Kinematic analyses of instrumentation cubes in vehicle impact experiments

Three-dimensional kinematics of body targets are frequently tracked during vehicle impact tests using instrumented cubes. While the components of linear acceleration and angular velocity are recorded in a cube local coordinate system, transformation to a global coordinate system is required to reconstruct the whole body motions. This paper presents a methodology for local-to-global kinematic transformations using a finite element cube model mounted on heads with local measurements. This methodology was used to reconstruct the head kinematics during occupant and pedestrian impact tests and shown to produce similar displacement, velocity, and acceleration results to those obtained by the Euler parameter method. In addition, the possible measurement errors of the local frame orientation were simulated and the proportional displacements and velocities were observed in simulation outputs: the maximum differences are 6.5 % of a global displacement and 9.1 % of a global velocity at applying a 10 degree rotated measurement error in the initial local frame.