针对高自由度机械臂,提出并行多目标规划方法,提升轨迹质量和成功率。
Many-RRT*: Robust Joint-Space Trajectory Planning for Serial Manipulators
- 并行生成多个逆运动学解,同步构建独立搜索树
- 相同时间内轨迹成本降低44.5%,成功率提升至100%
- 适合复杂环境下的高自由度机械臂实时路径规划
高自由度串联机械臂的快速发展要求在高维空间中使用快速采样规划算法。尽管基于采样的算法如RRT被广泛应用,但由于正运动学不可逆,关节空间规划面临挑战:同一末端执行器位姿可能对应多个构型,导致规划器陷入多臂赌博问题。在复杂环境中,仅选择错误的关节空间目标就可能造成次优轨迹甚至规划失败。为此,我们提出Many-RRT*,作为RRT*-Connect的扩展,可并行规划多个目标。通过生成多个逆运动学解,并从这些目标构型出发同时构建独立搜索树,与单一起始树协同推进,避免计算资源浪费在次优的逆运动学解上。该方法保持了鲁棒收敛性和渐近最优性。实验在多种机器人形态和障碍物环境中验证,Many-RRT*在相同运行时间内,轨迹成本降低44.5%,成功率达100%(次优方案为1.6%),显著优于以往RRT变体,且未牺牲运行效率。
原文摘要 · Abstract (English)
The rapid advancement of high degree-of-freedom (DoF) serial manipulators necessitates the use of swift, sampling-based motion planners for high-dimensional spaces. While sampling-based planners like the Rapidly-Exploring Random Tree (RRT) are widely used, planning in the manipulator's joint space presents significant challenges due to non-invertible forward kinematics. A single task-space end-effector pose can correspond to multiple configuration-space states, creating a multi-arm bandit problem for the planner. In complex environments, simply choosing the wrong joint space goal can result in suboptimal trajectories or even failure to find a viable plan. To address this planning problem, we propose Many-RRT*: an extension of RRT*-Connect that plans to multiple goals in parallel. By generating multiple IK solutions and growing independent trees from these goal configurations simultaneously alongside a single start tree, Many-RRT* ensures that computational effort is not wasted on suboptimal IK solutions. This approach maintains robust convergence and asymptotic optimality. Experimental evaluations across robot morphologies and diverse obstacle environments demonstrate that Many-RRT* provides higher quality trajectories (44.5% lower cost in the same runtime) with a significantly higher success rate (100% vs. the next best of 1.6%) than previous RRT iterations without compromising on runtime performance.
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