There was a symposium at the University of Michigan on September 14, 2019 to the celebrate and honor the life of Professor Elmer Gilbert, an intellectual giant in the field of controls, who passed away on June 16, 2019:
https://aero.engin.umich.edu/a-symposium-honoring-the-life-of-elmer-g-gilbert/
Elmer was my mentor and dear friend for more than 30 years. He was an exceedingly kind, generous, thoughtful man and a deep thinker. I met him for the first time when he and his wife Dr. Lois Verbrugge, renowned social scientist, came to the University of Minnesota in 1985. He played a central role in my move to the University of Michigan in 1989. It was an honor to speak about his work on controllability, observability, and Gilbert realization at the symposium. It is particularly interesting that this ground-breaking work intersected with the pioneering work of my advisor late Professor R. E. Kalman! My slides are posted in the presentation section and can be downloaded from
https://faculty.sites.uci.edu/khargonekar/files/2019/09/Gilbert_MIchigan_PPK.pdf