Precise and stable centroid estimation is crucial for many tasks that require locating a light spot. We present an algorithm for fitting a deformed sigmoid function (two-dimensional sigmoid function) to the edge shape and profiled intensity of a light spot. The information of the spot (such as the center position, the size, and the tilt,) can be obtained by this fitting. The robustness of our proposal against noise, contrast, aspect ratio, and tilt is assessed compared with the adaptive circle–ellipse fitting and the centroid weighted Kalman filter algorithm, and the performance is validated experimentally. We show that our proposed algorithm provides better results than these algorithms, especially with regards to noise immunity. It is an effective and precise algorithm for estimating the centroid location of a light spot and can be used in a wide variety of optical sensing applications.
The curing of epoxy adhesives is a complex phenomenon where the thermal, the chemistry and the mechanics are
coupled. Corresponding material properties such as mechanical and physics properties are evolving with the curing. This
paper focuses on their predictions by a multiphisics FEM approach of the thermal, chemical and mechanical couplings
involved by the curing for a novel assembly of radio telescope panel. The first part presents the constitutive model of an
epoxy adhesive that is considered for the curing. The numerical solving, performed with a specific user subroutine of
Ansys, is detailed and allows the study of real three-dimensional structure parts. Residual stresses and strains of different
metallic membranes and internal adhesives in the interconnect during the assembly of radio telescope panel are
investigated. The mechanical response of the interconnect is analyzed with respect to the poisson’s ratio, relaxation time
and adhesive thickness. It is shown that, although the overall residual stresses at the interconnect increase with the
adhesive curing, the local strains have different evolving trends, indicating the possibility of damage and decohesion that
might compromise mechanical integrity and interrupt the component processing precision.