Post-assembly in-situ check of parabolic trough modules by VISshed

An innovative instrument for the post-assembly in-situ check of parabolic trough modules is here reported. The instrument, named VISshed, is thought for the shed, where the parabolic trough modules are assembled just before their installation in the plant. The instrument is simply composed by one or more cameras installed on a motorized slide and a fake receiver. These components have to be precisely placed over the module; in the paper several indications for the accomplishment of this task are given. The sequence of images captured during the camera(s) translation from one rim of the module to the opposite one are processed according to the VIS method, here described in detail. The most important outputs are contour-map and mean value (for each facet) of the intercept factor. Furthermore, the image processing gives precise information to operators about how to improve the canting, as well as, at the end of optimization, the final shape quality of each facet (panel) installed in the module. This final panel check, after assembly, is a great opportunity for the customer to reject those panels which result too much deviating from the ideal parabola.