Performance Enhancement of Slip Control of a Lock-Up Clutch by Using Gain-Scheduled H_∞ Control Method

Abstract

It is well known that a good method for improving the fuel economy is to engage the lock-up clutch of a torque converter. In the lock-up clutch, it is necessary to control the slip speed from low vehicle speeds in order to improve the fuel-consumption performance. However, the plant parameters change with turbine speed, and the control of the slip speed is difficult. In this study, we apply the gain-scheduled H_∞ control method to the slip-speed-control system of the lock-up clutch. The implementation of gain-scheduled controllers is discussed in this paper. The effectiveness of the proposed method was verified by performing simulations and experiments in which the performance of the gain-scheduled controller was compared with that of a controller designed by using the µ-synthesis.