Development of a Legform Impactor with 4-DOF Knee-Joint for Pedestrian Safety Assessment in Omni-Direction Impacts

The issue of car-to-pedestrian impact safety has received more and more attention. For leg protection, a legform impactor with 2 degrees-of-freedom (DOF) proposed by EEVC is required in current regulations for injury assessment, and the Japan Automobile Manufacturers Association Inc. (JAMA) and Japan Automobile Research Institute (JARI) have developed a more biofidelic pedestrian legform since 2000. However, studies show that those existing legforms may not be able to cover some car-to-pedestrian impact situations. This paper documents the development of a new pedestrian legform with 4 DOFs at the knee-joint. It can better represent the kinematics characteristics of human knee-joint, especially under loading conditions in omni-direction impacts. The design challenge is to solve the packaging problem, including design of the knee-joint mechanisms and layout of all the sensors in a limited space of the legform. Furthermore, reusable elements are used to achieve the joint stiffness requirements instead of destructive elements used in the EEVC 2-DOF legform. A prototype of the 4-DOF legform has been manufactured based on the design. The preliminary impact tests against bumper systems are also introduced in this paper.