Design Of Greenhouse Variable Spraying Robot System Based On Laser Sensor

Variable spray technology is an important way to avoid and cure insect pests in the greenhouse.This paper studies the significance of spray robot to improve pesticide application in the greenhouse which reduces cost and environmental pollution.In recent years,laser sensor with high detection precision,good stability performance and fast response has become a hot spot in the field of real-time data acquisition and processing.In this paper,a laser sensor is used to acquire the greenhouse path and the target plant in real time.The embedded microcomputer is used to analyze the raw data in real time,realize robot autonomous driving and variable spray control.The main work of this thesis is summarized in the following manner:(1)According to the relevant study on development of spray robots at home and abroad,the spray robot's mechanical structure and control system was designed.The hardware part of the spray robot is modular designed,the remote control module,motor drive module and solenoid drive module are designed based on STM32F407VET6 main chip.The software part used C and C++ programming language to complete the design and development of robot's driving control and variable spraying subroutine.(2)An autonomous robot-based variable spray driving control system is designed based on virtual target point prediction algorithm and local trajectory planning algorithm.The current position of the spray robot is determined based on the path and direction data collected by the laser sensor and an inertial measurement unit respectively in real time.Realized precision position determined in the greenhouse.The accurate prediction of the target point and real-time driving speed and direction of the spray robot is realized by combining pure tracking algorithm,a virtual target point prediction algorithm and a local trajectory planning algorithm for the greenhouse.The autonomous driving control system for the spray robot was deigned based on the kinematics principle,and the experiment is conducted to analyze the real-time stability of the spray robot from two aspects: Speed and angle.The experimental results show that the mean value of the real-time position and the planned position error of the spray robot is less than 3.00 cm when it drives in a straight line.And the mean value of the real-time position and the planned position error is less than 3.50 cm when spray turn around.The results demonstrate that the amount of overshoot is small and has better autonomous driving effect.(3)A laser sensor-based variable spray control system was designed based on detected plant geometry characteristics.During the spray robot's variable spray process,the SICK laser sensor collects the distance information of the target plant on both sides,and transfers the information to the microcomputer in real time.The target plant three-dimensional image is reconstructed by the data pre-processing of the embedded microcomputer and the accumulation method.Depending on the location of each independent sprinkler,the reconstructed 3D image of the target plant is segmented accurately to ensure that each sprinkler corresponds to a spray area.The total delay time of the spray robot is calculated and compensated according to the speed of the spray robot and the delay time of the spray system.The PWM wave duty ratio of the spray head in different spray regions is calculated by the real-time spray control method.The MOS tube array is used to control the opening and closing of the solenoid valves,and the independent and accurate variable flow spray of the spray robot is realized.Through indoor and greenhouse variable spray test,the accuracy and real-time variable spray are verified.The experimental results show that the maximum relative error of the actual spray amount and the total spray amount needed in the spray process of the robot is less than 10%,which can meet the precision requirements of the actual spray.The spray robot designed in this paper uses Hokuyo laser sensor and SICK laser sensor to collect the information of the greenhouse path and the target plant in real time.It combines the virtual target point prediction algorithm and the local trajectory planning algorithm to realize its independent driving.It combines the target plant model reconstruction,the spray region segmentation,the spray quantity control and the delay time.The method of inter compensation is used to realize variable spray of spray robot,which provides a theoretical and experimental basis for the development of greenhouse spray robot.