A Dexterous and Compliant Gripper With Soft Hydraulic Actuation for Microgravity Manipulation

TL;DR

This paper introduces DexCoHand, a dexterous, compliant 6-DOF soft hydraulic gripper integrated with Astrobee for microgravity tasks, improving manipulation precision and reducing base disturbance.

Contribution

The integration of DexCoHand with Astrobee provides enhanced dexterous manipulation in microgravity, a novel development over existing underactuated compliant claws.

Findings

DexCoHand maintains pan and tilt motions while reducing base disturbance.

System evaluated successfully in MuJoCo simulation.

Hardware tests confirm dexterous manipulation capabilities.

Abstract

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.