From Poncelet´s invariance principle to Active Disturbance Rejection

This is a brief survey of a little known field of disturbance estimation and subsequent cancellation, a field with a long history and is still rather disorganized. Researchers and results are scattered over almost two centuries, across East and West: from Jean-Victor Poncelet´s Principle of Invariance in 1829, to Jingqing Han´s conception of Active Disturbance Rejection in 1995 and beyond. But the field in recent years is maturing and coming into a focus with significant practical and theoretical implications abound. It provides a powerful alternative to the modern control paradigm in how real world control problems, of which disturbance rejection is a central theme, are viewed and solved. In this paper a reader will find a brief history of ideas, a new, unifying, problem formulation, and a summary of recent stability analysis results.