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Control of a Driveline with a Slipping Clutch Andreas Myklebust, Lars Eriksson, Lars Nielsen (Vehicular Systems, LiU) Karl Redbrandt, Henrik Flemmer (SCANIA CV) Integrated Powertrain Control The behavior of a vehicle is not only controlled by the engine. There are several actuators available in a vehicles driveline (automatic clutch, Automated Manual Transmission (AMT),. . . ) that can be used to affect the vehicle drivebility. By using these different actuators in an integrated manner with common control targets, performance and comfort benefits can be achieved. Scania acts as industrial partner in this project and supplies hardware and specific problem formulations. Control of a Driveline with a Slipping Clutch The use of an automatic actuator for the clutch gives new opportunities for controlling the engine and driveline. Several applications would ben- efit from advanced clutch control. For example start and stop strategies for heavy trucks can be employed and in addition clutch control can be utilized in AMTs to reduce the time for gear changes, which is a crucial parameter for preventing stall in heavy trucks during hill climbing. Fur- thermore it is possible to use clutch control to damp oscillations in the driveline, e.g. through micro slip. Oil Reservoir Electric Motor x m x x 0 k linkage x cor ICE Transmission Shaft Throwout Bearing Diaphragm Spring Piston Torsional Spring Push Plate Friction Pads Cushion Spring Flywheel Clutch Model Original data 4 5 6 7 8 9 10 11 12 0 500 1000 1500 Piston Pos. [mm] Clutch Torque [Nm] Time [s] 20 40 60 80 Temperature compensated 4 5 6 7 8 9 10 11 12 0 500 1000 1500 Double Exp. Corrected Pos. [mm] Clutch Torque [Nm] Time [s] 20 40 60 80 Left graph shows data of the torque drift when energy is dissipated into the clutch. Right graph shows the data after the position has been cor- rected for temperature effects using the clutch model developed in this project. The clutch model is a linear temperature model together with a linear thermal expansion. Observer 0 200 400 600 800 1000 1200 1400 1600 0 200 400 600 Clutch Torque [Nm] Modeled Measured Observed 150 200 250 300 300 400 500 600 0 200 400 600 800 1000 1200 1400 1600 37 38 39 40 41 Zero Position [mm] Time [s] Measured when meas. Estimated Model ˆ x 4 0 200 400 600 800 1000 1200 1400 1600 50 100 150 Time [s] Temperature [C] engine mod. body mod. hous. mod. disc obs. body obs. hous. obs. disc An Extended Kalman Filter has been built in order to handle unknown initial values and wear. The observer can start to converge before the clutch is being slipped by using the available measurement of x 0 , see figure to the left. Driveline Model M e 1 2 F dr 1 2 F dr Measurement from a Scania truck compared with open-loop simulation of the model. Driveline oscillations are modeled and capture both the amplitude and frequency of those seen in experimental data. Future Work The next step is to use the observer when developing a micro-slip con- troller. Micro slip is when the clutch is controlled to be slipping all the time, but with a very low slip in order to avoid over heating and unnec- essary wear of the clutch. Publications Myklebust, A. and Eriksson, L. (2012a). Road slope analysis and filtering for driveline shuffle simulation. In 2012 IFAC Workshop on Engine and Powertrain Control, Simulation and Modeling. Myklebust, A. and Eriksson, L. (2012b). Torque model with fast and slow temperature dynamics of a slipping dry clutch. In 2012 IEEE Vehicle Power and Propulsion Conference. Myklebust, A. and Eriksson, L. (2013a). The Effect of Thermal Expan- sion in a Dry Clutch on Launch Control. In 7th IFAC Symposium on Advances in Automotive Control. Myklebust, A. and Eriksson, L. (2013b). Modeling and Estimation for Dry Clutch Control. Licentiate Thesis. Myklebust, A. and Eriksson, L. (2013c). Modeling, observability and es- timation of thermal effects and aging on transmitted torque in a heavy duty truck with a dry clutch. Submitted to IEEE/ASME Transac- tions on Mechatronics. http://www.linksic.isy.liu.se/ LINK-SIC Link¨ oping Center for Sensor Informatics and Control — A Vinnova Industry Excellence Center
