Soft fingers with variable stiffness for space gripping tasks: An assessment

The miniaturization of satellites and the problem of uncontrolled space debris demand highly flexible methods for space grippers. Soft grippers have surged as viable alternatives to overcome the limitations of traditional rigid grippers, such as lack of adaptability and dexterity. Although existent models have shown promising features, most have a high part count or make use of actuation systems that are inadequate for space, like pneumatic pumps or temperature-dependent materials. This work introduces novel designs of soft fingers that address the inherent challenges of grasping objects in space while overcoming these limitations. The proposed fingers use compliant structures based on several geometries of metamaterials. A detailed compliance and compressibility analysis is conducted using finite element methods to highlight the performance and behavior of each proposed design. Prototypes were fabricated, and their ability to exhibit different modes of actuation (variability in stiffness) by tendon compression was confirmed. The most apt design was selected and showcased in a three-fingered gripper to demonstrate the ability to grasp a given set of geometries with different sizes.