Three-Finger Chambered Pneumatic Gripper for Grasping and Rotation

In the industry, robotic grippers were used in handling different types of objects. Traditionally, most grippers used hard and rigid bodies which were designed to grasp specific shapes; limiting them to hold a few types of objects. In addition, rigid bodies lacked the delicateness in handling fragile objects that may be easily damaged. Recently, soft grippers were being used in the industry in handling multiple types of objects due to their flexibility and low-cost fabrication. The research presents a three-finger chambered pneumatic gripper design. Each finger consists of three air chambers where the middle chamber is used for grasping while the left and right chambers are used for bending. The combination of the air chambers made it possible to grasp and rotate the object it was holding. The soft fingers were fabricated by injecting silicone rubber into 3D printed molds made using a CAD modelling software. A pneumatic diaphragm pump was used to inflate the air chambers of the soft fingers regulated by solenoid valves that were controlled by a microcontroller. Pressure sensors were used to monitor the pressure of each chamber to provide feedback to the system. The control system of the test setup yielded a closed loop step response with a maximum settling time of 380 ms and a maximum overshoot of 20%. Soft robot characterization such as bending performance and force output at the fingertip were measured and described by quadratic equations. The grasping and rotation tests showed that the pneumatic gripper was capable of grasping and rotating objects of varying shapes, sizes, weight and delicateness