Dynamic Modeling of Pedestrian Legform and Prediction of Pedestrian Injuries

Abstract

Decreasing the death toll of pedestrians in traffic accidents is one of the most urgent tasks to be solved all over the world. This paper describes the prediction of pedestrian injuries for the TRL legform impactor using MATLAB. The TRL legform impactor consists of three parts: a femur, a tibia, and a ligament connecting them. The impactor was physically modelled with springs, dampers and two masses as a dynamic model. The impactor behaves in a translational and rotational motion during the collision with a vehicle. The behavior of the impactor during the crash event was captured by a high speed camera and is regarded as the four-degree-of-freedom system in terms of translational and rotational motions. Pedestrian injuries are evaluated by three physical quantities indexes: the acceleration of the tibia, both the displacement and the bending angle between the femur and the tibia. The physical model for the impactor was expressed mathematically by differential equations. In the case of modelling, the ligament connecting both the femur and the tibia in particular plays an important role. Shear forces were applied to the ligament in translational motions and the bending moments in rotational motion. Differential equations were expressed in the form of a state equation and an output equation by MATLAB. Numerical solutions were obtained by a block diagram with Simulink. As a result, it was found that the predicted injuries agree quite well with their experimented data in terms of acceleration, displacement, and the bending angle mentioned above.