TY - JOUR
T1 - A smartphone camera and built-in gyroscope based application for non-contact yet accurate off-axis structural displacement measurements
AU - Yu, Liping
AU - Lubineau, Gilles
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): BAS/1/1315-01-01
Acknowledgements: The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST) , under award number BAS/1/1315-01-01.
PY - 2020/9/16
Y1 - 2020/9/16
N2 - Image-based optical methods have been widely used for noncontact structural displacement measurements, due to their prominent advantages over conventional contact sensors. However, existing optical methods usually require complicated and expensive imaging systems, and have difficulties to accurately measure in-plane displacements when the optical axis is not perpendicular to surface of the object (i.e., off-axis measurement). In this work, we develop a low-cost and portable smartphone-based optical method for accurately measuring off-axis structural displacements. The theoretical equations of the in-plane physical displacements on the object surface are derived based on the smartphone gyroscope data that can be used to determine the rotation matrix between the defined world coordinate system and the camera coordinate system. Simple calibration tests are performed to validate the accuracy of the smartphone gyroscope in detecting the rotation angles. The effectiveness and accuracy of this method in off-axis structural displacement measurement are then verified by two in-plane translation tests in laboratory condition. Finally, the noise from the smartphone camera is evaluated, and the effectiveness of the proposed method in continuous displacement measurement is further confirmed the vibration measurement of a hanging light under random wind load.
AB - Image-based optical methods have been widely used for noncontact structural displacement measurements, due to their prominent advantages over conventional contact sensors. However, existing optical methods usually require complicated and expensive imaging systems, and have difficulties to accurately measure in-plane displacements when the optical axis is not perpendicular to surface of the object (i.e., off-axis measurement). In this work, we develop a low-cost and portable smartphone-based optical method for accurately measuring off-axis structural displacements. The theoretical equations of the in-plane physical displacements on the object surface are derived based on the smartphone gyroscope data that can be used to determine the rotation matrix between the defined world coordinate system and the camera coordinate system. Simple calibration tests are performed to validate the accuracy of the smartphone gyroscope in detecting the rotation angles. The effectiveness and accuracy of this method in off-axis structural displacement measurement are then verified by two in-plane translation tests in laboratory condition. Finally, the noise from the smartphone camera is evaluated, and the effectiveness of the proposed method in continuous displacement measurement is further confirmed the vibration measurement of a hanging light under random wind load.
UR - http://hdl.handle.net/10754/665222
UR - https://www.sciencedirect.com/science/article/pii/S0263224120309775
U2 - 10.1016/j.measurement.2020.108449
DO - 10.1016/j.measurement.2020.108449
M3 - Article
JO - Measurement
JF - Measurement
ER -