Development of a Soft Elastomeric Gripper for Dexterous Grasping

Awarded the prize of 2016 Excellent Bachelor Thesis (Top 1%) of Shanghai Jiao Tong University

Development of robotic grippers that can grasp universal objects analogous to humans hands is still a challenging and open problem in the robotics society. In this paper, a four-fingered soft gripper is designed, in which each finger is a bending multi-cavity pneumatic elastomer actuator (MCPEA). Different from the traditional robotic grippers, the fingers of the developed gripper are modularized and entirely composed of soft elastomer material that is inherent compliant. In addition, the mechanism and grasping function are achieved by the geometry design of simple multi-cavity networks. To provide a guideline for the design, a finite-element analysis (FEA) model is developed to analyze the kinematics of the MC-PEA. The influences of the geometric parameters on the bending performance in terms of the bending angle and output force at the distal tip are investigated as well. The FEA model is also validated by the experimental results of the MC-PEA with bending tests. Such an understanding and analysis allows achieving an optimum design of the soft MCPEA. Finally, the four-fingered soft gripper is assembled for dexterous grasping tests. The results shows that universal unknown objects with different sizes and shapes even frangible, such as vegetables, fruits, eggs, noodles, pens, candles, electronics, and cups can be grasped by the developed soft gripper. Furthermore, the payload tests are performed to show that the developed gripper can stably hold an object with the mass of 400 g, while each finger has the weight of 16.3g.