Design And Implementation Of Land Flatness Evaluation System Based On Laser Sensor

The land flatness has great correlation with irrigation, runoff, soil water infiltration rate and surface ponding, it’s a very important index in agricultural saving water. Because of the far distance of sampling point, low precision, long measurement time, short range of laser sensor and high price, the land flatness evaluation system based on laser sensor was designed in order to achieve the goal that collecting and dealing data of land flatness automatically in the whole process through coordination of electrical equipment and get three dimensional terrain figure. The main research contents and conclusions are as follows:(1)According to the requirement of function and technology, the general system was designed. It is mainly constitute of a micro control unit (MCU), a stepping motor, a laser sensor and a two dimensional mechanical platform. After analyzing all the possibilities, the main device was confirmed, STC12C5A60S2MCU was chosen as lower computer which send pulse signal and direction signal to drive stepper motor to make the slider move along the two dimensional mechanical platform and plan metric position was gotten. While three-dimensional terrain was gotten as elevation was measured by LRFS-0040-1laser sensor which adopts phase comparison principle. The upper computer connect with MCU and achieve the goal of data display, data storage and data dispose. The land flatness was evaluated by analyzing the Standard Deviation (SD) of elevation and the Absolute Deviation (AD) between relative elevation and expected elevation.(2)According to the system scheme, both the software and hardware of lower computer and upper computer were designed. The main part of lower computer hardware are MCU circuit, Power circuit, Buck regulator circuit, Reset circuit, Crystal oscillator circuit and Serial port communication circuit, while the software complete its design of system initialization,stepper motor running,serial port interrupt receiving data from the sensor and communication which are realized by C language. The main task of upper computer are drawing interface and realizing system initialization,setting serial port,receiving data,showing data and storing data.(3)Debugging the whole system, the results show that the upper computer accomplish the function of monitoring the three-dimensional data and the lower computer accomplish the function of controlling the start and stop of the motor, running of the motor and changing direction of the motor. The results show the system is in normal operation.(4)Calibration experiment was carried out, the results show that the measurement system running smoothly and the error is less than5millimeter which can evaluate land flatness.(5)Field experiments were carried out to compare the land flatness between freely selected land A and land B. The SD of land B is less than land A and the percent of AD less than2cm of land B is more than land A. The results show that two indexes SD and AD can be used to evaluate land flatness.