In Memoriam: Karl Johan Åström

Karl Johan Åström (August 5, 1934 - November 11, 2026) was a true giant in the field of automatic control. Åström’s contributions to control were broad and deep, and included the conceptual foundations of what is now called POMDP theory and the notion of the belief-state, the combination of online parameter estimation and minimum variance design in what is commonly referred to as self-tuning regulation, relay autotuning of PID controllers, and the concept of event-based (Lebesgue) sampling that helped start the field of event-triggered control.

He was an IEEE Fellow, a member of the Royal Swedish Academy of Sciences, and a Vice President of the Royal Swedish Academy of Engineering Sciences. He was awarded the Rufus Oldenburger medal from ASME in 1985 and the Quazza Medal from IFAC in 1987. In 1990, he received the IEEE Field Award in Control Systems, and in 1993 he was awarded the IEEE Medal of Honor for his "fundamental contributions to theory and applications of adaptive control technology." He was elected as an International Member of the NAE in 1995.

Åström founded the automatic control department at Lund University in 1965 and thereafter advised and mentored many of the leading control researchers and industry practitioners we all know today. In addition to his outstanding professional achievements, Karl Johan was an extraordinary human being. He was endlessly and energetically curious, kind, and thoughtful; he was a gifted teacher and author, a dedicated mentor to generations of students, and a true friend to those he connected with over the years. His enthusiasm and warmth touched people all over the world, and his influence will continue for decades to come.

Carolyn Beck, CSS President