Research On Obstacle Avoidance Technology Of Plant Protection UAV Based On Laser Displacement Sensor

Compared with the traditional manual spraying and ground mechanical application,UAV plant protection in the convenience,safety,spraying efficiency,water saving and other aspects of medicine have a more significant effect.In recent years,the domestic plant protection unmanned aerial vehicles to remote control multi-rotor models the fastest growing,this model is more suitable for open areas without obstructions to operate;and large areas of plant protection operations in China are more distributed in the wire Rods,trees,towers and even houses and other obstacles to the safety of UAV flight,artificial remote-controlled semi-automatic models difficult to meet the needs of these areas of plant protection operations.Domestic and foreign-related enterprises and research institutions are vigorously developing more intelligent plant protection UAV.As one of the key technologies of fully automatic model of plant protection UAV,automatic obstacle avoidance has important research and application value.The main work of this paper includes:(1)Based on laser displacement sensor technology,a new obstacle avoidance method is proposed for plant protection unmanned aerial vehicles.The method includes three parts: data block extraction,obstacle basic parameter calculation and obstacle pattern recognition.Based on the validity of the distance value,the data block is extracted from the data sequence.The average angle,average distance and width are used as the basic parameters to describe the obstacle.Based on the width of the obstacle,the maximum gap of the data block,The number of jumps and the variance of the characteristics of the pattern recognition classifier design.Finally,a set of laser displacement sensor is designed on the FLYING-BOX model.The data acquisition module of the obstacle avoidance system is designed by laser displacement sensor,PICO-CV01 industrial computer and lithium battery.(2)Completed the obstacle avoidance system software design.The obstacle avoidance software is divided into three parts,the detection part,the action part and the exception processing part.The detection part includes preflight self-test,data acquisition,data processing and pattern recognition.In the motion part,a set of obstacle avoidance strategy is designed for the UAV and the necessity of the motion correction in the obstacle avoidance is described.The method of correcting the detection distance according to the pitch angle and correcting the detection angle according to the yaw angle is proposed.Then it analyzes the factors that influence the instruction generation and the process of instruction generation.The exception handling function is distributed in the detection part and the action part.It is responsible for monitoring the running status of each sub-function in the whole obstacle avoidance system,and generating the corresponding error code and uploading the upper computer once error occurs in one or more places.The upper computer will respond differently depending on the situation.(3)Finally,the validity of the obstacle avoidance system and the effectiveness of the obstacle avoidance system are verified experimentally.The first experiment verifies the obstacle detection accuracy of the obstacle avoidance system.The second experiment verifies the obstacle detection accuracy of obstacle avoidance system.The third experiment verifies the accuracy of the obstacle avoidance system for the detection of the obstacle,including the angle value,the detection accuracy of the distance value and the accuracy of pattern recognition.The fourth experiment,is the outdoor flight test,verify whether the UAV in accordance with pre-designed obstacle avoidance strategies to complete the dynamic obstacle around the fly.Experiments show that the laser displacement sensor based obstacle avoidance system can effectively detect the angle and distance of obstacle in unknown environment,and can make a more accurate type discrimination of typical obstacle in plant protection environment.The dynamic obstacle avoidance in the flight process proves the validity of the obstacle avoidance system based on the laser displacement sensor.