Combining extremum seeking control and tracking control for high-performance CVT operation

The control design for the variator in a pushbelt continuously variable transmission (CVT) is investigated. The variator enables a stepless variation of the transmission ratio within a finite range. A conventional variator control design is typically obtained by the use of a variator model, which is highly uncertain and, therefore, limits the variator efficiency. In this paper, a variator control design is proposed, which simultaneously satisfies the variator control objectives: 1) tracking a transmission ratio reference, 2) optimizing the variator efficiency. Furthermore, the variator control design, which consists of a combination of extremum seeking control (ESC) and tracking control (TC), only uses measurements from sensors that are standard. Experiments illustrate that the variator control design achieves the variator control objectives and show that a conventional variator control design is outperformed.