A soft gripper driven by conical dielectric elastomer actuator to achieve displacement amplification and compliant grips

Flexible dielectric elastomeric actuators (DEAs) have become significant in soft robots with intelligent systems. They overcome the shortcomings of traditional rigid systems, thereby expanding their applications in wearable devices. However, existing soft robot end-effectors have limited grasping adaptability and often require a complex coupling of sensors and control algorithms to achieve application data-driven smart grasping. This complexity significantly increases manufacturing costs and design difficulties. In this context, we present a simple, adaptive, and versatile double-finger soft gripper (DFSG) driven by a conical DEA to achieve compliant grips. The DFSG consists of three main parts: a conical actuator, clamp, and force transmission mechanism. Initially, we optimize the output performance of the conical actuator by tailoring its geometric structure, preload force, and bias voltage. The DFSG exploits the tapered actuator's characteristic of large vertical displacement (i.e., large input force) by utilizing the efficient displacement amplification function (up to 9 times) of the designed force transmission mechanism. It converts the input force in the vertical direction into a gripping force in the horizontal direction. As a result, the developed DFSG can easily grasp not only regular and stiff objects but also challenging objects such as small, irregular, soft, or squeezable items. Notably, it can clamp up to 14.5 times its own weight with just one layer of DEA. This work provides guidance for designing soft grippers with adaptive and high reliability, offering a promising avenue for the advancement of soft robotic systems.