A Dexterous and Compliant Gripper With Soft Hydraulic Actuation for Microgravity Manipulation
For free-flying robots in microgravity, this gripper improves dexterous manipulation while minimizing disturbance to the base, enabling more complex tasks on the ISS.
DexCoHand, a dexterous and compliant two-finger 6-DOF gripper with soft hydraulic actuation, was integrated with Astrobee free-flying robot for microgravity manipulation. In simulation, it reduced unintended cross-axis base motion while preserving commanded pan and tilt motions compared to the existing 1-DOF gripper.
Astrobee's existing one-degree-of-freedom (DOF) underactuated compliant claw gripper enables perching on the International Space Station (ISS), but provides limited capability for continuous dexterous manipulation. More complex microgravity tasks require an end-effector that can maintain stable contact while limiting disturbance to the free-flying base, since contact forces directly couple into base motion. This article presents the integration of DexCoHand, a dexterous and compliant two-finger, 6-DOF gripper, with the Astrobee free-flying robot for microgravity manipulation. The system is evaluated in MuJoCo using Astrobee's standard handrail perching sequence, including approach, perching, and subsequent pan and tilt motions. Compared with Astrobee's existing gripper, DexCoHand preserves the commanded pan and tilt motions while reducing unintended cross-axis base motion. Hardware experiments on Earth further demonstrate DexCoHand's dexterous manipulation capabilities and its potential for more adaptable intelligent manipulation tasks.