解决冗余机械臂路径规划与执行不匹配问题,提升运动平滑性与成功率。
Bridging Discrete Planning and Continuous Execution for Redundant Robot

- 用26邻域动作与几何消歧机制优化离散规划,减少转向抖动。
- 在密集环境中规划成功率从0.58提升至1.00,路径长度由1.53米缩至1.10米。
- 适合需要高精度、平滑运动的工业机械臂控制场景。
基于体素网格的强化学习被广泛用于冗余机械臂路径规划,因其简单且可复现。然而,直接通过7自由度机械臂的逐点数值逆运动学执行,常导致步长抖动、关节突变及奇异位形附近的不稳定性。本文提出一种不修改离散规划器的规划与执行桥梁框架。规划侧引入步长归一化的26邻域笛卡尔动作与几何消歧机制,抑制无效转向并消除步长振荡;执行侧采用任务优先阻尼最小二乘(TP-DLS)逆运动学层,将末端位置作为主任务,姿态与关节中心化作为次级任务投影至零空间,并结合信任区域截断与关节速度约束。在随机稀疏、中等和密集环境下的7-DoF机械臂上测试,该框架使密集场景中的规划成功率从约0.58提升至1.00,代表性路径长度从约1.53米缩短至1.10米,同时保持末端误差低于1毫米,峰值关节加速度降低一个数量级以上,显著提升了基于体素强化学习路径在冗余机械臂上的连续执行质量。
原文摘要 · Abstract (English)
Voxel-grid reinforcement learning is widely adopted for path planning in redundant manipulators due to its simplicity and reproducibility. However, direct execution through point-wise numerical inverse kinematics on 7-DoF arms often yields step-size jitter, abrupt joint transitions, and instability near singular configurations. This work proposes a bridging framework between discrete planning and continuous execution without modifying the discrete planner itself. On the planning side, step-normalized 26-neighbor Cartesian actions and a geometric tie-breaking mechanism are introduced to suppress unnecessary turns and eliminate step-size oscillations. On the execution side, a task-priority damped least-squares (TP-DLS) inverse kinematics layer is implemented. This layer treats end-effector position as a primary task, while posture and joint centering are handled as subordinate tasks projected into the null space, combined with trust-region clipping and joint velocity constraints. On a 7-DoF manipulator in random sparse, medium, and dense environments, this bridge raises planning success in dense scenes from about 0.58 to 1.00, shortens representative path length from roughly 1.53 m to 1.10 m, and while keeping end-effector error below 1 mm, reduces peak joint accelerations by over an order of magnitude, substantially improving the continuous execution quality of voxel-based RL paths on redundant manipulators.
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