歩行者保護を目的とした小型無人搬送車用アクティブバンパの設計

抄録

Crash safety is an important issue pertaining to autonomous vehicles. Autonomous vehicles must have high safety for pedestrians so that these vehicles are accepted by society and are widely used. Although autonomous vehicles must avoid crashing into pedestrians, completely avoiding accidental contact with pedestrians is difficult when small, unmanned autonomous vehicles operate on sidewalks and in buildings for purposes such as bringing packages. We aim at avoiding any injury to a pedestrian when a small, unmanned autonomous vehicle crashes into the pedestrian; this is done by introducing an active bumper. The active bumper controls the force of contact between the bumper and pedestrian. We designed an active bumper with a series elastic actuator comprising an elastic element in series with a table driven by a ball screw and servo motor. The optimal torque of the servo motor for minimizing the maximum deflection of the object of the collision is derived, whereas the bumper stroke and the maximum and minimum torque of the servo motor are restrained. Numerical simulations were conducted where the crash speed ranged from 1.0 to 2.0 m/s. The numerical simulations demonstrated that the active bumper with the series elastic actuator controlled by the optimal torque decreases the maximum deflection of the object by at least 39 % compared with a passive bumper comprising a linear spring.