RESUMO
Soft grippers are garnering increasing attention for their adeptness in conforming to diverse objects, particularly delicate items, without warranting precise force control. This attribute proves especially beneficial in unstructured environments and dynamic tasks such as food handling. Human hands, owing to their elevated dexterity and precise motor control, exhibit the ability to delicately manipulate complex food items, such as small or fragile objects, by dynamically adjusting their grasping configurations. Furthermore, with their rich sensory receptors and hand-eye coordination that provide valuable information involving the texture and form factor, real-time adjustments to avoid damage or spill during food handling appear seamless. Despite numerous endeavors to replicate these capabilities through robotic solutions involving soft grippers, matching human performance remains a formidable engineering challenge. Robotic competitions serve as an invaluable platform for pushing the boundaries of manipulation capabilities, simultaneously offering insights into the adoption of these solutions across diverse domains, including food handling. Serving as a proxy for the future transition of robotic solutions from the laboratory to the market, these competitions simulate real-world challenges. Since 2021, our research group has actively participated in RoboSoft competitions, securing victories in the Manipulation track in 2022 and 2023. Our success was propelled by the utilization of a modified iteration of our Retractable Nails Soft Gripper (RNSG), tailored to meet the specific requirements of each task. The integration of sensors and collaborative manipulators further enhanced the gripper's performance, facilitating the seamless execution of complex grasping tasks associated with food handling. This article encapsulates the experiential insights gained during the application of our highly versatile soft gripper in these competition environments.
RESUMO
A new generation of soft functional materials and actuator designs has ushered the development of highly advanced soft grippers as adaptive alternatives to traditional rigid end-effectors for grasping and manipulation applications. While being advantageous over their rigid counterparts, soft gripper capabilities such as contact effort are mostly a consequence of the gripper workspace, which in turn is largely constrained by the gripper design. Moreover, soft grippers designed for highly specific grasping tasks such as scooping grains or wide payloads are usually limited in grasping other payload types or in their manipulation versatility. This article describes a reconfigurable workspace soft (RWS) gripper that exploits compliant structures and pneumatic actuators to reconfigure its workspace to suit a wide range of grasping tasks. To achieve desired kinematics, finite element analysis (FEA) studies are conducted to dictate actuator design and materials used. Various grasping modes and their reconfiguration of the gripper workspace are presented and characterized, including the gripper's capability to reliably scoop granular items with radii as small as 1.5 mm, precisely pick items as thin as 300 µm from flat surfaces, as well as grasp large convex, nonconvex, and deformable items as heavy as 1.4 kg. The RWS gripper can modify and increase its grasping workspace volume by 397%, enabling the widest range of grasping capabilities to date achieved by a single soft gripper.
