The invention discloses a
submarine cable shape monitoring method based on an ultra-weak
fiber bragg
grating, which comprises the following steps of: obtaining curvatures # imgabs0 #, # imgabs1 # and # imgabs2 # in X-axis and Y-axis directions from curvatures in two orthogonal directions of curvatures calculated by three uniformly distributed optical fibers, representing angle offset from an ith sensing unit to an X-axis
positive direction, and obtaining a bending curvature, an arc angle and a
direction angle; and coordinate information in the space is further obtained by combining rotation and translation matrix iterative calculation of a
shape reconstruction algorithm, namely, three-dimensional space coordinates of the measured curve can be determined point by point, and finally, complete
shape reconstruction and other steps are realized. According to the invention, high-precision large-scale three-dimensional
deformation monitoring can be realized. By optimizing the eccentric distance and the strain transmission efficiency of the
optical fiber, the tiny deformation of the
submarine cable is accurately captured, and by combining an innovative three-dimensional
curve reconstruction algorithm, the bending, inclination and other deformation states of the cable can be accurately reflected in different environments. Therefore, the method has obvious advantages in a monitoring task with a high-precision requirement, especially in a complex marine environment.