Towards Development of a Novel Variable Stiffness Instrumented Gripper

The need for the gripper becomes more demanding when it comes to automated manipulation or handling of fragile structures. Depending on the object and the task requirements, a single gripper with a fixed stiffness may not be enough, and a variable mechanism can facilitate the necessary adaption. Along with this, sensing local happening during the task may be effectively done with adequate instrumentation. Combining both, an instrumented griper whose stiffness can be altered along with a change in its sensing range is of great interest. In this work, we present preliminary results of a novel instrumented gripper comprising of 3D printed passive structure with assembly of shape memory alloy (SMA) spring, and piezoresistive microchannel based on PEDOT:PSS. The device exhibited a stiffness change of 21.5 % when switched from martensite to austenite phase, along with a force sensitivity adjustment of 53.7 %. The presented device can adapt a range of 50 mN or 100 mN based on the opted configuration of SMA.