which is one of the main factors that affect the stable and high yield of rice in China.Chemical pest control have highly efficient and fast,so far,it is still the most important and effective way to control rice diseases,insect pests and weeds.In recent years,the plant protection machinery in China has developed rapidly,but there is still a big clearance coMPared with the developed countries,especially the self-propelled high clearance wide range sprayer,which is suitable for the paddy field,which has the problems of low spray quality,poor uniformity and low degree of automation.At present,the mixture mode of the sprayer is mostly premixed,which cannot change the concentration of the liquid and realize the spraying on demand,and the residual liquid cannot be recovered and the operator is more harmful.The wide range paddy sprayer has greatly improved the efficiency of the working performance.As the hard bottom of the paddy field is different,the sprayer changes the posture frequently in the field.Leading to the slanting of the boom,spray height changes,the quality of the spray operation decreased.It is easy to cause uneven spray,less spray and multiple spray.In order to further improve the sprayer working performance and meet the development needs of the modern agriculture.In this paper,the on-line mixing medicine and boom attitude control technology is studied based on the high ground clearance paddy sprayer.The main research contents and results are as follows:(1)Designed an online mixed drug precision pump system.Set up the displacement model of the precision plunger pump、 determine the parameters of each model and designed the precision pump control system so that accurate pumps have been implemented.The maximum error of the precision pump control is 0.76%.The mixture ratio test and mixing uniformity test were carried out on the platform of high ground clearance paddy sprayer.The test results showed that the maximum error of the mixture ratio was 2.5% and the maximum of the uniformity of the mixture was 4.35%.(2)The automatic regulation system of the height of the spray rod is designed,which includes the height automatic regulation mechanism of the spray rod,the ultrasonic distance measuring sensor and the height control system of the spray rod based on the ultrasonic sensor.The dynamic response test results of the boom automatic adjustment system show that the height response time of the spray rod is within 60 ms,the rise of the spray rod and the drop speed of the spray rod are 58mm/s and 109mm/s,respectively.Simulating the field operation environment and testing the adjustment performance of the boom height control system under different operation conditions.The test results show that the height of the boom can be effectively controlled,and the absolute error value of the height control is 9.09% under different working conditions.(3)The automatic leveling system of the boom is designed,including automatic leveling mechanism,body inclination sensor and automatic leveling control system.The body tilt sensor obtains the obliquity by using Kalman filtering algorithm to fuse MEMS inertial accelerometer and gyroscope sensor data.The three axis multi function turntable is used as the test platform to simulate the field of the sprayer in the field,and the measurement accuracy of the body tilt sensor is tested.The test results show that the maximum error of the tilt angle measurement is 0.89 degrees,and the maximum error of the simulated turning is 0.50.Base on the platform of the high ground clearance paddy sprayer the tilt angle of the spray locomotive and two MTI-300 high precision inertial sensors are used to measure the dip angle of the sprayer.The experimental results show that the absolute error,the root mean square error and the maximum error of the tilting angle increase with the increase of vehicle body inclination rate.Among them,the maximum mean absolute error is 0.90 degrees,the maximum root mean square error is 1.39 degrees,and the maximum error is 1.70 degrees so we can draw the conclusion that the change rate of vehicle body inclination has great influence on the control accuracy of boom.(4)On the basis of the on-line mixing control system,the automatic control system of the height of the spray rod and the automatic leveling control system of the spray rod,not only integrated the control system of the high ground clenrance paddy sprayer,but also designed the overall structure of the software,which including the CAN(Controller Area Network)information solution of the ultrasonic distance measuring sensor and the auto body angle sensor,the work flow of the software main program,the online mixing control,the spraying rod elevation automatic control and the spraying rod automatic leveling control subroutine.(5)Field experiments were carried out for field mixed spraying and boom attitude control system of high ground clearance paddy sprayer,included on-line mixed drug system test(including mixing uniformity test and mixing ratio test)and boom attitude control test.Uniformity test of mixed pesticides using carmine solution simulates pesticides those test result shows that the system increases with the mixture ratio from 200:1 to 1000:1 under the 3 kinds of spray pressure of 0.8MPa,1.2MPa and 1.4MPa.The coefficient of variation increased and the uniformity of mixed drugs decreased.The uniformity of mixture is lower than that of static test when the maximum coefficient of variation is 5.56%.By simultaneous measurement of water and liquid quantity calculation of actual mixing ratio,the maximum error of the relative mixture ratio is less than 6.98%.The attitude control test of the boom is carried out by using the K728 GNSS vehicle orientation and orientation card to measure the data of the boom height and horizontal dip angle.The test results show that in paddy field,the posture range ability of the spray rod is obviously reduced,and the speed of the sprayer has a great influence on the posture adjustment precision of the spray rod.In one hand,the maximum absolute error of the relative level of the spray rod is 4.63 cm,in the other hand the maximum error of the root mean square error is 5.14 cm and the maximum error is 17.8cm.The maximum error of the flat average of the spray rod relative to the horizontal plane is 0.79 degrees,meantime,the root mean square root is the root mean square root.The mean square root error is 0.85 degrees and the maximum error is 1.70 degrees.The system can meet the field application requirements of high ground clearance paddy sprayer. |
