A Suction Cup With Tunable Stiffness Based on Shape Memory Alloy

Abstract

Abstract This paper presents the design and testing of a bioinspired compliant suction cup with tunable elastic stiffness using shape memory alloy (SMA). We embedded SMA wires into a compliant suction cup for stiffness tuning. When the voltage is input, it increases the stiffness of the suction cup body and helps prevent deformation. Further, a bending moment is applied to the suction cup lip in contact with the surface, which reduces the probability of gas leakage as well as the risk of adsorption failure. In the experiment, suction cups with and without embedded SMA are tested respectively. The maximum pull-off forces and adsorption time are measured via an MTS tester, and the pressure values induced by SMA’s tuning effect on the cup lip are recorded by membrane sensors. Results show that under the same preloading forces, the adsorption force is almost identical, while the adsorption maintaining time of the suction cup with embedded SMA is increased by 365% at the maximum compared with that without SMA. The force generated by the bending moment applied to the lip increases by 360% at the maximum when the SMA is activated. The strain of the sample embedded with SMA is 186% less than that of the sample made of pure soft material at 20kPa stress. The results indicate that the embedded SMA can help increase the stiffness, reduce the deformation of the suction cup body, and enhance adsorption maintenance ability.