Variable Stiffness Soft Actuator using Layer Jamming for Food Handling

This study proposes a novel hybrid actuator combining PneuNet with layer jamming actuation to address the problems with conventional soft pneumatic actuators such as stability and lack of integrated locking mechanisms. The introduction of sandpaper-based layer jamming element is made as a solution. A set of experiments were conducted to identify suitable sandpaper grit-level and possible layering arrangement for the jamming section. P220 grit sandpaper showed the best flexural strength change which was suitable for the jamming element. The hybrid actuator was tested to identify the deviation from the typical PneuNet actuator in the performance of bending angle and generated tip force. The novel actuator showed a 25% reduction in bending angle while producing a 30° maximum bending angle at 160 kPa pressure. Tip force of the novel actuator didn’t show a significant difference and it produced 2.3 N force at 160 kPa. The integrated jamming element can act as a locking mechanism for the novel actuator. Due to the relaxation of the PneuNet, actuating locking mechanism shows an average 30% bending angle reduction compared to the initial bending angle. A two-finger gripper was produced using the hybrid actuator and it was successfully tested on soft food handling with the integrated locking feature.