Robotiq Releases New 2F-85 Gripper Isaac Sim Assets on Newton

Robotiq has released updated Isaac Sim assets for the 2F-85 Adaptive Gripper, supporting both PhysX and Newton physics backends, with documentation explaining the mechanism. Previously, when a 2F-85 was placed into an Isaac Sim scene and closed on an object, the fingers often exhibited behaviors the real gripper never does: bending backwards, pivoting outward at the tip, or snapping out of alignment mid-grasp, which is the most reported problem from the community. The gripper is underactuated: each finger is a five-bar linkage in which two links form a virtual extendable link, with a pin limiting the minimum length; at minimum length the fingertip stays parallel, and when the virtual link extends, the fingertip rotates inward to produce an encompassing grip. A torsion spring at the inner finger joint provides a passive degree of freedom, allowing the gripper to conform to round objects. Isaac Sim solves an articulation as a tree of rigid bodies, which cannot contain loops, but the 2F-85 finger is a loop. The public asset offers two USD variants: cutting the loop and re-imposing it algebraically with mimic constraints, which can only reproduce the parallel grip; or keeping every joint and closing the loop as a constraint, marking one joint as excludeFromArticulation and letting the solver enforce it in maximal coordinates, preserving the underactuated degree of freedom. Under PhysX, this closing constraint is a best-effort constraint, so under certain loads it tolerates misalignment, accumulates error, and the linkage snaps out of alignment. Newton, built on MuJoCo-Warp, models a closed loop natively as an equality constraint, keeping the five-bar closure stable at joint limits, solving all 10 joints analytically, and allowing the parallel-grip spring to hold so the finger returns to parallel when released and rotates inward when demanded, enabling encompassing grip simulation in the assets for the first time. Users wanting a fast, robust parallel pinch can choose the PhysX variant, while those simulating grip realism can choose Newton. Next are the 2F-140, then Hand-E in all its variants, with work toward validation against the SimReady Foundation specification. These assets are one of three open-source developer pieces, alongside the C++ SDK and ROS 2 packages. Geometry and images are in Git LFS, and the .usda layers are plain text. After installation, refer to the gripper simulation guide and the Newton asset's README. To mount on a robot, reference the config file for the chosen physics variant, attach it to the wrist link with a fixed joint, and remove the gripper's own articulation root so the arm and gripper solve as one articulation. To switch fingertips at integration time, reference Robotiq_2F_85_edit.usd. Under the compliant and Newton variants, command only finger_joint and let the loop closure solve the rest. Issues and feedback are welcome on GitHub. Information comes from the original source and is organized by AI.