无人驾驶农机避障路径跟踪仿真与验证

    Simulation and verification for obstacle avoidance path tracking of unmanned agricultural machinery

    • 摘要:
      目的 为便于验证无人驾驶农机避障路径跟踪的效果,减少实际无人农机试验次数与消耗,设计一种无人驾驶农机避障路径跟踪仿真验证方法,构建一个仿真验证应用系统。
      方法 以无人农机为基础,集成真实复杂地形环境仿真、实际作业农机仿真和路径规划算法植入,构建一个一体化仿真验证应用系统。基于三维SLAM技术,采集环境点云数据,实现农田地形环境仿真建模,构建阿克曼转向机械结构的农机仿真建模,提出一种基于农机动力学约束的TEB局部路径规划算法;在仿真验证应用系统中实现路径规划跟踪及避障,并通过多次测试验证该算法的有效性。
      结果 避障路径跟踪有效性对比测试和避障路径跟踪平顺性验证测试结果表明,无人农机行驶过程中可有效动态避障,最短有效避障距离为4.1 m。路径跟踪控制效果良好,障碍物距离大于5.0 m时,可控平均误差≤0.4305 m,均方根误差≤0.3151 m;障碍物距离在4.5~5.0 m时,可控误差均值≤1.3538 m,均方根误差≤1.6126 m。
      结论 本文提出的改进TEB算法具有较强的作业能力以及较高的作业精度,满足农业机械导航避障路径跟踪仿真验证的需求,该算法可应用于无人农机在实际农田环境的避障路径跟踪。该应用系统易于扩充,为精准农业中针对各种复杂作业环境的农机运作状态的优化设计研究提供基础。

       

      Abstract:
      Objective In order to facilitate the verification of the effectiveness of obstacle avoidance path tracking for unmanned agricultural machinery, reduce the number of actual unmanned agricultural machine tests and consumables, a simulation verification method for obstacle avoidance path tracking for unmanned agricultural machinery was designed, and a simulation verification application system was constructed.
      Method Based on unmanned agricultural machinery, an integrated simulation and verification application system was constructed by integrating real complex terrain environment simulation, actual operation agricultural machinery simulation, and path planning algorithm implantation. Based on three-dimensional SLAM technology, environmental point cloud data was collected to achieve simulation modeling of farmland terrain environment. A simulation modeling of agricultural machinery was completed using unmanned agricultural machinery combined with ackermann steering mechanical structure. A TEB local path planning algorithm based on agricultural machinery dynamics constraints was proposed. Path planning tracking and obstacle avoidance were implemented in the simulation verification application system, and the effectiveness of the algorithm was verified through multiple tests.
      Result The comparison test of obstacle avoidance path tracking effectiveness and the verification test of obstacle avoidance path tracking smoothness showed that the unmanned agricultural machine could effectively avoid obstacles dynamically during driving, with the shortest effective obstacle avoidance distance of 4.1 m. The path tracking control effect was good. When the distance between obstacles was greater than 5.0 m, the controllable average error was within 0.430 5 m, and the root mean square error was within 0.315 1 m. When the distance between obstacles was 4.5−5.0 m, the controllable average error was within 1.353 8 m, and the root mean square error was within 1.612 6 m.
      Conclusion The improved TEB algorithm proposed in this article has strong operational capability and high operational accuracy, which meets the needs of simulation verification for obstacle avoidance path tracking in agricultural machinery navigation. This algorithm can be applied to obstacle avoidance path tracking of unmanned agricultural machinery in actual farmland environments in the future. This application system is easy to expand and can provide a foundation for the optimization design research of agricultural machinery operation status in precision agriculture for various complex working environments.

       

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