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An accurate and rapid engine speed control has been required to improve the shift quality of automated manual transmissions. However, conventional controls could not provide sufficient controllability. They caused the overshoot and steady-state error of engine speed from target values. Therefore, a two-degree-of-freedom sliding mode algorithm was newly designed and applied to the engine speed control. This algorithm can independently assign the disturbance suppression characteristic and tracking performance, and has excellent robustness against the changes in engine dynamics. As a result, the overshoot and steady-state error were prevented under all engine conditions.

The sliding mode algorithm is used for air fuel ratio control, device control, and other systems because of its high responsiveness and robustness. A special feature is that the disturbance suppression characteristic can be set as needed by changing the gradient of the switching line. However, there has been no research into applying this feature. Taking note of the fact that a servo system with a high compliance can be established by lowering the disturbance suppression characteristic, this algorithm was applied to gearing control in automated manual transmissions. During gear changes, automated manual transmissions require the positioning control of a shift rod, the contact control of a sleeve and synchronizer ring, and revolution synchronizing control of the main shaft and counter-shaft by pressing in the sleeve.

In recent years, electrification of powertrains has been promoted to improve fuel efficiency and CO2 emissions. Along with electrification, it is possible to reduce engine usage frequency and improve the fuel efficiency in traveling. Especially in a hybrid electric vehicle (HEV), the state changes from motor assist mode to engine firing mode. As a result, stay time in eigenvalue of a powertrain is shortened, and vibration of the vehicle body at the engine start situation is able to be reduced as compared with conventional engine-driven vehicle. However, since the HEV is equipped with a high compression ratio engine for improving fuel economy, there is cause for concern that excitation force generated by the powertrain at the time of engine start increases. Also, the vehicle body vibration at engine start situations requires further consideration, because the operation frequency of engine decreases.