3D Velocity Measurement of Translational Motion using a Stereo Camera

Abstract

This research aims to create a 3D velocity measurement system using a stereo camera. The 3D velocity in this paper is the velocity which consists of three velocity components in 3D Cartesian coordinates. Particular attention is focused on translational motion. The system set consists of a stereo camera and a mini-PC with Python 3.7, and OpenCV 4.0 installed. The measurement method begins with the selection of the measured object, object detection using template matching, disparity calculation using the triangulation principle, velocity calculation based on object displacement information and time between frames, and the storage of measurement results. The measurement system's performance was tested by experimenting with measuring conveyor velocity from forward-looking and angle-looking directions. The experimental results show that the 3D trajectory of the object can be displayed, the velocity of each component and the speed as the magnitude of the velocity can be obtained, and so the 3D velocity measurement can be performed. The camera can be positioned forward-looking or at a certain angle without affecting the measurement results. The measurement of the speed of the conveyor is 11.6 cm/s with an accuracy of 0.4 cm/s. The results of this study can be applied in the performance inspection process of conveyors and other industrial equipment that requires speed measurement. In addition, it can also be developed for accident analysis in transportation systems and practical tools for physics learning.