Research And Application Of UAV Obstacle Avoidance Based On Improved VFH Algorithm

With people’s life more and more intelligent,the application of four-rotor unmanned aerial vehicle(UAV)is more and more extensive.The flexible three-dimensional motion characteristics of four-rotor UAV and the complexity of space motion planning also greatly expand the development direction of UAV in the field of automation.This paper will select vector field histogram(VFH)algorithm to study the four-rotor UAV in unknown map,urban living area type and other unfamiliar environments,focusing on the introduction of visual sensor information,improving the data reduction process and cost function of the twodimensional VFH algorithm to adapt to the three-dimensional environment,in order to shorten the flight time,reduce the failure rate of obstacle avoidance,and finally ensure the UAV to reach the designated target point more efficiently,safely and stably.Compared with the original VFH mobile robot algorithm,the two-dimensional horizontal path is better,and the upper path of obstacles can be selected under appropriate conditions.Compared with the three-dimensional SLAM(simultaneous localization and mapping)obstacle avoidance scheme,the sensor cost is low and the algorithm complexity is reduced,thus the realtime performance is greatly improved.Firstly,the research background and significance of robot obstacle avoidance algorithm and the research status at home and abroad are analyzed.Secondly,the motion characteristics and common obstacle avoidance techniques of UAV,the basic principle of improved VFH algorithm in obstacle avoidance application are carefully verified.This thesis completed the following research content:(1)Propose an obstacle image processing method.According to the direction selection of the VFH algorithm under the condition of obstacle avoidance and the characteristics of the obstacle suitable for vertical direction movement,the obstacle information is calculated.Based on gray scale and maximum entropy threshold method,Prewitt edge operator is used to obtain the data of obstacle width and height on the center line of the picture.Experimental results show that this method can effectively extract obstacle information from simple contour and less texture scenes.(2)Propose an improved vector-based histogram algorithm by calculating the volume of UAV itself,the obstacle histogram is binarized,monocular vision sensor is introduced,and the obstacle height and width information extracted by image processing algorithm are fused to form a new moving cost function.The optimal vertical and horizontal steering angles are selected under the condition of safe distance and target.Experimental results show that in the environment of unknown map and urban residents living area type,compared with the traditional VFH algorithm,the proposed algorithm can achieve good three-dimensional obstacle avoidance effect,and has high application and reference value.