To receive the Control Systems Award is a great honor and a great feeling, which really overwhelms me.
It is a natural occasion to reflect on one's past research, influences, and scientific development.
As I look back, I realize that I haven't traveled very far: I am still in the same office I moved into in 1976, when I got my chair in Linkoping. Most of the research that is mentioned in the citation, I have performed within a stone's throw from my phD thesis in 1974. I am also, by the way, married to my dear wife, Ann-Kristin, since almost 40 years. So the picture that emerges is that of a quite conservative, faithful and not so adventurous person. This makes it important to look back to the 70's which clearly must have been formative years. I finished my masters degree in 1970 and then started as a PhD student in Karl Johan Astrom's famous and energetic group.
This was clearly the most decisive step in my research carrier. I spent half a year in 1972 in Yakov Tsypkin's laboratory in Moscow as a pre-doc, and visited Tom Kailath as a post-doc at Stanford after my PhD in 1974.
This means that I in the course of a few years in the early seventies had three influential mentors: Astrom, Tsypkin and Kailath. While these three mentors had quite different research focuses they had one common denominator: They taught me to have a constructive attitude to mathematics. By all means, study mathematics, use mathematics, master mathematics, and even occasionally indulge in mathematics, but realize that our problem area is not mathematics in its nature. The Quotation by Joshua Chover that Tom Kailath used in the preface of his Linear Systems book captures this nicely: "The goal of mathematics is discovery, not proof." Clearly this first half of the 70's formed my scientific tastes under the influence of these three scientific giants.
In 1976 I moved to Linkoping to fill the Chair of Automatic Control. There was virtually no activities there, and I had to put a lot of effort in building up a group and form an educational program. This was very educational, for me at least.
You know, the driving forces in life are good luck and timing. I guess nothing illustrates that better for me than the telephone call I got from Jack Little, the president of Mathworks, in March 1986. He asked me if I would like to write a Matlab toolbox on system identification. I said no, I am not a good programmer, but he persuaded me. I guess that I have had ample opportunities to prove that my judgment was right, but I have also enjoyed the programming of this toolbox and the interaction with its users immensely. I believe writing the software is the ultimate "follow through" for a theoretician: If you write the software, you will find that people use your perspective and methods, without having to like them and without having to understand them.
Being a scientist means that you are part of a collective and cosmopolitan effort. Having friends in science around the world and seeing PhD student grow up and continue to grow I think is the real joy for a researcher. I have had about 140 different coauthors in my publications and my 56th PhD student graduated last week. Time does not permit to name them here and now, so let me take this opportunity to thank them all collectively for all the fun we have had together.
I have also had another set of coworkers who have made me understand that there is much more to life than proving theorems and writing software. They are my four grandchildren, my two sons, and above all my wife Ann-Kristin. She is really the one who deserves the credit for this award.
