Learn more about SimDriveline

How SimDriveline Software Works

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About Driveline Simulation State, Constraint, and Motion Actuation Identification Independent State Selection and Initialization Dependent State Selection and Initialization Torque Analysis and Dynamical Simulation Clutch Mode Iteration

About Driveline Simulation

This brief overview of how SimDriveline software works should help you to construct models and understand errors. Troubleshooting Simulation Errors, previously, discusses fixing errors.

The driveline simulation sequence has five major phases, described below. The first three occur before driveline motion actually starts and are explained more completely in Analyzing Degrees of Freedom and Trimming and Linearizing Driveline Models previously.

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State, Constraint, and Motion Actuation Identification

The overall degrees of freedom (DoFs) of the driveline result from its connected block diagram and the driveline connection lines that represent idealized driveshafts. A set of states represents the DoFs, both dependent and independent.

The full specification of the driveline requires identifying motion actuations and constraints that reduce the independent DoFs to a set smaller than the full set of DoFs. Once identified, motion actuations and static constraints (gears) remain for the entire simulation. Dynamic constraints (clutches) require additional steps before and during simulation because they can change. The first step with clutches is to identify those required to be locked at the start of simulation.

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Independent State Selection and Initialization

The premotion analysis of states begins with the selection of independent states, respecting the constraints and motion actuations identified in the first step and identifying the effective rotational inertia associated with each state. User-specified initial conditions are then applied to any relevant DoFs. An initial condition of zero (no motion) is applied to any independent state without user-specified initial conditions.

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Dependent State Selection and Initialization

Of the total set of states, the dependent states are those that remain after independent states are selected. The initial conditions of the dependent states then result completely from the constraints, motion actuations, and independent state initial conditions.

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Torque Analysis and Dynamical Simulation

Torques acting on the independent states are identified and applied. Simulation begins by integrating the rotational equations of motion on the independent states with these applied torques. The motions of the dependent states requires no separate torque analysis or dynamics, as they result by constraints from the independent states and any applied motion actuations.

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Clutch Mode Iteration

During simulation, the Controllable Friction Clutch blocks in your model are checked for lockings and unlockings with zero-crossing analysis. If a locked clutch meets the criteria for unlocking, or an unlocked clutch the criteria for locking, the respective clutch modes change. By default, this locking-unlocking analysis requires non-time-increment steps (algebraic loops).

If one or more clutch constraints change, the overall driveline states have to be repartitioned into new sets of dependent and independent states. This in turns requires a partial reinitialization of the driveline, one that preserves the driveline's state before the mode change except for that subset of constraints and states affected by the clutch mode transition.

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Trimming and Linearizing Driveline Models

Generating Code

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