Design of impact reduction mechanism using momentum exchange and avoidance of impact transmission by mechanical singularity inspired by Break-Fall in Judo

Abstract

Because mechanical parts will be broken by high acceleration caused by impact of collision, a shock reduction mechanism takes an important role for mechanism design. Springs and dampers have been often used for a shock absorber, however, because of their mass, the impact is transmitted to the body. Momentum exchange impact damper (MEID) and mechanical singularity will be effective mechanism design. The former transfers momentum from body to damper-mass to reduce the body velocity. The latter avoids impact transmission. This paper proposes an impact mitigation mechanism inspired by break-fall in Judo. The mechanism exchanges momentum without additional sensor nor actuator, and avoids impact transmission by singular configuration. It is shown that the proposed mechanism has 1-DOF by Kutzbach-Gruebler’s equation using a planer model and two singular configurations by singularity analysis. Dynamics simulation confirms the concept of the proposed mechanism (Momentum exchange). And a prototype is designed and motion captured by a high speed camera to evaluate the momentum exchange.