State-dependent sliding mode observer for an electro-pneumatic clutch

Abstract

This paper presents a nonlinear observer design for a controlled electro-pneumatic clutch actuator for heavy trucks, which is required at start-up or during gear shifts to disconnect the combustion engine from the gear box. This automated actuator disburdens the driver and provides the necessary actuation force according to the large torque transmitted through the power train. The control structure consists of a flatness-based feedforward and an adaptive LQR feedback design based on extended linearisation techniques. Hysteresis effects of the nonlinear clutch force are considered in a Bouc-Wen hysteresis model. A state-dependent sliding mode observer is designed that estimates the effective internal pressure and a mass flow offset. The efficiency of the proposed control structure is demonstrated by experimental results from a dedicated test rig.