Adaptive torque control of wet dual clutch based on dynamic friction coefficient estimation

Fluctuations in oil temperature, changes in friction plate temperature, and friction plate wear significantly influence the precision of torque control in wet clutches, consequently impacting vehicle launch and gear shift quality. In this study, we introduce a novel approach for estimating the dynamic friction coefficient of wet clutches and develop a feedforward torque controller tailored to dual-clutch transmissions. This controller adeptly compensates for the effects of oil temperature variations, friction plate temperature shifts, and wear. We also incorporated an observer for real-time estimation of clutch torque. The dynamic friction coefficient of the clutch is continuously estimated using models that account for the influence of oil temperature, friction plate temperature, and service mileage. Leveraging this estimated dynamic friction coefficient, the clutch torque is precisely controlled during slip engagement. Our co-simulation results affirm the accuracy of the controller presented in this paper. Even after changes in factors affecting friction coefficients, it consistently maintains control precision, surpassing non-adaptive controllers based on pressure-torque and pressure-speed difference-torque models. Bench testing further validates the controller's accuracy in torque control and its adaptability to fluctuations in oil temperature, friction plate temperature, and wear.