The 3D measurement of a body displacement on a moving vehicle is a quite challenging process. Well-known displacement measuring device such as a dial gauge and strain gauge can measure the displacement in only limited areas. An accelerometer also can estimate body motion but it has an accumulated error and a bias issue for an acquisition of displacements. However, an optical measuring (Motion Capture) method which uses markers and multiple cameras can read 3D coordinates directly and carry out those measurements well.
In this paper, first, we determined how to extract a body displacement from global motion. Then we suggested a combining measurement methodology which uses a motion capture and an accelerometer simultaneously. Though it has failed to compensate each result and exact displacement, we showed an accuracy comparison between a motion capture and an accelerometer to measure a displacement along this process.
Next we verified the measuring error of the motion capture and considered data smoothing techniques, the low pass filter and the weighted moving average, to improve the accuracy. Finally we applied the motion capture methodology for real cases, static and dynamic cases. For static case, we measured the displacement around tailgate area on vehicle twist test and showed body deformation modes in 3D. For dynamic case, we measured full vehicle body displacement on a road simulator and traced body motions and deformations on a moving vehicle.