林木联合采育机机械臂避障路径规划

Obstacle Avoidance Path Planning of Manipulator of Forestry Felling&Cultivation Machine

【目的】针对林木联合采育机在林区复杂环境中的避障作业要求,提出一种新型机械臂避障路径规划方法,为林业机械装备发展提供理论依据。【方法】首先,对林木联合采育机机械臂进行运动学分析,同时为解决经典快速搜索随机树随机性强、路径不平滑、计算时间长的问题,引入改进人工势场思想,提出规避搜索随机树(A-RRT)算法进行路径搜索,运用B样条曲线拟合与机械臂能量最小逆解法优化运动路径;其次,采用多点碰撞检测法,实现机械臂的稳定以及快速规划避障路径。【结果】1)林木联合采育机机械臂在林区复杂环境中能够成功避开障碍物,到达目标点;2)无论是在单一障碍物还是在多个障碍物环境中,机械臂各关节角度变换相对平滑;3)相比经典RRT算法、偏置RRT算法和双向RRT算法,本研究提出的路径规划算法搜索效率分别提高95.9%、56.9%和40.5%,机械臂避障规划效率有效提升。【结论】本研究提出的林木联合采育机机械臂避障算法具有较好的避障效果和较快的搜索速度,可降低林业环境工作劳动强度,提高机械装备采伐、抚育以及归楞的工作效率。

【Objective】A novel method of obstacle avoidance path planning for a manipulator was proposed in response to meet the requirements of obstacle avoidance operations of forestry felling&cultivation machine in complex environments of forest areas.This method was expected to provide a theoretical basis for the development of forestry machinery and equipment.【Method】Firstly,the kinematic analysis of the manipulator of the forestry felling&cultivation machine was carried out.At the same time,in order to solve the problems of strong random unsmooth path and long calculation time of the classic rapidly-exploring random tree,the idea of improving the artificial potential field was introduced.An avoid rapidly-exploring random tree(avoid-rapidly exploring random tree,A-RRT)algorithm was utilized for path search,which used B-spline curve fitting and the minimum inverse solution of the manipulator energy to optimize the motion path.Then the multi-point collision detection method was used,to realize the stability and rapid planning of the obstacle avoidance path of the manipulator.【Result】Through experimental simulation analysis,the results showed that:1)the manipulator of forestry felling&cultivation machine could successfully avoid obstacles and reach the target point in the obstacle environments.2)Whether in a single obstacle or multiple obstacle environments,the angle transformation of each joint of manipulator was relatively smooth.3)Compared with the classic RRT algorithm,biasing RRT algorithm and bidirectional RRT algorithm,the proposed path planning algorithm in this study improved the search efficiency by 95.9%,56.9%and 40.5%respectively,which effectively improved the efficiency of robotic arm obstacle avoidance planning.【Conclusion】The proposed obstacle avoidance algorithm of the manipulator of forestry felling&cultivation machine in this paper might have a better obstacle avoidance effect and a faster searching speed,which could reduce the labor intensity of the forestry environments,and could also improve the efficiency of the harvesting,tending and pilling of forestry mechanical equipment.