Research On Path Planning Method Of Unmanned Tractor

Precision agriculture is the future development direction of agriculture.Unmanned tractors have gradually become the hotspot of scientific and technological research in recent years.The equipped automatic navigation technology is an important carrier of the development of precision agriculture,and path planning technology is one of the key components of the automatic navigation technology of tractors.First of all,GPS/BDS is used in this paper to collect the vertex coordinate information of the plot and carry out two-dimensional modeling.Based on the analysis of the advantages and disadvantages of five walking modes of agricultural machinery,the shuttle method was selected as the walking mode of tractor,the relationship between the minimum turning radius and operating width was compared to select the appropriate ground turning mode,and the optimal working Angle was obtained by combining the factors of different working conditions of the tractor.The concave plots and complex plots that need to be divided shall be divided by "sweep line method".The sub-areas shall be connected according to the optimized order of "top-down and right-to-left",and the path planning of each sub-plot shall be carried out separately.Secondly,according to the relationship between the abscissa of the end point of the parcel boundary vector,the offset direction of the parcel boundary is judged,and the actual operation area is constructed by combining with the different turning width of the headland.Combined with tractor,agricultural machinery and other basic parameters,the pear shaped and bow shaped turning trajectory was constructed by using geometric reasoning method.According to the "top-down,left to right" principle,the turning and straight-line path were connected into a complete global operation path.Thirdly,the risk assessment of obstacles is carried out by using the real-time acquisition of obstacle characteristic information by lidar.For the dynamic threat obstacle,the parking obstacle was used to avoid the obstacle,and for the static threat obstacle,the three-section circular arc path was used to construct the obstacle avoiding path based on the global path,and the multi-adjacent small static obstacle avoiding method was designed.The global path of offline planning was combined with the local path of realtime planning to form a complete field operation path,which ensured the global optimality and local real-time performance of field operation path.Finally,the path planning system software of the unmanned tractor was designed with LabVIEW to realize the complete field path planning algorithm,and the land,obstacles and related parameter information were set in the software to test under different working conditions.Real-vehicle tests were carried out based on HT-1504 D real vehicle platform to verify the effectiveness of the algorithm.The test results show that the algorithm software can plan the corresponding global path under different plot models and working conditions,and can plan the corresponding local obstacle avoidance path in real time according to the obstacle information,so as to meet the full area coverage and real-time coverage of the plot.Obstacle avoidance requirements have strong versatility and practicability,and can be used as a reference path for unmanned tractors to operate in the field,which has practical significance.