Real-time panoramic-deformation measurement of cabin structure of launch vehicle based on camera network

Abstract

<p indent="0mm">To satisfy the requirement of real-time panoramic-deformation measurement of a cabin structure in a large-diameter launch vehicle, a camera-network deformation-measurement system composed of 24 cameras and real-time three-dimensional (3D) deformation-measurement software based on CPU parallel computing was developed. The 360° full-circle deformation measurement of the inner surface of a cylindrical coordinate system and real-time measurement of the local deformation of a local Cartesian coordinate system were successfully realized. The camera-network measurement system consisted of 12 sets of binocular systems. The field of view of a single set of binocular systems was 3.6 m×3.6 m, and a certain overlap area was set between two adjacent binocular systems to ensure continuity of measurements. Photogrammetry and binocular stereo vision were used to reconstruct the 3D coordinates of the coded points, and coordinate transformation between the local and global coordinate systems was realized using the coded points. Finally, coordinate unification of the 12 sets of binocular systems was performed. A single set of binocular systems could be connected to a computer. By implementing the seed-point-based parallel algorithm and initial guess-estimation-algorithm-based deformation-transfer scheme, real-time 3D displacement and surface-strain measurements at 70000 points per second were successfully realized. On the basis of the 360° full-circle deformation-measurement results in the cylindrical coordinate system, high-precision calculation of the diffusion angle was successfully realized. The standard deviation of the static noise in the three directions was less than 0.01 mm, and the standard deviation of the static noise in the strain was less than 50 microstrains.