Karl Johan Åström

Karl Johan Astrom was born on 5 August 1934 in Ostersund, Sweden. He studied at the Royal Institute of Technology (KTH) in Stockholm, receiving an M.Sc. in engineering physics in 1957 and a PhD in automatic control and mathematics in 1960. From 1955 to 1960 he also taught at KTH while working on inertial guidance for the Swedish National Defence Research Institute.

In 1961 Astrom joined the IBM Nordic Laboratory to work on computerised process control, with periods at IBM Research in Yorktown Heights, New York, in 1962 and San Jose, California, in 1963. Back in Sweden he led efforts in the computer control of paper manufacturing machinery, early industrial work that grounded his later theory in practice.

In 1965 he was appointed professor at Lund University's Faculty of Engineering (LTH) and founded the Department of Automatic Control, which he chaired until 1999. The same year he described a general framework for Markov decision processes with incomplete information, which led to the notion of the partially observable Markov decision process. With Bjorn Wittenmark he published the influential 1973 paper on self tuning regulators, and his work on system identification, stochastic control and adaptive control was incorporated into engineering practice worldwide.

His textbooks included Introduction to Stochastic Control (1970), Adaptive Control (1989, with Wittenmark), Computer Controlled Systems (with Wittenmark, IFAC textbook prize 1993), Advanced PID Control (2005, with Tore Hagglund) and Feedback Systems (2008, with Richard Murray, IFAC textbook prize 2011). From 2002 he was a distinguished visiting professor at the University of California, Santa Barbara, and he remained professor emeritus at Lund.

Astrom was a Fellow of the IEEE, a member of the Royal Swedish Academy of Sciences, vice president of the Royal Swedish Academy of Engineering Sciences (IVA) and, from 1995, a foreign associate of the US National Academy of Engineering. He received the ASME Rufus Oldenburger Medal (1985), the IFAC Quazza Medal (1987), an honorary doctorate from the Institut National Polytechnique de Grenoble (1987), the IEEE Donald G. Fink Prize Paper Award (1989), the IEEE Control Systems Science and Engineering Award (1990) and the IEEE Medal of Honor (1993) for fundamental contributions to the theory and applications of adaptive control technology. In 2026 he was awarded Lund University's gold medal.

Karl Johan Astrom died in Lund on the morning of 12 November 2026, aged 92, his department announced. LTH flew its flags at half mast the following day. In its tribute the Department of Automatic Control wrote that he would be remembered worldwide for his groundbreaking contributions to control, and that beyond his professional achievements he was an exceptional human being, kind, generous and endlessly curious.

In Sweden Astrom is regarded as the father of modern control and the founder of one of the world's most respected control departments. His theory of adaptive control and self tuning regulators, his work on identification and PID control, and the many students he supervised, among them Lennart Ljung and Karl Henrik Johansson, carried his influence across academia and industry. His textbooks remain standard references for engineers and scientists around the world.