让机器人更敢抓草莓,能自动判断何时该放弃。
UNCLE-Grasp: A Task-Adapted Framework for Uncertainty-Aware Grasping of Leaf-Occluded Strawberries
- 用多组补全结果评估抓取可行性,而非单个形状估计。
- 在高遮挡下尝试抓取成功率提升至87%,整体成功率达74%。
- 适合需要安全决策的农业机器人场景,尤其遮挡严重时。
机器人采摘草莓在叶片遮挡下仍具挑战,因叶片会掩盖果实结构,仅依赖单一形状估计会导致抓取失败。单一观测可能对应多个合理的3D补全结果,而某个补全下的可行抓取在另一补全下可能失效。现有方法虽估算姿态或形状不确定性,但未整合多种补全假设下的抓取可行性,无法做出对象级的“尝试或放弃”决策。本文提出UNCLE-Grasp框架,融合学习型形状补全、基于蒙特卡洛丢弃的变异性估计、物理合理的抓取评估与风险感知的目标级决策,用于叶片遮挡草莓的抓取。通过蒙特卡洛丢弃生成多个补全样本,对每个样本保留的抓取候选进行力封闭性评估,形成力矩空间评分。以各补全间评分的变异性(而非几何点差异)衡量目标级抓取不确定性,并采用保守置信下界决定是否执行抓取。在仿真与真实机器人上评估,最高仿真遮挡下,尝试抓取成功率从0.780提升至0.870,整体成功率从0.680升至0.740;物理实验中约87%遮挡下,尝试成功率达0.800,优于基线的0.483,尽管尝试率略低。结果表明,该框架通过选择性放弃提升了抓取可靠性,存在可靠性和收获量之间的权衡。
原文摘要 · Abstract (English)
Robotic strawberry harvesting remains challenging under partial occlusion, where leaves obscure fruit geometry and make grasp decisions based on a single shape estimate unreliable. A partial observation may admit multiple plausible 3D completions, so a grasp feasible on one completion may fail on another. Existing uncertainty-aware grasping methods estimate uncertainty in pose, shape, or individual candidates, but do not aggregate grasp feasibility across completion hypotheses for an object-level attempt-or-abstain decision. We present UNCLE-Grasp, a task-adapted framework integrating learned shape completion, dropout-based variability estimation, physically grounded grasp evaluation, and risk-aware target-level decisions for leaf-occluded strawberries. Monte Carlo dropout generates multiple completion samples. For each sample, retained grasp candidates are combined into a wrench space to compute a completion-level force-closure score. Variability in this score across plausible completions, rather than geometric point variability alone, quantifies target-level grasp uncertainty. A conservative lower confidence bound determines whether to grasp or abstain. We evaluate the framework in simulation and on a physical robot under increasing synthetic and real leaf occlusion. At the highest simulated occlusion, UNCLE-Grasp raises success among attempted grasps from 0.780 for the strongest completed baseline to 0.870, with similar attempt rates of 0.860 and 0.880, respectively, and raises overall success from 0.680 to 0.740. On the physical robot at approximately 87% synthetic occlusion, it achieves 0.800 success among attempted grasps versus 0.483 for the strongest completed baseline, although at a lower attempt rate. These results show that UNCLE-Grasp enables more reliable risk-aware execution through selective abstention, with a trade-off between grasp reliability and harvesting yield.
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