Model-based control of an electro-pneumatic clutch using a sliding-mode approach

This paper presents a nonlinear model-based control design for an electro-pneumatic clutch 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 powertrain. The proposed cascaded control structure consists of a fast inner control loop for the internal pressure, which is estimated by a nonlinear reduced-order observer, as well as an outer control loop for the clutch position. The design of the feedback part for the clutch position is based on sliding-mode techniques. A Lyapunov-based approach is used for the inner control loop of the internal pressure, which is usually not measured in truck applications. Thereby, high tracking accuracy is achievable for the piston position as controlled variable. The efficiency of the proposed control structure is demonstrated by experimental results from a dedicated test rig.