Accurately measuring the kinematics of a vehicle is necessary to understand vehicle dynamics. As such, a new technique for measuring planar motion of a vehicle using downward-facing high-speed or high-definition camera is presented in this paper. Forward, lateral, and angular velocities can be obtained simultaneously from a calibrated image sequence by using concepts from digital image correlation (DIC). The technique requires the use of a camera, mounting device (e.g. tripod) and computer for post processing the image sequence. The technique is shown to agree with Radar, GPS, and Accelerometer based techniques for measuring velocity. The camera based system may be well suited to measure lower velocities compared to other common instrumentation systems.
Digital image correlation is a technique used to study displacement, deformation, and strain by examining a sequence of digital images of a random pattern on the surface of a material. The basic principles of DIC are used in digital particle image velocimetry (DPIV), where instantaneous velocity measurements are obtained. This paper explains how image correlation produces displacement data and, with a known time base, can produce velocity data. A least squares method is presented to determine planar velocities from a grid of translational velocities. Laboratory and field tests show that a modern digital video camera can be used to measure vehicle performance.