Robust and Simplified Design of Slip Control System for Torque Converter Lock-Up Clutch

A torque converter lock-up clutch slip control system, which is designed to improve fuel economy, must be able to precisely regulate slip speed. Also the system must have a high level of robustness for coping with changes in the operating conditions and any deterioration in the automatic transmission fluid and the clutch. Moreover, to reduce the design time, the design process must be as simple as possible. In this paper, we first propose a loop shaping that aims to optimize complementary sensitivity function of the control system, while satisfying the abovementioned requirements of performance and robustness. Next, a method for simplifying the design process is proposed, that is, a model and a controller are expressed by interpolation. A controller set, which has a relationship of duality to the interpolation parameters of the model, is created in advance so that the construction of a new control system can be realized by identifying the characteristic parameters only. From application to the actual design process for a vehicle, we verified that the design time was reduced to less than 1/3 of that required for the conventional method. This new method has already been adopted for the design and fitting of new products.