Design and Analysis of a Novel Soft Bending Actuator Based on Eccentric Structure

Due to safe interaction and intrinsic compliance, soft actuators have been developed in robotics around the world, and robots composed of soft actuators have been widely used in many fields such as grasping. However, for the fiber-reinforced actuators (FRAs), the non-circular design of cavity structure causes the problem of stress concentration, which can impact the performance of the soft actuators. In this paper, the eccentric soft bending actuators (ESBAs) with circular cavities were proposed to solve the problem and improve the performance. Particularly, the proposed actuators can be fabricated and assembled modularly with customized design of molds and terminal connectors, which can increase the repeatability and consistency of the actuators. To quantify the performance of the ESBAs, the bending angles and output forces are measured. Experimental results show that the maximum bending angle and output force of the proposed ESBAs could reach 131.6° and 1.5N at 190kPa, respectively. Additionally, comparative experiments on the performance of the ESBAs designed of cavity structure with different parameters were carried out to obtain the optimal ESBAs structure. Furthermore, a three-jaw soft gripper consisted of the ESBAs was developed and its grasping performance was also tested. The results showed that the proposed actuators had potential application in the manipulation of the soft gripper.