A full description of Robet can be found on Nancy Talbot's BLT Research website:
http://www.bltresearch.com/robbert.php

As far as is known Robbert van den Broeke, a young Dutchman who lives in the southern Netherlands' village of Hoeven, is singular in his ability to consistently and accurately predict the appearance of new crop formations in his general vicinity.   He has since early adolescence experienced "visions" which contain both the location and the design of the new crop circle accompanied by a clear sense that the new formation is either occurring at that precise moment or that it will occur soon. In the days just prior to these experiences he generally feels a build-up of physical and/or mental "angst" (nervousness and tension) which dissipates once the crop circle has actually formed.