Inaugural Bode Lecture by Dr. Gunter Stein, CDC, 1989
Keywords: Stability, robustness, fundamental limitations, Bode integral, sensitivity, waterbed effect
Summary
In this classic entertaining lecture delivered by Dr. Gunter Stein, fundamental limitations arising in control pertaining to stability, performance, and robustness are addressed. In particular, the Bode integral is advocated as a fundamental “conservation law” of control, despite its relative obscurity at the time, which arguably persists to this day. Other highlights include demonstrations of the effect of unstable poles both on the ubiquitous simple inverted pendulum, as well as the then-state-of-the-art X-29 aircraft with forward-swept wings; these two systems are more similar than a passing glance would suggest! Dr. Stein’s prescient observations on the twin trends of ever more dangerous systems being controlled and increasing detachment of control theoreticians from these systems, whether due to over-emphasis on formal mathematics or due to automatic “optimal” control synthesis, are perhaps more sobering than ever today in light of recent developments in autonomous driving systems, power networks, and data-driven learning control.