Clutch fill control is critical for automotive transmission performance and fuel economy, including both automatic and hybrid transmissions. To ensure proper function of the transmission systems, it is important to have a precise and robust clutch fill process. Current clutch fill control is realized in an open loop fashion, due to the lack of a pressure or position sensor in the clutch chamber. To improve the accuracy and robustness of this system, a new clutch control mechanism is proposed, which includes an internal feedback structure without a pressure or position sensor. First, the design and working principles of the new mechanism are presented. Second, the advantages of the internal feedback mechanism are analyzed and shown to be superior to the traditional clutch fill mechanism. To this end, the dynamic model of the new mechanism is formulated. Through a series of simulations and case studies, the new clutch control mechanism is demonstrated to be effective, efficient, and robust for solving the clutch fill and engagement control problem. Copyright © 2009 by ASME.