Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
VALIDATION OF A LOW-COST IMU FOR VIBRATION TRACKING ALONG OFFSHORE LINE MODELS
Submission Author:
André Fujarra , SC
Co-Authors:
Aline Leal de Lima Gontarski, Rafael Chiara, Monique Ellen Bruner, André Fujarra
Presenter: André Fujarra
doi://10.26678/ABCM.ENCIT2022.CIT22-0063
Abstract
It is known that field measurement of offshore structures is highly dependent on environmental conditions, availability and accuracy of applied equipment, external interference, among other aspects. Currently, the cost to reliably predict displacements and frequencies of risers, umbilicals or mooring lines is very high, and alternatively, careful signal treatments and validation studies are required to obtain good results through low-cost solutions. Seeking a solution of the latter nature, this work aims to carry out experimental studies related to an embedded vertical tube using an inertial measurement unit (IMU) to track the movement of some discrete points along the length. Different positions and initial excitation are tested to validate the IMU readings against those obtained by an optical tracking system used as a reference. The aluminum tube is filled with sand to lower the natural frequency values. The IMU is composed of a set of three-axis accelerometers, rate gyroscopes and magnetometers, from which the angles are obtained indirectly through a complementary filter to build the rotation matrix at each time step. Thus, the acceleration vector can be rotated to a fixed coordinate system, north-east-down (NED) frame, to be represented on a local basis. The double integration of the acceleration vector is studied, filtering out noise and drift problems to calculate the tube displacements. The amplitudes and frequencies obtained by the IMU are compared to those from the optical tracking system, which is composed of six cameras tracking reflective targets. Modes and frequencies are also verified with analytical equations and finite element method (FEM) to complete the validation procedure.
Keywords
Inertial Measurement Unit, tracking vibration, experimental validation, digital filtering, signal processing
