steel grade
2011年5月4日 by admin
steel grade, as an effective tool for preventing soil contamination, is very important to increase the yield and income at present. Using pesticide depends on the development of the equipment for crop protection. If the equipment for crop protection is not advanced or pesticide is used improperly, it may result in a series of bad consequence, such as medicine damage, drug resistance, the poor quality of agriculture products, cost rising, and environment worsens. In this paper, a variable spraying system based on a prescription map was studied and developed with a S3C44B0 microcontroller. In this system, electronic technology, variable control technology and information technology were combined in a spraying machine. The goal of this paper is to accomplish a variable spraying according to weed distribution in the farmland to raise the utilization rate of pesticide and reduce ecological environment contamination.This variable spraying system was granted by National high-tech research and development project （2006AA10A309） and the national 11th Five-year technology based plan topic （2006BAD11A08）. The research results are as follows:（1） A variable spraying system was composed of a variable spraying control system and a set of spraying pipe.‘Bypass pressure control model’was selected after examining the three kinds of control ways which were pressure control, flow control and changing medicine concentration and considering the characteristic of incompressible fluid in the bypass pipe. The opening size of nozzle was controlled by the electric control valve in the bypass pipe. The change range of electric control valve was 0.02.0V. The experiment results showed that there was an exponential function relation between control valve voltage and pressure in the pipe and there exists an exponential function relation between the control valve voltage and the spray flow.（2） Variable spraying controlling system was developed. The hardware of it consisted of a variable spraying controller, a real time signal collection system, an executor, a power supporting unit. The variable controller was developed with a S3C44B0X microcontroller. Drive circuit of electric control valve consisted of shift register 74HC595, D/A chip DAC0832 and an amplifierμA741. The filter circuit for receiving the digital signals was made up of an optically coupled isolator TLP521 and hex inverting Schmitt trigger 74HC14 to collect the signals of velocity and flow. An operational amplifier OP07 and an adjustable precision shunt regulator TL431 were used to gather signals of the pressure in the pipe. The Power supporting unit consisted of 12VDC220VAC inverter, 220VAC24VAC transformer, 5VDC and 24VDC power module. And design ideas involved were described in detail.（3） In the UCOS-Ⅱoperation system, C-language and ARM assemble language were used to program for the variable spraying control system. The software includes signal collection and analysis, dead reckoning and grid recognizing, controlling the electric valve, real time recording operating parameter and touch input module. Three work modes were available, these were manual or automatic control with GPS positioning and dead reckoning automatic control without GPS. Signals of position and vehicle of the machine were collected by using the timer and counter in the signal collection and analysis module. Pressure signal was collected by the A/D convertor embedded in the S3C44B0X microcontroller. In order to accomplish the close-loop control in the variable spraying system, pressure signal was selected as a feedback signal to correct the output. When the system works in the field, the variable spraying controller csteel gradean execute different variable spraying operation depended on the work mode selected. Besides, additional functions such as power-off protection, pause, restore and real data record of operating parameter were designed to return to an original state when an abnormity interruption occurs.（4） A grid division was developed by Object ARX to meet data storage in the Auto CAD2000 platform. The software function included GPS file opening, drawing foul line of the farms, checking, picking up and saving information of longitude and latitude in the working grids. Three new algorithms which were by means of calculating orthogonal, triangle area with the determinant and summing of inner angle were deduced for grid recognition with GPS, and a grid recognition algorithm fosteel grader the dead reckoning was provided when working without GPS in the field. It will be a theoretical base for the grid recognition.（5） Tests and field applications were carried①Test results showed that droplet size, nozzle spray angle and deposit of droplet were diminished with electric control valve voltage increasing when the control voltage was changed form 0.0V to 2.0V. Leaking spurts could be avoided when the height of nozzles from ground is 603mm. The max variation coefficient of droplet distribution was 5.31%. The delay time was 1.81s, 1.57s and 1.51s respectively in the manual or automatic control with GPS positioning and in the dead reckoning without GPS.②Field spraying works were carried out in 2009 and 2010, which the sum of working area was coved 10hm2. The result of field experiment showed the grid identification error with GPS positioning was 2.975%. The positioning error was less than 6% while the operation grid is 40m×40m and operation ridge length was less than 1440m with the method of dead reckoning. The experiment was done under the following conditions: the soil water content was 17.3%, the soil compaction and the average intensity of pressure 6cm under the soil surface was 26.74kg and 1909.2 kPa, when the soil compaction and the average intensity of pressure 16cm under the soil surface was 44.46kg and 1934.4kPa. The max of relative error was less than 5% when the dosage was 275kg/hm2600kg/hm2.The achievements of this paper are as follows: a variable spraying system is studied and developed with a S3C44B0X microcontroller. The system works in three modes which are manual control, automatic control with GPS positioning or without GPS. The functions include power-off protection, pause, restore and real time record of working parameter. Three new methods and an algorithm are deduced respectively for the grid recognition with GPS and the dead reckoning without GPS. The grid division software is developed by using Object ARX in the AutoCAD. Comparing with other spraying systems, the advantages of this system are as follows: convenient operation, simple structure and precision, and good for protecting environment at present.steel grade
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