Soft robots, known for their flexible and gentle movements, have gained prominence in precision tasks and handling delicate objects. Most soft grippers developed thus far have relied on molding processes using high-elasticity rubber, which requires additional molds to produce new shapes, limiting design flexibility. To address this constraint, we present a novel approach of fabricating pneumatic soft grippers using thermoplastic polyurethanes (TPU) through the Fused Filament Fabrication (FFF) technique. The FFF technique enables the creation of various gripper shapes without the need for additional molds, allowing for enhanced design freedom. The soft grippers were designed to respond to applied air pressure, enabling controlled bending actions. To evaluate their performance, we conducted quantitative measurements of the gripper’s shape deformation under different air pressure conditions. Moreover, force measurements were performed during gripper operation by varying the applied air pressure and adjusting the mounting angle. The results of this study provide valuable insights into the design and control of soft grippers fabricated using TPU and the FFF process. This approach offers promising opportunities for employing soft robots in various fields and paves the way for further advancements in robotics technology.

In this work, the degradation progression of a polyurethane (PU) hydraulic reciprocating seal with respect to the sliding distance were investigated using a pin-on-reciprocating tribo-tester. Also, the acceleration effect of alumina particles added in lubricant on degradation of PU seal were assessed, with an aim to contribute to the development of accelerated wear testing methods. As a result, It was shown that the height of PU specimens decreased drastically at the initial stage of sliding. Then, the height decrease was found to become gradual as sliding distance further increased. The result also shows that the height decrease of the PU specimen was mainly due to the effect of the compression set and wear. In addition, the noted abrasive wear of the PU specimens was found to be significantly accelerated due to the alumina particles in lubricant, which determined a further result in 50 % faster height decrease with increasing sliding distance, as compared to the normal lubricant. The outcome of this work may provide significant and useful information for the prediction of the lifetime of a hydraulic reciprocating seal, and for the continued development of accelerated wear testing of the hydraulic reciprocating seal.