This study presents the design of an underactuated, two-finger, motor-driven compliant gripper for grasping size-varied unknown objects. The gripper module consists of one main frame structure and two identical compliant fingers. The compliant finger is a monolithic compliant mechanism synthesized using a topology optimization method, and then prototyped by 3D printing using flexible filament. The input port for each finger is mounted on a moving platform driven by a gear motor, whereas the fixed port of the finger is mounted on a fixed platform. Each compliant finger can be actuated through the linear motion of the moving platform, and can deform elastically to generate the grasping motion. To demonstrate the effectiveness of the proposed design, the gripper module is mounted on a six-axis robotic arm to pick and place a variety of objects. The results show that objects with the sizes between 42 and 141 mm can be grasped by the developed soft robotic gripper. The maximum payload for the gripper is 2.1 kg. The proposed compliant gripper is a low-cost design that can be used in grasping of size-varied vulnerable objects.
Keywords: compliant mechanism; finger; gripper; soft robot; topology optimization.