Control System Research And Design Of Automatic Detection And Alarm For Rice Storing Humidity

In large-scale reserve grain depot, purchased grain can cause the storage to mildew because of the excessive moisture. At present, manual random inspections are hard to control the humidity befor the grain is garnered in.Only when the excessive moisture have affected the appearance and odor can grain be checked out. How to detect the humidity of on-line transporting grain by detectors befor store it into warehouses is an important topic of concern, in order that preventing the disqualified grain at the access for improve the quality of stored grain.At present, methods detecting humidity at home and abroad are use psychrometers and electronic humidity sensor. The purpose of this paper is to explore the method of real-time humidity detection during unpacked transport befor the grain be stored up for large-scale reserve grain depot,at the same time give alarms to inform the inspectors in time and automatically control the transport.A grain humidity measure system befor storing up is desiged based on AT89C51 that is widly used in instrumentation fields.The conversion of humidity into electric signals is realized by humidity sensor JCJ100D,and A/D is completed by ADC0809 and humidity display implemented by shift register 74LS164 .Finnally the grain humidity is analysised for cutting off the motor and alarm so that the wet grain can be prevented to transported into depots.This pager studies and analysis the principle of the humidity measure alarm control system on the basis of full research of it at home and abroad,and focuses on the design of the system's hardware and software.In the respect of hardware design, according to the precision, time and the cost of the detector, appropriate components is selected.The whole hardware system is divided into several modules to design respectively following the theory of module design. When each module is adjusted successfully, we combine them into a complete entity to ensure the high quality of hardware and makes it easy to test and maintain.In the respect of software, according to the predicted function of this detector and the design of the hardware circuit, the software is specified as follows: MCU and system chips initialization, analog signals sampling, signal processing, real time display , serial port communication, motor control interface design of PC and programe of serial port communication of MCU, and program interface design serial port communication and data processing etc. As the system is calibrated and tested and the grain humidity is measured several times ,we completed the collection of the humidity signal and the real-time display of LED,at the same time real-time data can be uploaded to the PC for data preservation and processing.The measurement accuracy of the system is 1.005%.Data acquisition and preservation is done 3 times/sec. It has been proved that the system can work steadily and measured accurately, so it has reached the design requirement basically.