An experimental gripper for harvesting scallops

This paper presents a gripper design for selective collection of scallops (Pecten novaezelandiae) in an effort to minimise damage to the seabed and scallop populations, which have been significantly affected by traditional dredging methods. The proposed gripper will be integrated into a Towed Underwater Vehicle (TUV) that utilises a computer vision system to identify scallops. Grippers would be attached to the TUV in an array that would be deployed simultaneously for scallop collection. The gripper design features a bi-stable mechanism that drives actuation to reduce actuation complexity when a large number of grippers are in operation. A linkage-based finger design has been used to minimise seabed contact during operation. This allows for selective collection of scallops which reduces the environmental impact compared to traditional harvesting methods that are usually indiscriminate. Operational characteristics of the gripper have been experimentally analysed with a 3D printed prototype. The current gripper design requires at most 7.5 N of force and 47.0 mJ of work to successfully actuate. To accidentally lose grasp of a scallop, a force of at least 100 N is required. Development of the presented gripper contributes to ongoing efforts in designing sustainable marine resource harvesting practises, with potential applications in other fields requiring quick response, passively actuated grippers.