Abstract
Soft grippers have been developed to replace the traditional rigid end effectors due to their versatility in handling different geometries by making use of the material prop erties which conform to the shape of the object. However, the compliance of the soft grippers is limited by design which restricts its mode of operation. Fingered grippers are suitable for power grasping mode whereas not suitable for scooping granular items. This demands the need for two separate grippers in highly dynamic industries where different modes of operations for end effectors are common. A multimodal gripper with a soft palm capable of switching between three modes of operation namely power grasping, scooping and pinching was developed. The grip per consists of three soft pneumatic actuators as fingers required for power grasping of different geometries and the soft palm is required for its aperture control. The gripper employs two additional features; petals for switching to scooping mode required for granular items and nails for switching to pinching mode required for thin form factor objects laying on flat surfaces. This thesis primarily focuses on optimizing the petal actuator in the multimodal soft gripper which allows it to switch between the scooping and power grasping mode by making use of compliant structures and actuators. The kinematics and design of the petal actuator are studied using finite element analysis (FEA) and verified through various experiments. Firstly, the petal shape is optimized to ensure proper closing between the petals of the gripper for reliable scooping. Secondly, the bellows actuator responsible for opening and closing of the petal, is improved by optimizing the bellows structure. Finally, the finger bending is improved by reducing the interference caused due to an active petal. The gripper capability to reliably scoop granular items less than 5mm diameter is tested through experiments of scooping granular items by employing the optimized petal actuator to the initial version of the multimodal soft gripper