Adaptive Control of Automotive Transmissions

Production clutch-to-clutch automatic transmissions contain a number of subcomponents difficult to characterize from a traditional modeling stance. Variation inherent to both manufacturing processes and anticipated wear increase the bounds over which a parameter may be expected to range. The most critical of these is observed to be the value associated with the coefficient of friction of the clutch surfaces. Formulated from Lyapunov stability requirements, three adaptive algorithms are proposed to compensate for these variations. The first, a direct adaptive approach, bases parameter behavior on a sliding control law. The second technique incorporates an indirect least squares estimator term into the direct law, forming a composite adaptive result. The third extends the composite principle from the inertia to the torque phases of the shift. It is shown that identification of the friction parameters will occur with eihter of the techniques, and that the rate of convergence and the stability of the parameter improves with the increasing complexity of the technique applied.