On the 50th Birthday of the Kalman Filter: Remembrances of a Great Teacher [Historical Perspectives]

Prof. Kalman played a determining role in my becoming a system theorist (in those times I did not address him yet as "Rudy!") In this tribute I want to concentrate on the way Rudy Kalman was able to engage, generate, and stimulate thinking in his students and how I experienced this in a meaningful way. My first contacts with him go back to 1968-1970, when he was still a professor at Stanford University, where I was a Ph.D. student, but he was in the process of moving to Gainesville, Florida. I had heard of state-space theory and its importance for circuit theory through my contacts with Vitold Belevitch and my thesis adviser Bob Newcomb, but when I came to Stanford to finish my Ph.D. I had the occasion to take a course in system theory taught by Rudy Kalman. "KFA" or the Kalman, Falb, and Arbib landmark text on system theory had just appeared and was evidently chosen as the textbook for the course. I remember how thrilled I was when I saw Rudy Kalman's commanding posture entering the classroom. Although I did not consider myself a control engineer I had heard of the Kalman filter and its tremendous impact on engineering, and I knew that it represented a decisive paradigm change, whereby control of a system would and could be done based on its algebraic properties rather than on pure input/output transfer functions. The change was not only in mathematical techniques but also and foremost in philosophy, namely, estimate the properties of a system first and then base control on its structural properties.