无需规划轨迹,直接用距离场实现安全且高质量的多指抓取。
Grasp Execution Without a Planner: Configuration-Space Grasp Distance Fields with Certified Safety & Guaranteed Quality

- 用配置空间抓取距离场替代传统规划,实时反馈控制抓取
- 在20毫秒控制周期内每步计算仅需0.09毫秒,抓取质量保持94%以上
- 适用于动态环境中的欠驱动手抓取,适合工业机器人部署
主流的多指抓取执行方法采用先规划后跟踪的模式,需选定抓取姿势、规划无碰撞轨迹,并通过反馈控制器跟踪。执行中姿态估计误差或场景运动可能导致开环计划失效,触发重规划。为此,本文提出抓取距离场(GDFs),即对有限个机械臂-手抓取配置集合的平滑软最小距离。利用其负梯度作为反馈,实现抓取的联合选择与执行,无需单独轨迹规划。通过带有约束保证反馈(CBF)与控制李雅普诺夫函数(CLF)的二次规划(QP)同时满足自碰撞、工作空间、物体及障碍物避让约束,且CLF松弛项可量化任务进展受阻程度。我们证明了软最小近似误差上界为 $\log N/ρ$,并确保滤波后安全集的前向不变性。为应对接触拓扑变化,引入滞后接触模式切换机制与力闭合质量约束的CBF,限制实际力闭合裕度相对于抓持开始时的退化。实验表明,固定基座机械臂和配备相同欠驱动手的Unitree G1在杂乱环境与移动障碍物中成功抓取50个测试物体中的46个。实现的抓取仍保持合成质量裕度的中位数94%,每个QP求解耗时仅0.09毫秒,可在20毫秒控制周期内完成。
原文摘要 · Abstract (English)
Mainstream plan-then-track approaches to multifingered grasp execution entail selecting a grasp, planning a collision-free trajectory, and tracking the resulting trajectory via a feedback controller. Pose-estimation error during execution or scene motion can invalidate this open-loop commitment and trigger replanning. We thus present Grasp Distance Fields (GDFs), smooth softmin distances to finite sets of arm-hand grasp configurations. Using their negative gradients as feedback, we jointly select and execute grasps without planning a trajectory. A CBF-CLF quadratic program (QP) enforces self-collision, workspace, object, and obstacle-clearance constraints, while its CLF slack quantifies obstruction of task progress. We bound the softmin approximation error by $\log N/ρ$ and prove forward invariance of the filtered safe set. To handle changes in contact topology, we combine a hysteretic contact-mode transition with a wrench-quality CBF that limits degradation of the realized force-closure margin relative to hold onset. Using our method, a fixed-base manipulator and a Unitree G1 equipped with the same underactuated hand grasp and lift 46 of 50 test objects amid clutter and moving obstacles. The realized grasps also retain a median 94% of their synthesized quality margin, and each QP solve requires 0.09 ms within a 20 ms control interval. Project page: www.clintonenwerem.com/gdf.
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