  We used the TAROT network of telescopes to search for the electromagnetic
counterparts of GW150914, GW170104 and GW170814, which were reported to
originate from binary black hole merger events by the LIGO and Virgo
collaborations. Our goal is to constrain the emission from a binary black hole
coalescence at visible wavelengths. We developed a simple and effective
algorithm to detect new sources by matching the image data with the Gaia
catalog data release 1. Machine learning was used and an algorithm was designed
to locate unknown sources in a large field of view image. The angular distance
between objects in the image and in the catalog was used to find new sources;
we then process the candidates to validate them as possible new unknown
celestial objects. Though several possible candidates were detected in the
three gravitational wave source error boxes studied, none of them were
confirmed as a viable counterpart. The algorithm was effective for the
identification of unknown candidates in a very large field and provided
candidates for GW150914, GW170104 and GW170814. The entire 90\% GW170814 error
box was surveyed extensively within 0.6 days after the GW emission resulting in
an absolute limiting R magnitude of -23.8. This strong limit excludes to a
great extent a possible emission of a gamma-ray burst with an optical
counterpart associated with GW170814.
