A Novel Self-locking Finger Based on Variable Stiffness Mechanism Using Polycaprolactone

In this paper, a new soft finger is presented to achieve self-locking performance based on variable stiffness mechanism using polycaprolactone (PCL). The variable stiffness structure demonstrates the capability of 167 times stiffness variation. A pneumatic soft finger with PCL structure is fabricated, which achieves different bending shape under the same air pressure when stiffness changed. The soft finger also demonstrates self-locking performance even under load. Two different multi-finger soft hands are fabricated to test the corresponding self-locking capacity. The experimental results demonstrate that the multi-finger soft hands can hold different objects with weight up to 184 g. In conclusion, the soft finger based on PCL structure shows an alternative for the variable stiffness mechanism. It can potentially be developed into manipulators in practical applications to prevent failed grasping incurred by actuator fault, and also be used to save energy consumption for the objects needed to be holden for a long time based on self-locking mechanism.