2018-01-0866 Published 0 3 Apr 2018 © 2018 SAE International. All Rights Reserved.Coordinated Engine Torque and Clutch Control During Gear-Shifting Process of Automated Manual Transmission Pan Song, Rui Fang, and Jingang Dai CATARC Citation: Song, P., Fang, R., and Dai, J., “Coordinated Engine Torque and Clutch Control During Gear-Shifting Process of Automated Manual Transmission,” SAE Technical Paper 2018-01-0866, 2018, doi:10.4271/2018-01-0866. Abstract This paper presents a novel powertrain control system specifically designed for longitudinal motion-control applications of an automated-manual-transmission vehicle, whereby the clutch and throttle modulation and gear change are highly coordinated such that the vehicle can precisely track the target acceleration or deceleration command even during an upshift or a downshift. An observer-free method for estimation of the engine’s operating point under various working condition is developed to compensate for limited sensing and enable effective feed-forward control of the engine torque and the clutch pressure. With minor modifications of the coordination strategies in the existing powertrain control system, the proposed control system can prevent stalling the engine from a standing start and achieve smoother shifting and faster dynamic response of the powertrain system, where non-smooth actuator nonlinearities are addressed explicitly, robustly, and effi - ciently. As revealed through off-line simulation, the proposed control methodology brings an average decrease in the clutch-slipping duration of 35.73% with negligible loss of the motion-tracking performance, such that system reliability, driving comfort, and fuel economy of the vehicle can be guaranteed. Introduction For both manual and autonomous driving scenarios, the intelligent vehicles nowadays are capable of following the target acceleration commands either desired by the human driver or computed by an Electronic Control Unit (ECU), such as the Adaptive Cruise Control (ACC). ACC is believed to reduce the risk of accidents, improve safety, increase highway capacity, reduce fuel consumption, and enhance overall comfort and performance for drivers. IHS Automotive forecasts 7.2% of vehicles produced globally by 2020 will feature ACC, up from 2.2% in 2014 [ 1]. Based on the control schemes summarized in [ 2], the ACC system normally adopts a hierarchical architecture, which consists of two layers: a high-level supervisory controller and low-level actuator controllers. In more integrated systems, the ACC controller directly computes control actions for the low-level controllers [ 3]. However, this kind of centralized control approach distinctively increases system complexity and costs. With such a control configuration, coordination and collabo - ration of cross-domain ECUs would be much harder, causing the whole ACC system to exhibit undesirable behaviors in some hazardous situations, such as a gearshift. The design of the low-level controllers requires a good understanding of the longitudinal dynamics of the vehicle. In order to continuously maintain the target acceleration of the vehicle, the Engine Management System (EMS) controller should effectively control the Internal Combustion Engine (ICE) to exert the appropriate traction torque during different phases even in an automatic gear changing. The ICE’s oper - ating point moves rapidly due to decrease and increase of the engine speed when the transmission upshifts and downshifts, respectively. A wide gear spread with close gear ratios allows for mitigation and elimination of the unwanted effect, such as by using the multi-speed Automatic Transmission (AT) [ 4] and the Continuously Variable Transmission (CVT) [ 5]. However, mass-produced ATs with torque converters can hardly achieve a direct response to accelerator operation and gives the lowest efficiency (typically <80%). Whereas belt-driven CVTs have a limited amount of torque capacity and transmitting moti