A Vacuum-Powered Soft Linear Actuator Strengthened by Granular Jamming

Vacuum-powered soft pneumatic actuators (V-SPAs) are considered to be fail-safe, because their maximum forces and displacements are restricted by environmental pressure from actuating. However, their performances are significantly influenced by the selection of materials. V-SPAs fabricated by materials with low modulus of elasticity might fall short of output forces for many tasks. This article proposes a novel approach aiming to improve the performance of V-SPAs. Based on our previously developed vacuum-powered soft linear actuators (called as "VSLA"), a new vacuum-powered soft linear actuator strengthened by granular jamming (called as "J-VSLAs") is proposed to achieve higher actuation stress without sacrificing compliance. The new J-VSLA changes the stiffness partially and it can lift about four times of weight (at 20% of strains) compared to its no-granule version. In addition, the mechanical efficiencies of the J-VSLAs is increased by about 10%. Our results highlight the effectiveness of J-VSLAs for improving the mechanical properties of soft actuators and reducing the material selection constraints on the performance of V-SPAs.