Robust Stabilization of Slip Control System for Torque Converter Lock-Up Clutch Using H-Infinity Control Theory (1st Report, Control System Design)

Abstract

H-infinity control theory is applied as a systematic design method in order to ensure robust stability against large variation in characteristics under vehicle operating conditions and variation in friction characteristics of the torque converter lock-up clutch induced by aging deterioration. In this theory the robust stability for the characteristics variation is guaranteed by small gain theorem. However, since the theorem cannot guarantee the system to achieve sufficient stability margin for all uncertainty in practical use, transient characteristics may be not good. In this paper, from a viewpoint that the transient characteristics in the perturbed conditions are specified by the cosensitivity function T(s), we improve the transient characteristics with a method of doing loopshaping for T(s) in order to be obtained in the adequate shape. The results of simulations show that the designed controller keeps sufficient stability compared with that of the PID controller.