Development of an impulsive motion generator inspired by cocking slip joint of snapping shrimp.

We propose an impulsive motion generator inspired by snapping shrimp. The proposed device mimics the geometrical arrangement of a unique claw joint calledand integrates it with an artificial rack-pinion actuator mechanism rather than adopting the musculoskeletal system as it is. The design approach allows the proposed device to reproduce the impulsive slip motion through the torque reversal and unlatching mechanism of the underlying unique joint by using a single servo motor. Static and dynamic analyses revealed that the actuator force required to store and release elastic energy was remarkably small compared with the resulting acceleration force and rotation/tip speed. Through simulations and experiments, we validated the mechanical analyses and confirmed that the resulting ultrafast slip motion was comparable with the claw closure of snapping shrimp based on the cocking slip joint. Moreover, from an engineering perspective, the motion profiles are modifiable through design parameters, and the repeatability of the impulsive slip motion is satisfactory.