Vehicle with Dual Clutch Transmission
This example shows a vehicle with a five-speed automatic dual-clutch transmission. The transmission controller converts the pedal deflection into a demanded torque. This demanded torque is then passed to the engine management. The pedal deflection and the vehicle speed are also used by the transmission controller to determine when the gear shifts should occur. Gear shifts are implemented via the two clutches, one clutch pressure being ramped up as the other clutch pressure is ramped down. Gear pre-selection via dog clutches ensures that the correct gear is fully selected before the on-going clutch is enabled.
You can set the transmission controller to work for up to 10 gears. The base workspace variable 'GrMax' sets the maximum gear of the transmission controller. The transmission controller in this example uses a maximum gear of 5.
This model can be configured for fixed-step simulation, making it suitable for hardware-in-the-loop testing.
Dual Clutch Transmission Subsystem
Two Disk Friction Clutch components from Simscape™ Driveline™ are connected in parallel, modeling the two clutches in a dual-clutch transmission. Only one of these clutches is engaged at a time. Engaging and disengaging these clutches is how gear changes are made.
Five Dog Clutch components from Simscape Driveline are connected between the follower shaft of each gear to the transmission output shaft. The controller preselects the next gear to which the transmission will shift by engaging the dog clutches. At any point, two of the dog clutches will be engaged, that for the current gear and that for the next gear to which the transmission will shift.
This subsystem implements a logic for auto transition of gear. The logic is implemented in Stateflow™, it has four parallel flows for gear up/down shift, velocity limit calculation for gear shifting, Next gear prediction based on limits and gear state to compute the current gear.
Tire models from Simscape Driveline that are characterized by the Magic Formula are connected to a longitudinal model of the vehicle dynamics. The driveshaft is connected to the rear wheels. The normal force for each axle is used in the slip calculation for each wheel.
Simulation Results from Simscape Logging
The plots below show the engine and vehicle speed as it accelerates through the first three gears in the dual-clutch transmission. The half-gear states indicate gear shifts are taking place by engaging and disengaging the dual clutches.