For many years Adolf Leonhard developed the Chair for Electrical Systems Engineering, which was founded when he was appointed professor and later became a whole separate institute. His trademark was his very wide field of teaching and research, which not only covered electrical drive systems, but also electrical energy transmission, automatic control and systems engineering.
The main focus of his research was automatic control and systems engineering. In this field Leonhard became known throughout the world as one of the co-founders of classical control engineering, a discipline which is now indispensable for almost all areas of engineering science.