Documentation

Vehicle with Manual Transmission

This example shows a vehicle that has a four-speed manual transmission. The key elements of the transmission are four synchronizers. By engaging or disengaging these synchronizers and associated dog clutches, the transmission provides four ratios 3.581, 2.022, 1.384, and 1, respectively. The synchronizers are modeled using the Cone Clutch and Dog Clutch blocks.

The model also provides an abstracted representation of the gearbox that is significantly less complex and thus simulates much faster. It uses simply a variable ratio gear to represent the various gear ratios in the detailed transmission, plus a clutch to represent neutral. By eliminating nearly all of the discontinuities, it is designed for hardware-in-the-loop simulation. To select this variant, use the hyperlinks in the model.

Model

Clutch Pedal Linkage Subsystem

Abstract Transmission Variant

This is the simplified version of the transmission. Using a variable ratio gear that accepts the gear ratio as an input signal, we remove nearly all of the discontinuities. When properly tuned, it can match the results of the detailed variant.

Detailed Transmission Variant

This is the detailed version of the transmission. It contains all the gears plus the dog clutches and cone clutches. This variant provides very accurate results and is perfect for tuning control algorithms and estimating fuel economy.

Synchronizer 1 Subsystem

This subsystem implements a customized model of a synchronizer. Here, the structure of the synchronizer can be seen and modified. Simscape Driveline also provides pre-built single and double-synchronizer blocks.

Vehicle Body Subsystem

This subsystem implements the longitudinal vehicle dynamics and the tire model. It is sufficient for running drive cycles to estimate fuel economy and to tune transmission control algorithms.

Simulation Results from Simscape Logging

The plots below show the driver inputs to the engine and transmission. The top plot shows the forces applied to the synchronizers to select the active gear, and the bottom plot shows the inputs to the throttle and clutch.

The plot below show the speeds of various shafts in the drivetrain. The output shaft speed is equal to the speed of the gear whose synchronizer is engaged. The engine stays in appropriate speed speed range even though the vehicle is accelerating because of the chosen gear.

The plot below show the behavior of the abstract models and the detailed model. The results are very similar, indicating that the abstract models can be used without a significant loss of accuracy.

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