  In this paper, we propose a novel grasp pipeline based on contact point
detection on the truncated signed distance function (TSDF) volume to achieve
closed-loop 7-degree-of-freedom (7-DoF) grasping on cluttered environments. The
key aspects of our method are that 1) the proposed pipeline exploits the TSDF
volume in terms of multi-view fusion, contact-point sampling and evaluation,
and collision checking, which provides reliable and collision-free 7-DoF
gripper poses with real-time performance; 2) the contact-based pose
representation effectively eliminates the ambiguity introduced by the
normal-based methods, which provides a more precise and flexible solution.
Extensive simulated and real-robot experiments demonstrate that the proposed
pipeline can select more antipodal and stable grasp poses and outperforms
normal-based baselines in terms of the grasp success rate in both simulated and
physical scenarios.
