Development And Research Of 3D Target Detection System Based On Laser Scanning Sensor

Variable spray technology using intelligent method and control strategy to achieve precision spraying according to the need, can effectively improve the utilization rate of pesticide, reduce non-target deposition and reduce pollution of the environment, promote the sustainable development of precision agriculture. The accurate detection of three-dimensional target information is the prerequisite and basis for the implementation of intelligent variable spray. In recent years, with the development of real-time sensor technology, laser sensor has the advantages of high detection accuracy, stable performance, not being affected by the lighting and so on,compared with the ultrasonic and infrared sensor. Therefore, the variable spray target detection based on laser sensor has become a hot research issue. Using UTM-30 LX laser sensor with wide viewing angle and high speed as real-time three-dimensional target detection device, the indoor slider table three-dimensional target detection system and outdoor electromobile three-dimensional target detection system are designed and developed, and the accuracy of the laser sensor to detect the regular objects, trees and other complex three-dimensional targets is analyzed. The following research will be done:(1) Taking linear slider as a campaign platform and a servo motor as driving device, an indoor three-dimensional target detection system is built to verify the accuracy of the laser detection in the indoor condition. The laser sensor is mounted on the slide block of the linear slider. Through servo motor to control the movement of slide block, the speed and the motion distance of the laser sensor can be controlled precisely.STM32f103VET6 MCU is used as the core of control unit so as to design hardware circuit and software program. The hardware circuit includes MCU minimum system, power conversion, switch button input, data communication, servo motor control, photoelectric tachometer. The software program includes human-machine interface, system initialization, switch key input, data communication, servo motor control, distance speed detecting and other data processing program.(2) An outdoor three-dimensional target detection system is built to simulate the uneven pavement, machine vibration and other actual detection environment. In order to further verify the accuracy of the laser detection in the open air, the system takes electromobile as the power equipment for real-time scanning and detection of the laser sensor. Information of speed concerned the electromobile during the process of experiment can be obtained by the speed calibration test before experiment.(3) Taking regular object, artificial tree and actual tree as the experiment targets,the combination experiment of different distance and different sensor’s moving speed is designed on the basis of indoor and outdoor three-dimensional target detection system. During the experiments, target objects will be scanned in real time, and contour data will be acquired and stored by the data acquisition software urgbenri of the laser sensor. Taking matlab software to analyze the data off-line,reconstruct the target images, and extract the characteristic value of the target sizes of the laser scanning measurement. Compared with the manual measurement, the maximum relative errors of the measuring errors were less than 7.40% and 6.50% respectively in indoor and outdoor experimental conditions by using laser sensor.(4) However, due to the irregular structure of the trees, another evaluation method based on the similarity of boundary distance field can be introduced here,which quantitative analyze the contour of images scanned by laser sensor and taken by camera to figure out similarity degree. The calculated values of image contour similarity were large than 0.9200 and 0.8900 respectively in indoor and outdoor experimental condition.(5) By analyzing the data of measurement accuracy and similarity of contour,under indoor and outdoor experimental environment with different detection distance and sensor movement speed, the target detection based on UTM-30 LX laser sensor has high accuracy and be able to provide effective spray quantity basis for the implementation of variable pesticide spraying.