How disturbance observer changed my life

Disturbance Observer made its first appearance in 1983, when prof. Ohnishi presented a paper entitled "Torque- Speed Regulation of a DC Motor Based on Load torque Estimation Method". In 1990, during a stay at Keio University, I become aware of this innovative concept but, at that time, I had to convince my skeptical colleagues about the powerful disturbance rejection of the DOB, compared to standard, old-fashioned PID-based controllers. Since then, the idea of estimating and compensating unknown disturbances has been extended, refined, formally analyzed and deployed in a multitude of applications. This talk will be a narration of the numerous times in which the DOB (and its extensions) surprised me for its flexibility and effectiveness in dealing with different problems, ranging from the high precision motion control to the teleoperation and rehabilitation.