Transforming Soft Robotics: Laminar Jammers Unlocking Adaptive Stiffness Potential in Pneunet Actuators

Abstract

PneuNet actuators emulate human finger function and have broad application potential in domestic and industrial settings. To unlock their full potential, enhancing their controlled stiffness is crucial. This study presents the innovative design, fabrication, and evaluation of a cost-effective soft hybrid bending actuator by merging a homogeneous laminar structure, composed of 75 GSM printer paper, with a PneuNet actuator produced through soft lithography techniques. This research also characterizes the ensemble based on its tunable stiffness properties and examines the friction tests on jamming layers, highlighting the stabilization of frictional properties over time, which is critical for achieving consistent tunable stiffness. Experiments revealed that the actuator's resistive force increases due to deformation when subjected to an external load. Furthermore, this linear rise in resistive force can be modulated through the use of an integrated laminar jammer by adjusting the vacuum pressure. Results reveal a negligible stiffness increase beyond -53.33 kPa of vacuum pressure, signifying an ideal vacuum pressure limit for energy conservation during vacuum jamming. A maximum stiffness of 0.116 N was achieved at -80 kPa of vacuum pressure. This study propels the field of soft robotics by offering enhanced tunable stiffness characteristics for diverse applications.

Variable stiffness soft robotic gripper: design, development, and prospects

“…This involves enhancing interlayer friction between laminar materials, fiber bundles, and fiber layers through negative pressure and other techniques, thus creating interactions that restrict the movement of the materials and consequently enhance structural stiffness. Singh et al [62,284] have developed a hybrid power gripper with variable stiffness based on layer jamming using 3D printing technology, thus demonstrating the potential of layer jamming in flexible grippers. Combined with experimental research, layer jamming variable stiffness grippers exhibit significant advantages in cost-effectiveness and stiffness modulation effects compared to existing approaches [293].…”

Composite Laminar Jamming: Toward Designing a Tunable Stiffness Hybrid Soft Robotic Actuator

“…Seven separate vacuum pressure levels ranging from −93.33 kPa to −13.33 kPa were used to extensively investigate the composite jamming structure's rigidity. 13,33 As per experimentation such pressure range is found to be suitable to generate variable jamming force. These comprehensive tests revealed the tunable stiffness behavior of such composites, while a comparative analysis with a uniform jammer made solely of printer copy paper further highlighted the superior performance of the composite jamming structure.…”

Development of a novel two-way 3D printed flexible spiral composite actuator based on shape memory alloy wire and its control

“…concept can be encountered in many different applications [1,2], such as in the bio-inspired soft robotics [3][4][5][6], artificial muscles [7][8][9], morphing structures [10], microrobots [11], soft wearable designs-robots [12][13][14] or soft grippers [8,[15][16][17][18], and origami structures [16,19,20]. Also, soft robotic technology advances into the future by integrating with innovative sensory feedback systems [21] and laminar designs that improve its functionality [22].…”