Push or pull: grasping performance analysis between a pulling gripper inspired by Tetraonchus monenteron parasite versus an actively pushing gripper developed through many-objective design optimization

Investigation and subsequent abstraction of biological systems have become a popular approach to innovate new mechanisms. Robot gripper design is an active research area that seeks continuous improvements to cater to its wide spectrum of applications. Tetraonchus momenteron is an infamous parasite which has a robust gripping system (haptor) inserted into the fish-gills. We have redesigned this pull-based gripper for practical application by adjusting the link lengths using many-objective optimization. An existing pusher type of gripper mechanism is also selected to elucidate the similarities and dissimilarities between both the mechanisms. Both push and pull based grippers have been analyzed based on quasi static kinematics and are formulated as many objective optimization problems subjected to geometric-cum-force constraints. The goal of optimization is to find the best link lengths and joint angles for each configuration based on desired criteria. Four possible variants of piezoelectric actuator models are integrated into the optimization formulation to actuate the gripper models. These integrations have led to four different optimization problems for each case. Evolutionary many-objective optimization method is used to obtain non-dominated solutions. The optimized designs are compared based on objective function values to evaluate the performance of each gripper. The results of many-objective optimization are normalized and represented using parallel coordinate plots to aid the decision maker. Our comparative study reveals that while the new nature inspired pull based design has shown promising results in many cases, each gripper configuration has its own merits and requires decision maker’s intervention to choose a particular model based on specific requirement.