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Adaptive estimator for the friction characteristics of the clutch in automatic transmission

In this paper, based on a hydraulic automatic transmission, the friction characteristics estimation problem of clutch is studied, and an online estimated, adjustable adaptive estimator is proposed. At the beginning, four-speed gearshift simulation is set up in MATLAB/Simulink. By simplifying the simulation system, the power deriveline model fits for estimator design is obtained. Since the friction coefficient of clutch has the slow time-varying property, an adaptive estimator is designed, while the estimated value converges to the real friction characteristics of clutch step by step, with each shift process and online estimation, adjustment. At last, taking 1–2 upshift for example, the friction characteristics estimation in inertia phase is simulated, and the result indicates its validity.