A Smartphone-Based Six-DOF Measurement Method With Marker Detector

The visual measurement methods of the six-degrees-of-freedom (DOFs) of a rigid body always require expensive and professional instruments, while the camera of smartphones is so powerful that they can perform the task of visual measurement, which will reduce the cost of measurement. Therefore, a low-cost smartphone-based six-DOF measurement method with the marker detector is proposed, which uses two smartphones to achieve dynamic measurement for the moving rigid body. Specifically, the proposed method improves the accuracy of depth measurement based on the parallax principle. Based on the LeNet-5, the marker detector with the tracking compensation mechanism is proposed to detect and track markers. We carry out experiments to verify the feasibility of the proposed method and to evaluate its performance. In the experiment, the average absolute error of the rotation angles and the translations measurement are 2.2888° and 3.5763 mm. The results show that the proposed method achieves dynamic measurement using two smartphones.